If you liked this, please check out @SuperFastMatt's much more humorous version, and he shows how to connect it if you want to use it in another car: th-cam.com/video/SRZ8XDNz2vU/w-d-xo.html
Nice overview of the product, normally nobody takes care about :) I have been working with iBoosters at Bosch for 6 years as an product engineer. One remark - there is no torque sensing, boost force is given purerly based on the stroke sensor.
There most definitely is pedal pressure sensing, I clearly showed how this works. When you press on the pedal, you are compressing an additional spring, just as you would in a Vacuum Brake booster. The hall-effect sensor detects how far this moves, which is pedal pressure, not pedal travel.
@@kossaKSF In addition, if ESP3 (ABS) fails, there are still 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (if loss of HV), 3 & 4. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2. DI plug braking can happen without ANY power in the car.
Great description of the braking hardware. I’m guessing that when you discuss regen braking you will talk about the differences in how iBooster is integrated into regen braking on most hybrids and EVs but not on Tesla cars.
Yeah, Tesla does not use regen/brake blending. Now since Tesla has introduced "1 pedal" driving, it's definitely not needed. Anytime you press the brake pedal on a Tesla, it's just brakes. (Regen comes on when you release the "go" pedal)
I like how simple the iBooster setup is. I've had other EVs with electro hydraulic brake boosters (500e, ELR), one of which had adaptive cruise control. The iBooster's operation is smoother, there's no annoying pump sound, no buzzing pump feel through the pedal, and no constant brake fluid level changes drawing moisture into the master cylinder reservoir*. And the iBooster has better brake pedal feel IMO. It's basically power steering for the brake pedal! On some cars with ESP, there was a computer controlled valve on the vacuum booster that could cause the booster to apply the master cylinder. It was used to "precharge" the master cylinder during ESP intervention, and for emergency crash avoidance. It's not as smooth / metered as the iBooster. *On the Fiat and Cadillac, there was a 2nd ABS pump that would charge an accumulator, which was used to run a hydraulic brake booster. Whenever the car was turned off the pressure in this accumulator was bled off, and it would recharge every time the door was opened on the Fiat, or the ignition turned on with the Cadillac. This would change the fluid level several CM in the reservoir.
Wow, that circuit board is PACKED! Crazy how even the most seemingly simple things have a microcontroller inside. I wonder how reliable this solution is compared to the more "basic" version.
1:07 - Typical brake circuits are not one for front and one for rear. Instead they are combined in an X like fashion: one brake circuit for FR and RL. One brake circuit for FL and RR.
What is left for another video regarding the braking system: there is also an hydraulic control unit (with some hydraulic valves) in the path to the actual brake calipers, that takes care of brakeforce distribution to the individual wheels in each brake circuit including functions like anti-lock braking system, front/rear distribution, stability control, dynamic traction control and electronic locking differential.
This is super interesting and gives me peace of mind. For some reason I thought the braking was done by the ABS module and I was wonder if the solenoid that would have activated every times you come to a complete stop (one petal driving) would prematurely wear out. Now it looks like there's two systems (on top of even more safe guards) that can stop the car not just one. Thanks for the break down!
Yes, I didn't cover the ABS/ESP valve body, but maybe in a future video. Keep in mind there are still 5 ways to stop the car even if the iBooster fails and your foot doesn't work: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2. DI plug braking can happen without ANY power in the car.
@@Ingineerix I think the newer Teslas can also run the motors as steppers at low speeds, bringing the car to a stop. So I guess even if regen is all you have, the car would stop.
@@tomsixsix No, the new "1 pedal driving" uses the iBooster to apply the brakes, and the ESP3 valve body to hold it once stopped. Regan can only slow the car down to about walking speed.
@@Ingineerix So, how does this relate to “Stopping Mode” that Tesla introduced about a year ago? ISTR it uses the motor down to a very low speed to slow the car - though I concede that it could well use the brake door the final stop.
Thank you! 😃 If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
I know that you aren't trying to teach about brake systems here, but I will mention that it's not front and rear, but diagonal brake pairs on all the modern cars I know of. It's a safer form of redundancy so that even if one circuit fails you have one brake on each end of the car still functional. Having only front or only rear is an excellent way to lose control! Older cars often had only a single circuit, and race cars will often do front and rear to enable them to adjust the brake bias easily. Tesla might have done it differently, and you have an easy way to check, but I would be surprised if they aren't using diagonal pairs.
Yes, it's diagonal out of ESP3, but the 2 outputs on the master cylinder are called front and rear. If one circuit fails, ESP3 (ABS Valve body) can lock that circuit off and individually pressurize the remaining circuit. If ESP3 intervention fails there are still 4 other ways to stop the car: 1. Regen, 2. DI Plug braking (if loss of HV), 3 & 4. EPB (Electronic Parking Brake) The EPB has 2 independent channels, so it counts for 2.
A very clever solution to get rid of the vacuum brake booster. And it's brushless to, so should be maintenance-free for a long time. I really hate troubleshooting vacuum leaks on on a car, so this is a welcome addition.
@@MyProjectBoxChannel Could be a custom part number, that has to be translated to a normal part number. Often things are rebranded. The same with brakes and shit. It may say "Tesla 365726" on it but it is a Bosch or Brembo 764543 or similar.
this is actually 2nd generation of iBooster. Model S/X had first gen. The cool thing is they work well in limp mode (no CAN required), so widely used in EV conversions. I personally fitted 1st gen ibooster to my ICE DeLorean as a 40year old vacuum booster was not an option. Great video! Was that tank out of model 3?
I can see that the 3 motors phase are passing right thought the PCB to something else in the housing? Aluminum heatsink. It also seems that the motor phase are not soldered but press fit into something. Thanks
Yes press-fit pins, just like Tesla uses in pretty much all the ECUs now. Many automakers and suppliers now use this method as it's much more reliable and reduces assembly labor as well.
I love these videos you've been doing recently... I mean, I loved all the old videos too, but these are just really great... and you making more of them is great too.👍
Glad you like them! If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
I appreciate that! If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
So when auto hold is engaged at a light or whatever, it's the motor shown here that must constantly apply pressure or is there something else that locks the brake pressure? Let's say you're stationary for a while, surely it isn't good for the motor applying force without turning and probably heating up as well?
@@Ingineerix so the little click I hear when doing single pedal driving is the ABS valve activating? I don't hear it if I use the brake pedal (even light pressing) but I do every time with single pedal. Thanks.
@@Melds If you watch the pedal when you are coming to a stop in one-pedal mode, it will move slightly and there is a very subtle noise when regen tapers and it has to fade the brakes in. Then once the car is fully stopped, the ESP3 (ABS) valves close on all 4 wheels to lock the brakes on, then the iBooster "lets go" and the spring returns it to resting position. That return also makes a slight noise. 1 pedal mode is really well done! It doesn't surprise me it took so long to be released.
Yes, it has an ABS module that the brake lines route to from the master cylinder. That module has electronically actuated valves and electronics. The brake lines going to each of the 4 wheels go out from the ABS module.
great infos - many thanks! what me wounders is, there is only one motor and one fullbridge, from single fault safety side I'm not sure to achive with this level 4/5, may the breaking (in case of a fault) is combined with the abs system? does anyone have some infos about that?
Definitely. She is lying or mistaken. Even without the iBooster, there are still 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2. DI plug braking can happen without ANY electrical power in the car.
@@Ingineerix thanks for all the explanation. Question, so even if Ibooster fails one could just on the brake harder right? Similar to some race cars without a booster.
@@rudyyyxu Exactly, but you wouldn't have to, as one of the backups would kick in first. (ESP3 emergency hydraulic boost being the first, after regen of course)
Btw that crazy woman spent one week in jail for the false claims and brand damages. Few others Chineses who also spread fake accidents stories of fake defects were forced to present public apologies.
Interesting to see this iBooster, but I don't understand why it is required for autopilot. Combustion cars have had dynamic stability control for decades now. Those systems are able to apply the brakes individually to keep the car stable, and even execute an emergency stop (when the parking brake switch is hold for a couple of seconds). This is all build in the ABS system, since it already has a pump. Judging from this video, Tesla still needs an ABS system, so why would it require an iBooster for autopilot?
The ESP3 system (ABS) does not have the finesse to stop a car as smooth as a human. Yes, it can do emergency braking, but it's very rough, as the braking force can only be modulated by the PWM frequency of the solenoid valves. In addition, the system is noisy so presents a valid NVH concern even if it was smooth enough. AEB (Emergency Braking) is not the only function here, as Autopilot must operate in stop an go traffic, as well as Tesla's "one pedal" driving mode, where it's activated at every stop. I suspect the life of the valve body is also a concern, as it's probably not rated for this continuous operation.
I appreciate that, Eugene! If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
Hydrovac? I'm not sure that that is. I know GM used the "Hydroboost", and there were some other hydraulically based systems, but most used the standard Vacuum brake booster, and many cheap cars still do. (cost)
@@Ingineerix actually i already bought 2 generation ibooster for replacing hydro booster in my full size truck. But am still trying to see if ibooster is enough...
Awesome video! I'm wondering how the iBooster ECU positions the 3-phase motor? Does it use some encoder? I guess the hall effect sensors is used only to monitor if driver pressed the pedal?
There is a TDK hall-effect angle sensor on the PCB that gives the brushless motor inverter direct position feedback of the rotor. The other hall-effect sensor I show in the video detects not only that the driver is pressing the brake, but also how hard.
Tesla also is unconventional about Park. Is this involved with applying the service brakes in addition to the electric parking brake when Park gear is selected?
Question please: With my 2021 Model S Plaid, if I take my foot completely off the accelerator and thus regeneration braking takes effect, do the hydraulic electronic assist brakes ever activate other than Hold when the car stops? Thank you
Yes, Regen only is good down to about walking speed, then it uses the iBooster to apply the hydraulic brakes and the ABS system to hold them. On 3/Y you can disable this, but I don't think they give you the option in Plaid. (yet)
You stated that auto pilot can apply the hydraulic electric assist brakes. Does auto pilot then activate normal brakes during a Normal stop light stop, or does auto pilot predominately use regenerate braking?
@Motofan16 is correct. Tesla has now rolled out 1-pedal driving which automatically fades in the brakes using the iBooster when you release the "go" pedal. It works really well. For most driving you don't even need to touch the brake.
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Thanks! It's shown at the bottom of this page: th-cam.com/users/Ingineerixabout Here is the direct link: www.paypal.com/donate/?hosted_button_id=DT4S6DVGSBX3W
This is great stuff. I have watched all of you videos and they are all very educational. I think some of the Tesla models might not have iBooster but a less intelligent unit, and that's why some models don't have regen blending. I'm not so sure. Is this right?
Tesla does not use blending as e.g. VW. In their cars, the braking pedal only operates hydraulic. Old Teslas have conventional VB, but since 2016 all their cars have iBooster, at first iB gen 1 and now iB gen 2 from Bosch.
@@kossaKSF thanks a lot. I was likely wrong. They do have iBoostet, but not the ESP that provides the blending which is why they can not have the feature. And that's also why they default have high regen at lift off to recover more energy. Is this correct? I can't remember where I found this.
Prior to late 2014, they used a vacuum booster with an electric pump. Since then all have an iBooster. Tesla has NEVER done regen/brake blending on the brake pedal. Now starting on Model 3, they have one-pedal driving, but this is only for the "go" pedal, not the brake pedal.
Where does brake force arbitration occurr? Does the ibooster scale sensor travel to brake force and request it from the vehicle? I know they can run in stand alone mode, so it makes me think all of thebwork is done in the iBooster and it gets the available brake force from the car, requests what it can then fills in the rest.
The iBooster in boost mode doesn't care about brake force, only your pedal application force. However when AP or the DU is braking (one pedal) there is closed loop feedback. (AP or DU requests brake pedal pressure) Basically it brakes like you would, sensing the deceleration and modulating the pedal to achieve a smooth stop.
@@Ingineerix I see, that makes sense. But what about when the foot brake is applied? In my Honda Clarity which also runs an iBooster, when I apply the foot brake it brings in re-gen first then blends that with the foundation brakes to achieve the desired deceleration. It's pretty good at blending the two as well. So does I booster do that calculation and tell the drive unit how much retarder torque is required or does the vehicle read pedal throw and then tell the iBooster how much brake force to apply when the Drive unit can't supply the required retarder torque?
@@brandondelgado4153 Tesla doesn't do blended braking. If your foot is off the go pedal, the car is doing all the regen it can. If you press the brake pedal, it's all friction brakes.
@@brandondelgado4153 Tesla doesn't believe in blending on the brake pedal. Now they have one-pedal mode on the "go" pedal though, and that does blend regen into hydraulic when you let off the "go" pedal. It brings the car to a smooth stop without ever needing to touch the brake. The ESP3 (ABS) valve body then implements full 4-wheel brake hold until you touch the pedal again.
Is it mechanically possible for the FSD Beta hardware to overpower a driver, or is there some limits on the torque it can apply to the steering wheel? In light of the recent NHTSA complaint that FSD Beta overpowered the driver and caused a wreck, maybe you could do a video on the steering system and show whether the driver can mechanically override or overpower the FSD steering system. I am sure there are multiple electronic safeguards, but assuming that the motor was shorted to 12v full power trying to turn the wheel to the left, can you turn it to the right? A physical demonstration of it would be nice!
@@Ingineerix are you talking about the steering system or the brake booster? I may not have made my question clear that I was asking a different question about the steering system, and I can't tell which you are referring to lol
@@ke6gwf I believe there is a torque sensor on the steering wheel shaft (same sensor that detects your hand on the wheel) that will instantly disengage autosteer at a threshold, and the power steering motor goes back to assisting you, rather than steering the car. Now if the torque sensor failed I believe you would not be able to overcome the power steering motor, it's probably quite powerful. However you would hope the testers of FSD would familiarize themselves with how to disengage in an emergency and not just YOLO into traffic as soon as they got the update!
@@ke6gwf Yes, sorry EPAS is the Electric Power Assisted Steering. It's double redundant, with 2 torque sensors, 2 processors, and even 2 independent power feeds. They cross-check each other continuously. It's super highly unlikely that it could overpower the driver. As soon as the torque sensor detects driver intervention, it stops all externally commanded force. I'll do a video on this system soon!
@@Ingineerix I guess I need to learn the acronyms better lol Ok, double redundancy is pretty good, especially if it's hard coded in the controller rather than just software in the FSD computer. I was basically wondering how possible it would be for the claim to be true, that they were unable to steer because it took over. But with double everything looking for torque input, it sounds like a low probability of it being a car problem. Though I wonder if the power steering assist system momentarily failed, and what they reported as the FSD taking over was actually lack of power steering combined with scrub forces on the curve, and they just weren't pulling hard enough. Anyway, it will be interesting what the investigation finds, and I look forward to your expert overview of the system, so all the interested parties can understand the system better.
You would be surprised of the amount of non Tesla components there is in a car. The same goes for all brands, Volvo, Honda, Citroën, Mercedes, BMW, ... Mostly the same shit under the shell.
I just got a gen 2 honda one. Its a bit different with the pinout. I tried getting it to turn on but it wont even take any current. I wonder if the circuit board is fried. Do you know if the system should make any mechanical sound when the ignition is switched on? Thanks for reading.
I can't comment on the Honda version, but all the ones I've played with work in a fail-safe mode with just the 4 input sensor wires, ground, +12v, and ignition (drive) inputs. (Total of 7 wires needed on the large connector)
With iBooster style systems specifically for ABS, does that meant it cam be calibrated to actually be smooth? In cars I’ve driven ABS has been jerky (high frequency pulsation ) or really loud sounding like grinding. In the same way Motorsport level TCS and ABS work offer superior performance and not just superior safety, it seems normal cars can do better here
ABS always make this pulsation in order to release pressure from a wheel that is over braking. iBooster does not change this behavior. New ESP generation is however much quieter, but noise is still noticeable.
Not sure on ABS intervention, but I can tell you for normal driving the iBooter has a much smoother pedal feel than electro hydraulic system like other EVs used. The iBooster's feel is really quite good IMO!
I'd say the pedal feel in boost mode is superior to that of a vacuum boosted system, and when autopilot or one-pedal is braking it's every bit as smooth as a human.
@@Ingineerix Ya it really is quite good! I'd be interested to drive a blended regen car with an iBooster, the "older generation" cars could be quite non-smooth in the transition from regen to friction brakes. And if you were moderately braking, and hit a pothole or ice there would be a moment of NO deceleration as the system switched from reegen to all friction brakes. Not good.
They are split into 4 separate channels by ESP3. The only thing I discussed in the video was the outputs from the mastery cylinder, which are only 2 channels: front and rear.
10:22 i wonder what is the reliability of the circuits such as this in a Tesla. I mean, resistors or capacitors could go wrong or short. edit: ah there is a redundant circuit! 👍
Not just one redundancy, 5 other ways! 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2.
i wonder how autopilot deals with emergency brake situations. does it just activate the pedal (the motor takes time) or just send signals to the abs box as its faster or both and sees what is faster.
The iBooster is way faster than the hydraulic pump in the ESP3 (ABS) valve body. ESP3 is set up for high pressure, but has relatively low displacement, so cannot move a large amount of fluid in a short time. I assure you it would be quite obvious if ESP3 activated, as it's noisy.
ibooster can build up very high amount of brake force in short amount of time. on my car i can lock up the brakes with ibooster actuating in autonomous mode. although car is only 750kg...
Deceleration sensor (3 axis gyro) in the car detects slowing. When it goes above a threshold level, the brake lights are activated. Also there is a conventional switch on the brake pedal lever arm.
pretty sure this is the kind of motor which spins freely if there is no power applied to it, so it does spin backwards by the spring tension when not powered
what if the motor fails while on autopilot, and how fast can it engage the brake with just the motor alone? Edit: also those gears look plastic, couldn't they snap quite easily?
The motor can't fail on, it's a 3-phase motor that requires AC to run. It can apply the brakes faster than you can. No the nylon gears are more than adequate for the forces and reliability needed.
No, as I show there is a one-way slider clutch that lets either your foot or the motor apply force. The motor cannot push the pedal back, and when it's applying it, all you see is slightly less return force on the pedal. (You can see it move slightly, but it doesn't have any force)
@@Ingineerix ah ok i get it, the piston connected to the pedal is only connected to the white plastic thing which rides inside the gear and not directly to the metal thing pressing onto the master cylinder.. Makes sense, as otherwise the pedal would move if the ECU is braking :D
@@Spacefish007 Pedal moves when ECU is braking. As I wrote above, there is a detection system implemented to prevent your foot from being crushed by the pedal. In normal braking motor is always engaged and this sliding feature is not necessary. It is only in emergency when it is needed as a backup mode to allow you to brake w/o support.
First gen Prius used 12v hydraulic oil pump to generate pressure when needed. An accumulator stored hydraulic pressure. 1st gen Honda Insight used a vaccum booster like the one described with a switch to start the gas engine when the vaccum got to low.
Very interesting, thanks for sharing! -- Just looking at the video and unable to measure the forces myself, but suppose you have a software bug aren't there two fail scenarios: 1) Motor stops pushing entirely, you're working against the spring and the master cylinder to brake the car manually... Or is the force of the foot enough to overcome both? 2) Motor wrongly goes in reverse do to a software issue... Does this impede you breaking? Probably it means you're just not assisted at all though.
It has that spline that gives you the ability to manually apply the brakes regardless of what the booster is trying to do. Worst failure mode would be fully applying the brakes by mistake, but the ABS may be able to mitigate that. If you have ever tried using the brakes on coasting cat you would know exactly what it would feel like if this stopped working. Instead of using your big toe to stop the car, you have to push pretty hard, but it's possible.
@@ke6gwf The point is that in contrast with traditional manual breaking if your vacuum fails, here you are *also* fighting against that big spring. Doesn't that make it even worse??
@@purpleidea the vacuum boosters also have a big spring in them, that's what returns the brake pedal after use. In addition, the brake pedal has a LOT of mechanical advantage from leverage, so if you have, say, just replaced your master cylinder and you step on the brake pedal to start bleeding it, before it has fluid in it, you feel almost no resistance on the pedal, but it always comes back up.. That's that big spring, and it's probably about the same strength as in a vacuum booster system. And compared to the force it takes to apply hydraulic pressure to the brakes, the spring might as well not be there from what you can feel.
Yes, it would be full manual control. The motor cannot fight your foot. Keep in mind there are 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2.
Vacuum boosters have a similar spring. The spring force is nothing compared to the hydraulic force needed. Keep in mind there are still 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2.
This is all super helpful. I just got my Tesla Plaid delivered a week ago and I LOVE the damn thing! My only criticism is the manual breaks. They suck big time! For a 1020HP car with 0.99 0-60M/H quickness, those breaks are unacceptable! Why didn't Tesla put better breaks into the Plaid??
That will be when they have Direct Drive motors, one for each wheel. That will make all the braking system redundant. At the moment, DD doesn't work at low car speeds.
Super interesting and surprised of how much technology is involved. Every Tesla has all the hardware even if you do not pay for Autopilot. Volkswagen on the other hand has an endless number of models. For example the Transporter T3 has e-gas. If one does not pay for cruise control at purchase, not only is the physical button array missing, they have written the software in a way that the fitting of the cruise involves extra huge costs to re-flash the whole motor control system. They did that to stop 3rd party cruise control makers to have huge extra costs. A reason never to buy a Volkswagen.
I think Tesla would never build iBooster if Bosch don't overprice it, or they don't go different solution. Because this human part is less and less important, so why put parts for this? Put per wheel system and control it by computer, airbags are done this way, so safety part is same.
Computer applied braking is done through the ABS system. ABS is computer controlled in the first place. It has a pump to supply pressure and 8 or more control valves. All you have to do is provide a command to apply the brakes. The motor starts, the valves are closed and the brakes are engaged. No additional hardware is required. It is not done through the brake booster unless the brake pedal moves when the computer brakes are applied. The ABS system is VERY fast, responds within milliseconds. That pump motor has a lot of power. P.S. ABS is required on all new cars.
It is not working like this. In normal conditions, ABS stays always open and brake pressure is built up by a booster. iBooster can obviously also do it via external request, you do not have to push the brake pedal.
Incorrect. The ESP3 (ABS) Valve body doesn't have the finesse to be used in this way, plus the PWM of the valves is noisy and creates a lot of NVH issues, in addition to poor pedal feel. It is used as a backup should the iBooster fail though.
this same part is found in many new vw/audi hybrid and electric cars, and also some honda. many oems use the ibooster. Just with different pin config and software but hardware is mostly the same (except mounting points and master cylinder)
If you liked this, please check out @SuperFastMatt's much more humorous version, and he shows how to connect it if you want to use it in another car: th-cam.com/video/SRZ8XDNz2vU/w-d-xo.html
Nice overview of the product, normally nobody takes care about :) I have been working with iBoosters at Bosch for 6 years as an product engineer. One remark - there is no torque sensing, boost force is given purerly based on the stroke sensor.
Do the abs pump comunicate with the iBooster over canbus?
Brilliant device! Such clever design.
@@flo_neke Yes, it does. When iB diagnostic detects a failure in the system, ABS gives the necessary boost.
There most definitely is pedal pressure sensing, I clearly showed how this works. When you press on the pedal, you are compressing an additional spring, just as you would in a Vacuum Brake booster. The hall-effect sensor detects how far this moves, which is pedal pressure, not pedal travel.
@@kossaKSF In addition, if ESP3 (ABS) fails, there are still 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (if loss of HV), 3 & 4. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2. DI plug braking can happen without ANY power in the car.
Great description of the braking hardware. I’m guessing that when you discuss regen braking you will talk about the differences in how iBooster is integrated into regen braking on most hybrids and EVs but not on Tesla cars.
Yeah, Tesla does not use regen/brake blending. Now since Tesla has introduced "1 pedal" driving, it's definitely not needed. Anytime you press the brake pedal on a Tesla, it's just brakes. (Regen comes on when you release the "go" pedal)
i must say i absolutely love your videos and explanation!
I like how simple the iBooster setup is. I've had other EVs with electro hydraulic brake boosters (500e, ELR), one of which had adaptive cruise control. The iBooster's operation is smoother, there's no annoying pump sound, no buzzing pump feel through the pedal, and no constant brake fluid level changes drawing moisture into the master cylinder reservoir*. And the iBooster has better brake pedal feel IMO.
It's basically power steering for the brake pedal!
On some cars with ESP, there was a computer controlled valve on the vacuum booster that could cause the booster to apply the master cylinder. It was used to "precharge" the master cylinder during ESP intervention, and for emergency crash avoidance. It's not as smooth / metered as the iBooster.
*On the Fiat and Cadillac, there was a 2nd ABS pump that would charge an accumulator, which was used to run a hydraulic brake booster. Whenever the car was turned off the pressure in this accumulator was bled off, and it would recharge every time the door was opened on the Fiat, or the ignition turned on with the Cadillac. This would change the fluid level several CM in the reservoir.
Wow, that circuit board is PACKED! Crazy how even the most seemingly simple things have a microcontroller inside. I wonder how reliable this solution is compared to the more "basic" version.
I haven't seen a single failure of the iBooster. I'd say it's more reliable than a Vacuum boost system.
A lot of components IMHO for a pretty simple function (BDLC driver, 2 Hall-Effectsensors, CAN-Communication)
@@Spacefish007 Because this is considered safety critical, it's definitely overbuilt and has some amount of redundancy.
1:07 - Typical brake circuits are not one for front and one for rear. Instead they are combined in an X like fashion: one brake circuit for FR and RL. One brake circuit for FL and RR.
Yes, that is correct.
What is left for another video regarding the braking system: there is also an hydraulic control unit (with some hydraulic valves) in the path to the actual brake calipers, that takes care of brakeforce distribution to the individual wheels in each brake circuit including functions like anti-lock braking system, front/rear distribution, stability control, dynamic traction control and electronic locking differential.
I doubt I'll ever own a Tesla but I find this stuff so fascinating.
Great explanation. I didn’t understand vacuum or electric boosters before, very cool.
You'll be the first TH-camr I'll support with FIAT once I'll get my hands on enough of it. Can't do it yet sorry :(
so this is what makes all the music I hear in all these podcasts :D
This is super interesting and gives me peace of mind. For some reason I thought the braking was done by the ABS module and I was wonder if the solenoid that would have activated every times you come to a complete stop (one petal driving) would prematurely wear out. Now it looks like there's two systems (on top of even more safe guards) that can stop the car not just one. Thanks for the break down!
Yes, I didn't cover the ABS/ESP valve body, but maybe in a future video. Keep in mind there are still 5 ways to stop the car even if the iBooster fails and your foot doesn't work: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2. DI plug braking can happen without ANY power in the car.
@@Ingineerix I think the newer Teslas can also run the motors as steppers at low speeds, bringing the car to a stop. So I guess even if regen is all you have, the car would stop.
@@tomsixsix No, the new "1 pedal driving" uses the iBooster to apply the brakes, and the ESP3 valve body to hold it once stopped. Regan can only slow the car down to about walking speed.
@@Ingineerix So, how does this relate to “Stopping Mode” that Tesla introduced about a year ago? ISTR it uses the motor down to a very low speed to slow the car - though I concede that it could well use the brake door the final stop.
What is DI Plug braking?
I love your way of explaining!
Thank you! 😃 If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
I know that you aren't trying to teach about brake systems here, but I will mention that it's not front and rear, but diagonal brake pairs on all the modern cars I know of. It's a safer form of redundancy so that even if one circuit fails you have one brake on each end of the car still functional.
Having only front or only rear is an excellent way to lose control!
Older cars often had only a single circuit, and race cars will often do front and rear to enable them to adjust the brake bias easily.
Tesla might have done it differently, and you have an easy way to check, but I would be surprised if they aren't using diagonal pairs.
In many countries, the law dictates how the brake system must be constructed.
Yes, it's diagonal out of ESP3, but the 2 outputs on the master cylinder are called front and rear. If one circuit fails, ESP3 (ABS Valve body) can lock that circuit off and individually pressurize the remaining circuit. If ESP3 intervention fails there are still 4 other ways to stop the car: 1. Regen, 2. DI Plug braking (if loss of HV), 3 & 4. EPB (Electronic Parking Brake) The EPB has 2 independent channels, so it counts for 2.
Amazing explanation. Thanks so much!
A very clever solution to get rid of the vacuum brake booster. And it's brushless to, so should be maintenance-free for a long time. I really hate troubleshooting vacuum leaks on on a car, so this is a welcome addition.
Trouble free for the rest of the warranty and then.......
@@Xanthopteryx if it has a Bosch part number maybe it's possible to source the part
@@MyProjectBoxChannel Could be a custom part number, that has to be translated to a normal part number.
Often things are rebranded. The same with brakes and shit. It may say "Tesla 365726" on it but it is a Bosch or Brembo 764543 or similar.
Yes, I've been working on Teslas since they introduced the iBooster. I have never seen one fail unless the car was in a flood and it gets submerged.
We are now going to change hydralic braking to electriv thanks o you!! Great Video!! Thanks for uploading. Keep up the wonderful teardowns you do!!
Great channel for engineers
Bosch is a very good company. Good product as usual.
Great video. What an awesome piece of engineering
thanks for explanation
this is actually 2nd generation of iBooster. Model S/X had first gen. The cool thing is they work well in limp mode (no CAN required), so widely used in EV conversions. I personally fitted 1st gen ibooster to my ICE DeLorean as a 40year old vacuum booster was not an option. Great video! Was that tank out of model 3?
Hi, Can you show the boards without moving? ie not in you hands, but sturdy on a table. I'd like to read the text on the components. Thanks.
Email me (my email is available in the "about" tab of my channel's info page) and I'll send you pictures.
@@Ingineerix Many thanks. I appreciate that very much.
Thank you! Love the vid
Thanks
I can see that the 3 motors phase are passing right thought the PCB to something else in the housing? Aluminum heatsink. It also seems that the motor phase are not soldered but press fit into something. Thanks
Yes press-fit pins, just like Tesla uses in pretty much all the ECUs now. Many automakers and suppliers now use this method as it's much more reliable and reduces assembly labor as well.
I love these videos you've been doing recently... I mean, I loved all the old videos too, but these are just really great... and you making more of them is great too.👍
Glad you like them! If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
Really cool
Excellent work as usual
I appreciate that! If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
New knowledge! Thanks!!!
Wow! Learned a lot here. Thank you!
So when auto hold is engaged at a light or whatever, it's the motor shown here that must constantly apply pressure or is there something else that locks the brake pressure? Let's say you're stationary for a while, surely it isn't good for the motor applying force without turning and probably heating up as well?
The ESP/ABS valve body does the hold. The iBooster only applies the brakes for one-pedal at the end. You can even see it if you watch the brake pedal.
@@Ingineerix Thanks! I was pretty sure there was probably something else doing the hold but nice to know exactly
@@Ingineerix so the little click I hear when doing single pedal driving is the ABS valve activating? I don't hear it if I use the brake pedal (even light pressing) but I do every time with single pedal. Thanks.
@@Melds If you watch the pedal when you are coming to a stop in one-pedal mode, it will move slightly and there is a very subtle noise when regen tapers and it has to fade the brakes in. Then once the car is fully stopped, the ESP3 (ABS) valves close on all 4 wheels to lock the brakes on, then the iBooster "lets go" and the spring returns it to resting position. That return also makes a slight noise. 1 pedal mode is really well done! It doesn't surprise me it took so long to be released.
@@Ingineerix Interesting! Thank you very much for explaining it.
Does the car still have a conventional ABS/ traction control system, distributing force to each wheel as needed?
Yes, it has an ABS module that the brake lines route to from the master cylinder. That module has electronically actuated valves and electronics. The brake lines going to each of the 4 wheels go out from the ABS module.
Yes, that will be a future teardown.
@@Ingineerix thanks! I appreciate your work!
great infos - many thanks! what me wounders is, there is only one motor and one fullbridge, from single fault safety side I'm not sure to achive with this level 4/5, may the breaking (in case of a fault) is combined with the abs system? does anyone have some infos about that?
oh - just read someone had the same question below - thank for the answer to @Ingineerix
the crazy woman standing on top of tesla staging braking faliure should watch this
Definitely. She is lying or mistaken. Even without the iBooster, there are still 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2. DI plug braking can happen without ANY electrical power in the car.
@@Ingineerix thanks for all the explanation. Question, so even if Ibooster fails one could just on the brake harder right? Similar to some race cars without a booster.
@@rudyyyxu Exactly, but you wouldn't have to, as one of the backups would kick in first. (ESP3 emergency hydraulic boost being the first, after regen of course)
@@Ingineerix oh wow, so Tesla have more redundancy (passive and active) in its breaking system than probably 99.9% of ICE cars.
Btw that crazy woman spent one week in jail for the false claims and brand damages.
Few others Chineses who also spread fake accidents stories of fake defects were forced to present public apologies.
If you already know how brakes work, skip to 5:00
Very useful video again, thanks #Ingineerix. I was thinking how other ICE cars with AEB do brake automatically?
Most all vehicles with AEB or even Radar cruise control now use either this exact same device, or something similar from another supplier.
Mesmerizing stuff...
What is the supply voltage? Max current?
Diesel engines also don't give you a source of vacuum, either, or at least not a very good one. How do things like power brakes get done in that case?
Very interesting Thanks
Interesting to see this iBooster, but I don't understand why it is required for autopilot. Combustion cars have had dynamic stability control for decades now. Those systems are able to apply the brakes individually to keep the car stable, and even execute an emergency stop (when the parking brake switch is hold for a couple of seconds). This is all build in the ABS system, since it already has a pump. Judging from this video, Tesla still needs an ABS system, so why would it require an iBooster for autopilot?
The ESP3 system (ABS) does not have the finesse to stop a car as smooth as a human. Yes, it can do emergency braking, but it's very rough, as the braking force can only be modulated by the PWM frequency of the solenoid valves. In addition, the system is noisy so presents a valid NVH concern even if it was smooth enough. AEB (Emergency Braking) is not the only function here, as Autopilot must operate in stop an go traffic, as well as Tesla's "one pedal" driving mode, where it's activated at every stop. I suspect the life of the valve body is also a concern, as it's probably not rated for this continuous operation.
@@Ingineerix Thanks, that makes sense!
Thank you for the priceless knowledge
I appreciate that, Eugene! If you are feeling generous, you can also support my channel! There is a link at the bottom of my channel's "about" page: th-cam.com/users/Ingineerixabout
@@Ingineerix lmk if you want me to try and make a thumbnail for a video
Thank you. Great video. How does 'old school' cruise control slow/stop? only using "engine brake"? using the vacuum pump?
The abs is commanded to generate break pressure from the assistance systems, at least that's how VW did it in their cars
Yeah, Old school cruise only operated the throttle.
And old school cruise control would run into stopped emergency vehicles, too. I wonder if NHTSA knows that....
Unrelated: how hard would it be for Tesla to implement variable steering ratio into their current system?
Impossible lol
Takes an entirely different steering system design, so a new system by definition.
Ben is correct, it would need a totally different steer-by-wire system. Infiniti has done one, so it's doable.
What do you think of ibooster vs. traditional hydrovac? I think ibooster is much smaller so that it can make a smaller power than traditional one does
Hydrovac? I'm not sure that that is. I know GM used the "Hydroboost", and there were some other hydraulically based systems, but most used the standard Vacuum brake booster, and many cheap cars still do. (cost)
@@Ingineerix actually i already bought 2 generation ibooster for replacing hydro booster in my full size truck. But am still trying to see if ibooster is enough...
Awesome video! I'm wondering how the iBooster ECU positions the 3-phase motor? Does it use some encoder? I guess the hall effect sensors is used only to monitor if driver pressed the pedal?
There is a TDK hall-effect angle sensor on the PCB that gives the brushless motor inverter direct position feedback of the rotor. The other hall-effect sensor I show in the video detects not only that the driver is pressing the brake, but also how hard.
@@Ingineerix Great, thanks!
Tesla also is unconventional about Park. Is this involved with applying the service brakes in addition to the electric parking brake when Park gear is selected?
No, the EPB (Electric Parking Brake) is used for park, and it's double redundant. The drive unit can also plug brake in an emergency too.
new to breaking systems, so this is much appreciated... i know what a master cylinder is now!
Question please: With my 2021 Model S Plaid, if I take my foot completely off the accelerator and thus regeneration braking takes effect, do the hydraulic electronic assist brakes ever activate other than Hold when the car stops? Thank you
No, only if you press the brake pedal or if the Automatic Emergency Braking activates to keep from crashing into something.
Yes, Regen only is good down to about walking speed, then it uses the iBooster to apply the hydraulic brakes and the ABS system to hold them. On 3/Y you can disable this, but I don't think they give you the option in Plaid. (yet)
You stated that auto pilot can apply the hydraulic electric assist brakes. Does auto pilot then activate normal brakes during a Normal stop light stop, or does auto pilot predominately use regenerate braking?
Same as what a human driver does: release accelerator, if car does not slow down enough, add hydraulic pressure.
@Motofan16 is correct. Tesla has now rolled out 1-pedal driving which automatically fades in the brakes using the iBooster when you release the "go" pedal. It works really well. For most driving you don't even need to touch the brake.
Why not simply using the already existing ESC module to apply preasure to the breaks?
Because it's not very smooth or controllable. This is used as a failsafe though should the iBooster fail.
Does Tesla have antilock brakes and does it also employ ACTIVE HANDLING Technology?
Yes, of course. I don't think cars are made without ABS anymore. By "Active Handling" I assume you mean stability control? If so, Yes.
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Thanks! It's shown at the bottom of this page: th-cam.com/users/Ingineerixabout Here is the direct link: www.paypal.com/donate/?hosted_button_id=DT4S6DVGSBX3W
This is great stuff. I have watched all of you videos and they are all very educational. I think some of the Tesla models might not have iBooster but a less intelligent unit, and that's why some models don't have regen blending. I'm not so sure. Is this right?
Tesla does not use blending as e.g. VW. In their cars, the braking pedal only operates hydraulic. Old Teslas have conventional VB, but since 2016 all their cars have iBooster, at first iB gen 1 and now iB gen 2 from Bosch.
@@kossaKSF thanks a lot. I was likely wrong. They do have iBoostet, but not the ESP that provides the blending which is why they can not have the feature. And that's also why they default have high regen at lift off to recover more energy. Is this correct? I can't remember where I found this.
Prior to late 2014, they used a vacuum booster with an electric pump. Since then all have an iBooster. Tesla has NEVER done regen/brake blending on the brake pedal. Now starting on Model 3, they have one-pedal driving, but this is only for the "go" pedal, not the brake pedal.
Where does brake force arbitration occurr? Does the ibooster scale sensor travel to brake force and request it from the vehicle? I know they can run in stand alone mode, so it makes me think all of thebwork is done in the iBooster and it gets the available brake force from the car, requests what it can then fills in the rest.
The iBooster in boost mode doesn't care about brake force, only your pedal application force. However when AP or the DU is braking (one pedal) there is closed loop feedback. (AP or DU requests brake pedal pressure) Basically it brakes like you would, sensing the deceleration and modulating the pedal to achieve a smooth stop.
@@Ingineerix I see, that makes sense. But what about when the foot brake is applied? In my Honda Clarity which also runs an iBooster, when I apply the foot brake it brings in re-gen first then blends that with the foundation brakes to achieve the desired deceleration. It's pretty good at blending the two as well. So does I booster do that calculation and tell the drive unit how much retarder torque is required or does the vehicle read pedal throw and then tell the iBooster how much brake force to apply when the Drive unit can't supply the required retarder torque?
@@brandondelgado4153 Tesla doesn't do blended braking. If your foot is off the go pedal, the car is doing all the regen it can. If you press the brake pedal, it's all friction brakes.
@@compu85 ok thanks, I had not realized that was the case.
@@brandondelgado4153 Tesla doesn't believe in blending on the brake pedal. Now they have one-pedal mode on the "go" pedal though, and that does blend regen into hydraulic when you let off the "go" pedal. It brings the car to a smooth stop without ever needing to touch the brake. The ESP3 (ABS) valve body then implements full 4-wheel brake hold until you touch the pedal again.
Is the iBoost controlled via the Bosch ABS or directly from the Tesla systems?
CAN messages tell it how to run
Tesla controls it over CAN. The Drive unit can ask for braking for one-pedal driving, as can the Autopilot ECU.
@@Ingineerix Interesting, wonder why they did not go with an accumulator based system.
@@allan80supra More expensive(?), louder, worse pedal feel.
@@allan80supra @compu85, is right, yeah all of that, plus it's less reliable and more expensive.
Is it mechanically possible for the FSD Beta hardware to overpower a driver, or is there some limits on the torque it can apply to the steering wheel?
In light of the recent NHTSA complaint that FSD Beta overpowered the driver and caused a wreck, maybe you could do a video on the steering system and show whether the driver can mechanically override or overpower the FSD steering system.
I am sure there are multiple electronic safeguards, but assuming that the motor was shorted to 12v full power trying to turn the wheel to the left, can you turn it to the right?
A physical demonstration of it would be nice!
I don't believe this is possible. It doesn't use a Brushed DC motor in EPAS, and there are 2 controllers cross-checking each other.
@@Ingineerix are you talking about the steering system or the brake booster? I may not have made my question clear that I was asking a different question about the steering system, and I can't tell which you are referring to lol
@@ke6gwf I believe there is a torque sensor on the steering wheel shaft (same sensor that detects your hand on the wheel) that will instantly disengage autosteer at a threshold, and the power steering motor goes back to assisting you, rather than steering the car. Now if the torque sensor failed I believe you would not be able to overcome the power steering motor, it's probably quite powerful. However you would hope the testers of FSD would familiarize themselves with how to disengage in an emergency and not just YOLO into traffic as soon as they got the update!
@@ke6gwf Yes, sorry EPAS is the Electric Power Assisted Steering. It's double redundant, with 2 torque sensors, 2 processors, and even 2 independent power feeds. They cross-check each other continuously. It's super highly unlikely that it could overpower the driver. As soon as the torque sensor detects driver intervention, it stops all externally commanded force. I'll do a video on this system soon!
@@Ingineerix I guess I need to learn the acronyms better lol
Ok, double redundancy is pretty good, especially if it's hard coded in the controller rather than just software in the FSD computer.
I was basically wondering how possible it would be for the claim to be true, that they were unable to steer because it took over.
But with double everything looking for torque input, it sounds like a low probability of it being a car problem.
Though I wonder if the power steering assist system momentarily failed, and what they reported as the FSD taking over was actually lack of power steering combined with scrub forces on the curve, and they just weren't pulling hard enough.
Anyway, it will be interesting what the investigation finds, and I look forward to your expert overview of the system, so all the interested parties can understand the system better.
Is this totally Bosch designed and built or is it a Tesla part?
All Bosch.
You would be surprised of the amount of non Tesla components there is in a car.
The same goes for all brands, Volvo, Honda, Citroën, Mercedes, BMW, ...
Mostly the same shit under the shell.
I just got a gen 2 honda one. Its a bit different with the pinout. I tried getting it to turn on but it wont even take any current. I wonder if the circuit board is fried. Do you know if the system should make any mechanical sound when the ignition is switched on? Thanks for reading.
I can't comment on the Honda version, but all the ones I've played with work in a fail-safe mode with just the 4 input sensor wires, ground, +12v, and ignition (drive) inputs. (Total of 7 wires needed on the large connector)
👍👍👍👍
With iBooster style systems specifically for ABS, does that meant it cam be calibrated to actually be smooth? In cars I’ve driven ABS has been jerky (high frequency pulsation ) or really loud sounding like grinding.
In the same way Motorsport level TCS and ABS work offer superior performance and not just superior safety, it seems normal cars can do better here
ABS always make this pulsation in order to release pressure from a wheel that is over braking. iBooster does not change this behavior. New ESP generation is however much quieter, but noise is still noticeable.
Not sure on ABS intervention, but I can tell you for normal driving the iBooter has a much smoother pedal feel than electro hydraulic system like other EVs used. The iBooster's feel is really quite good IMO!
I'd say the pedal feel in boost mode is superior to that of a vacuum boosted system, and when autopilot or one-pedal is braking it's every bit as smooth as a human.
@@Ingineerix Ya it really is quite good!
I'd be interested to drive a blended regen car with an iBooster, the "older generation" cars could be quite non-smooth in the transition from regen to friction brakes. And if you were moderately braking, and hit a pothole or ice there would be a moment of NO deceleration as the system switched from reegen to all friction brakes. Not good.
Breaks don't spit Front/Rear. They split Front Left, Right Rear/Front Right, Left Rear.
They are split into 4 separate channels by ESP3. The only thing I discussed in the video was the outputs from the mastery cylinder, which are only 2 channels: front and rear.
10:22 i wonder what is the reliability of the circuits such as this in a Tesla. I mean, resistors or capacitors could go wrong or short. edit: ah there is a redundant circuit! 👍
Not just one redundancy, 5 other ways! 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2.
@@Ingineerix 🔥 thanks!
Nice
i wonder how autopilot deals with emergency brake situations. does it just activate the pedal (the motor takes time) or just send signals to the abs box as its faster or both and sees what is faster.
iBooster is faster than ESP in building up pressure.
@@kossaKSF i am not an expert but i am pretty sure the motor on the brake thingy is slower then the actual abs solenoid.
The iBooster is way faster than the hydraulic pump in the ESP3 (ABS) valve body. ESP3 is set up for high pressure, but has relatively low displacement, so cannot move a large amount of fluid in a short time. I assure you it would be quite obvious if ESP3 activated, as it's noisy.
ibooster can build up very high amount of brake force in short amount of time. on my car i can lock up the brakes with ibooster actuating in autonomous mode. although car is only 750kg...
How does the system activate the brake lights?
Deceleration sensor (3 axis gyro) in the car detects slowing. When it goes above a threshold level, the brake lights are activated. Also there is a conventional switch on the brake pedal lever arm.
@@morrisg is correct, but the DI (Drive Inverter) supplies the signal when regen is over a certain negative torque value.
Does the motor spin backwards? Under power? Or does it release from the mechanism and the spring just returns it directly?
pretty sure this is the kind of motor which spins freely if there is no power applied to it, so it does spin backwards by the spring tension when not powered
I'm pretty sure the spring returns it. There is no need to force it back.
@@Ingineerix I'm wondering though, if you ran the motor the other way, would it prevent braking? Edit: And if this is how it achieves ABS.
@@henrikmikaelkristensen4784 No, I've already covered this in the video and answered it here in the comments several times.
what if the motor fails while on autopilot, and how fast can it engage the brake with just the motor alone?
Edit: also those gears look plastic, couldn't they snap quite easily?
The motor can't fail on, it's a 3-phase motor that requires AC to run. It can apply the brakes faster than you can. No the nylon gears are more than adequate for the forces and reliability needed.
Will it break your foot if you have the foot under the brake pedal und the ECU is braking?
Nope, there is a detection method implemented in the software. You will certainly feel it hurts, but the brake pedal will not injure your foot.
No, as I show there is a one-way slider clutch that lets either your foot or the motor apply force. The motor cannot push the pedal back, and when it's applying it, all you see is slightly less return force on the pedal. (You can see it move slightly, but it doesn't have any force)
@@Ingineerix ah ok i get it, the piston connected to the pedal is only connected to the white plastic thing which rides inside the gear and not directly to the metal thing pressing onto the master cylinder.. Makes sense, as otherwise the pedal would move if the ECU is braking :D
@@Spacefish007 You got it!
@@Spacefish007 Pedal moves when ECU is braking. As I wrote above, there is a detection system implemented to prevent your foot from being crushed by the pedal. In normal braking motor is always engaged and this sliding feature is not necessary. It is only in emergency when it is needed as a backup mode to allow you to brake w/o support.
I wonder how Toyota tackled these problems in the first gen Prius?
First gen Prius used 12v hydraulic oil pump to generate pressure when needed. An accumulator stored hydraulic pressure.
1st gen Honda Insight used a vaccum booster like the one described with a switch to start the gas engine when the vaccum got to low.
@@brandondelgado4153 Interesting, thanks
That is called and electronic stroke sensor.
Very interesting, thanks for sharing! -- Just looking at the video and unable to measure the forces myself, but suppose you have a software bug aren't there two fail scenarios:
1) Motor stops pushing entirely, you're working against the spring and the master cylinder to brake the car manually... Or is the force of the foot enough to overcome both?
2) Motor wrongly goes in reverse do to a software issue... Does this impede you breaking? Probably it means you're just not assisted at all though.
It has that spline that gives you the ability to manually apply the brakes regardless of what the booster is trying to do.
Worst failure mode would be fully applying the brakes by mistake, but the ABS may be able to mitigate that.
If you have ever tried using the brakes on coasting cat you would know exactly what it would feel like if this stopped working.
Instead of using your big toe to stop the car, you have to push pretty hard, but it's possible.
@@ke6gwf The point is that in contrast with traditional manual breaking if your vacuum fails, here you are *also* fighting against that big spring. Doesn't that make it even worse??
@@purpleidea the vacuum boosters also have a big spring in them, that's what returns the brake pedal after use.
In addition, the brake pedal has a LOT of mechanical advantage from leverage, so if you have, say, just replaced your master cylinder and you step on the brake pedal to start bleeding it, before it has fluid in it, you feel almost no resistance on the pedal, but it always comes back up..
That's that big spring, and it's probably about the same strength as in a vacuum booster system.
And compared to the force it takes to apply hydraulic pressure to the brakes, the spring might as well not be there from what you can feel.
Yes, it would be full manual control. The motor cannot fight your foot. Keep in mind there are 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2.
Vacuum boosters have a similar spring. The spring force is nothing compared to the hydraulic force needed. Keep in mind there are still 5 other ways to stop the car: 1. Regen, 2. DI Plug braking (loss of HV), 3. ESP3 (ABS pump), 4 & 5. EPB (Electronic Parking Brake) EPB has 2 independent channels, so it counts for 2.
Now I know how I keep getting dinged for hard braking!
I start to understand why magnets are that fancy.
Nylon gears?!? For braking?
Yes, they are sized appropriately. They will easily outlast the rest of the vehicle.
This is all super helpful. I just got my Tesla Plaid delivered a week ago and I LOVE the damn thing! My only criticism is the manual breaks. They suck big time! For a 1020HP car with 0.99 0-60M/H quickness, those breaks are unacceptable! Why didn't Tesla put better breaks into the Plaid??
engineering explained has a great new video about that.
@@JackMott please send me link. thanks
@@emeseszorenyi5245 th-cam.com/video/rh12lK53hss/w-d-xo.html
See Jason at Engineering Explained's excellent explanation: th-cam.com/video/rh12lK53hss/w-d-xo.html
I suspect if Tesla ever makes their own version it will be if/when they switch to brake by wire.
That will be when they have Direct Drive motors, one for each wheel. That will make all the braking system redundant. At the moment, DD doesn't work at low car speeds.
Does this run off the 12v system?
Yes. This way in the event of a HV fault, the braking system will still work as expected.
the very case when the TESLA brake system is cooler than a home router in terms of computing power
How does Tesla autopilot braking work? Not very well with all the crashes from failure to auto stop.
It uses the iBooster. Autopilot/AEB stops way better than most humans. It's not perfect, but it's saved my ass more than once!
How can she stop! ✋
Super interesting and surprised of how much technology is involved. Every Tesla has all the hardware even if you do not pay for Autopilot. Volkswagen on the other hand has an endless number of models. For example the Transporter T3 has e-gas. If one does not pay for cruise control at purchase, not only is the physical button array missing, they have written the software in a way that the fitting of the cruise involves extra huge costs to re-flash the whole motor control system. They did that to stop 3rd party cruise control makers to have huge extra costs. A reason never to buy a Volkswagen.
The MOSFET transistors are oversized ten times!
Speak about safety factor...
I think Tesla would never build iBooster if Bosch don't overprice it, or they don't go different solution. Because this human part is less and less important, so why put parts for this?
Put per wheel system and control it by computer, airbags are done this way, so safety part is same.
Computer applied braking is done through the ABS system. ABS is computer controlled in the first place. It has a pump to supply pressure and 8 or more control valves. All you have to do is provide a command to apply the brakes. The motor starts, the valves are closed and the brakes are engaged. No additional hardware is required.
It is not done through the brake booster unless the brake pedal moves when the computer brakes are applied. The ABS system is VERY fast, responds within milliseconds. That pump motor has a lot of power. P.S. ABS is required on all new cars.
It is not working like this. In normal conditions, ABS stays always open and brake pressure is built up by a booster. iBooster can obviously also do it via external request, you do not have to push the brake pedal.
Incorrect. The ESP3 (ABS) Valve body doesn't have the finesse to be used in this way, plus the PWM of the valves is noisy and creates a lot of NVH issues, in addition to poor pedal feel. It is used as a backup should the iBooster fail though.
Except when it doesn’t. How much Tesla stock do you own?
Actually, I don't own any, and never have. I can't afford it!
Now make one that runs off 48v and shrink that motor.
Lower volume, more expensive. No thanks.
@@morrisg is right. Plus the motor wouldn't be that much smaller. It would just use slightly smaller windings.
Basically the Tesla using standard German suppliers like everyone else
Use the best until you can do better!
Bosch was way ahead of the competition when this system came into production.
Yes of course. Most parts in a Tesla is non Tesla parts. As with all manufacturer of cars...
this same part is found in many new vw/audi hybrid and electric cars, and also some honda. many oems use the ibooster. Just with different pin config and software but hardware is mostly the same (except mounting points and master cylinder)
Using a relatively simple approach, the Tesla Autopilot stops when it rams into the back of a semi at highway speeds.
This is boring as hell. As long as the car stops I am happy.
Bye!!!!
👍👍