So, from what I've gathered from some of this and other sources, to summarise: Step 1: Place zi along the axis of rotation or translation for revolute or prismatic joints respectively. Step 2: Place the origin where zi-1 and zi intersect, or if they're parallel, choose where convenient. Step 3: Place xi along the common normal of zi-1 and zi (although Oussama contradicts this at 47:21???) Step 4: Find the DH variables. Correct me if I'm wrong.
+Stephen Scanlon how do we apply this or translate all this into programming such as C++ or C# ? "obj oriented language" ? im trying to put a Humanoid Robot together and worry about limb collision while servoing and im not sure im getting solid detail by this videos , if i was in this lecture i be that guy raising my hand every other word outta Mr. Khatib mouth
30:27 How was x6 defined? Why is it the same as x5? Is it because so that theta_6 can become 0? if we choose x6 to be on z5, then theta could be 90 degrees.
I really cant stress it enough, if you want a more clear explanation of this concept then try reading Chapter 3 of the book "Introduction to Robotics Mechanics and Control 3rd edition" by John J.Craig. It made all the concepts clear for me.
Hi everybody! can someone explain to me why he had chosen frame 3 at that position. Since the rule said the origin Oi of frame i is located at the intersection of the common normal between Z(i) and Z(i-1) and the axe Z(i) and when the two axes intersect the origin is in the intersection, and at that example Z(2) and Z(3) intersect so the origin of frame 3 should be identical to O(2).????
O4 is not correct in the figure. If O4 where placed there d4=0, and d5=L5. The current matrix defines O4 coincident with joint 4, therefore d4=L5 and d5=0. Does anyone else see this?
Alin Dumitrescu When i is 3, then a(i-1)=a2 and your angle is between z2 and z3 about x2. This is equal -90. When i is 4, then a(i-1)=a3 and your angle is between z3 and z4 about x3. This is equal +90.
how do we apply this or translate all this into programming such as C++ or C# ? "obj oriented language" ? im trying to put a Humanoid Robot together and worry about limb collision while servoing and im not sure im getting solid detail by this videos , if i was in this lecture i be that guy raising my hand every other word outta Mr. Khatib mouth
But you need to be careful with the notations because the video used normal D-H parameters while the professor is teaching the modified D-H parameters.
So, from what I've gathered from some of this and other sources, to summarise:
Step 1: Place zi along the axis of rotation or translation for revolute or prismatic joints respectively.
Step 2: Place the origin where zi-1 and zi intersect, or if they're parallel, choose where convenient.
Step 3: Place xi along the common normal of zi-1 and zi (although Oussama contradicts this at 47:21???)
Step 4: Find the DH variables.
Correct me if I'm wrong.
+Stephen Scanlon how do we apply this or translate all this into programming such as C++ or C# ? "obj oriented language" ? im trying to put a Humanoid Robot together and worry about limb collision while servoing and im not sure im getting solid detail by this videos , if i was in this lecture i be that guy raising my hand every other word outta Mr. Khatib mouth
There are many variations, here I think the professor was right
Step 3 Obeys the right hand rule.
50:40 I was a little bit lost, I think what Prof.Khatib meant to say was alpha 4 -> angle (z_4, z_5) about x5
Yes, he accidentally said that wrong. It should be like you said.
30:27 How was x6 defined? Why is it the same as x5? Is it because so that theta_6 can become 0? if we choose x6 to be on z5, then theta could be 90 degrees.
Yes, in a previous lecture we state O0=O1 and Ofinal =O(final-1) for mathematical convenience.
I really cant stress it enough, if you want a more clear explanation of this concept then try reading Chapter 3 of the book "Introduction to Robotics Mechanics and Control 3rd edition" by John J.Craig. It made all the concepts clear for me.
You were right, it had the best explanation I managed to find on the topic. Thank you!
Hi everybody! can someone explain to me why he had chosen frame 3 at that position. Since the rule said the origin Oi of frame i is located at the intersection of the common normal between Z(i) and Z(i-1) and the axe Z(i) and when the two axes intersect the origin is in the intersection, and at that example Z(2) and Z(3) intersect so the origin of frame 3 should be identical to O(2).????
hello thank you sir , if you have a time please explain us about manipulation mechanism 2 hands .
I think at the row for frame 4. the theta parameter should be 180+theta4. Is it correct? or I missed something?
Hi, I think youre correct it should (theta4 + 180).
O4 is not correct in the figure. If O4 where placed there d4=0, and d5=L5. The current matrix defines O4 coincident with joint 4, therefore d4=L5 and d5=0. Does anyone else see this?
exactly.................................................
28:28 he corrects it.
where can I find the lecture notes
why is X2 pointing downwards? shouldn't it be pointing same direction as X1 to become perpendicular to the plane formed by Z1 and Z2?
Yeah, 4 years later, I have the same question as you did...so confused
It is not pointing downward it is pointing upward. You are seeing X4 in the direction X3 X5, coincident with O3.
no, x2 has to be perpendicular to z2 and z3, so it has to point up- or downward
43:37, is theta2 = -90?
theta2 is variable. Don't confuse theta with alpha.
How come alpha 3 is -90?
From Z3 to Z4 about X3 you rotate CCW so it should be +90.
Am I wrong?
Minute 24:46.
Alin Dumitrescu When i is 3, then a(i-1)=a2 and your angle is between z2 and z3 about x2. This is equal -90. When i is 4, then a(i-1)=a3 and your angle is between z3 and z4 about x3. This is equal +90.
sadel23 thnx bro 1 more thing can you tell me how come alpha between z1 and z2 is -90?
tanks that but it is not clear the screen
how do we apply this or translate all this into programming such as C++ or C# ? "obj oriented language" ? im trying to put a Humanoid Robot together and worry about limb collision while servoing and im not sure im getting solid detail by this videos , if i was in this lecture i be that guy raising my hand every other word outta Mr. Khatib mouth
The 2D gets a little confusing when dealing with assigning parameters in 3D space, for me, the following video helped a lot: watch?v=rA9tm0gTln8.
But you need to be careful with the notations because the video used normal D-H parameters while the professor is teaching the modified D-H parameters.
stupid camera-man ... cant he zoom out so that we see the SCREEN as well??