spot_micro_kinematics_python
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mike4192
updating comments on leg matrix t01 to show differences between origi…
Thanks for going through the paper and finding the discrepancies with matrix t01 and t12. It helped me a lot as I was looking through this. I found one typo I think in the comments of your code, where the paper t01 matrix i see here https://www.ijstr.org/final-print/sep2017/Inverse-Kinematic-Analysis-Of-A-Quadruped-Robot.pdf in row index 1 col index 1 has positive cos(theta1).
The matrix in the paper still has weird stuff going on in the row index 2. I only threw this PR out as the comments confused me slightly as I was comparing the matrices in your comments to the paper.
I agree with you, and did out the matrix math using their DH parameters and arrive at the same thing you got. https://wikimedia.org/api/rest_v1/media/math/render/svg/6963d0c47a3a894ff0719c8df348d188b996074e
| joint i | theta i (degree) | alpha i (degree) | r i (meters) | d i (meters) |
|---|---|---|---|---|
| 0-1 | theta1 | 0 | l1 | 0 |
Looking at t01:
| cos(theta1) | -sin(theta1)*cos(0) | sin(theta1) * sin(0) | -l1 * cos(theta1) |
| sin(theta1) | cos(theta1) * cos(0) | -cos(theta1) * sin(0) | -l1 * sin(theta1) |
| 0 | sin(0) | cos(0) | 0 |
| 0 | 0 | 0 | 1 |
so that is:
| cos(theta1) | -sin(theta1)* 1 | sin(theta1) * 0 | -l1 * cos(theta1) |
| sin(theta1) | cos(theta1) * 1 | -cos(theta1) * 0 | -l1 * sin(theta1) |
| 0 | 0 | 1 | 0 |
| 0 | 0 | 0 | 1 |
so that is:
| cos(theta1) | -sin(theta1) | 0 | -l1 * cos(theta1) |
| sin(theta1) | cos(theta1) | 0 | -l1 * sin(theta1) |
| 0 | 0 | 1 | 0 |
| 0 | 0 | 0 | 1 |
I did the same thing for matrix t12, and also got something that agrees with you, just with a different sign on the 1 in row index 2. This is probably do to spot micro doing legs pointing back, and alpha being positive pi/2 instead of -pi/2 as in the paper model.
