Lab 3: Romeo and Juliet

Goals:

  1. Learn how to compute inverse kinematics

  2. Use FK+IK to create a mirroring setup

../../../_images/lab3.jpg

Step 1. Code inverse kinematics

  1. Download starter code from here: https://github.com/cs123-stanford/lab_3_romeo_and_juliet.git and fill out deliverables in [template doc here](https://docs.google.com/document/d/1eVlykTsy5krLiFD5Apgt6rBzp-t0tfXLXmJ1NIIOQTQ/edit?usp=sharing)

  2. Implement distance in kinematics.h as the squared-norm of the error between the position returned by FK(guess) and target_location.

  3. Implement calculate_gradient in kinematics.h

  4. Implement inverse_kinematics in kinematics.h

Step 2. Test the consistency between forward kinematics and inverse kinematics

  1. Look at the tests written for you in test_ik within test_inv_kinematics.h

  2. The test works by taking some reachable (x,y,z) point in space, and calling your IK function to get the corresponding joint angles, then passing them to your FK function to retrieve the original (x,yz).

  3. Make sure the test passes before moving on

Deliverable: Write about why we are doing an IK -> FK consistency test rather than an FK -> IK test (2-3 sentences). Hint: Think about the robot leg configuration(s)

Deliverable: Why is it important that the point we are testing is reachable? Describe what you expect IK to return for this case?

Step 4. Put it together! Make your two robot arms match each other’s end-effector positions

  1. Implement the rest of loop() in main.cpp and deploy on the robot

Deliverable: Send a video of the arms roughly matching each other when you move them

  1. Try more iterations of IK in kinematics.h, and observe the behavior (Careful may be unstable)

Deliverable: Why does more iterations of IK cause instability?