What I did last week

Watched and read lectures on inverse kinematics

Did initial calculations for inverse kinematics implementation

Wrote a script to communicate with Arduino and send it commands over UART to control the arm

What I did this week

This week I worked on getting inverse kinematics working for the arm.  In the process of doing this I ran into some trouble because the arm we are working with has limited capabilities which makes it incompatible with many existing tools.  In order to handle this I have decided to implement the inverse kinematics module myself.  This will allow us significantly more control over our set up and should increase our ease of use in the long term.

Our robotic arm has 6 servo motors.  One of these is used to open and close the gripper and another is used to rotate the gripper.  These degrees of freedom are not relevant to how the arm is actually moved from position A to position B in the state space.  This leaves 4 servos that are responsible for the movement.  One of these servos is located at the base and causes the arm to rotate around the Z axis.  This rotation around the base means it is trivial to align the arm into the 2D plane of the point we want to reach.  This reduces the dimensional of the problem from 3D to 2D.  From here we can use the Rule of Cosines to find the angles of the final three servo motors.

Implementing this has been my main focus over the past week.  Doing this ourselves will give us significantly more control over the state space and will allow us to easily interface with the RRT accelerator.

What I plan to do next week

My work on this inverse kinematics module and its calibration will be continued in this next week.

SMA* is still in progress