Kinematic Analysis of 3 DOF Arm
Timeline: 2 Weeks
For my robot kinematics course, I decided my final project would be to design and build a 3 degree of freedom arm and derive and program its forward and inverse kinematic relationships. The full write up and kinematic equation derivations can be found here. The robot was built around several 3D printed segments and 3 stepper motors, using shoulder bolts as the joint axles. The final cad design is shown to the left. Each stepper motor was controlled by an H-bridge driver with a supply voltage of 12 volts, and the brains of the robot were an Arduino Mega.
Forward Kinematics
Using three given joint angles, Ø1, Ø2, and Ø3, the end effector's location and orientation could be controlled, which was then implemented onto the robot as seen in the video to the right. The robot was commanded to go to the point defined by Ø1 = 50 degrees, Ø2 = 60 degrees, and Ø3 = -50 degrees, which can be seen being executed within decent accuracy. The system came with many inefficiencies that can be ascribed to using cheap motor drivers that led to the stepper motors skipping steps under load, but with upgraded electronics, this should no longer be an issue.
Inverse Kinematics
To solve the robot's inverse kinematic equations, I set up a system of three equations from the forward kinematics to get the X, Y, and φ components of the end effector location in cartesian coordinates centered on the first joint of the robot. Given the location of the end effector, I could calculate the robot parameters and send the angles to the stepper motors, which is shown in the video to the left.