High Speed Motor Control

Overview

The project suggested was to design a system for high speed motor control using the PIC 32. To demonstrate the motor control, a two degree of freedom (2DOF) robot arm was designed to throw and catch one ball with itself.

Team Members

• Sam Bobb (Electrical Engineering senior)
• Daniel Cornew (Mechanical Engineering junior)
• Ryan Deeter (Mechanical Engineering junior)

Mechanical Design

Theory of Parallelogram Design

Equations of Motion

Commanding the arm is much easier for a user to do in x- and y- coordinates than in motor angles or encoder counts. Therefore, equations were required that would translate x- and y- coordinates into angles from horizontal and then into encoder counts. Equations to express the reverse (encoder counts to angles to x- and y- coordinates) were also needed to evaluate the accuracy of the execution with respect to the command path.

• $x=L\cos(\theta _{1})\ +\cos(\theta _{1}+\theta _{2})$
• $y=L\sin(\theta _{1})\ +\sin(\theta _{1}+\theta _{2})$
• $\theta _{1}={\frac {-(2L\sin(\theta _{2}))x+(L+2L\cos(\theta _{2}))y}{(2L\sin(\theta _{2}))y+(L+2L\cos(\theta _{2}))x}}$
• $\theta _{2}=cos^{-1}\left({\frac {x^{2}+y^{2}-L^{2}-(2L)^{2}}{2L^{2}}}\right)$

Note: In the code, $\theta _{2}\,$ is written out explicitly in the equation for $\theta _{1}\,$, but was defined as above for ease of reading.

Results

It was awesome.