We are working in Professor Kim’s Applied Dynamics Lab. This week our major task was to measure the current through a servo motor. We interfaced and tested the Adafruit Motor Shield with servo motors and DC motors. We discussed with Professor Kim’s team ways to measure current used to move a robotic limb. After an overview of how the robotic arm is controlled we continued to look for the best way to measure the current. We decided that we need to determine the direction of the electrical current through the DC motor. The first thing we tried was to compare the voltage across the motor by measuring the voltages at each terminal of the 18 VDC motor with the analog input pins of the Arduino microcontroller.

Unfortunately, this experiment burned the microcontroller’s ADC . Very quickly, we realized that a microcomtroller’s analog inputs can only take up to 5 VDC. This experience taught us a lesson to never connect anything with a voltage greater than allowable range to the analog pins of the microcontroller. The work that we did with DC motor will help our students design system that protect the digital microcontroller.