…(Our) robots need to be even more robust than the original one.
One piece of that is preventing the motors from burning out. During normal operation with a good locomotion controller, the motors barely even get above ambient (even going 3.7 m/s, the motors weren’t warm to the touch afterwards). However, it’s really easy to write a controller that rapidly heats up the motors without actually doing anything – railing torque commands back-and-forth due to instability, joints mechanically stuck against something, machine-learning algorithm flailing around wildly, etc.
The usual way to do this would probably be to add a thermistor in the windings. But one can use some math to get an idea of what’s going on without such sensors.
The temperature estimate uses an observer to combine two sources of information: A thermal model of the motor, and a temperature “measurement” based on the resistance temperature coefficient of the copper in the windings. The resistance of the motor is estimated based on applied voltage, measured current, measured speed and known motor parameters, and compared against the resistance at a known temperature. Sounds pretty simple, right? Of course not.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.
