Ball Heater Controller

I needed a way to gently heat flies walking on air supported balls during experiments. I added a heater to the aluminum ball holder by insulating with a thin layer of kapton, and adding a nichrome wire coil made on a 3D printed mandrel for uniformity and consistency. A thermistor temperature sensor is added and the whole assembly is potted in thermally conductive epoxy.

I designed and built a custom PCB to sense and control the temperature of the heater using a PID loop. The setpoint can be changed via a rotary encoder on the front in local control mode, or by a computer via usb-serial. A ROS2 node can change the setpoint according to a ROS topic, reports the current temperature and status via another topic, and also records a log at a user-defined time interval. I added a GUI node that shows the current status and lets researchers update the setpoint directly.