Improving the “Active Heading Control Platform” (CHAD) for Active Experiment Pointing During Stratospheric Balloon Flights

Payloads carried into the stratosphere using weather balloons typically spin and sway during ascent, limiting the types of experiments that can be performed. This project aimed to improve the functionality and performance of the Arduino-controlled active anti-rotation camera platform called CHAD (Controlled Heading Automation Device) that was reported upon at AHAC 2016 by Andrew Kruger from Wilbur Wright College in Chicago. The CHAD device senses its orientation using a magnetometer and an inertial measurement unit, then counters rotation by turning its main shaft with a stepper motor so as to hold fixed the absolute heading of the attached experiment (such as a video camera). The goals of this project were to make CHAD more low-temperature tolerant, to add the capability to adjust the heading in flight by radio command, and to add on-board logging of sensor data, stepper motor commands, actual orientation (independent from what the stepper motor was told to do), and all radio communications. This log was valuable for post-flight analysis if the unit did not hold its heading as effectively as desired. Some thermal issues were identified and addressed. The stepper motor was found to be powerful enough to control the heading of a full video-telemetry system, not just a bare video camera. The implementation of an in-flight-reset command proved valuable. A shaft-rotation encoder was added to assist in knowing orientation independently from the stepper motor commands. Although significant progress has been made, in-flight performance of the modified CHAD device remains somewhat inconsistent in stratospheric conditions