Radiation Response and Adaptive Control-Based Degradation Mitigation of MEMS Accelerometers in Ionizing Dose Environments

This paper investigates the effects of gamma radiation on the operation of commercially available capacitive microelectromechanical accelerometers intended for use in robotic systems deployed for nuclear disaster remediation. Radiation-induced accelerometer degradation is examined in terms of its effects on the input-output relationship of ADXL325 accelerometers (Analog Devices, Inc., Norwood, Massachusetts, USA) prior to sensor failure. Results show a moderate increase in sensor nonlinearity as well as significant, non-monotonic changes to accelerometer axis sensitivity and zero-$g$ bias. Both part-to-part variation and axis-to-axis variation within individual accelerometers are observed. The effects of the observed accelerometer degradation on the performance of a simple robotic manipulator that relies on acceleration feedback are evaluated in simulation. Additionally, using tools derived from adaptive control theory, this paper presents a real-time recalibration technique for mitigating the effects of the measured accelerometer degradation on the performance of robotic systems that can be applied in-field, without the knowledge of the degradation mechanisms. An example implementation of this technique is also evaluated. Results suggest that control-based strategies for mitigating hardware degradation may be able to extend the useful operating lifetime of non-radiation-hardened sensors in robotic systems deployed in extreme radiation environments.