Robust sensor systems using evolvable hardware

This paper describes a system that is robust with respect to sensor failure. The system utilizes multiple sensor inputs (three in this case) connected to a programmable device (FPAA) that averages the outputs from the sensors. The programmable device is programmed using evolvable hardware (EHW) techniques. If one or more of the input sensors fails, then the controller detects the failure and initiates a reprogramming of the circuit. The system then continues to operate with a reduced number of sensors. The failure detection is accomplished by comparing the actual system output with a Kalman filter estimate of the output. If the actual output and the filter estimate differ by amount greater than the system uncertainty, then a failure is noted. The system is robust to several different failure modes: sensor fails as open circuit, sensor fails as short circuit, multiple sensors fail, FPAA input amplifier failure. The experimental setup is described as well as results using simulated inputs (individual voltage sources) and actual temperature sensors (PRTDs). The paper also discusses some interesting results as well as issues that must be overcome to expand the system.