Evolutionary design of fault-tolerant analog control for a piezoelectric pipe-crawling robot

Abstract

In this paper, a genetic algorithm (GA) is used to design faulttolerant analog controllers for a piezoelectric micro-robot. Firstorder and second-order functions are developed to model the robot's piezoelectric actuators, and the GA is used to evolve closed-loop controllers for both models. The GA is first used to assist in traditional PID design and is later used to synthesize variable topology analog controllers. Through the use of a compact circuit representation, runtimes are minimized and controllers are synthesized with minimum population sizes and components. Fault-tolerance is built into the fitness function to facilitate the design of controllers robust to both actuator failure and component failure. The GA is successfully used to design synthetic controllers and to optimize a traditional PID design. This research shows the advantages of GA assisted design when applied to robot-control problems.

Design Methodology for Robust and Fault-Tolerant Control of a Microprehensile Microrobot-On-Chip

“…In the worst case, our controller implementation will be equivalent to the existing robust control design. Similar results of robustness and fault-tolerance are obtained when considering faults produced by mechanical contacts due to attraction of the fingers (adhesive forces) or noisy sensing 17th IFAC World Congress (IFAC'08) Seoul, Korea, July [6][7][8][9][10][11]2008 signals provided by the strain gauge force microsensors during micromanipulation tasks.…”

“…The FTC scheme proposed by Tan et Habib [7] consists mainly of a fault reconstruction scheme where the outputs are firstly separated into non-faulty and potentially faulty actuatorsensor components. However, it should be mentioned as far as we know, several works have been reported for robust control of microactuation systems, i.e., electromagnetic [8], piezoelectric [9] and magnetostrictive [10] driving systems but few works reported fault tolerant control in micro and nanorobotics [11]. The results of this work relates to the areas of fault tolerant control and robust control for a microrobotic piezoelectric microgripper.…”

Automated synthesis of resilient and tamper-evident analog circuits without a single point of failure

“…The computational cost of evaluation increases significantly because multiple simulations are required, proportional to the number of components in the circuit multiplied by the number of failure modes per component. Specific application areas that have been targeted are robots with a noisy environment or actuation error [1] and analog circuit working in extreme environment like space [3].…”

“…In previous studies (e.g., [1,7]), robustness is defined as the average or worst case performance of a circuit after deleting one component at a time from the circuit. However, circuit failures are often more subtle in nature.…”

“…Such circuits have no single point of failure, yet present an even more challenging design task. A number of studies exploring this approach focus on different types of defects in analog circuits such as component removal [1], parameter variations [2], and external environment change [3].…”