Multi-axis fuzzy control and performance analysis for an industrial robot

Robot control systems can be considered as complex systems, the design of the controller involving the determination of the dynamic model for the system. Fuzzy logic provides functional capability without the use of a system model or the characteristics associated with capturing the approximate, varying values found in real world systems. Development of a multi-axis fuzzy logic control system was implemented on an industrial robot, replacing the existing control and hardware systems with a new developmental system. During robot control no adaptation of the rule base or membership functions was carried out online; only system gain was modified in relation to link speed and joint error within predetermined design parameters. The fuzzy control system had to manage the effects of frictional and gravitational forces whilst compensating for the varying inertia components when each linkage is moving. Testing based on ISO 9283 for path accuracy and repeatability verified that real time control of three axes was achievable with values of 938 μm and 864 μm recorded for accuracy and repeatability, respectively