Design Based on a Shared Lookup-Table for an Obstacle Avoidance Fuzzy Controller for Mobile Robots

Fuzzy algorithms provide intuitive method for robot obstacle avoidance. Fuzzy controllers incorporating a design based on lookup tables (LUT) enable faster obstacle avoidance in environment with multiple obstacles. In an earlier study, we introduced a full LUT-based architecture for an 18-rule positive/negative (P/N) fuzzy controller. In this study, the number of fuzzy rules is expanded to 50. Because of the extra rules, the controller apparently needs more LUT(s) buffers. In other words, the buffer size increases with the complexity of the fuzzy controller. Therefore, we propose a LUT sharing method to reduce the buffer size without significantly degrading the performance of the controller. The final objective of this work is to design a LUT-based fuzzy controller whose buffer size is independent of the complexity of the fuzzy system. The proposed method is evaluated by simulating a 50-rule P/N fuzzy controller using Microsoft Robotics Developer Studio (MSRDS). The simulation results show that in comparison with the method not using LUT(s), full LUT-based method and the LUT sharing method reduce the operational time by nearly 80% and 70%, respectively. Although the LUT sharing method needs 1.5 times more operational time than the full LUT methods, it reduces the buffer size by more than 90%.