A mobile robot is required for the inspection, maintenance, construction, in the flexible manufacturing environment. In this thesis, mechanisms of the mobile robot was developed, a steering controller was studied, and the performance was checked through experiments. The 4-wheeled mobile robot is steered by the differential steering of 2 drive forewheels which are controlled by the IBM PC computer. The DC servo motors of forewheels are controlled by the servo motor controller using closed-loop PI control of speed and torque. PWM, and H-typed MOSFET drive are employed as foreward path, and the incremental encoder and F/V converter as feedback. The trajectory of mobile robot is controlled by a beacon navigation system, and an odometric navigation system.
The experiments of tracking a straight-line trajectory are practiced in 3 ways; that is, (1) by the independent speed control, (2) by the computer-compensation speed control, and (3) by 1 beacon-tracking error compensation speed control. The experimental results are measured in terms of the lateral tracking error, the orientation error, and the speeds of 2 drive wheels. The tracking errors are occurred in actual running by 60-70[cm] after 2 m-long travel at the method (1), and by 4-10[cm] at the method (2). But the experiments at the method (3) are not succeeded due to system design problems. The tracking error is dependent on the control algorithm, sampling time, programmable gains, and road conditions.
