Báo Cáo Tracking control of a welding mobile robot based on aaptive backstepping method

ABSTRACT
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In this paper, an adaptive controller is proposed and applied to two-wheeled welding mobile robot
to track a smooth curved welding path. The mobile robot is considered in terms of dynamics model in
Cartesian coordinates with unknown parameters such as moment of inertia, wheel radius and distance
from the center of the platform to a rear wheel of the mobile robot. The system is considered with the
nonholonomic constraints in relation with its coordinates and the reference welding path. To obtain the
controller, the tracking errors are defined, and the controller is derived based on backstepping
technique to guarantee that the tracking errors converge to zero asymptotically. In the proposed
controller, the unknown parameters are estimated using update laws in adaptive control scheme. To
obtain the tracking errors, a simple measurement scheme using touch sensor is proposed. The touch
sensor consists of two potentiometers including one linear potentiometer for measuring distance error,
and one rotating potentiometer for measuring angular error. To implement the experiment, a control
system is developed based on the integration of three PIC18F452’s: two for servo DC motor
controllers, and one for main controller. The two servo controllers can perform indirect servo control
using one encoder. The main controller which functions as master links to the three servo controllers,
as slave, via I2C communication. Also, the simulation and experimental results are included to
illustrate the performance of the proposed controller.