Simulation of Three-Joint Robot with Variable Structure Control Implementation

In the field of robotics control, simulation studies of three-joint robots hold significant importance as they enable validation of control algorithm effectiveness without requiring physical device deployment. This program focuses on applying nonlinear variable structure control methods to three-joint robot dynamic control, implementing a corresponding variable structure controller through MATLAB/Simulink environment.

Variable structure control represents an effective control strategy for nonlinear systems, characterized by its core feature of designing specific switching logic to drive system states toward and maintain them on predetermined sliding surfaces within finite time. For three-joint robots, strong dynamic coupling and nonlinear characteristics make traditional control methods challenging to achieve ideal performance. Variable structure control effectively addresses these challenges by providing robust disturbance rejection capabilities through discontinuous control actions implemented via switching functions.

During simulation implementation, the process begins with establishing the three-joint robot's dynamic model, including inertia matrix calculation, Coriolis and centrifugal force matrices, and gravity terms derivation. Subsequently, sliding surfaces are designed and control laws determined to ensure rapid convergence to desired trajectories. The variable structure controller design typically comprises equivalent control terms and switching control terms - the former compensates for system nonlinear dynamics through model-based calculations, while the latter suppresses uncertainty impacts using signum functions or saturation functions to mitigate chattering phenomena.

Through simulation experiments, researchers can visually observe robot trajectory tracking performance, analyze controller response speed, steady-state error, and adaptability to parameter variations. This variable structure control-based approach not only suits theoretical research but also provides critical references for practical robot control system design, where implementation typically involves real-time computation of Lyapunov-based stability conditions and boundary layer techniques for smooth control transitions.