Fast integral terminal synchronous sliding mode control for pantograph robots.

Area of Science:

• Robotics and Control Systems
• Mechatronics Engineering
• Applied Mathematics

Background:

• Pantograph robots (PRs) require precise control for synchronized movement.
• Existing control methods may struggle with fast convergence and robustness to disturbances.

Purpose of the Study:

• To propose a novel Fast Integral Terminal Synchronous Sliding Mode Control (FITSSMC) for a 2-DOF PR.
• To ensure fast synchronous convergence of position tracking errors for PR servo motors.
• To enhance robustness against uncertainties and external disturbances.

Main Methods:

• Mathematical modeling of the PR using inverse/forward kinematics and servo motor dynamics.
• Development of FITSSMC utilizing norm-normalized sign function (NNSF) and exponential piecewise functions.
• Design of two finite-time state observers (FTSOs) for unmeasurable state estimation.
• Lyapunov stability analysis to prove synchronous and finite-time stability.

Main Results:

• FITSSMC achieves fast synchronous convergence of position tracking errors for both motors.
• The integral term ensures singularity avoidance and strong robustness.
• Finite-time state observers effectively estimate unmeasurable states.
• Comparative simulations and experiments validate superior performance in tracking accuracy and convergence speed.

Conclusions:

• The proposed FITSSMC effectively minimizes synchronous position tracking errors in PRs.
• The control scheme demonstrates superior performance compared to existing methods, especially under uncertainties.
• This research contributes a robust and efficient control strategy for pantograph robot applications.