Abstract: To deal with the fast position control problem of a howitzer shell transfer arm with load change and nonlinear friction disturbance, a nonsingular fast terminal sliding mode control strategy is designed combined with adaptive control. The dynamical equations of shell transfer arm with load change and nonlinear friction are established. To avoid singular problem of the control law and improve the convergence rate of reaching the sliding surface, a new nonsingular fast terminal sliding mode control strategy is used to design the control law of the howitzer shell transfer arm. An adaptive law is presented to estimate the unknown upper bound of the uncertain disturbance which is difficult to obtain. The state of the closed-loop system is finite time convergence based on the Lyapunov theory. In order to realize the friction compensation control, a genetic algorithm is used to identify the Stribeck model parameters of the system. The experiment results of shell transfer arm under three different load conditions show that the controller designed in this paper can position accurately, and it has a good robustness against load change and nonlinear friction. The correctness and effectiveness of the proposed control strategy are proved by experimental results.

Key words: nonsingular fast terminal sliding mode control, adaptive control, nonlinear friction, genetic algorithm, parameter identification