Abstract
Electromechanical actuator (EMA) systems are widely employed in missiles. Due to the influence of the nonlinearities, there is a flat-top of about 64 ms when tracking the small-angle sinusoidal signals, which significantly reduces the performance of the EMA system and even causes the missile trajectory to oscillate. Aiming to solve these problems, this paper presents a hybrid control for flat-top situations. In contrast to the traditional PID or sliding mode controllers that missiles usually use, this paper utilizes improved sliding mode control based on a novel reaching law to eliminate the flat-top during the steering of the input signal, and utilizes the PID control to replace discontinuous control and improve the performance of EMA system. In addition, boundary layer and switching function are employed to solve the high-frequency chattering problem caused by traditional sliding mode control. Experiments indicate that the hybrid control can evidently reduce the flat-top time from 64 ms to 12 ms and eliminate the trajectory limit cycle oscillation. Compared with PID controllers, the proposed controller provides better performance—less chattering, less flat-top, higher precision, and no oscillation.
Highlights
The actuator system is an important operating unit in modern applications such as in autonomous vehicles, robotics, aircraft equipment and submarine operations
From Equations (26) and (27), because of the role of ”flag”, it can be deduced that when the position error passes through the boundary layer, the sliding mode controller will work once for each, which will reduce the time of flat-top and the influence on the key performance indexes of Electromechanical actuator (EMA) system
The proposed method sliding mode a order to compensate the static and reduce the flat-top time,utilizes this paper provides hybrid control with PID–improved sliding mode controller
Summary
The actuator system is an important operating unit in modern applications such as in autonomous vehicles, robotics, aircraft equipment and submarine operations. In order to address these issues, various control schemes are proposed to control the position of the EMA system, including PID control algorithms [4,5,6,7],fuzzy control [8,9], intelligent algorithms [10], sliding mode control [11,12,13], the ADRC algorithm [14], robust control [15], active control [16], model-based prognostic algorithms [17], and compensation control [18,19,20]. In contrast to traditional PID or traditional sliding mode controllers that missiles or aircraft usually use, this paper utilizes improved sliding mode control based on a novel reaching law Sensors 2018, 18, x FOR PEER REVIEW to compensate friction andand eliminate the flat-top thehigh-frequency steering of the input signal,problem, utilizes signal, utilizes static boundary layer switching functionduring to solve chattering boundary layer and switching function to solve high-frequency chattering problem, and utilizes.
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