Dead-zone Compensation Research Articles

Research on Feedforward-Feedback Composite Anti-Disturbance Control of Electro-Hydraulic Proportional System Based on Dead Zone Compensation

Considering the complexity and difficulty of obtaining certain parameters in the electro-hydraulic proportional control system, a precise transfer function of the system was derived through parameter identification using experimental data obtained from an Amesim simulation model after establishing a basic mathematical model. This approach reduces the reliance on accurate parameters of individual components. A feedforward-feedback composite controller was designed, and its effectiveness was validated in Simulink using the system’s transfer function. Subsequently, the dead zone range of the proportional valve was determined through experiments, and a dead zone compensation strategy was designed, which reduced the time required for the proportional valve to traverse the dead zone by 89.4%. Based on the dead zone compensation, trajectory tracking experiments were conducted to validate the effectiveness of the feedforward-feedback composite controller. Under fixed disturbances, the trajectory tracking error was reduced by 53.8% compared to feedback control. Under time-varying load disturbances, the trajectory tracking error was reduced by 51.2% compared to feedback control.

Adaptive visual servoing control for uncalibrated robot manipulator with uncertain dead-zone constraint

This paper addresses the adaptive visual tracking control problem of an uncalibrated camera robot system with unknown dead-zone inputs. The uncertainties include camera extrinsic and intrinsic parameters, robot dynamic parameters, and feature depth parameters. The control achieves a better performance by establishing a smooth inverse model of the dead-zone input, which eliminates the nonlinear effect of the actuator constraint. A novel adaptive control scheme is presented which does not require a priori knowledge of the parameter intervals of dead-zone model, to update the parameter values online. Furthermore, adaptive laws are provided to estimate the uncertainties that exist both in robot and in camera models. Meanwhile, in order to avoid the singularity of the image Jacobian matrix, a projection algorithm is also introduced. Subsequently, a novel robust adaptive controller together with dead-zone compensation is established so that the tracking error image space converges to the origin. Simulations and experimental studies are conducted to verify the effectiveness of the proposed method.

Discrete-Time Reinforcement Learning Adaptive Control for Non-Gaussian Distribution of Sampling Intervals.

This article proposes an optimal controller based on reinforcement learning (RL) for a class of unknown discrete-time systems with non-Gaussian distribution of sampling intervals. The critic and actor networks are implemented using the MiFRENc and MiFRENa architectures, respectively. The learning algorithm is developed with learning rates determined through convergence analysis of internal signals and tracking errors. Experimental systems with a comparative controller are conducted to validate the proposed scheme, and comparative results show superior performance for non-Gaussian distributions, with weight transfer for the critic network omitted. Additionally, the proposed learning laws, using the estimated co-state, significantly improve dead-zone compensation and nonlinear variation.

Adaptive fuzzy control for high-order nonlinear systems with asymmetric time-varying full-state constraints and dead-zone input

The issue of adaptive fuzzy control for a category of high-order uncertain nonlinear systems is discussed in this paper. The time-varying full-state constraints are asymmetric, and the input is subjected to dead-zone. The asymmetric time-varying high-order barrier Lyapunov functions (BLFs) are constructed to depict the constraints characteristic and a controller design strategy is proposed. A dead-zone compensation mechanism is used to eliminate the influence of dead-zone input. Based on adding a power integrator technique and the adaptive control method, an adaptive state feedback controller is designed. As a consequence, all the constraints are not breached and the tracking error converges into a prescribed small region around the origin. Finally, a numerical example and a practical example are given to show the effectiveness of the proposed method.

Enhancing pressure control of low-friction pneumatic actuator with eddy current damper via valve dead-zone compensation

This article addresses the high-performance pressure control of a pneumatic actuator that incorporates an air-bearing piston and an eddy current damper (ECD). After optimizing the pneumatic actuator, achieving precise pressure control relies on maintaining an accurate and stable airflow through the control valve. A terminal sliding mode adaptive control method (TSMAC) is proposed, proficiently integrating considerations for dead zone nonlinearities in the proportional valve and the effects of unmodeled disturbances in the pneumatic actuator. Using the opening area of the proportional valve as the input to the pneumatic system greatly simplifies the control process and reduces the workload required for valve parameter calibration. The Lyapunov-based stability analysis demonstrates that excellent asymptotic output tracking can be achieved with low steady-state error simply by knowing the boundaries of the valve opening area. The control effect of the proposed control strategy is compared with an adaptive backstepping sliding mode control method based on a linearly fitted proportional valve model on an established constant pressure control test bench. Experimental results under various loads and operating conditions illustrate the effectiveness of the proposed approach.

Deep Reinforcement Learning-Based Control for Asynchronous Motor-Actuated Triple Pendulum Crane Systems With Distributed Mass Payloads

For transporting large cargoes in practice, the triple pendulum hoisting pattern is widely utilized, where the distributed mass payload (DMP) is suspended under the hanger, the hanger is suspended on the hook, and the hook is connected with the hoisting mechanism. However, existing studies mainly focus on single pendulum and double pendulum hoisting patterns, and few of them pay attention to triple pendulum hoisting patterns. Compared with single pendulum and double pendulum cranes, triple pendulum cranes, which control 4 degrees of freedom (DoFs) with merely 1 control input, have a higher underactuation degree, with higher control difficulties. In addition, the nonlinear characteristics of alternating current (AC) asynchronous motors, such as unknown nonlinear dead zones and time delays, will degrade tracking accuracy and control performance. To solve the above problems, a model-free deep reinforcement learning-based trajectory planning method is proposed for triple pendulum DMP cranes. Furthermore, an identification model for AC asynchronous motors is established. On this basis, a trajectory tracking method including an adaptive dead zone compensation (ADC) and a modified Smith predictor (MSP) is proposed. Finally, experiments are carried out on a self-built 2-ton crane experimental platform, which is actuated by AC asynchronous motors. Hardware experiments demonstrate that triple pendulum cranes can accurately track the planned trajectory, and the DMP residual swing is effectively suppressed.

Recent advances in control strategies and algorithms for pilot-operated electro-hydraulic proportional directional valves

Pilot-operated electro-hydraulic proportional directional valve is a key hydraulic component to control the motion of large power equipment such as construction machinery and agricultural equipment. The control accuracy and response speed of the valve control element are very important to the performance of the hydraulic system. In this paper, control strategies for dead-zone control and valve control systems are reviewed. In order to eliminate the dead-zone of pilot-operated proportional valve control, the current control schemes for dead-zone detection and dead-zone compensation are summarized, and the control schemes are evaluated. The proportional–integral–derivative-related control, nonlinear control, and robust control of the pilot-operated electro-hydraulic proportional directional valve control system are reviewed, the relationship between the control strategies is analyzed, and the different control algorithms are evaluated. The shortcomings of the research program are analyzed, and the corresponding solutions are proposed. Based on the current research, future research progresses for eliminating the control dead-zone and optimizing control strategies are presented.

A distributed strategy for games in Euler–Lagrange systems with actuator dead zone

This paper explores a distributed Nash equilibrium (NE) seeking problem for games in which the involved players are of Euler–Lagrange (EL) dynamics with actuator dead zone. To find NE of such games, a novel distributed algorithm with a dynamical dead-zone compensator is proposed. The compensating module in this new strategy is regarded as a fast dynamics that rapidly addresses the effect caused by actuator dead-zone characteristic. The other module of this algorithm is a slow optimizer that enables the actions of EL players to approach the NE. Since the designed strategy is a two-time-scale model, semi-global practical asymptotic stability of this strategy can be obtained by utilizing the generalized singular perturbation method. Finally, an electricity market game with six turbine-generator dynamics is utilized to validate the theoretical result of the proposed method.

Adaptive Fuzzy Predefined-Time Control for Third-Order Heterogeneous Vehicular Platoon Systems With Dead Zone

This paper investigates the problem of fuzzy adaptive predefined-time terminal sliding mode (TSM) control for a third-order heterogeneous vehicular platoon system (HVPS) with an unknown dead-zone. For the purpose of approximating unknown nonlinear functions, fuzzy logic systems (FLSs) are utilized. Additionally, the impact of the dead-zone on the performance of the control may be lessened by building the dead-zone compensation. A tracking error based on the modified constant time headway (MCTH) policy is built to get rid of the assumption of zero initial spacing and decrease the distance between vehicles at the same time. A unique nonsingular TSM control system is then built using the predefined-time stability criterion, with the help of Lyapunov functions, it is possible to demonstrate both the individual and the string stability (SS) of the whole heterogeneous vehicle platoon in a predefined time. Finally, a series of simulations are shown to demonstrate the validity of the proposed results.

Path Following With Prescribed Performance for Under-Actuated Autonomous Underwater Vehicles Subjects to Unknown Actuator Dead-Zone

This paper investigates the problem of path following with prescribed performance for autonomous underwater vehicles subjects to unknown actuator dead-zone nonlinearity. To cope with this practical problem abstracted from hydrodynamic noise measurement, an adaptive command filtered backstepping method with actuator dead-zone compensation is proposed. By introducing a damped exponential barrier functions, new tracking errors are defined to satisfy the prescribed performance requirements. The path following control method is theoretically based on the command filtered backstepping technique for handling the complexity explosion problem attribute to the repeating derivations. Moreover, the filter compensation mechanism is designed to eliminate the negative effect of the filter errors. To deal with the actuator dead-zone nonlinearity, a fuzzy logic system based dead-zone compensation method is developed that dose not need the inverse of the dead-zones. Numerical simulations are conducted to demonstrate the theoretical analysis, and the usefulness and potential of the new design scheme is revealed.

Adaptive simplified surge-heading tracking control for underwater vehicles with thruster’s dead-zone compensation

Adaptive simplified surge-heading tracking control for underwater vehicles with thruster’s dead-zone compensation

Dead-zone compensation via passivity-based control for a class of mechanical systems

This manuscript introduces a passivity-based control methodology for fully-actuated mechanical systems with symmetric or asymmetric dead-zones. To this end, we find a smooth approximation of the inverse of the function that describes such a nonlinearity. Then, we propose an energy and damping injection approach — based on the PI-PBC technique — that compensates for the dead-zone. Moreover, we provide an analysis of the performance of the proposed controller near the equilibrium. We conclude this paper by experimentally validating the results on a two degrees-of-freedom planar manipulator.

RCMACNN control of flexible space robot with dead-zone compensator and friction observer

In order to improve the trajectory tracking performance of space robots, it is necessary to consider the influence of various working conditions such as dead zone and friction. To deal with them, a compensator is designed to eliminate the effects of the joint torque dead zone and a dual observer is used to estimate the friction state. In order to suppress the vibration of the links, a virtual control force is proposed. Based on this, a hybrid trajectory control based on recurrent cerebellum model articulation controller neural network (RCMACNN) is designed. This method can not only achieve trajectory tracking, but also suppress flexibly vibration, and at the same time eliminate the vibration coupling between various working conditions. Using Lyapunov function, it is proved that the filtering error is ultimately uniformly bounded (UUB). Finally, a planar space robot with two flexible links is applied for simulation, and the results prove the effectiveness of the method.

A receptance-based vibration control with dead-zone compensation for systems with input delay

This paper presents a novel compensation approach for receptance-based second-order systems with long input delay and unknown dead-zone input nonlinearity. The approach is based on a filtered Smith predictor for systems with long input delay based on the receptance model. An innovative discrete-time adaptive strategy approach for dealing with unknown input dead-zone is also based on a receptance model realization. The receptance-based second-order model is used on several fundamental applications, including active control vibration of mechanical vibrating systems. In the proposed approach, a filtered prediction error that considers the effects of time delay can be applied to pursue state feedback design for active vibration control purposes. The dead-zone compensation is treated by a discrete-time state observer, which is based on displacement, velocity, and control effort signals to estimate the unknown parameters to be used on an adaptive algorithm. The main contribution of this work is to combine unknown dead-zone adaptive mechanism and a receptance-based time delay compensation in a unified design. Some numerical examples illustrate the effectiveness of the innovative proposed approach.

Control methodology of synchronous lifting for the dual forging manipulator at clamping condition

Asynchronous coupling force of dual forging manipulator frequently results in poor forging and even equipment failure. In this paper, a synchronous control strategy in dual forging manipulator systems (DFMS) is proposed to stabilize its operation. Kinematic model of the hanging system and finite element model of the forgings are established to investigate the relationships of tension, forging deformation and deformation rate. The rigid-flexible coupling model of DFMS is further established and simulated concerning hydraulics, mechanics and controls. A correction based on the independent feedback state difference is concerned, simulated results show good agreements with experimental data, validating the dead zone compensation algorithm of the proportional valve. Moreover, by the control strategy, the vertical synchronous error of the pincers end is rather small as ± 0.125 mm. The methodology presented in this paper represents a fundamental step towards the cooperation of DFMS and the press to realize collaborative operations.

Effect of Dead Zone Compensation by Mass-Flow-Rate Twin-Drive System with Anti-Windup for Pressure Control System

Effect of Dead Zone Compensation by Mass-Flow-Rate Twin-Drive System with Anti-Windup for Pressure Control System

Observer-based self-organizing adaptive fuzzy neural network control for non-linear, non-affine systems with unknown sign of control gain and dead zone: A case study of pneumatic actuators

In this paper, an observer-based self-organizing adaptive fuzzy neural network (OSOAFNN) control for non-linear, non-affine systems with the unknown sign of control gain and dead zone is presented. First, a reverse dead-zone compensator scheme to cope with the impact of dead-zone phenomenon existing in control input is investigated. Then, an observed-based control approach to address immeasurable states of the system is proposed, utilizing this approach all states of the system are not needed to be available. A self-organizing fuzzy neural network (SOFNN) technique is presented to approximate the non-linear and unknown function of the observer error dynamics. The proposed fuzzy neural network (FNN) model benefits from two main advantages: (1) the number of rules is automatically generated or pruned and (2) the parameters of antecedent and consequent part of SOFNN are updated through the hybrid tuning, simultaneously. Furthermore, the control law contains a Nussbaum function which deals with the unknown sign of control gain. As the system states are immeasurable, the strictly positive real (SPR) Lyapunov function to guarantee the closed-loop system stability, and tracking error convergence to zero is employed, as well as the boundedness of control parameters are assured through a projection law merged with adaptive law. Finally, the controller is practically implemented on a non-linear, non-affine pneumatic system with unknown dead zone which exploits just a sensor for output measuring. Experimental results show that the proposed controller has satisfactory performance in tracking different trajectories, and tracking error for desired signal case I and case II is limited to [−1.5, 1.5] and [−1,1]mm, respectively.

Trajectory Tracking of Autonomous Ground Vehicles with Actuator Dead Zones

This paper investigates the trajectory tracking problem of autonomous ground vehicles (AGVs). The dynamics considered feature external disturbances, model uncertainties, and actuator dead zones. First, a novel time-varying yaw guidance law is proposed based on the line of sight method. By a state transformation, the AGV is proved to realize trajectory tracking control under the premise of eliminating guidance deviation. Second, a fixed time dead zone compensation control method is introduced to ensure the yaw angle tracking of the presented guidance. Furthermore, an improved fixed-time disturbance observer is proposed to compensate for the influence of the actuator dead zone on disturbance observation. Finally, the trajectory tracking control strategy is designed, and simulation comparison shows the effectiveness of the compensate method. The CarSim–MATLAB cosimulation shows that the proposed control strategy effectively makes the AGV follow the reference trajectory.

Dead Zone Compensation Method by Mass Flow Rate Twin Drive System for a Pneumatic Driving System

Dead Zone Compensation Method by Mass Flow Rate Twin Drive System for a Pneumatic Driving System

Research on Control Strategy for Vibration and Noise Reduction of Permanent Magnet Synchronous Motor

In order to reduce the vibration and noise of permanent magnet synchronous motors, this paper proposes a control strategy by analyzing the relationship between the vibration and noise of the permanent magnet synchronous motor and the current harmonics of the inverter based on actual project applications. Some methods include random switching frequency modulation technology, random pulse position modulation technology and dead zone compensation technology on current harmonics are analyzed respectively in this paper. Then this paper proposed a mixed control strategy, which combined with random switching frequency-random and pulse position-dead zone compensation methods. Matlab tools are used to simulation and verification the Mixed control strategy. Simulation and experimental results show that this control strategy can effectively reduce the total underwater noise level of permanent magnet synchronous motors.