Desired Tracking Precision Research Articles

Moedling and Control Strategy of a Multi-Pump Multi-Actuator Hydraulic System With On/Off Valve Matrix

A single-pump multi-actuator hydraulic system has an amount of coupling loss because the output pressure of the pump adapts the actuator with the highest load and the other actuators with lower loads have to consume the pressure difference in throttling valves. In this paper, a multi-pump multi-actuator system with on/off valve matrix is developed to reduce the coupling throttling loss. The total flow rate of all pumps matches the requirement of all actuators so as to avoid unnecessary increase of installation power. With the help of the on/off valve matrix, on the one hand, the multiple actuators can be decoupled into several single-pump single actuator systems separately in low flow demand. On the other hand, the multiple pumps can interflow to satisfy large flow demand. A two-level control strategy is proposed to achieve energy saving and good precision tracking simultaneously. The first level is to control the on/off switches and actuator modes based on the optimal energy consumption. The second level is to control the pumps and the throttling valves aiming at desired tracking precision. In addition, a compensation strategy is proposed to reduce the flow shock in on/off switches by transiting the control signals smoothly. Finally, the effectiveness of the proposed hydraulic system and control strategy are verified by experimental results.

Digital control design for an IPMC actuator using adaptive optimal proportional integral plus method: Simulation and experimental study

In this paper, the application of a novel digital control method, called adaptive optimal proportional-integral-plus (AOPIP), to beam-like ionic polymer-metal composite (IPMC) actuators is investigated. First, as a gray-box system, the dynamical model of the IMPC cantilevers is obtained and then AOPIP method is derived and applied to several IPMCs with different physical properties to evaluate the efficacy of the control method. Basically, AOPIP is a proportional-integral-plus (PIP) controller with two additional terms; an optimal gain tuner mechanism with means of linear quadratic regulator (LQR) method and an adaptation term based on recursive least square (RLS) method with Kalman filter (KF), RLS-KF. Therefore, the main advantages of this controller are a) independence of parameters of the system; and b) an optimal performance. To perform a comparative study, in addition to AOPIP, a digital PID controller is designed and applied to the system in simulation. Besides, the comparison of opened-loop techniques to closed-loop ones is investigated as well. Furthermore, an experimental test for comparing AOPIP and digital PID is performed to show the performance of the IPMC in real-time, and under real conditions such as existence of external noise and disturbances. Using several proper numerical indicators, both simulation and experimental results demonstrate the efficacy of the AOPIP and its superiority to the opened-loop techniques and digital PID controller in terms of control effort, desired tracking precision of the IPMCs actuators and its optimality.

A mechatronic approach for ball screw drive system: modeling, control, and validation on an FPGA-based architecture

This paper presents a novel mechatronic approach to modeling, control design, and experimental validation of a two-axis high-accuracy ball screw drive system. At first, a general mathematical model is developed by the Lagrange’s equation of Motion to characterize the dynamic behaviors of all the variables for an N-degrees of freedom system that includes electric behavior of the DC motors. Thus, the model provides a general framework for the control algorithm design. A robust PD-hyperbolic–type control strategy is proposed based on the representation of a nonlinear dynamic model for the trajectory tracking that solves the problem of regulation and position control. The stability method of Lyapunov is applied; in addition, the asymptotic stability of an equilibrium point is analyzed for the closed-loop dynamic model. The proposed control law ensures the dynamic performance of the closed-loop signals and desired tracking precision. On the other hand, the description of a new and original FPGA-based programmable microprocessor design is introduced which consists of its own design approaches of a hardware/software architecture. Finally, based on a built prototype of a ball screw drive system, experimental tests and simulations with motion trajectory tracking are conducted to verify the proposed general mathematical model and the control law. Experimental results demonstrate an excellent tracking trajectory and desired precision performance, which validates the feasibility and effectiveness of the proposal.

Adaptive resource management in multiple targets tracking for co‐located multiple input multiple output radar

Co-located multiple input multiple output (MIMO) radar is one kind of new style radar, whose transmitting waveforms of each sub-array are orthogonal to each other. Compared with phased array radar, its beam width is wider. Therefore, different targets may be illuminated simultaneously with one beam in co-located MIMO radar. An adaptive resource management in tracking for co-located MIMO radar is proposed, where the sub-array number, the illuminated targets set and the transmitting waveform of the system can be controlled. The optimal parameters are chosen according to a cost function that takes both the desired tracking precision and consumed energy into consideration. Simulation results demonstrate the effectiveness of the algorithm. Using the algorithm, co-located MIMO radar can achieve the desired tracking precision with less cost compared with phased array radar.

Motion Control of Piezoelectric Positioning Stages: Modeling, Controller Design, and Experimental Evaluation

In this paper, a general skeleton on modeling, controller design, and applications of the piezoelectric positioning stages is presented. Toward this framework, a general model is first proposed to characterize dynamic behaviors of the stage, including frequency response of the stage, voltage-charge hysteresis and nonlinear electric behavior. To illustrate the validity of the proposed general model, a dynamic backlash-like model is adopted as one of hysteresis models to describe the hysteresis effect, which is confirmed by experimental tests. Thus, the developed model provides a general frame for controller design. As an illustration to this aspect, a robust adaptive controller is developed based on a reduced dynamic model under both unknown hysteresis nonlinearities and parameter uncertainties. The proposed control law ensures the boundedness of the closed-loop signals and desired tracking precision. Finally, experimental tests with different motion trajectories are conducted to verify the proposed general model and the robust control law. Experimental results demonstrate the excellent tracking performance, which validates the feasibility and effectiveness of the proposed approach.

Adaptive Regulation of Tracking Servo for Next Generation Optical Data Storage Systems

The tracking servo control has played an important role in the data storage servo systems. In the next generation optical data storage systems, i.e. the near-field recording system, the tracking error of the servo system should be below 10 nanometers under various unknown situations. However, higher data transfer rate and higher data density make it difficult to maintain the desired tracking precision during normal disk operation. It is proposed in this paper to use an adaptive regulation approach to maintain the tracking error below its desired value, despite unknown track eccentricity and external force disturbance. The performance of the proposed control approach is analyzed and simulation results are presented to illustrate the capability of the proposed adaptive regulator to achieve and maintain the desired tracking precision.

Output Variables Control in Mechanical Systems

Manipulator endpoint location autonomous control procedures are suggested. A method of uplimited control hierarchy has been designed, which allows to provide a desired tracking precision under conditions of uncertainty of the control object operator and the effect of external unmeasured disturbances. Sliding mode state observers synthesis procedures have been designed, which allow, in a theoretically limited time interval, to obtain information on immeasurable variables of the state vector and available uncertainty. The results of the designed algorithms modeling are presented.

Direct Method of Manipulator Endpoint Control Synthesis

Manipulator endpoint location autonomous control procedures are suggested. A method of uplimited control hierarchy has been designed, which allows to provide a desired tracking precision under conditions of uncertainty of the control object operator and the effect of external unmeasured disturbances. Sliding mode state observers synthesis procedures have been designed, which allow, in a theoretically limited time interval, to obtain information on immeasurable variables of the state vector and available uncertainty. The results of the designed algorithms modeling are presented.

Adaptive sliding inverse control of a class of non-linear systems preceded by unknown non-symmetrical dead-zone

This paper deals with the adaptive control of a class of continuous-time non-linear dynamic systems preceded by unknown non-symmetrical, non-equal slope dead-zones. By exploring the properties of the dead-zone model intuitively and mathematically, a dead-zone inverse is constructed. Based on this inverse construction, an adaptive sliding controller is designed. Lyapunov stability analysis shows that the proposed adaptive control law ensures global stability of the adaptive system and achieves desired tracking precision. Simulation results attained for an uncertain non-linear system are presented to illustrate and further validate the effectiveness of the proposed approach.

Robust adaptive control of a class of nonlinear systems with unknown dead-zone

This paper deals with the adaptive control of a class of continuous-time nonlinear dynamic systems preceded by an unknown dead-zone. By using a new description of a dead-zone and by exploring the properties of this dead-zone model intuitively and mathematically, a robust adaptive control scheme is developed without constructing the dead-zone inverse. The new control scheme ensures global stability of the adaptive system and achieves desired tracking precision. Simulations performed on a typical nonlinear system illustrate and clarify the validity of this approach.

Model reference adaptive control of continuous-time systems with an unknown input dead-zone

The adaptive control of continuous-time linear dynamic systems preceded by an unknown dead-zone in state space form is discussed. A lemma to simplify the error equation between the plant and the matching reference model is introduced which allows the development of a robust adaptive control scheme by involving the dead-zone inverse terms. This adaptive control law ensures global stability of the entire system and achieves the desired tracking precision even when the slopes of the dead-zone are unequal. Simulations performed on a typical linear system illustrate and clarify the validity of this approach.