Closed Loop Step Servo Systems

Mechanical resonance is one of the most pervasive problems in servo control. Closed-loop simulations are requisite when the servo control system with high accuracy is designed. The mathematical model of resonance mode must be considered when the closed-loop simulations of servo systems are done. There will be a big difference between the simulation results and the real actualities of servo systems when the resonance mode is not considered in simulations. Firstly, the mathematical model of resonance mode is introduced in this paper. This model can be perceived as a product of a differentiation element and an oscillating element. Secondly, the second-order differentiation element is proposed to simulate the resonant part and the oscillating element is proposed to simulate the antiresonant part. Thirdly, the simulation approach for two resonance modes in servo systems is proposed. Similarly, this approach can be extended to the simulation of three or even more resonances in servo systems. Finally, two numerical simulation examples are given.

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Output-Feedback Position Tracking Servo System with Feedback Gain Learning Mechanism via Order-Reduction Speed-Error-Stabilization Approach

Actuators ◽

10.3390/act10120324 ◽

2021 ◽

Vol 10 (12) ◽

pp. 324

Author(s):

Sung Hyun You ◽

Seok-Kyoon Kim ◽

Hyun Duck Choi

Keyword(s):

System Parameter ◽

Closed Loop ◽

Order Reduction ◽

Feedback Gain ◽

Position Tracking ◽

Position Measurement ◽

Servo Systems ◽

Learning Mechanism ◽

Speed Error ◽

Hardware Configuration

This paper presents a novel trajectory-tracking technique for servo systems treating only the position measurement as the output subject to practical concerns: system parameter and load uncertainties. There are two main contributions: (a) the use of observers without system parameter information for estimating the position reference derivative and speed and acceleration errors and (b) an order reduction exponential speed error stabilizer via active damping injection to enable the application of a feedback-gain-learning position-tracking action. A hardware configuration using a QUBE-servo2 and myRIO-1900 experimentally validates the closed-loop improvement under various scenarios.

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Backstepping control for gear transmission servo systems with unknown partially nonsymmetric deadzone nonlinearity

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406216639343 ◽

2016 ◽

Vol 231 (14) ◽

pp. 2580-2589 ◽

Cited By ~ 1

Author(s):

Zhiguang Shi ◽

Zongyu Zuo ◽

Hao Liu

Keyword(s):

Tracking Control ◽

Closed Loop ◽

Gear Transmission ◽

Closed Loop System ◽

Unknown Parameters ◽

Servo Systems ◽

Output Tracking ◽

Output Tracking Control ◽

Break Points ◽

Backstepping Controller

This paper deals with the output tracking control of gear transmission servo (GTS) systems in the presence of deadzone nonlinearity with nonsymmetric beak points and unknown parameters. A novel differentiable deadzone model with nonsymmetric break points is put forward, which greatly facilitates the control design for a class of mechanical systems in the presence of deadzone nonlinearity. A new smooth backstepping controller, based on the newly-developed model, is proposed for the nominal system. Then, guaranteed robust steady-state performance of the closed-loop system with parametric uncertainties is derived by using Lyapunov analysis for the perturbed nonlinear systems. Simulations are carried out to validate the proposed algorithm and analysis in this paper.

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Experimental evaluation of the parameter-based closed-loop transfer function identification for electro-hydraulic servo systems

Advances in Mechanical Engineering ◽

10.1177/1687814016684425 ◽

2017 ◽

Vol 9 (1) ◽

pp. 168781401668442 ◽

Cited By ~ 2

Author(s):

Guang-Da Liu ◽

Ge Li ◽

Gang Shen

Keyword(s):

Closed Loop ◽

Transfer Functions ◽

Servo System ◽

Proportional Integral Derivative ◽

Servo Systems ◽

Closed Loop Systems ◽

Loop Transfer Function ◽

Tracking Controllers ◽

Hydraulic Servo ◽

Hydraulic Servo System

Closed-loop systems of an electro-hydraulic servo system including position, acceleration, and force closed-loop systems and their closed-loop transfer functions based on parameter model are adaptive identified using a recursive extended least-squares algorithm. The position and force closed-loop tracking controllers are designed by a proportional–integral–derivative controller and are tuned by the position and force step signals. The acceleration closed-loop tracking controller is designed by a three-variable controller and the three states include position, velocity, and acceleration. Experimental results of the estimated position, acceleration, and force closed-loop transfer functions are performed on an actual electro-hydraulic servo system using xPC rapid prototyping technology, which clearly demonstrate the benefit of the adaptive identification method.

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Direct force control for human-machine system with friction compensation

Kybernetes ◽

10.1108/k-08-2015-0205 ◽

2016 ◽

Vol 45 (5) ◽

pp. 760-771 ◽

Cited By ~ 1

Author(s):

Lie Yu ◽

Jianbin Zheng ◽

Yang Wang ◽

Enqi Zhan ◽

Qiuzhi Song

Keyword(s):

Control Strategy ◽

Force Control ◽

Closed Loop ◽

Static Friction ◽

Low Velocity ◽

Servo Systems ◽

Content Type ◽

Machine System ◽

Rotary Joint ◽

Machine Force

Purpose – The purpose of this paper is to present a direct force control which uses two closed-loop controller for one-degree-of-freedom human-machine system to synchronize the human position and machine position, and minimize the human-machine force. In addition, the friction is compensated to promote the performance of the human-machine system. Design/methodology/approach – The dynamic of the human-machine system is mathematically modeled. The control strategy is designed using two closed-loop controllers, including a PID controller and a PI controller. The frictions, which exist in the rotary joint and the hydraulic wall, are compensated separately using the Friedland’s observer and Dahl’s observer. Findings – When human-machine system moves at low velocity, there exists a significant amount of static friction that hinders the system movements. The simulation results show that the system gives a better performance in human-machine position synchronization and human-machine force minimization when the friction is compensated. Research limitations/implications – The acquired results are based on simulation not experiment. Originality/value – This paper is the first to apply the electrohydraulic servo systems to both actuate the human-machine system, and use the direct force control strategy consisting of two closed-loop controllers. It is also the first to compensate the friction both in the robot joint and hydraulic wall.

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