Velocity-Free Adaptive Time Delay Control of Robotic System

To improve the trajectory tracking performance of a complex nonlinear robotic system, a velocity-free adaptive time delay control is proposed. First, considering that conventional time delay control (TDC) may cause large time delay estimation (TDE) error under nonlinear friction, a TDC with gradient estimator is designed. Next, since it is complicated and time-consuming to adjust gains manually, an adaptive law is designed to estimate the gain of the gradient. Finally, in order to avoid the measurement of velocity and acceleration in the controller while enabling the robot to implement position tracking, an observer is designed. The proposed control can not only offset the nonlinear terms in the complex dynamics of the robotic system but also reduce the TDE error, estimate the gain of the gradient online, and avoid the measurement of velocity and acceleration. The stability of the system is analyzed via Lyapunov function. Simulations are conducted on a 2-DOF robot to verify the effectiveness of the proposed control.

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The Development of Anti-Windup Scheme for Time Delay Control With Switching Action Using Integral Sliding Surface

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.1636775 ◽

2003 ◽

Vol 125 (4) ◽

pp. 630-638 ◽

Cited By ~ 10

Author(s):

Sung-Uk Lee ◽

Pyung Hun Chang

Keyword(s):

Time Delay ◽

Sliding Mode ◽

Control Area ◽

Time Delay Estimation ◽

Sliding Surface ◽

Time Delay Control ◽

Delay Control ◽

Switching Action ◽

Integral Sliding Surface ◽

The Stability

The Time Delay Control with Switching Action (TDCSA) method, which consists of Time Delay Control (TDC) and a switching action of sliding mode control (SMC), has been proposed as a promising technique in the robust control area where the plant has an unknown dynamics with parameter variations and substantial disturbances are preset. When TDCSA is applied to the plant with saturation nonlinearity, however, the so-called windup phenomenon is observed to arise, causing excessive overshoot and instability. The integral element of TDCSA and the saturation element of a plant cause the windup phenomenon. There are two integral effects in TDCSA. One is the integral effect caused by time delay estimation of TDC. The other is the integral term of an integral sliding surface. To solve this problem, we have proposed an anti-windup scheme method for TDCSA. The stability of the overall system has been proved for a class of nonlinear system. Experimental results show that the proposed method overcomes the windup problem of the TDCSA.

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Stability of Uncertain Linear Systems With Time Delay

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.2896458 ◽

1991 ◽

Vol 113 (4) ◽

pp. 558-567 ◽

Cited By ~ 41

Author(s):

K. Youcef-Toumi ◽

J. Bobbett

Keyword(s):

Time Delay ◽

Linear Time ◽

Sufficient Condition ◽

Single Input Single Output ◽

Time Delay Control ◽

Linear Time Invariant ◽

Single Output ◽

Uncertain Dynamics ◽

Delay Control ◽

The Stability

The control of systems with uncertain dynamics and unpredictable disturbances has raised some challenging problems. This is particularly important when high system performance is to be guaranteed at all times. Recently, Time Delay Control has been suggested as an alternative control scheme. The proposed control system does not require an explicit plant model nor does it depend on the estimation of specific plant parameters. Rather, it combines adaptation with past observations to directly estimate the effect of the plant dynamics. This paper outlines the Time Delay Control law for a class of linear dynamic systems and then presents a sufficient condition for stability of linear uncertain systems with time delay. The ideas of Nyquist and Kharitonov are used in the development of a sufficient condition, which does not resort to using approximations for time delay. Like Nyquist, the condition depends on maps of the Nyquist path and, like Kharitonov, stability depends on four functions each yielding a stable system. In this paper we combine these ideas to determine the stability of systems where the Time Delay Controller is applied to single input single output, linear time-invariant plants whose coefficients are known to vary within certain defined intervals. The development is carried out in the context of Time Delay Control but it can be applied in more general cases. Two examples will illustrate the approach and the usefulness of the technique.

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Multistability in the Centrifugal Governor System Under a Time-Delay Control Strategy

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4044501 ◽

2019 ◽

Vol 14 (11) ◽

Author(s):

Shuning Deng ◽

Jinchen Ji ◽

Shan Yin ◽

Guilin Wen

Keyword(s):

Time Delay ◽

Control Strategy ◽

Large Amplitude ◽

Stability Boundary ◽

Physical Parameters ◽

Time Delay Control ◽

Delay Control ◽

Delayed Feedback Controller ◽

Trivial Equilibrium ◽

The Stability

Abstract The centrifugal governor system plays an indispensable role in maintaining the near-constant speed of engines. Although different arrangements have been developed, the governor systems are still applied in many machines for its simple mechanical structure. Therefore, the large-amplitude vibrations of the governor system which can lead to the function failure of the system should be attenuated to guarantee reliable operation. This paper adopts a time-delay control strategy to suppress the undesirable large-amplitude motions in the centrifugal governor system, which can be regarded as the practical application of the delayed feedback controller in this system. The stability region of the trivial equilibrium of the controlled system is determined by investigating the characteristic equation and generic Hopf bifurcations. It is found that the dynamic behavior of multistability can be induced by the Bautin bifurcation, arising on the stability boundary of the trivial equilibrium with a constant delay. More specifically, a coexistence of two desirable stable motions, i.e., an equilibrium or a small-amplitude periodic motion, can be observed in the controlled centrifugal governor system without changing the physical parameters. This is a new feature of the motion control in the centrifugal governor systems, which has not yet been reported in the existing studies. Finally, the results of theoretical analyses are verified by numerical simulations.

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A new discrete-time robust adaptive time-delay control for a class of uncertain nonlinear strict-feedback systems using sliding mode

ISA Transactions ◽

10.1016/j.isatra.2019.03.005 ◽

2019 ◽

Vol 93 ◽

pp. 40-54 ◽

Cited By ~ 1

Author(s):

Omid Mohammadpour ◽

Ali Tavasoli

Keyword(s):

Time Delay ◽

Discrete Time ◽

Sliding Mode ◽

Feedback Systems ◽

Time Delay Control ◽

Delay Control ◽

Adaptive Time ◽

Robust Adaptive ◽

Strict Feedback

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A new fuzzy time-delay control for cable-driven robot

International Journal of Advanced Robotic Systems ◽

10.1177/1729881419835017 ◽

2019 ◽

Vol 16 (2) ◽

pp. 172988141983501 ◽

Cited By ~ 1

Author(s):

Surong Jiang ◽

Yaoyao Wang ◽

Feng Ju ◽

Bai Chen ◽

Hongtao Wu

Keyword(s):

Time Delay ◽

Trajectory Tracking ◽

Time Delay Estimation ◽

Delay Estimation ◽

Experimental Result ◽

Tracking Accuracy ◽

Nonlinear Controller ◽

Time Delay Control ◽

Delay Control ◽

Mean Square Errors

To overcome the problems of structural parametric uncertainty and cable transmission model complexity, a nonlinear controller based on time-delay estimation and fuzzy self-tuning is proposed. The unknown dynamics and disturbances are estimated by time delaying the state of motion immediately before. The control gains are self-tuned by a fuzzy controller, which can reduce the errors caused by system’s uncertainties and external disturbances. Compared with the conventional Proportional-derivative (PD) and time-delay control, the result shows that the proposed control scheme based on time-delay estimation can improve the joint trajectory tracking accuracy of cable-driven robot by significantly reducing the control gains. With the PD gains self-tuned by fuzzy strategy, the mean square errors of trajectory tracking are decreased approximately by 5–20% more than the conventional time-delay control with constant gains. In addition, the experimental result shows that the proposed method has an effective inhibitory effect on dead zone in cable-driven joints. Experiment performed on position tracking control of a 2-degree-of-freedom cable-driven robot is presented to illustrate that the controller has the advantages of simple and reliable structure, model-free, strong robustness, and high tracking accuracy.

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Time delay control of cable-driven manipulators with artificial bee colony algorithm

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-2017-0043 ◽

2018 ◽

Vol 42 (2) ◽

pp. 177-186 ◽

Cited By ~ 3

Author(s):

Fei Yan ◽

Yaoyao Wang ◽

Wei Xu ◽

Bai Chen

Keyword(s):

Time Delay ◽

Artificial Bee Colony ◽

Control Method ◽

Weight Ratio ◽

Time Delay Estimation ◽

Time Delay Control ◽

Tuning Method ◽

Model Free ◽

Bee Colony ◽

Delay Control

Cable-driven manipulators (CDM) are widely-used for their unique advantages such as light weight, low moving mass, high payload-to-weight ratio, and large reachable workspace. However, their complex dynamic character and low stiffness with flexible joints make the control design much more difficult than for traditional robot manipulators. In this paper, time delay control (TDC), which combines the proportional-integral–derivative (PID) control method and time delay estimation (TDE) technology, will be investigated to build a model-free controller for CDM. PID parameters are reduced dramatically as TDE compensates for a large proportion of unknown dynamics. To handle the problem in tuning parameters of this controller, artificial bee colony (ABC) algorithm is utilized to obtain optimal parameters of PID. Finally, simulations are conducted to verify the effectiveness of the propose controller and the tuning method.

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