Torque Control in Harmonic Drives with Nonlinear Dynamic Friction Compensation

2004 ◽  
Vol 16 (4) ◽  
pp. 388-396 ◽  
Author(s):  
Rached Dhaouadi ◽  
Keyword(s):  
Differential Equation ◽  
Computer Simulation ◽  
Torque Control ◽  
Nonlinear Observer ◽  
Position Tracking ◽  
Friction Compensation ◽  
Dynamic Friction ◽  
Nonlinear Stiffness ◽  
Nonlinear Friction ◽  
Harmonic Drive

This paper proposes a nonlinear observer-based controller designed to compensate for friction in harmonic drives with hysteresis. Hysteresis in a harmonic drive is described by a nonlinear differential equation representing the combination of nonlinear stiffness and nonlinear friction. Nonmeasurable friction is derived using a nonlinear observer to provide asymptotic stability and position tracking. The performance of the proposed system is confirmed by computer simulation.

Friction Compensation of Geared Actuators With High Presliding Stiffness

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Myo Thant Sin Aung ◽  
Ryo Kikuuwe ◽  
Motoji Yamamoto
Keyword(s):  
Static Friction ◽  
The Other ◽  
New Method ◽  
Friction Compensation ◽  
Dynamic Friction ◽  
Kinetic Friction ◽  
Harmonic Drive ◽  
Rate Dependent ◽  
Friction Models ◽  
Three Components

Most of existing friction compensation techniques are based on friction models that uses the velocity as its input. These methods are difficult to apply to inexpensive encoder-based actuator systems that do not exhibit sufficiently large presliding displacement. This paper presents a new method of friction compensation that can be applied to geared actuators with high presliding stiffness. The compensator consists of three components that compensate: (a) static friction, (b) rate-dependent kinetic friction, and (c) dynamic friction involving presliding viscoelasticity. The first component employs dither-like torque command, and the other two are based on friction models involving precalibrated parameters. The proposed method is validated through experiments employing a harmonic drive transmission. In particular, it is suggested that the dither-like static friction compensation and the viscosity in the presliding model significantly improve the performance of the compensator.

Nonlinear Friction Compensation of a Flexible Robotic Joint with Harmonic Drive

2017 ◽  
Vol 868 ◽  
pp. 39-44
Author(s):  
Peng Fei Zeng ◽  
Ge Dong Jiang ◽  
Chuang Zou ◽  
Xian Zhang ◽  
Cheng Xuan Xie
Keyword(s):  
Control Strategies ◽  
Industrial Robot ◽  
Friction Compensation ◽  
Nonlinear Friction ◽  
Harmonic Drive ◽  
Stribeck Effect ◽  
Compensation Control ◽  
Polynomial Fit ◽  
Feedback Compensation ◽  
Control Accuracy

To suppress the abrupt and unexpected turning velocity fluctuation of the industrial robot under the condition of trajectory tracking, a flexible robotic joint experimental setup with the harmonic drive was established. The measured friction with Stribeck effect and velocity were modeled by a simple polynomial fit method. Two friction compensation control strategies of feedforward and feedback were designed. The friction compensation experiments were carried out on the dSPACE system, the good restraint effect of fluctuation on the turning velocity was verified and the control accuracy of feedback compensation control strategy proved better.

H ∞ -Based Robust Torque Control of Harmonic Drive Systems

1998 ◽  
Vol 123 (3) ◽  
pp. 338-345 ◽  
Author(s):  
H. D. Taghirad ◽  
P. R. Be´langer
Keyword(s):  
Closed Loop ◽  
Loop System ◽  
Torque Control ◽  
Free Motion ◽  
Friction Compensation ◽  
Harmonic Drive ◽  
Constrained Motion ◽  
Closed Loop System ◽  
Experimental Frequency ◽  
Low Frequencies

In this paper, the torque control of a harmonic drive system for constrained-motion and free-motion applications is examined in detail. A nominal model for the system is obtained in each case from experimental frequency responses of the system, and the deviation of the system from the model is encapsulated by a multiplicative uncertainty. Robust torque controllers are designed using this information in an H∞-framework, and implemented on two different setups. From time and frequency domain experiments, it is shown that the closed-loop system retains robust stability, while improving the tracking performance exceptionally well. To further improve the performance of the system for free-motion case, a feedforward friction-compensation algorithm is implemented in addition to the robust torque control. It is shown that friction-compensation will shrink the model uncertainty at low frequencies and hence, the performance of the closed-loop system will be improved at those frequencies.

Research on Dynamic Friction Compensation of High-Speed Precision Slider

2011 ◽  
Vol 130-134 ◽  
pp. 2742-2745
Author(s):  
Sun Hua ◽  
Yue Hong Dai ◽  
Chuan Sheng Tang
Keyword(s):  
Mathematical Model ◽  
High Speed ◽  
Linear Motor ◽  
Experimental Results ◽  
Friction Compensation ◽  
Dynamic Friction ◽  
Nonlinear Friction ◽  
Feed Forward ◽  
Liapunov Functions

. The tracing precision is greatly influenced because of the friction when high-precise linear motor moved in a low speed.Explore the ways of nonlinear friction compensation in a practical angle. A tribology mathematical model has been found based on the viscoplasticity theory and Stribeck friction mathematical model.This paper aims at applying the Stribeck friction mathematical model to linear motor slider system and designing the controller.The controller can be designed by the feed-forward Integral to conduct identification and compensation online, according to the characters of tribology model.the stability of systems has also been analyzed by using Liapunov functions and LaSalle Invariance Principle.As has been demonstrated by the experimental results, the friction compensation of this model has improved the tracing performance of linear motor slider system.

scholarly journals Sightline Jitter Minimization and Shaping Using Nonlinear Friction Compensation

2007 ◽  
Vol 1 (3) ◽  
pp. 259-283 ◽  
Author(s):  
David Anderson ◽  
Matt MacDonald ◽  
Paul Ingleby ◽  
Nick Brignall
Keyword(s):  
Friction Compensation ◽  
Nonlinear Friction
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