Dynamic Friction Compensation Research Articles

Advanced Motion Control of Hydraulic Manipulator With Precise Compensation of Dynamic Friction

Advanced Motion Control of Hydraulic Manipulator With Precise Compensation of Dynamic Friction

Adaptive robust control for fully electric pitch system of tank with dynamic friction compensation

Adaptive robust control for fully electric pitch system of tank with dynamic friction compensation

Proportional-integral-proportional control and compensation design for low-speed motions of permanent magnet synchronous motor driven servomechanism with position-dependent disturbance

ABSTRACT Position-dependent disturbances have a significant impact on the low-speed positional motions of a permanent magnet synchronous motor (PMSM) driven servomechanism; therefore, this study has aimed to develop a control and compensation design, based on the proportional-integral-proportional (PIP) feedback control extensively used in commercialized PMSM drivers, for improving the low-speed positional motions of the PMSM-driven servomechanism without excessively increasing the computational burden on commercialized PMSM drivers and without hardware modifications to commercialized PMSM servomotor packs. The angular position and driving torque signals of the PMSM in low-speed motions were used for a spatial fast Fourier transform analysis to build the position-dependent disturbance model and determine the dominant positional frequencies. Then, a low-speed positional motion control and compensation design was developed that integrates the dynamic compensation, friction compensation, and position-dependent disturbance compensation approaches for the PMSM-driven servomechanism to improve its low-speed positional motion performance. The positional motion experiments performed on a PMSM test bench demonstrated that, in comparison with the PIP feedback control extensively used in commercialized PMSM drivers, the PIP control and compensation designed in this study improved the position and speed responses and suppressed the position and speed fluctuation phenomenon of the PMSM-driven servomechanism during low-speed motions.

Distributed Adaptive Synchronization Control with Friction Compensation of Networked Lagrange Systems

In this paper, the problem of dynamic friction compensation of networked Lagrange system is considered to design the synchronization controller with better performance. LuGre friction model is introduced to obtain accurate description of friction. The tracking control algorithms for certain and uncertain parameters are provided. Control algorithm for certain parameters has lower computation load, while control algorithm for uncertain parameters has the capability of adapting changes by learning from the tracking error. Both control algorithms achieve synchronization rapidly. Simulations are given to show the effectiveness of the proposed tracking algorithm.

High precision tracking control of a servo gantry with dynamic friction compensation

This paper is concerned with the tracking control problem of a voice coil motor (VCM) actuated servo gantry system. By utilizing an adaptive control technique combined with a sliding mode approach, an adaptive sliding mode control (ASMC) law with friction compensation scheme is proposed in presence of both frictions and external disturbances. Based on the LuGre dynamic friction model, a dual-observer structure is used to estimate the unmeasurable friction state, and an adaptive control law is synthesized to effectively handle the unknown friction model parameters as well as the bound of the disturbances. Moreover, the proposed control law is also implemented on a VCM servo gantry system for motion tracking. Simulations and experimental results demonstrate good tracking performance, which outperform traditional control approaches.

Output torque tracking control of direct-drive rotary torque motor with dynamic friction compensation

Accurate output torque tracking control problem of Direct-Drive Rotary (DDR) torque motor is concerned in this paper. An adaptive robust torque control algorithm with LuGre model based dynamic friction compensation is proposed to improve the torque tracking accuracy. Adaptive robust control (ARC) backstepping design technique and Lyapunov stability theorem are employed to design the controller to deal with both structured and unstructured uncertainties in a practical control system. In the ARC algorithm, discontinuous projection based parameter adaptive law is utilized to estimate unknown system parameters, and robust control law ensures the robustness of closed-loop control system. In order to further improve the torque tracking control performance, LuGre model based dynamic friction compensation is designed to estimate and compensate friction torque in the practical torque motor system. The mathematically design procedure of the proposed algorithm is developed. Finally, the proposed algorithm is implemented on a practical DDR torque motor control system. Experimental results with three compared control algorithms validate that the proposed algorithm can effectively improve the torque tracking performance and LuGre model based dynamic friction compensation is also necessary for high-accuracy torque tracking control.

Motorized vehicle active suspension damper control with dynamic friction and actuator delay compensation for a better ride quality

This paper describes motorized active suspension damper control with dynamic friction and actuator delay compensation for an enhanced ride quality. The control algorithm consists of a supervisory controller, an upper-level controller and a lower-level controller. The supervisory controller determines the control modes, such as the passive control modes and the active control mode. The upper-level controller, which incorporates the existing actuator delay, computes the damping force using linear quadratic control theory. The actuator input is determined by the lower-level controller by compensating the dynamic friction torque. To estimate the sprung-mass displacement, the sprung-mass velocity, the unsprung-mass displacement and the unsprung-mass velocity, two state estimators are proposed. An adaptive observer is developed for the non-linear dry friction to estimate the ball-screw dynamic friction caused by the axial movement of the actuator and the viscosity. The performance of the proposed control algorithm was evaluated from simulations. It was shown from simulations that the proposed motorized active suspension damper control with a friction and delay compensation algorithm can improve the ride quality.

Adaptive robust motion trajectory tracking control of pneumatic cylinders with LuGre model-based friction compensation

Friction compensation is particularly important for motion trajectory tracking control of pneumatic cylinders at low speed movement. However, most of the existing model-based friction compensation schemes use simple classical models, which are not enough to address applications with high-accuracy position requirements. Furthermore, the friction force in the cylinder is time-varying, and there exist rather severe unmodelled dynamics and unknown disturbances in the pneumatic system. To deal with these problems effectively, an adaptive robust controller with LuGre model-based dynamic friction compensation is constructed. The proposed controller employs on-line recursive least squares estimation (RLSE) to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. In addition, in order to realize LuGre model-based friction compensation, the modified dual-observer structure for estimating immeasurable friction internal state is developed. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology is applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping is used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Finally, the proposed controller is tested for tracking sinusoidal trajectories and smooth square trajectory under different loads and sudden disturbance. The testing results demonstrate that the achievable performance of the proposed controller is excellent and is much better than most other studies in literature. Especially when a 0.5 Hz sinusoidal trajectory is tracked, the maximum tracking error is 0.96 mm and the average tracking error is 0.45 mm. This paper constructs an adaptive robust controller which can compensate the friction force in the cylinder.

A Research on Dynamic Friction Compensation of High-speed Linear motor

The tracing precision of high-precise linear motor is greatly influenced when moved at a low speed because of the friction. This paper aims at a practical angle, on the base of traditional Stribeck friction model, we added in position parameter to set up a new model .According to the new model, we designed out the forward back controller to identificate and compensate the system. at last, the stability of systems has also been analyzed by using Liapunov functions and LaSalle Invariance Principle.The simulation results shows our model has improved the tracing performance. DOI: http://dx.doi.org/10.11591/telkomnika.v10i8.1645 Full Text: PDF

Results on the Robust Observer-based Position Controller for Parallel Kinematic Machines

The problem of state observation and position control by output feedback for a nonlinear three degrees-of-freedom (3-DOF) parallel kinematic machine (PKM) system is considered, based on the limited signal availability (only the moving platform displacement measurements are assumed available). Unknown velocity signals are estimated via a nonlinear robust observer that is designed for the nonlinear system with observable linear dynamics part and bounded nonlinearities and disturbances, and that guarantees global exponential stability of the observation error. A proportional-derivative (PD) controller is designed to solve the position control problem, utilizing the estimated velocity, as well as the gravitation compensation, dynamic friction and external disturbance compensation for the PKM. The closed-loop system is proven to have global asymptotical stability according to the Lyapunov analysis method and LaSalle's invariance principle. Performance of the resulting observer and controller is illustrated in a simulation study of a 3-DOF PKM. Modifications to the nonlinear observer and control law are discussed, that assure convergence of the position error and state observation error to zero when the upper bounds on the model uncertainties/disturbances are not known a priori.

High Performance Adaptive Control of Mechanical Servo System With LuGre Friction Model: Identification and Compensation

LuGre dynamic friction model has been widely used in servo system for friction compensation, but it increases the difficulty of controller design because its parameters are difficult to be identified and its internal state is immeasurable. This paper presents a parameter identification technique based on novel evolutionary algorithm (NEA) for LuGre friction model. In order to settle the practical digital implementation problem of LuGre model, this paper also proposes a modified dual-observer with discontinuous mapping and smooth transfer function. On the basis of the parameter identification results and the modified dual-observer, this paper designs an adaptive control algorithm with dynamic friction compensation for hydraulic servo system. The comparative experiments indicate that the proposed parameter identification technique and the adaptive control algorithm with modified dual-observer are effective with high tracking performance.

Research on Dynamic Friction Compensation of High-Speed Precision Slider

. 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.

Robust adaptive deadzone and friction compensation of robot manipulator using RWCMAC network

A robust adaptive compensation scheme is presented for compensation of asymmetric deadzone, dynamic friction and uncertainty in the direct-drive robot manipulator. Simple estimation laws are derived to build observers for estimation of deadzone and friction based on the LuGre friction model. A model-free RWCMAC controller to mimic the ideal control law is employed to overcome some shortcomings of the traditional model-based adaptive controller, which requires information on the robots dynamics in advance. The Lyapunov stability analysis yields the adaptive laws of the RWCMAC network as well as observers of deadzone and friction. Furthermore, the stability and optimal convergence speed of the learning rates of the RWCMAC is also guaranteed by employing the fully informed particle swarm (FIPS) algorithm. Robust tracking performance of the proposed control schemes is verified by simulations of direct-drive robots with deadzone in joint input torque, joint dynamic friction and uncertainty.

Adaptive Trajectory Control and Dynamic Friction Compensation for a Flexible-Link Robot

AbstractFriction compensation techniques are studied for control of a flexible-link robot based on the LuGre friction model. To overcome the problem of uncertain parameters in the friction model, adaptive control schemes are used for two different types of parametric uncertainties. A novel dual-observer technique is proposed to estimate the internal state inside the friction model. A distributed-parameter dynamic model is used for the flexible arm to design the controllers. The Lyapunov stability theorem is used to guarantee the global asymptotic stability of the controllers. The performance of position tracking and link vibration attenuation is verified through experimental results. The results also confirm the effectiveness of the proposed friction compensation schemes.

Robust friction state observer and recurrent fuzzy neural network design for dynamic friction compensation with backstepping control

In this article, we investigate a robust friction compensation scheme for the purpose of accomplishing high-precision positioning performance in a servo mechanical system with nonlinear dynamic friction. To estimate the friction state and tackle the robustness problem for uncertainty, a recurrent fuzzy neural network (RFNN) and reconstructed error compensator as well as a robust friction state observer are developed. The asymptotic stability of the series of friction compensation methodologies are verified from the Lyapunov’s stability theory. Some simulations and experiments on a frictional servo mechanical system were carried out to evaluate the effectiveness of the proposed control scheme.

High Precision Position Control Using an Adaptive Friction Compensation Approach

The presented work concerns the development of a trajectory tracking controller which is able to improve clearly the dynamical performance of a high precision positioning stage. Experiments in the pre-rolling and rolling friction regimes are conducted and a hybrid parameter estimation algorithm is used to fit the parameters of a simple dynamic friction model based on experimental data. Further experiments show that the identified model does not represent the system behavior over the whole operating range of 200 mm. To solve this problem the linear model parameters are adjusted online to ensure precise dynamic friction compensation. Finally, the extended friction model is utilized in a feed-forward controller in combination with a standard feedback controller to compensate for the effects of the friction force and other disturbances while moving.

Adaptive robust control of linear motors with dynamic friction compensation using modified LuGre model

LuGre model has been widely used in dynamic friction modeling and compensation. However, there are some practical difficulties when applying it to systems experiencing large range of motion speeds such as, the linear motor drive system studied in the article. This article first details the digital implementation problems of the LuGre model based dynamic friction compensation. A modified model is then presented to overcome those shortcomings. The proposed model is equivalent to LuGre model at low speed, and the static friction model at high speed, with a continuous transition between them. A discontinuous projection based adaptive robust controller (ARC) is then constructed, which explicitly incorporates the proposed modified dynamic friction model for a better friction compensation. Nonlinear observers are built to estimate the unmeasurable internal state of the dynamic friction model. On-line parameter adaptation is utilized to reduce the effect of various parametric uncertainties, while certain robust control laws are synthesized to effectively handle various modeling uncertainties for a guaranteed robust performance. The proposed controller is also implemented on a linear motor driven industrial gantry system, along with controllers with the traditional static friction compensation and LuGre model compensation. Extensive comparative experimental results have been obtained, revealing the instability when using the traditional LuGre model for dynamic friction compensation at high speed experiments and the improved tracking accuracy when using the proposed modified dynamic friction model. The results validate the effectiveness of the proposed approach in practical applications.

Adaptive robust control of mechanical systems with non-linear dynamic friction compensation

In this paper, an adaptive robust control (ARC) scheme based friction compensation strategy is presented for a mechanical system in the presence of dynamic friction effects. The system may be subjected to both parametric uncertainties (e.g., unknown parameters in the dynamic friction model) and uncertain non-linearities such as external disturbances and modelling errors. In contrast to existing deterministic robust control (DRC) and robust adaptive control (AC) schemes, the proposed ARC scheme utilizes both the structural information of the dynamic friction model and the a priori information of the system, such as the bounds on the parameters and unmeasured internal friction state. In particular, the bounds on the friction state are fully exploited to construct certain projection-type modifications to the state observers. By doing so, a controlled state estimation process is achieved even in the presence of disturbances. The resulting controller achieves a guaranteed transient performance and final tracking accuracy. Furthermore, in the absence of uncertain non-linearities, asymptotic position tracking is achieved. Comparative simulation results illustrate the effectiveness of the proposed scheme.

Comparison of Fractional Robust- and Fixed Point Transformations- Based Adaptive Compensation of Dynamic Friction

The features of fractional order robust and fixed-point transformation based adaptive controllers of a “Ball-Beam System” are compared to each other. The speciality of this task is that the position of the ball along the beam is indirectly controlled via directly controlling the other axis, the tilting angle of the beam. It is assumed that this tilting axle suffers from considerable dynamic friction mathematically approximated by the LuGre model. By neglecting the internal physics of the tilting drive this system can be modeled as a 4thorder one because only the 4thtime-derivative of the ball’s position can directly be influenced by the tilting torque. The system also has saturation since the available acceleration of the ball is limited by the gravitation. It is shown that little reduction of the order of the differential equation controlling the decay of the error metrics in a Sliding Mode / Variable Structure controller considerably improves the robust controller. However, really precise solution can be obtained by the adaptive controller. These statements are illustrated and substantiated via simulation.

ADAPTIVE PAYLOAD AND DYNAMIC FRICTION COMPENSATION IN ROBOTIC SYSTEMS

In this paper a tracking control algorithm is introduced for robotic systems with unknown friction in the joints and unknown payload mass and inertia. To perform the adaptive payload compensation, the effect of the payload on dynamic behaviour of the machine is separated from the robot arm dynamics. For adaptive compensation of dynamic LuGre friction, a piecewise linearly parameterized friction model is developed. The tracking performances of the introduced control algorithm is analysed using Lyapunov techniques. Simulation results are presented to show the applicability of the control algorithm.