A Novel Virtual Sensor for Estimating Robot Joint Total Friction Based on Total Momentum

Xu, Tian; Fan, Jizhuang; Fang, Qianqian; Wang, Shoulong; Zhu, Yanhe; Zhao, Jie

doi:10.3390/app9163344

Cited by 6 publications

(5 citation statements)

References 47 publications

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“…erefore, it can be known that (e, _ e) � (0, 0) is the global asymptotically stable equilibrium point of the exoskeleton system from the LaSalle theorem. In addition, more similar robot controller stability analyses can also be found in [31,37,38].…”

Section: System Stability Analysismentioning

confidence: 99%

A Simplified Inverse Dynamics Modelling Method for a Novel Rehabilitation Exoskeleton with Parallel Joints and Its Application to Trajectory Tracking

Fang

et al. 2019

Mathematical Problems in Engineering

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In this paper, a new modular upper limb rehabilitation exoskeleton, which is actuated by a parallel mechanical structure, is designed to help stroke patients. For analysing the relationship between motor torque and joint torque of the novel exoskeleton, a conversion algorithm mapping motor motion to joint motion is developed here. Then, to simplify the dynamics model of exoskeleton with parallel actuated joints, the serial equivalence configuration dynamics of the exoskeleton is established to be equivalent to the parallel joints dynamics. Afterwards, a torque controller used for our exoskeleton is designed based on the proposed conversion algorithm and the inverse dynamics of exoskeleton. It should be noted that the controller mentioned above combines both conversion algorithm and joint position decoupling. At last, for verifying the effectiveness of the proposed algorithms, a trajectory tracking simulation is given, and the simulated results show the proposed algorithms are valid.

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Section: System Stability Analysismentioning

confidence: 99%

A Simplified Inverse Dynamics Modelling Method for a Novel Rehabilitation Exoskeleton with Parallel Joints and Its Application to Trajectory Tracking

Fang

et al. 2019

Mathematical Problems in Engineering

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“…With an increase in speed, the joint friction effect becomes significant [20,21], and friction effect plays an important role in controlling and tracking the accuracy of the parallel manipulator [22]. Unsworth's [23] experiments with artificial hip joint friction measurements using the Durham friction simulator showed that hip joint friction under high loads cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Analysis and Trajectory Tracking Control for a Parallel Manipulator with Joint Friction

Chen

Pang

2022

Applied Sciences

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To overcome the bearing capacity deficiencies of traditional serial hip joint simulators, complex trajectory simulation, among others, as well as a parallel manipulator with two pairs of artificial hip joints and two moving platforms are proposed. The movements and driving forces of the parallel manipulator under the required motion and loading are studied to provide a basis for further research. In this study, the modeling and analysis of inverse kinematics and dynamics for a parallel manipulator with joint friction are derived. In the inverse kinematic model, kinematic relationships between the linear module slider and the moving platform are established, and expressions for the slider are deduced. Subsequently, by analyzing the frictional forces of the artificial hip joint and thrust ball bearing, a rigid body dynamics model of the parallel manipulator with joint friction is established, which is subsequently decomposed into four driving torques associated with the moving platform, joint lever, slider, and screw. Finally, the difference in the kinematic performance between the two moving platforms is analyzed using numerical simulations and experiments, and the accuracy of the established model is verified.

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“…This process is performed by rewriting the equations in matrix form and linear regression, using the least-squares method. Xu et al 5 showed the total friction in the system by one term in these equations and considered it a disturbance term, and designed a virtual sensor to observe its value by considering the dynamic equations of the system. For the obtained equation, a diagonal matrix was developed to determine its correct values, and subsequently to result in the precise friction value.…”

Section: Introductionmentioning

confidence: 99%

Extended nonlinear time-varying lugre-based friction model identification of robot manipulator with sliding mode control compensation approach

Moradi

Korayem

Lademakhi

2022

Proceedings of the Institution of Mechanical Engineers, Part I:

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In this article, the values of torque loss due to the friction phenomenon in the robot joints are initially identified; then, by considering the lugre friction model and applying the nonlinear least-squares error-estimation method, a model for this phenomenon is presented. To make the studies more efficient, the general lugre friction model has been used in three forms for modeling the system’s friction that the first model was the general lugre model, and in the other two Extended models, the parameters are considered as time variables that are estimated online. It should be noted that the third model includes the nonlinear viscous term too. Then, by using the nonlinear sliding mode controller, which is a robust control against possible uncertainties in the system, the performance of the designed algorithms is examined. The results show the superiority of the identified models with time-varying parameters over the model with constant parameters. Finally, by the use of represented friction models, a more accurate model for this system has been introduced. Eventually, the results of the simulations have been tested on a 6R laboratory robot to prove the validation of the results with the proposed algorithm, and as it showed, the final friction model has performed better.

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A Novel Virtual Sensor for Estimating Robot Joint Total Friction Based on Total Momentum

Cited by 6 publications

References 47 publications

A Simplified Inverse Dynamics Modelling Method for a Novel Rehabilitation Exoskeleton with Parallel Joints and Its Application to Trajectory Tracking

A Simplified Inverse Dynamics Modelling Method for a Novel Rehabilitation Exoskeleton with Parallel Joints and Its Application to Trajectory Tracking

Dynamic Analysis and Trajectory Tracking Control for a Parallel Manipulator with Joint Friction

Extended nonlinear time-varying lugre-based friction model identification of robot manipulator with sliding mode control compensation approach

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