A Robust Method Based on Dual Encoders to Eliminate Velocity Ripple for Modular Drive Joints

Xin, Qiang; Chen, Chin-Yin; Wang, Chongchong; Yang, Guilin; Zhang, Chi; Fang, Zaojun; Chen, C. L. Philip

doi:10.3390/act9040135

Cited by 4 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In earlier works, the modular joint system is described as a simplified two-inertia model in (2). Figure 4 shows the rigid-body state observer, where the nominal model J n is the sum of motor inertia and load inertia, expressed as J n = J m + J l .…”

Section: Rigid-body State Observer Designmentioning

confidence: 99%

“…The modular joint with flexible Harmonic Drive (HD) is commonly used in collaborative robots due to its lightweight, high gear reduction ratio, and high power density [1]. However, its inherent resonance is easy to induce vibration if the command velocity changes abruptly, seriously affecting the system stability [2]. Moreover, due to the inaccurate dynamic models and impeded external disturbances, the accuracy of velocity control seriously degrades.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Robust Vibration Control Based on Rigid-Body State Observer for Modular Joints

et al. 2021

Self Cite

View full text Add to dashboard Cite

The vibration caused by resonance modes frequently occurs during acceleration and deceleration of the modular joint integrated with flexible harmonic drive. The conventional equivalent rigid-body velocity method with observer can suppress the residual vibration induced by resonant frequency but has poor robustness to model uncertainties and external disturbances. Moreover, it cannot eliminate the torque ripple caused by the harmonic drive during low-speed uniform motion, reducing the velocity tracking accuracy. Hence, a velocity controller with a rigid-body state observer and an adjustable damper is designed to improve the robust performance and velocity tracking accuracy. The designed rigid-body state observer allows a higher gain so that the bandwidth of the observer can increase, and the equivalent rigid-body velocity can be acquired more accurately. Notably, the high gain observer reduces the sensitivity to model uncertainties and exotic disturbances, especially near the resonant frequency. In addition, the observer combined with an adjustable damper can suppress the residual vibration and torque ripple simultaneously. The proposed method is compared experimentally with a PI method and two other rigid-body velocity methods, such as the conventional equivalent rigid-body observer method and the self-resonance cancellation method, to verify its advantages.

show abstract

Section: Rigid-body State Observer Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Robust Vibration Control Based on Rigid-Body State Observer for Modular Joints

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, the lightweight design reduces the mechanical body's stiffness, leading to vibrations easily, which seriously affects the accuracy of motion control and the system's stability. Hence, vibration suppression research has been very urgent in recent years [2].…”

Section: Introductionmentioning

confidence: 99%

Decoupling Vibration Control for a Two-Link Manipulator

2022

Proceedings of WCSE 2022 Spring Event: 2022 9th International Conference on Industrial Engineering and Applications

View full text Add to dashboard Cite

Due to the influence of the coupling torque in the two-link manipulator, the disturbance observer (DOB) method cannot achieve an ideal vibration suppression effect. A velocity controller is proposed, including a decoupler and a rigid-body state observer (RBSO), to simultaneously decrease the coupling torque and vibrations. The two-link manipulator is modelled as a two-input two-output (TITO) system in this paper. The decoupler is designed based on the dynamic model of the TITO system in a simplified structure. The RBSO contains a state observer (SOB) and a damper. The SOB obtains a rigid-body velocity from its state variable. The damper feeds back the error between the rigid-body velocity and link velocity to a proportional-integral controller to add system damping, achieving vibration suppression. The effectiveness to decrease coupling torque and vibrations of the proposed method are verified in simulations.

show abstract

“…Other control algorithms can also achieve vibration suppression of contact force [27][28][29]. Since the stiffness of the joint of the manipulator has a significant influence on that of the robot, the suppression of joint vibration is another primary method [30][31][32]. However, many industrial robots do not provide an interface for users to arbitrarily modify robot dynamics because their control architecture is closed, so users cannot modify the control algorithms.…”

Section: Introductionmentioning

confidence: 99%

Suppress Vibration on Robotic Polishing with Impedance Matching

et al. 2021

Self Cite

View full text Add to dashboard Cite

Installing force-controlled end-effectors on the end of industrial robots has become the mainstream method for robot force control. Additionally, during the polishing process, contact force stability has an important impact on polishing quality. However, due to the difference between the robot structure and the force-controlled end-effector, in the polishing operation, direct force control will have impact during the transition from noncontact to contact between the tool and the workpiece. Although impedance control can solve this problem, industrial robots still produce vibrations with high inertia and low stiffness. Therefore, this research proposes an impedance matching control strategy based on traditional direct force control and impedance control methods to improve this problem. This method’s primary purpose is to avoid force vibration in the contact phase and maintain force–tracking performance during the dynamic tracking phase. Simulation and experimental results show that this method can smoothly track the contact force and reduce vibration compared with traditional force control and impedance control.

show abstract

A Robust Method Based on Dual Encoders to Eliminate Velocity Ripple for Modular Drive Joints

Cited by 4 publications

References 29 publications

Robust Vibration Control Based on Rigid-Body State Observer for Modular Joints

Robust Vibration Control Based on Rigid-Body State Observer for Modular Joints

Decoupling Vibration Control for a Two-Link Manipulator

Suppress Vibration on Robotic Polishing with Impedance Matching

Contact Info

Product

Resources

About