Dynamic modeling and decoupled control of a flexible Stewart platform for vibration isolation

Yang, Xiaolong; Wu, Hongtao; Bai, Chen; Kang, Shengzheng; Cheng, Shili

doi:10.1016/j.jsv.2018.10.007

Cited by 87 publications

(39 citation statements)

References 28 publications

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“…Wang et al [30] developed a Stewart platform using piezoelectric actuators for micro-vibration isolation. Yang et al [31] proposed an isolation system for space precision system. They also developed the control strategy to compensate for the parasitic stiffness induced due to flexible joints.…”

Section: Introductionmentioning

confidence: 99%

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

et al. 2020

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The technological developments in the field of image based sensing have led to a vast growth in the use of drones in various domains. The drone is usually equipped with an image sensor (camera) which collect images over the target area. These images are then post-processed to extract the important information. Efficiency and accuracy of the image based sensing are largely dependent on the captured image quality. Therefore, it is important to prevent the transmission of the drone vibrations to the camera. Most of the current camera mounting systems use passive rubber mounts for isolation. However, these mounts are effective only in vertical direction and essentially adds damping to the system which degrades the performance of the isolation at high frequency. In this paper, a multi-degree of freedom isolation system, based on a Stewart platform configuration, is proposed for drone camera stabilization. The important features of the proposed isolation system are-(i) high frequency roll-off, (ii) no use of flexible joints, (iii) uses non-contact voice coil actuator thus avoiding spurious resonances of the legs, (iv) adjustable stiffness, (v) 3D printed lightweight parts and (vi) centralized control using a single sensor (inertial measurement unit). A prototype of the proposed system has been manufactured and validated experimentally. The proposed isolation system is found to reduce the response of the isolation system near resonance without compromising performance at high frequency. The application of the isolation system can be easily extended to other fields which require high quality image acquisition.

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Section: Introductionmentioning

confidence: 99%

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

et al. 2020

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“…Similarly, the force feedback combined with the RPF also has the same control effect. In a flexible stewart platform, Yang et al [ 17 ] compensated for the stiffness of the flexure hinge using the position feedback control and employed the PI force feedback to broaden the vibration isolation bandwidth and add to the absolute damping. To resist the disturbances during the positioning process, Yun et al [ 18 ] combined the position control loop and acceleration control loop in the compliant parallel manipulator to achieve vibration attenuation and micro-positioning.…”

Section: Introductionmentioning

confidence: 99%

A Novel Piecewise Frequency Control Strategy Based on Fractional-Order Filter for Coordinating Vibration Isolation and Positioning of Supporting System

Tao

Jiang

Han

et al. 2020

Sensors

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A piecewise frequency control (PFC) strategy is proposed in this paper for coordinating vibration isolation and positioning of supporting systems under complex disturbance conditions, such as direct and external disturbances. This control strategy is applied in an active-passive parallel supporting system, where relative positioning feedback for positioning and absolute velocity feedback for active vibration isolation. The analysis of vibration and deformation transmissibility shows that vibration control increases low-frequency position error while positioning control amplifies high-frequency vibration amplitude. To overcome this contradiction across the whole control bandwidth, a pair of Fractional-Order Filters (FOFs) is adopted in the PFC system, which increases the flexibility in the PFC design by introducing fraction orders. The system stability analysis indicates that the FOFs can provide a better stability margin than the Integral-Order Filters (IOFs), so the control gains are increased to get a better performance on the AVI and positioning. The PFC based on FOFs can suppress the peak amplitude at the natural frequency which cannot be avoided when using the IOFs. The constrained nonlinear multivariable function is formed by the required performance and the stability of the system, then the controller parameters are optimized effectively. Lastly, the effectiveness of the proposed method is verified by experiments.

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“…Despite this, scholars have obtained excellent insights into this field and their research mainly focuses on four aspects: the construction of the vibration model [3][4][5], the study of the control strategy [6,7], the optimization of the vibrational performance [8][9][10] and the parametric design [11,12]. As a research hotspot of vibration analysis since the beginning, the vibration analysis of the Stewart platform has been successful and its studies have gradually transitioned from theoretical vibration analysis to a wide range of practical applications [13,14]. Since both the number of DOFs and the number of branches of the Stewart platform are equal to six, its Jacobian matrix, stiffness matrix and damping matrix are sixth-order matrices and since the six branches are identical and only the axis-stiffness is considered, the derivation of the vibration equation of the 6-DOF vibration system is feasible.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the traditional vibration model of parallel robots can be obtained by replacing the branches with the spring-damper system in the dynamic models [14,31,32]. However, even if the influence of the passive branch is considered in our test of prototype, the traditional spring-damper system still differs from the actual system since the amplitude of the vibration is much larger than the value that is obtained using the spring-damper system.…”

Section: Introductionmentioning

confidence: 99%

Vibration Modelling and the Difference Between Different Vibration Models for a Fewer-DOF Parallel Robot

Fan

Zhang

et al. 2020

Preprint

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Abstract The accuracy of the vibration model used in the design process directly affects the vibration performance of a parallel robot in practice, which determines the machining accuracy and the surface finish of the manufactured products. Considering a drilling parallel robot with a passive branch and few degrees of freedom as the implementation object, a vibration modelling method is proposed in which Kane’s equation is utilized, and various commonly ignored factors, such as the passive branch, the joint clearances and gravity, are considered. To explore the effects of the passive branch, which was considered ideal in previous studies, two dynamic models are derived in which the passive branch is rigid or flexible. To explore the effects of the joint clearances, which were ignored in previous studies, two stiffness models of branches are derived, in which the joint clearances are considered or ignored. Finally, numerical examples are presented for analysing the effects of these commonly ignored factors on the vibration performance of the drilling parallel robot. Regarding to the effects of these commonly ignored factors, the findings of this paper can serve as a reference for designers in simplifying the vibration model in the design process of parallel robot.

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Dynamic modeling and decoupled control of a flexible Stewart platform for vibration isolation

Cited by 87 publications

References 28 publications

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

Multi-Degree of Freedom Isolation System With High Frequency Roll-Off for Drone Camera Stabilization

A Novel Piecewise Frequency Control Strategy Based on Fractional-Order Filter for Coordinating Vibration Isolation and Positioning of Supporting System

Vibration Modelling and the Difference Between Different Vibration Models for a Fewer-DOF Parallel Robot

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