Human-Robot Interaction Control for Robot Driven by Variable Stiffness Actuator With Force Self-Sensing

Ning, Yinghao; Liu, Yifan; Xi, Fengfeng; Huang, Ke; Li, Bing

doi:10.1109/access.2020.3048418

Cited by 10 publications

(4 citation statements)

References 29 publications

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“…A controllable virtual stiffness allows the creation of a virtual environment at the output of the stepper motor. Actuators can achieve variable stiffness with the aid of series elastic actuators [10] or variable-stiffness mechanisms [28]. As far as we know, virtual stiffness control using stepper motors with sensorless torque control has not been realized.…”

Section: Virtual Stiffness Control Experimentsmentioning

confidence: 99%

Torque-Sensorless Control of Stepper Motors for Low-Cost Compliant Motion Generation

et al. 2021

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Actuators that can generate controllable compliant output motion are suitable for robots that need to interact safely with humans or the environment. To obtain the accurate output torque required to control the compliant motion, existing robotic actuators use one or more sensors to measure the deformation of a stiff or compliant element between the actuator and the output. The complexity, reliability, and cost of sensors are the current challenges. Deformation-based sensing also suffers from limited bandwidth and stability range. This paper proposes a torque-sensorless control method of stepper motors to generate compliant motion. Stepper motors are used because of their low cost and reliability. They also have a much higher torque-to-weight ratio and torque-to-rotor-inertia ratio than other DC motors. Torque and impedance controllers based on stepper motor current feedback are developed. Torque-sensorless impedance, and gripping force control experiments are provided to show the advantages of the proposed method. It is expected that the new control method for stepper motors can offer a competitive alternative when cost, stability, or bandwidth of complaint actuators are the major concerns.

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Section: Virtual Stiffness Control Experimentsmentioning

confidence: 99%

Torque-Sensorless Control of Stepper Motors for Low-Cost Compliant Motion Generation

et al. 2021

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“…With proper hardware, studies show that it is possible to simulate compliant behavior through stiffness control with rigid robots as well [9]- [12]. However, certain behavior of the robot is heavily affected by the inherent stiffness of the hardware [13]- [15]. Even under stiffness control, the apparent stiffness reverts back to the mechanical stiffness under high frequency excitations due to the limited control bandwidth [16], [17].…”

Section: Introductionmentioning

confidence: 99%

Differential Spiral Joint Mechanism for Coupled Variable Stiffness Actuation

Kim¹,

Deshpande²

2023

Preprint

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In this study, we present the Differential Spiral Joint (DSJ) mechanism for variable stiffness actuation in tendondriven robots. The DSJ mechanism semi-decouples the modulation of position and mechanical stiffness, allowing independent trajectory tracking in different parameter space. Past studies show that increasing the mechanical stiffness achieves the wider range of renderable stiffness, whereas decreasing the mechanical stiffness improves the quality of actuator decoupling and shock absorbance. Therefore, it is often useful to modulate the mechanical stiffness to balance the required level of stiffness and safety. In addition, the DSJ mechanism offers a compact form factor, which is suitable for applications where the size and weight are important. The performance of the DSJ mechanism in various areas is validated through a set of experiments.

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“…5,6 In essence, in such applications, the bandwidth limitation can be overcome by adjusting the natural frequencies of the system, improving the regulating ability of the external environment. 7 The task of industrial robots requires large-load and high-precision, reducing vibration by natural frequencies modulation has great significance for improving both machining stability and product quality. [8][9][10] Meanwhile, how to accomplish it with consideration of the external excitation will be a challenging issue.…”

Section: Introductionmentioning

confidence: 99%

Natural frequency modulation of a kinematically redundant planar parallel robot

Xie

Zhang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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When a parallel robot is equipped with kinematic redundancy, it has sufficient capabilities of natural frequency modulation through adjusting geometric configuration. To reduce resonance of a mechanism, this paper investigates the natural frequency modulation of a kinematically redundant planar parallel robot. A double-threshold searching method is proposed for controlling the inverse kinematics solution and keeping the natural frequencies away from the excitation frequency. The effectiveness of modulating the natural frequencies is demonstrated by comparing it with a non-modulation method. The simulation results indicate that, in all directions, the responses are coupled, and every order should be taken into consideration during natural frequency modulation. Compared to the non-modulation method, the proposed method can reduce the resonance amplitude to a certain extent, and the effect of vibration suppression is remarkable.

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Human-Robot Interaction Control for Robot Driven by Variable Stiffness Actuator With Force Self-Sensing

Cited by 10 publications

References 29 publications

Torque-Sensorless Control of Stepper Motors for Low-Cost Compliant Motion Generation

Torque-Sensorless Control of Stepper Motors for Low-Cost Compliant Motion Generation

Differential Spiral Joint Mechanism for Coupled Variable Stiffness Actuation

Natural frequency modulation of a kinematically redundant planar parallel robot

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