Optimal Design of a Nonlinear Series Elastic Actuator for the Prosthetic Knee Joint Based on the Conjugate Cylindrical Cam

Sun, Yuanxi; Tang, Pei; Jia, Zheng; Dong, Dianbiao; Chen, Xiaohong; Bai, Long; Ge, Wenjie

doi:10.1109/access.2019.2944206

Cited by 18 publications

(14 citation statements)

References 50 publications

(55 reference statements)

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“…The GFB prosthetic knee consists of a GFB mechanism and a cam-based nonlinear series elastic actuator. Specific theoretical modeling and formula derivation are presented in [30,33]. Its schematic diagram, structure, actuation mechanism, and the CAD model are all depicted in Figure 1.…”

Section: Design Of the Powered Gfb Prosthetic Kneementioning

confidence: 99%

Design and Speed-Adaptive Control of a Powered Geared Five-Bar Prosthetic Knee Using BP Neural Network Gait Recognition

Sun

Huang

Jia

et al. 2019

Sensors

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To improve the multi-speed adaptability of the powered prosthetic knee, this paper presented a speed-adaptive neural network control based on a powered geared five-bar (GFB) prosthetic knee. The GFB prosthetic knee is actuated via a cylindrical cam-based nonlinear series elastic actuator that can provide the desired actuation for level-ground walking, and its attitude measurement is realized by two inertial sensors and one load cell on the prosthetic knee. To improve the performance of the control system, the motor control and the attitude measurement of the GFB prosthetic knee are run in parallel. The BP neural network uses input data from only the GFB prosthetic knee, and is trained by natural and artificially modified various gait patterns of different able-bodied subjects. To realize the speed-adaptive control, the prosthetic knee speed and gait cycle percentage are identified by the Gaussian mixture model-based gait classifier. Specific knee motion control instructions are generated by matching the neural network predicted gait percentage with the ideal walking gait. Habitual and variable speed level-ground walking experiments are conducted via an able-bodied subject, and the experimental results show that the neural network control system can handle both self-selected walking and variable speed walking with high adaptability.

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Section: Design Of the Powered Gfb Prosthetic Kneementioning

confidence: 99%

Design and Speed-Adaptive Control of a Powered Geared Five-Bar Prosthetic Knee Using BP Neural Network Gait Recognition

Sun

Huang

Jia

et al. 2019

Sensors

Self Cite

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“…[6][7][8] However, the springs used in lSEA have fixed stiffness, so their adaptability is limited. In view of these limitations, nSEA is proposed, [9][10][11] but the nonlinear spring used in nSEA has complex structure and large volume. So, elastomer is applied in SEA.…”

Section: Introductionmentioning

confidence: 99%

Adaptive sliding mode observer–based integral sliding mode model-free torque control for elastomer series elastic actuator–based manipulator

Wei

Wang

Tian

2021

Proceedings of the Institution of Mechanical Engineers, Part I:

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In this brief, an adaptive nonsingular terminal sliding mode observer–based adaptive integral terminal sliding mode model-free control is proposed for the trajectory tracking control of the output torque of elastomer series elastic actuator–based manipulator. Considering the tip load and its external disturbance, an elastomer series elastic actuator–based manipulator model is established. In order to realize the output torque tracking control of elastomer series elastic actuator–based manipulator, by using the characteristics of elastomer series elastic actuator, the output torque control is transformed into position control. Based on the idea of model-free control, an ultra-local model is applied to approximate the dynamic of the manipulator, and all the model information is considered as an unknown lumped disturbance. The adaptive nonsingular terminal sliding mode observer is designed to estimate the lumped disturbance, and the absolute value of the tracking error is introduced into the sliding surface to make the selection of parameters more flexible. Then, on the basis of adaptive nonsingular terminal sliding mode observer, the adaptive integral terminal sliding mode model-free control is proposed under model-free control framework. The design and analysis of both observer and controller do not rely on accurate model information. Finally, the performance of the proposed method is verified by simulation results.

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“…Robotic actuators with inherent compliance [1]- [6] are suitable for applications whose main objective is fast and accurate force interaction with a human or environment. Although intrinsic compliance can be provided by using pneumatic [2], fluidic, or unconventional soft actuators [6], the issues of inaccurate position control and complicated driving equipment have limited their applications.…”

Section: Introductionmentioning

confidence: 99%

“…SEAs that provide linear motion [1], [3], [5], [8], [10], [12], [15] and rotary motion [4], [11], [14], [16]- [19] can both be found. Although the type of motion and structure of the elastic spring are not the same, the majority of SEAs in the literature uses brushed or brushless direct-current (DC) motors as the actuators.…”

Section: Introductionmentioning

confidence: 99%

Improving the Dynamic Force Control of Series Elastic Actuation Using Motors of High Torque-to-Inertia Ratios

2020

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A series elastic actuator (SEA) includes an elastic spring in series with an actuator. SEAs provide more accurate force and impedance control than conventional rigid actuators. They are ideal for robots and machines that need to interact safely with the environment. The majority of existing SEAs uses brushless or brushed DC motors as the actuators. The advantages of using step motors as the actuators of SEAs have not received enough attention. Step motors have much higher torque-to-weight ratio and torqueto-inertia ratio than other DC motors. Hence they can provide better stability and high-speed accuracy of force control while maintaining lightweight. When the rotor position feedback is used, step motors can achieve accurate dynamic position response smoothly. This paper develops the dynamic model of a linear series elastic step motor and presents its prototype. Force and impedance control responses will be provided to show the advantages due to the high torque-to-inertia ratio of step motors. It is expected that the results presented here can offer a better actuator selection of SEAs when high-performance dynamic force control is required.

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Optimal Design of a Nonlinear Series Elastic Actuator for the Prosthetic Knee Joint Based on the Conjugate Cylindrical Cam

Cited by 18 publications

References 50 publications

Design and Speed-Adaptive Control of a Powered Geared Five-Bar Prosthetic Knee Using BP Neural Network Gait Recognition

Design and Speed-Adaptive Control of a Powered Geared Five-Bar Prosthetic Knee Using BP Neural Network Gait Recognition

Adaptive sliding mode observer–based integral sliding mode model-free torque control for elastomer series elastic actuator–based manipulator

Improving the Dynamic Force Control of Series Elastic Actuation Using Motors of High Torque-to-Inertia Ratios

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