• Title, Summary, Keyword: Antagonistic Actuation

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Model Estimation and Precise Position Control of an Antagonistic Actuation with Pneumatic Artificial Muscles (공압형 인공근육을 이용한 상극 구동의 모델 추정 및 정밀 위치제어)

  • Kang, Bong-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.5
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    • pp.533-541
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    • 2011
  • This paper presents a frequency-response test performed on an antagonistic actuation system consisting of two Mckibben pneumatic artificial muscles and a pneumatic circuit with pressure valves. Varying switching frequency to pressure valves from 0.1 Hz to 5 Hz, parameters of a linear model were estimated optimally to predict dynamic characteristics of the antagonistic actuation. A model-base control scheme with estimated parameters was built for the precise trajectory tracking of the antagonistic structure and realized on a reconfigurable embedded control system, CompactRIO. Experimental results showed that the proposed model-based control scheme gave good performance in trajectory tracking comparing with a PD control scheme when square wave and sinusoidal wave were given as references to follow.

Multiple Simultaneous Specification Control of Antagonistic Actuation by Pneumatic Artificial Muscles (공압형 인공근육으로 구동되는 상극구동의 다중 동시 사양 제어)

  • Kang, Bong-Soo
    • The Journal of Korea Robotics Society
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    • v.6 no.1
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    • pp.34-41
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    • 2011
  • This paper presents a frequency-response test performed on an antagonistic actuation system consisting of two Mckibben pneumatic artificial muscles and a pneumatic circuit. A linear model, capable of estimating the dynamic characteristics of the antagonistic system in the operating range of pneumatic artificial muscles, was optimally calculated based on frequency-response results and applied to a multiple simultaneous specification control scheme. Trajectory tracking results showed that the presented multiple simultaneous specification controller, built experimentally by three PD typed sample controllers, satisfied successfully all required control specifications; rising time, maximum overshoot, steady-state error.

Performance analyses of antagonistic shape memory alloy actuators based on recovered strain

  • Shi, Zhenyun;Wang, Tianmiao;Da, Liu
    • Smart Structures and Systems
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    • v.14 no.5
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    • pp.765-784
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    • 2014
  • In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.

Dynamic Characteristics of an Antagonistic Actuation with Pneumatic Artificial Muscles (공압형 인공근육을 이용한 상극구동의 동적 특성)

  • Kang, Bong-Soo;Song, Seung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1081-1086
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    • 2009
  • This paper presents dynamic characteristics of pneumatic artificial muscles. Since the actuating performance of a pneumatic muscle is closely related to the input pressure of a pneumatic muscle, the air flow model on a valve orifice and an elastic bladder of the muscle is formulated to estimate precisely the pressure variance of pneumatic muscles during deflating and inflating process. Frequency response experiments are performed with an antagonistic system consisting of two pneumatic muscles and fast pneumatic control valves. Comparing with experimental results, the proposed model yielded good performance in estimating dynamic motions of the antagonistic system as well as the pressure variance of the pneumatic artificial muscles

Stiffness Analysis in a Redundantly Actuated Four-Bar Mechanism (잉여구동을 지닌 4절 기구에서의 강성효과에 대한 해석)

  • 이병주
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.846-855
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    • 1994
  • An effective stiffness, analogous to that of a wound spring, can be created by antagonistic redundant actuation of general closed-chain mechanisms. The qualitative and quantitative characteristics of the effective stiffness are investigated through a Four-bar mechanism, and a load distribution method is introduced which simultaneously guarantees the required system motion and the effective stiffness of the Four-bar mechanism. Furthermore, a simulation is performed to understand the inter-relationship among the effective stiffness, the Four-bar geometry, and the actuation effort. Based on this analysis, the Four-bar synthesis problem for effective stiffness generation is discussed.

Teleoperation of Pneumatic Artificial Muscles Based on Joint Stiffness of Master Device (마스터장치의 회전강성을 고려한 공압인공근육의 원격조정)

  • Kim, Ryeong Hyeon;Kang, Bong Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.12
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    • pp.1521-1527
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    • 2013
  • This study proposes a wearable master device that can measure the joint stiffness and the angular displacement of a human operator to enhance the adapting capability of a slave system. A lightweight inertial sensor and the exoskeleton mechanism of the master device can make an operator feel comfortable, and artificial pneumatic muscles having a working principle similar to that of human muscles improve the performance of the slave device on emulating what a human operator does. Experimental results revealed that the proposed master/slave system based on the muscle stiffness sensor yielded uniform tracking performance compared with a conventional position-feedback controller when the payload applied to the slave system changed.

Development of Ankle Power Assistive Robot using Pneumatic Muscle (공압근육을 사용한 발목근력보조로봇의 개발)

  • Kim, Chang-Soon;Kim, Jung-Yup
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.8
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    • pp.771-782
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    • 2017
  • This paper describes the development of a wearable robot to assist ankle power for the elderly. Previously developed wearable robots have generally used motors and gears to assist muscle power during walking. However, the combination of motor and reduction gear is heavy and has limitations on the simultaneous control of stiffness and torque due to the friction of the gear reducer unlike human muscles. Therefore, in this study, Mckibben pneumatic muscle, which is lighter, safer, and more powerful than an electric motor with gear, was used to assist ankle joint. Antagonistic actuation using a pair of pneumatic muscles assisted the power of the soleus muscles and tibialis anterior muscles used for the pitching motion of the ankle joint, and the model parameters of the antagonistic actuator were experimentally derived using a muscle test platform. To recognize the wearer's walking intention, foot load and ankle torque were calculated by measuring the pressure and the center of pressure of the foot using force and linear displacement sensors, and the stiffness and the torque of the pneumatic muscle joint were then controlled by the calculated ankle torque and foot load. Finally, the performance of the developed ankle power assistive robot was experimentally verified by measuring EMG signals during walking experiments on a treadmill.

Development of an Intrinsic Continuum Robot and Attitude Estimation of Its End-effector Based on a Kalman Filter (내부형 연속체로봇 개발 및 칼만필터를 이용한 말단장치 자세추정)

  • Kang, Chang Hyun;Bae, Ji Hwan;Kang, Bong Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.4
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    • pp.361-367
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    • 2015
  • This paper presents the design concept of an intrinsic continuum robot for safe man-machine interface and characteristic behaviors of its end-effector based on real experiments. Since pneumatic artificial muscles having similar antagonistic actuation to human muscles are used for main backbones of the proposed robot as well as in the role of the actuating devices, variable stiffness of robotic joints can be available in the actual environment. In order to solve the inherent shortcoming of an intrinsic continuum robot due to bending motion of the backbone materials, a Kalman filter scheme based on a triaxial accelerometer and a triaxial gyroscope was proposed to conduct an attitude estimation of the end-effector of the robot. The experimental results verified that the proposed method was effective in estimating the attitude of the end-effector of the intrinsic continuum robot.