Power assisted pnumatic-based knee-ankle-foot-orthosis for rehabilitation

Wong, ZhenYang; Teng, ChunMan; Chong, Yu Zheng

doi:10.1109/iecbes.2012.6498058

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…The PAM mechanism will perform small tracking error if it shows high following characteristics of its motion. The control law of the improved NCTF controller is formulated in (5). The constructed NCT of the conventional NCTF controller is adopted in the improved NCTF controller, while the PI compensator is required to redesign due to the changes of the control law.…”

Section: Improved Nctf Control Systemmentioning

confidence: 99%

“…As compared to conventional actuators, the PAM has simpler structure, lighter weight, higher power-to-weight ratio and higher safety in use. Owing to these factors, the PAM has been widely used in the power assist devices [2]- [5], biomimetic robot [6]- [10], medical applications [11], industry machinery [12], [13] and so on. However, the PAM system exhibits significant nonlinear characteristics such as hysteresis, low damping ability and creep phenomenon, which are caused by the air compressibility, the internal friction and the deformation of the elastic tube.…”

Section: Introductionmentioning

confidence: 99%

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Practical Control Strategy for Positioning Control of Pneumatic Artificial Muscles Driven Stage: Improved NCTF Control

et al. 2019

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This paper presents a practical control strategy for motion control of a pneumatic muscle actuated the system. Pneumatic artificial muscle (PAM) exhibits strong nonlinear characteristics which are difficult to be modeled precisely, and these characteristics have led to low controllability and difficult to achieve high precision control performance. This paper aims to propose nominal characteristic trajectory following (NCTF) control system, which emphasizes simple design procedure without the need of exact model parameters, and yet is able to demonstrate high performance in both point-to-point and continuous motions. However, the conventional NCTF controller does not offer a promising positioning performance with the PAM mechanisms, where it exhibits large vibration in the steady state before the mechanism stopping and tends to reduce the motion accuracy. Therefore, the objective of this study is to improve the conventional NCTF controller by removing the actual velocity feedback to eliminate vibration problem, added an acceleration feedback compensator to the plant model, and a reference rate feedforward to solve low damping characteristic of the PAM mechanism simultaneously improve tracking following characteristic. The design procedure of the improved NCTF controller remains easy and straightforward. The effectiveness of the proposed controller is verified experimentally and compared with the conventional NCTF and classical PI controllers in the performances of positioning and continuous motion. The improved NCTF controller reduces the positioning error up to 90% and 63% as benchmarked to the PI and conventional NCTF controllers, respectively, while it reduces up to 92% (PI) and 95% (NCTF) in the tracking error. INDEX TERMS Motion control, NCTF control, nonlinear system, pneumatic artificial muscle, practical controller.

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Section: Improved Nctf Control Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Practical Control Strategy for Positioning Control of Pneumatic Artificial Muscles Driven Stage: Improved NCTF Control

et al. 2019

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“…In particular, PAMs attract a great deal of attention in welfare devices. Owing to its high safety, low weight, and powerful output, it has been applied as a power assist device for rehabilitation applications such as an upper limb exoskeletal rehabilitation robot [5] and a knee-ankle-foot orthosis [6].…”

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confidence: 99%

Precise Positioning of Pneumatic Artificial Muscle Systems

Wang¹,

Sato²,

Kagawa³

2014

JFCMV

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Pneumatic artificial muscles (PAMs) currently possess a high power-to-weight ratio, a high powerto-volume ratio, and a high degree of safety. They have therefore been applied to many power assist devices and positioning mechanisms such as bionic robots, welfare devices, and parallel manipulators. However, the significant nonlinear characteristics of PAM mechanisms limit their positioning accuracies. The accuracies are generally lower than 5 µm, which preclude the PAM from precision systems. Nevertheless, enhancing the positioning accuracy is desired to extend the application fields of PAMs. This study aims to clarify a practical controller design method to achieve the precise positioning of PAM systems. As the first step of this research, a linear motion mechanism with a pair of McKibben PAMs was constructed and a conventional dynamic model for this system is introduced. The dynamic model is used to explain the basic characteristics of the PAM mechanism and discuss the necessary characteristics for precise positioning. Then open-loop step and sinusoidal responses of the PAM mechanism were examined by experimental and simulated results. Next, for precise positioning, the practical controller design procedure is discussed and determined based on the measured open-loop responses. The proposed controller design procedure can be easily implemented into PAM mechanisms without an exact dynamic model. The positioning performance of such a system was experimentally evaluated. The experimental results show that although the positioning accuracy depends on the target position, the positioning error is lower than 1 µm even in the worst case and the positioning resolution can be set to 0.5 µm.

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Sensorless angle and stiffness control of antagonistic PAM actuator using reference set

Shin

Kogiso

2022

Advanced Robotics

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Power assisted pnumatic-based knee-ankle-foot-orthosis for rehabilitation

Cited by 6 publications

References 7 publications

Practical Control Strategy for Positioning Control of Pneumatic Artificial Muscles Driven Stage: Improved NCTF Control

Practical Control Strategy for Positioning Control of Pneumatic Artificial Muscles Driven Stage: Improved NCTF Control

Precise Positioning of Pneumatic Artificial Muscle Systems

Sensorless angle and stiffness control of antagonistic PAM actuator using reference set

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