A Pneumatic Artificial Muscle Actuated Above-Knee Prosthesis

2010 ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Xiangrong Shen
Keyword(s):  
Sliding Mode ◽  
Mechanical Design ◽  
Knee Prosthesis ◽  
Artificial Muscle ◽  
Torque Control ◽  
Stair Climbing ◽  
Pneumatic Artificial Muscle ◽  
Control Approach ◽  
Energy Consuming ◽  
And Control

This paper describes the mechanical design and control approach for an above-knee (AK) prosthesis actuated by pneumatic artificial muscle. Pneumatic artificial muscle (PAM) affords great potential in prosthetics, since this type of actuator features a high power density, and similar characteristics to human muscles. However, there is no application of PAM in AK prosthetics in existing literature to the best knowledge of the authors. In this paper, a design of the prosthesis is presented, which provides sufficient actuation torque for the knee joint in energy consuming locomotive functions such as fast walking and stair climbing. The corresponding control approach is also presented, which combines an impedance-based locomotive controller with a lower-level sliding-mode torque control approach. Experiments on the proposed AK prosthesis have also been conducted to demonstrate the ability to mimic normal gait characteristics.

A Pneumatic Artificial Muscle Articulated Knee Prosthesis

2010 ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Xiangrong Shen
Keyword(s):  
Mechanical Design ◽  
Knee Prosthesis ◽  
Artificial Muscle ◽  
Stair Climbing ◽  
Pneumatic Artificial Muscle ◽  
Motion Controller ◽  
Control Approach ◽  
Energy Consuming ◽  
Human Motor ◽  
And Control

This paper describes the mechanical design and control approach for an above-knee (AK) prosthesis actuated by pneumatic artificial muscle. Pneumatic artificial muscle (PAM) affords great potential in prosthetics, since this type of actuator features a high power density, and similar characteristics to human muscles. However, there is no application of PAM in AK prosthetics in existing literature to the best knowledge of the authors. In this paper, a design of the prosthesis is presented, which provides sufficient actuation torque for the knee joint in energy consuming locomotive functions such as fast walking and stair climbing. The corresponding control approach is developed to mimic the human motor control in locomotive functions, which includes a lower-level equilibrium-point hypothesis-inspired motion controller, and a higher-level joint-behavior-based motion planner.

Design and Control of a Pneumatic Artificial Muscle Actuated Above-Knee Prosthesis

2011 ◽  
Vol 5 (3) ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Xiangrong Shen
Keyword(s):  
Control Algorithm ◽  
Knee Prosthesis ◽  
Radial Profile ◽  
Artificial Muscle ◽  
Torque Control ◽  
Effective Control ◽  
Pneumatic Artificial Muscle ◽  
Knee Prostheses ◽  
Control Approach ◽  
Highly Nonlinear

This paper presents the authors’ investigation results of applying the pneumatic artificial muscle actuation to above-knee prostheses. As a well-known muscle actuator, the pneumatic artificial muscle actuator features a number of unique advantages, including high power density, and similar elastic characteristics to biological muscles. Despite multiple applications in related areas, the application of pneumatic artificial muscle in above-knee prostheses has not been explored. Inspired by this fact, the research presented in this paper aims to develop a pneumatic artificial muscle-actuated above-knee prosthesis, with three specific objectives: (1) demonstrate the pneumatic artificial muscle actuation’s capability in generating sufficient torque output to meet the locomotive requirements; (2) develop an effective control approach to enable the restoration of locomotive functions; (3) conduct preliminary testing of the prosthesis prototype on a healthy subject through a specially designed able-body adaptor. In the prosthesis design, an agonist–antagonist layout is utilized to obtain a bidirectional motion. To minimize the radial profile, an open-frame structure is used, with the purpose of allowing the expansion of the muscle actuators into the center space without interference. Also, the muscle actuator parameters are calculated to provide sufficient torque capacity (up to 140 N m) to meet the requirements of level walking. According to this design, the fabricated prototype weighs approximately 3 kg, with a range of motion of approximately 100°. For the control of the prosthesis, a model-based torque control algorithm is developed based on the sliding mode control approach, which provides robust torque control for this highly nonlinear system. Combining this torque control algorithm with an impedance-based torque command generator (higher-level control algorithm), the fabricated prosthesis prototype has demonstrated a capability of providing a natural gait during treadmill walking experiments.

Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part Two—Robust Control

2011 ◽  
Author(s):  
Sai-Kit Wu ◽  
Garrett Waycaster ◽  
Tad Driver ◽  
Xiangrong Shen
Keyword(s):  
Robust Control ◽  
Nonlinear Model ◽  
Sliding Mode ◽  
Artificial Muscle ◽  
Control Approach ◽  
Actuation System ◽  
Highly Nonlinear ◽  
Pressure Dynamics ◽  
System Part ◽  
And Control

A robust control approach is presented in this part of the paper, which provides an effective servo control for the novel PAM actuation system presented in Part I. Control of PAM actuation systems is generally considered as a challenging topic, due primarily to the highly nonlinear nature of such system. With the introduction of new design features (variable-radius pulley and spring-return mechanism), the new PAM actuation system involves additional nonlinearities (e.g. the nonlinear relationship between the joint angle and the actuator length), which further increasing the control difficulty. To address this issue, a nonlinear model based approach is developed. The foundation of this approach is a dynamic model of the new actuation system, which covers the major nonlinear processes in the system, including the load dynamics, force generation from internal pressure, pressure dynamics, and mass flow regulation with servo valve. Based on this nonlinear model, a sliding mode control approach is developed, which provides a robust control of the joint motion in the presence of model uncertainties and disturbances. This control was implemented on an experimental setup, and the effectiveness of the controller demonstrated by sinusoidal tracking at different frequencies.

scholarly journals Design of Hybrid Phase Sliding Mode Control Scheme for Lower Extremity Exoskeleton

2019 ◽  
Vol 9 (18) ◽  
pp. 3754
Author(s):  
Lingling Chen ◽  
Chao Wang ◽  
Jie Wang ◽  
Xiaowei Song
Keyword(s):  
Lower Extremity ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Artificial Muscle ◽  
Phase Changes ◽  
Working Environment ◽  
Phase Detector ◽  
Pneumatic Artificial Muscle ◽  
Mode Control ◽  
Control Scheme

Aiming at a pneumatic artificial muscle (PAM) lower extremity exoskeleton, a control mechanism based on hybrid phase sliding mode control (SMC) is proposed. First of all, the human gait cycle is mainly divided into the swing phase and stance phase, and the lower extremity exoskeleton phase models are established by the Euler–Lagrange method, respectively. Secondly, the lower limb exoskeleton is inevitably affected in the diverse working environment, and the exoskeleton model has nonlinear and strong coupling characteristics, which both increase the control difficulty. In this situations, a robust sliding mode control method is designed based on an Extended State Observer (ESO). Thirdly, the pneumatic muscle takes time to contract and relax, and then the joint input torque cannot jump when the gait phase changes, hence, the smoothing switching of the assistive control scheme is introduced to solve it. The smoothing switching time is detected by a phase detector, and the phase detector is designed by the plantar pressure information. Finally the comparative simulation shows that this control strategy has the advantages of fast time, high control precision and no jump during control torque switching. Pneumatic artificial muscle contraction rate curve shows that the pneumatic muscles’ motion range meets the control requirement of the exoskeleton.

Supervisory Control of Drilling

1996 ◽  
Vol 118 (1) ◽  
pp. 10-19 ◽  
Author(s):  
R. J. Furness ◽  
A. Galip Ulsoy ◽  
C. L. Wu
Keyword(s):  
Process Control ◽  
Torque Control ◽  
Feed Speed ◽  
Machining Time ◽  
Control Approach ◽  
Drilling Operation ◽  
Control Functions ◽  
Control Concept ◽  
Supervisory Process ◽  
And Control

A supervisory process control approach to machining is presented in this paper, and demonstrated by application to a drilling operation. The supervisory process control concept incorporates optimization and control functions in a hierarchical structure. This approach utilizes feedback measurements to parameterize the constraints of a process optimization problem whose solution determines both strategies and references for process control. For this particular drilling operation, a three-phase strategy (utilizing a combination of feed, speed, and torque control) evolved due to inherent variation in constraint activity as a function of hole depth. A controller comparison study was conducted which demonstrates the advantages of this approach compared to (1) uncontrolled “conventional” drilling, (2) feed and speed controlled drilling, and (3) torque and speed controlled drilling. Benefits of reduced machining time, improved hole quality, and the elimination of tool breakage are demonstrated, and the potential economic impact is highlighted for an example production application.

Wheel-Based Stair Climbing Robot with Hopping Mechanism – Demonstration of Continuous Stair Climbing Using Vibration –

2008 ◽  
Vol 20 (2) ◽  
pp. 221-227 ◽  
Author(s):  
Yuji Asai ◽  
◽  
Yasuhiro Chiba ◽  
Keisuke Sakaguchi ◽  
Naoki Bushida ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Stair Climbing ◽  
Design Parameters ◽  
Mass Ratio ◽  
Climbing Robot ◽  
Soft Landing ◽  
Hopping Mechanism ◽  
And Control ◽  
Two Bodies

We propose a simple hopping mechanism using vibration of a two-degrees-of-freedom (2-DOF) system for a fast stair-climbing robot. The robot, consisting of two bodies connected by springs and a wire, hops by releasing energy stored in springs and travels quickly using wheels mounted on its lower body. The trajectories of bodies during hopping change based on mechanical design parameters such as reduced mass of the two bodies, the mass ratio between the upper and lower bodies, and spring constant, and control parameters such as initial contraction of the spring and wire tension. This property allows the robot to quickly and economically climb stairs and land softly without complex control. In this paper, we propose a mathematical model of the robot and investigate required tread length for continuous hopping to climb a flight of stairs. Furthermore, we demonstrate fast stair-climbing and soft landing for a flight of stairs in experiments.

204 Modeling and Control of Pneumatic Artificial Muscle Actuator

2008 ◽  
Vol 2008.83 (0) ◽  
pp. _2-4_
Author(s):  
Nobutaka TSUJIUCHI ◽  
Takayuki KOIZUMI ◽  
Hiroto KAN ◽  
Shinya NISHINO ◽  
Tatsuwo KUDAWARA ◽  
...  
Keyword(s):  
Artificial Muscle ◽  
Pneumatic Artificial Muscle ◽  
Modeling And Control ◽  
And Control

Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part One—Design Process

2011 ◽  
Author(s):  
Garrett Waycaster ◽  
Sai-Kit Wu ◽  
Tad Driver ◽  
Xiangrong Shen
Keyword(s):  
Controller Design ◽  
Artificial Muscle ◽  
The Other ◽  
Robotic Systems ◽  
Pneumatic Artificial Muscle ◽  
Actuation System ◽  
Torque Curve ◽  
System Part ◽  
New Feature ◽  
And Control

This paper describes the design and control of a compact and flexible pneumatic artificial muscle (PAM) actuation system for bio-robotic systems. The entire paper is divided into two parts, with the first part covering the mechanism design and the second part covering the corresponding controller design. This novel system presented in this part incorporates two new features, including a variable-radius pulley based PAM actuation mechanism, and a spring-return mechanism to replace the PAM in the “weak” direction. With the pulley radius as a function of the joint angle, this new feature enables the designer to freely modulate the shape of the torque curve, and thus achieves a significantly higher flexibility than the traditional configuration. The other new feature, the spring-return mechanism, is inspired by the fact that a large number of bio-robotic systems require a significantly larger torque in one direction than the other.

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