• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.289-296
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• 2016

This study presents the kinematics of an intrinsic continuum robot actuated by pneumatic artificial muscles. The single section of a developed continuum robot consisted of three muscles in parallel. The contraction of each muscle according to applied air pressure produced spatial motions of a distal plate with respect to a base plate. Based on the bending behaviors of artificial muscles, the orientation and position of the end-effector of a continuum robot were formulated using a transformation matrix. The orientation and position was also determined for a single section of the distal plate. A Jacobian matrix relating the contraction rate or the pressure rate of the muscles to the velocity vector of the end-effector was calculated considering the assembled position of actuators between neighboring sections of the robot. Experimental results showed that the motions of the intrinsic continuum robot were accurately estimated by the proposed kinematics.

• 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.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.5
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• pp.100-107
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• 1997

A pneumatic artificial muscle type of actuator, which acts similar to human muscle, is developed recently. In this paper, an adaptive controller is presented for the trajectory tracking problem of a two-degree- of-freedom manipulator using two pairs of pneumatic artificial muscle actuators. Due to the nonlinearity and the uncertainty on the dynamics of the actuator, it is difficult to make the effective control schemes of this system. By the adaptive control law which inclueds a nonlinear "feedforward" term compensating paramet- ric uncertainties in addition to P.I.D. scheme, both golbal stability of the system and convergence of the tracking error are guaranted. The effectiveness of the proposed control method for the manipulator using this actuator is illustrated through experiments.periments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1882-1892
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• 1996

This paper is concerned with the position control of the ond degree-of freedom manipulator using pneumatic artificial muscle actuator which is built to have a proper compliance. For t his pneumatic artificial muscle actuator though, it is difficult to make an effective control scheme due to the nonlinearity and uncertainties on the dynamics of the actuator. In this paper, a third-order equation of motion is derived for the actuator including the dynamics of the pneumatic servovalve. Later, various modeling uncertainties due to the nonlinearity and unmodeled dynamics of the servo vlave and the actuator are taken care of, as a trade-off between the closed-loop performance of the controlled system and its robustness to uncertainties. A controller using .mu. synthesis thchnique is designed, and robust performance against measurement noise, various modeling uncertainties due to the dynamics of the servo valve and actuator is achieved. The effectiveness of the proposed control methods is illustrated through simulations and experiments.

• Journal of Power System Engineering
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• v.10 no.3
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• pp.97-103
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• 2006

In this study, a position trajectory tracking control algorithm is proposed for a pneumatic artificial muscle driving apparatus composed of a actuator which imitates the muscle of human, a position sensor and a control valve. The controller applied to the driving apparatus is composed of a state feedback controller and disturbance observer. The feedback controller which feeds back position, velocity and acceleration is derived from the linear model of pneumatic artificial muscle driving apparatus. The disturbance observer is designed to improve trajectory tracking performance and to reduce the effect of model discrepancy. The effectiveness of the designed controller is proved by experiments and the experimental results show that the pneumatic artificial muscle driving apparatus with the proposed control algorithm tracks given position reference inputs accurately.

• 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

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.82-90
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• 2009

Pneumatic cylinder is one of the low cost actuation sources which have been applied in industrial and prosthetic application since it has a high power/weight ratio, a high-tension force and a long durability However, the control problems of pneumatic systems, oscillatory motion and compliance, have prevented their widespread use in advanced robotics. To overcome these shortcomings, a number of newer pneumatic actuators have been developed such as McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle (PAM) Manipulators. In this paper, one solution for position control of a robot arm, which is driven by two pneumatic artificial muscles, is presented. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external load of the robot arm. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is proposed in this paper. This estimates the external load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external working loads.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1217-1224
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• 2013

In this paper, a hand exoskeleton actuated by air muscles(soft hand exoskeleton) is introduced. Some soft hand exoskeletons have already been developed to overcome the defects of hand exoskeletons based on linkage and pneumatic piston system-they are usually bulky and do not have enough degree of freedom(DOF). However, soft hand exoskeletons still have defects. Their motions are not precise as linkage based hand exoskeletons, because their actuator, such as air muscle is made of soft materials. So we developed a new linkage which is not bulky and has redundant DOF. It is combined with air muscle in a specific way so that it acts as a guide when air muscle is actuated. Some experiments were conducted to evaluate the validity and usability of our hand exoskeleton.