• ETRI Journal
• /
• v.40 no.5
• /
• pp.653-663
• /
• 2018

Patients with spinal cord injuries cannot move their limbs using their intact muscles. A suitable controller can be used to move their arms by employing the functional electrical stimulation method. In this article, a fuzzy exponential sliding-mode controller is designed to move a musculoskeletal human arm model to track an optimal trajectory in the sagittal plane. This optimal arm trajectory is obtained by developing a policy for the central nervous system. In order to specify the optimal trajectory between two points, two dynamic and static optimal criteria are applied simultaneously. The first dynamic objective function is defined to minimize the joint torques, and the second static optimization is offered to minimize the muscle forces at each moment. In addition, fuzzy logic is used to tune the sliding-surface parameter to enable an appropriate tracking performance. Simulation results are evaluated and compared with experimental data for upward and downward movements of the human arm.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.399-402
• /
• 2002

In this study, we constructed a four-channel impedance measurement system including a two-channel goniometer to analyze human arm movement. Impedances and joint angles were simultaneously measured for wrist and elbow movements. As the impedance changes resulting from wrist and elbow movements depended heavily on electrode placement, we determined the optimal electrode configurations for those movements by searching for high correlation coefficients, large impedance changes, and minimum interferences in ten subjects (age: 29+6). Our optimal electrode configurations showed very strong relationships between the wrist joint angle and forearm impedance (correlation coefficient = 0.95+0.04), and between the elbow joint angle and upper arm impedance (correlation coefficient = -0.98+0.02). Although the measured impedances changes of the wrist (1.1+1.5 ohm) and elbow (-5.0+2.9 ohm) varied among individuals, the reproducibilities of wrist and elbow impedance changes of five subjects were 5.8+1.8 % and 4.6+1.4 % for the optimal electrode pairs, respectively. We propose that this optimal electrode configuration would be useful for future studies involving the measurement of accurate arm movements by impedance method.

• Industrial Engineering and Management Systems
• /
• v.3 no.1
• /
• pp.78-84
• /
• 2004

To optimize movement of a multi-joint robot arm is known to be a difficult problem, because it is a kind of redundant system. Although the end-effector is set its position by each angle of the joints, the angle of each joint cannot be uniquely determined by the position of the end-effector. There exist the infinite number of different sets of joint angles which represent the same position of the end-effector. This paper describes how to manage the angle of each joint to move its end-effector preferably on an X-Y plane with obstacles in the end-effector’s reachable area, and how to optimize the movement of a multi-joint robot arm, evading obstacles. The definition of “preferable” movement depends upon a purpose of robot operation. First, we divide viewpoints of preference into two, 1) the standpoint of the end-effector, and 2) the standpoint of joints. Then, we define multiple objective functions, and formulate it into a multi-objective programming problem. Finally, we solve it using multi-purpose genetic algorithm, and obtain reasonable results. The method described here is possible to add appropriate objective function if necessary for the purpose.

• The Journal of Korea Robotics Society
• /
• v.7 no.1
• /
• pp.35-44
• /
• 2012

This paper presents a method to optimize motion planning for industrial manipulators with redundancy. For optimal motion planning, first of all, particular inverse kinematic solution is needed to improve efficiency for manipulators with redundancy working in various environments. In this paper, we propose three kinds of methods for solving inverse kinematics problems; numerical and combined approach. Also, we introduce methods for optimal motion planning using potential function considering the order of priority. For efficient movement in industrial settings, this paper presents methods to plan motions by considering colliding obstacles, joint limits, and interference between whole arms. To confirm improved performance of robot applying the proposed algorithms, we use two kinds of robots with redundancy. One is a single arm robot with 7DOF and another is a dual arm robot with 15DOF which consists of left arm, right arm with each 7DOF, and a torso part with 1DOF. The proposed algorithms are verified through several numerical examples as well as by real implementation in robot controllers.

• The Journal of Korea Robotics Society
• /
• v.15 no.2
• /
• pp.100-106
• /
• 2020

In the agricultural field, interests in research using robots for fruit harvesting are continuously increasing. Dual arm manipulators are promising because of its abilities like task-distribution and role-sharing. To operate it efficiently, the task sequence must be planned adequately. In our previous study, a collision-free path planning method based on a genetic algorithm is proposed for dual arm manipulators doing tasks cooperatively. However, in order to simplify the complicated collision-check problem, the movement between tasks of two robots should be synchronized, and thus there is a problem that the robots must wait and resume their movement. In this paper, we propose a heuristic algorithm that can reduce the total time of the optimal solution obtained by using the previously proposed genetic algorithm. It iteratively desynchronizes the task sequence of two robots and reduces the waiting time. For evaluation, the proposed algorithm is applied to the same work as the previous study. As a result, we can obtain a faster solution having 22.57 s than that of the previous study having 24.081 s. It will be further studied to apply the proposed algorithm to the fruit harvesting.

• The Journal of Korea Robotics Society
• /
• v.6 no.2
• /
• pp.130-140
• /
• 2011

This paper proposes an optimal posture for the task-oriented movement of dual arm manipulator. A stability criterion function which consists of three kinds of feature-representative parameters has been utilized to define the optimal posture. The first parameter is the force which is applied to the object. The torque of each joint and position of arm are attained from the current sensor and encoder, respectively. From these two data, the applied force to an object is estimated using sum of vectors of the joint torques estimated from the measured current. In order to investigate the robustness of each posture, the variation of the end-effector from the encoder information has been utilized as the second parameter. And for the last parameter for the optimality, the total energy consumption has been used. The total consuming energy of each posture can be computed from the current information and the battery voltage. The proposed robot structure consists of a mobile inverted pendulum and dual manipulators. In order to define the optimal posture for the each object, external disturbances are applied to the mobile inverted pendulum robot and the first and second parameters are investigated to find the optimal posture among the pre-selected most representative postures. Finally, the proposed optimal posture has been verified by the proposed stability criterion function which consists of total force to the object, the fluctuation of the end-effector position, and total energy consumption. The effectiveness of the proposed algorithms has been verified and demonstrated through the practical simulations and real experiments.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.161.5-161
• /
• 2001

Robots are required to assist our activities in daily life. In this paper, we focus on arm movement to catch moving object as one of important tasks frequently performed by human. We propose an algorithm which enables a robot to perform human-like arm motion to catch a moving object. First we analyze human hand trajectories and velocity profiles to catch an object. From the experimental results, we extract some characteristics in the process of approaching and following a moving object and confirm that these are necessary to realize human-like motion. We then adopt an instantaneous optimal control method which evaluates the error and energy cost at each sampling step, and design two time-varying weight matrices to introduce human characteristic into robot motion. The matrix concerning the error is defined as a time-increasing ...

• The Journal of Korean Physical Therapy
• /
• v.15 no.4
• /
• pp.412-430
• /
• 2003

Functional stability is dependent on integrated local and global muscle function. Movement dysfunction can present as a local and global problem, though both frequently occur together. To good understand how movement induces pain syndrome, the optimal actions and interaction of the multiple anatomic and functional systems involved in motion must be considered. Minor alterations in the precision of movement cause microtrauma and, if allowed to continue, will cause macrotrauma and pain. These alteration of the movement result in the development of compensatory movement and movement impairment. Muscle that become tight tend to pull the body segment to which they are attached, creating postural deviation. The antagonistic muscles may become weak and allow postural deviations due to lack of balanced support. Both hypertonic and inhibited muscles will cause an alteration of the distribution of pressure over the joint(s) that they cross and, thus, may not only result from muscle dysfunction, but produce joint dysfunction as well. Alteration of the shoulder posture and movement dysfunction may sometimes result in compression of neurovascular structures in the shoulder and arm. There is a clear link between reduced proprioceptive input, altered motor unit recruitment and the neurovascular compression. This report start with understanding of the impaired alignment, movement patterns and neuromuscular compression of the shoulder girdle by movement impairment to approach method of the movement dysfunction.

• Fashion & Textile Research Journal
• /
• v.17 no.6
• /
• pp.881-894
• /
• 2015

The silver generation have clothing style of optimal daily life comparing than young generation because they do not participate a specific sport event but daily- life exercise. As the human body ages, the figure of the silver generation shows different body shape because upper body changes to curved figure including the belly and waist part. Therefore, clothing characteristics for the silver generation should be considered with proper function, design and textiles to optimize body movement. This study investigated various exercise types according to motion analysis of the silver generation in order to develop the design of the active T-shirts reflecting the structural properties and providing the optimum exercise circumstance. The results to consider design needs are as followed; As the T-shirts design for the flexible exercise which required frequent movement of upper body such as bending and waist twisting during body stretching, a stretch fabric applied to the waist part considering T-shirts allowance and length to make extreme elongation and support for well-fitting appearance of the T-shirts. As the T-shirts design for the instantaneous reactionary exercise, high elastic four-way stretch fabric is applied to the part of arm hole to optimize skeletal and muscle movement for entire body and arm work. As the T-shirts design for the endurance exercise such as climbing, cycling, and walking, the shoulder line of the back part has cutting line allowance to make optimum movement of the upper body but no change of the waist part.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10b
• /
• pp.592-598
• /
• 1992

For a high bandwidth, accurate end of arm motion control with good disturbance rejection, the, Momentum Management Approach to Motion control (MMAM) is proposed. The MMAM is a kind of position control technique that uses inertial forces, applied at or near the end of arm to achieve, high bandwidth and accuracy in movement and in the face of force disturbances. To prove the concept of MMAM, the, end point, control of a flexible manipulator is considered. For this purpose, a flexible beam is mounted on the x-y table, and the MMAM actuator is attached on the top of the flexible beam. A mathematical model is developed for the flexible, beam being controlled by the, MMAM actuator and slide base DC motor. A system identification method is applied to estimate some system parameters in the, model which can not be determined because of the complexity of the mechanism. For the end point, control of the. flexible beam, the, optimal linear output feedback control is introduced.