• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.113-118
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• 2000

Collision free task planning for dual-arm robot which perform many subtasks in a common work space can be achieved in two steps : path planning and trajectory planning. Path planning finds the order of tasks for each robot to minimize path lengths as well as to avoid collision with static obstacles. A trajectory planning strategy is to let each robot move along its path as fast as possible and delay one robot at its initial position or reduce speed at the middle of its path to avoid collision with the other robot.

• 로봇학회논문지
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• 제12권1호
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• pp.11-18
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• 2017

Static balance of an articulated robot arm at various configurations requires a torque compensating for the gravitational torque of each joint due to the robot mass. Such compensation torque can be provided by a spring-based counterbalance mechanism. However, simple installation of a counterbalance mechanism at each pitch joint does not work because the gravitational torque at each joint is dependent on other joints. In this paper, a 6 DOF industrial robot arm based on the parallelogram for multi-DOF counterbalancing is proposed to cope with this problem. Two passive counterbalance mechanisms are applied to pitch joints, which reduces the required torque at each joint by compensating the gravitational torque. The performance of this mechanism is evaluated experimentally.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.78-84
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• 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.

• 로봇학회논문지
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• 제15권1호
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• pp.48-54
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• 2020

Home robot arms require a payload of 2 kg to perform various household tasks; at the same time, they should be operated by low-capacity motors and low-cost speed reducers to ensure reasonable product cost. Furthermore, as robot arms on mobile platforms are battery-driven, their energy efficiency should be very high. To satisfy these requirements, we designed a lightweight counterbalance mechanism (CBM) based on a spring and a wire and developed a home robot arm with five degrees of freedom (DOF) based on this CBM. The CBM compensates for gravitational torques applied to the two pitch joints that are most affected by the robot's weight. The developed counterbalance robot adopts a belt-pulley based parallelogram mechanism for 2-DOF gravity compensation. Experiments using this robot demonstrate that the CBM allows the robot to meet the above-mentioned requirements, even with low-capacity motors and speed reducers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.8-13
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• 1993

This paper presents deterministic and adaptive control laws for two-link flexible arm. The flexible arm has considerable structural flexibility. Because of its flexbility, dynamic equations are very complex and difficult to get, dynamic equations for two-link flexible arm are derived from Bernoulli-Euler beam theory and Lagrangian equation. Using the fact that matrix is skew symmetric, controllers which have a simplified structure with less computational burden are proposed by using Lyapunov stability theory.

• 대한기계학회논문집
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• 제16권6호
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• pp.1075-1088
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• 1992

본 연구에서는 두개의 팔을 가지는 실험용 로보트를 모델링 하기위해 사용된 기법들을 제시한다. 로보트는 수직 평면상에서 움직이므로 중력의 영향을 받는다. 그리고 두팔은 모두 탄성을 가진다. 이 로보트는 탄성 멤버들을 가지는 로보트의 여 러 제어기법들을 연구하기위해 만들어졌다. 시스템의 특성들은 아주 유연한 멤버들 을 가지게끔 정해진다.이것은 제어를 위해 쓰이는 전자부품들에 요구되는 밴드폭을 제안하고, 탄성이 크고 빠른 로보트에서 관찰 되어지는 유연한 운동들을 흉내낸다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.817-821
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• 1991

Coordinated motion control of two arms of a dual-arm robot has been studied by many researchers, because of it's potential application in assembly as well as the handling of large and heavy objects beyond the capacity of single arm. This paper derives dynamic equation of a dual-arm robot, and describes some constrains to pick up a simply shaped object at prespecified position on it. This paper concludes with describing both PD and self-tunning control algorithm for the above task.

• 대한기계학회논문집A
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• 제21권1호
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• pp.144-153
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• 1997

The determination of the direct kinematics of the parallel mechanism is a difficult problem but has to be solved for any practical use. This paper presents the efficient formulation of the direct kinematics for double parallel robot arm. The robot arm consists of two parallel mechanism, which generate positional and orientational motions, respectively. These motions are decoupled by a passive central axis which is composed of four revolute joints and one prismatic joint. For a set of given lengths of linear actuators, the direct kinematics will find the joint displacements of th central axis from geometric constraints in each parallel mechanism. Then the joint displacements will be converted into the position and the orientation of the end effector of the robot arm. The proposed formulation is decoupled and compacted so that it will be implemented as a real-time direct kinematics. With the proposed formulation, we analyze the motion of the double parallel robot and show its characteristics. Specially, we investigate the workspace in terms of positional space as well as orientational space.

• 제어로봇시스템학회논문지
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• 제14권7호
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• pp.672-678
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• 2008

This paper proposes a new rehabilitation robot with upper and lower limb connections for gait training. As humans change a walking speed, their nervous systems adapt muscle activation patterns to modify arm swing for the appropriate frequency. By analyzing this property, we can find a relation between arm swinging and lower limb motions. Thus, the lower limb motion can be controlled by the arm swing for walking speed adaptation according to a patent's intension. This paper deals with the design aspects of the suggested gait rehabilitation robot, including a trajectory planning and a control strategy. The suggested robot is mainly composed of upper limb and lower limb devices, a body support system. The lower limb device consists of a slider device and two 2-dof footpads to allow walking training at uneven and various terrains. The upper limb device consists of an arm swing handle and switches to use as a user input device for walking. The body support system will partially support a patient's weight to allow the upper limb motions. Finally, we showed simulation results for the designed trajectory and controller using a dynamic simulation tool.

• 한국정밀공학회지
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• 제17권11호
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• pp.206-212
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• 2000

This paper presents a hybrid actuator scheme to actively control the end-point position and vibration of a two-link flexible robot arm. Control scheme consists of four different actuators; two servo-motors at the hubs and two piezoceramics bonded to the surfaces of the flexible links. Two sliding hyperplanes are designed for two servo-motors which have time varying parameters to maintain control performance in any configuration. The surface gradients of the hyperplanes are determined by pole assignment technique to guarantee the stability on the hyperplanes themselves. During the motion, undesirable oscillations caused by the torques based on the rigid link dynamics are actively suppressed by applying feedback control voltages to the piezoceramic actuators. Consequently, desired tip motion is achieved. In order to demonstrate the effectiveness of the proposed methodology, experiments are performed for the regulating and tracking control problems.