• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.507-512
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• 1997

This paper presents a method of finding optitnal joint torques of two robots when they hold an object simultaneously. Although the importance of the multiple cooperating robot system increases for more flcviblc ni;mufacturing automation, dynamic solutions to multi-robot system forming closcd kinematic chain is not easy to find. Newton-Eulcr approach is used for the dynamic formulation of two robots fonn~ng closcd kincmatic chains gmsping a rigid body object. The nrcthodology to optimize the joint torques to satisfy given criterta and obtain bettcr control of the system is discussed. The scheme is illustrated by an example.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.337-342
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• 1992

The load distribution problem of two cooperating robots grasping one object is studied. The optimal joint torque needed for the desired motion is obtained by using a new objective function. A new objective function is defined for the minimization of joint torque effort and internal force. The optimal solution can be found by geometrical approach and analysis using the concept of force ellipsoid. Simulation results are presented with 6DOF PUMA robots.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.6
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• pp.477-483
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• 2002

This paper deals with a workspace analysis of multi-legged walking robots in velocity domain(velocity workspace analysis). Noting that when robots are holding the same object in multiple cooperating robotic arm system the kinematic structure of the system is basically the same with that of a multi-legged walking robot standing on the ground, we invented a way ot applying the technique for multiple arm system to multi-legged walking robot. An important definition of reaction velocity is made and the bounds of velocities achievable by the moving body with multi-legs is derived from the given bounds on the capabilities of actuators of each legs through Jacobian matrix for given robot configuration. After some assumption of hard-foot-condition is adopted as a contact model between feet of robot and the ground, visualization process for the velocity workspace is proposed. Also, a series of application examples will be presented including continuous walking gaits as well as several different stationary posture of legged walking robots, which validate the usefulness of the proposed technique.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.2
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• pp.163-172
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• 2007

A swarm-bot docking with two independent robots aiming at overcoming obstacles or climbing up/down stairs is introduced how it can be manufactured and controlled. Utilizing the fast mobility of the vehicle robot and cooperating between robots expands the applications of the robot. An algorithm for identifying the partner robot and its generic mechanism enabling the docking of two robots are addressed. The designed swarm-bot has advantages in terms of overcoming obstacle or stair climbing which is not easily implemented by a single robot, increasing the adaptability to the environment.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.65-71
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• 2007

Adjustable autonomy architecture provides various ways for a human operator to participate as a member of a human-robot team in improving the performance of the team by resolving issues that the robots cannot deal with or performing tasks that the robots alone would unable to do. According to the level of involvement of the human operator, the robots have to adjust their level of autonomy and, in consequence, the operation mode of the overall system shifts. This paper deals with the implementation issues of seamless switching when the level of autonomy of the human-robot team shifts from one level to another. Especially, we focus on developing reliable methods for monitoring the task progress and maximizing the system flexibility by coping with the detailed differences between humans and robots in their characteristics of motions and their choices of positions, paths, and sequences of sub-goals to achieve a given task. To test and motivate the proposed methods, we have assembled three heterogeneous robots which work together to dock both ends of a suspended beam into stanchions.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.930-939
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• 2004

In this paper, both dynamic constraints and kinematic constraints are considered for the analysis of manipulability of robotic systems comprised of multiple cooperating arms. Given bounds on the torques of each Joint actuator for every robot, the purpose of this study is to drive the bounds of task-space acceleration of object carried by the system. Bounds on each joint torque, described as a polytope, is transformed to the task-space acceleration through matrices related with robot dynamics, robot kinematics, object dynamics, grasp conditions, and contact conditions. A series of mathematical manipulations including the procedure calculating minimum infinite-norm solution of linear equation is applied to get the reachable acceleration bounds from given actuator dynamic constrains. Several examples including two robot systems as well as three robot system are shown with the assumptions of complete-constraint contact model(or' very soft contact') and insufficient or proper degree of freedom robot.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.162-167
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• 1991

The manipulability ellipsoid and the force ellipsoid for a single robot are extended to the case of a multi-robot system. The force ellipsoid is applied to solve the optimal load distribution for the multi-robot system. Two cases are considered in solving the optimal load distribution. In one case, there are no constraints on the joint torques, and the analytic solution ;a given. In the other case, the torque constraints are given in terms of the maximum power consumption, and the algorithm for the solution is proposed.

• The Journal of Korea Robotics Society
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• v.3 no.3
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• pp.226-236
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• 2008

In this paper, control software architecture is designed to enable a heterogeneous multiple humanoid robot demonstration executing tasks cooperating with each other. In the heterogeneous humanoid robot team, one large humanoid robot and two small humanoid robots are included. For the efficient and reliable information sharing between many software components for humanoid control, sensing and planning, CORBA based software framework is applied. The humanoid tasks are given in terms of finite state diagram based human-robot interface, which is interpreted into the XML based languages defining the details of the humanoid mission. A state transition is triggered based on the event which is described in terms of conditions on the sensor measurements such as robot locations and the external vision system. In the demonstration of the heterogeneous humanoid team, the task of multiple humanoid cleaning the table is given to the humanoid robots and successfully executed based on the given state diagram.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.501-506
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• 1993

An efficient solution algorithm of the optimal load distribution problem with joint torque constraints is presented. Multiple robot system where each robot is rigidly grasping a common object is considered. The optimality criteria used is the sum of weighted norm of the joint torque vectors. The maximum and minimum bounds of each joint torque in arbitrary form are considered as constraints, and the solution that reduces the internal force to zero is obtained. The optimal load distribution problem is formulated as a quadratic optimization problem in R, where I is the number of robots. The general solution can be obtained using any efficient numerial method for quadratic programming, and for dual robot case, the optimal solution is given in a simple analytical form.

• The Journal of Korea Robotics Society
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• v.18 no.2
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• pp.225-232
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• 2023

With the recent increase of multiple robots cooperating in smart manufacturing logistics environments, it has become very important how to predict the safety and efficiency of the individual tasks and dynamically assign them to the best one of available robots. In this paper, we propose a novel task policy learner based on deep relational reinforcement learning for predicting the safety and efficiency of tasks in a multi-robot manufacturing logistics environment. To reduce learning complexity, the proposed system divides the entire safety/efficiency prediction process into two distinct steps: the policy parameter estimation and the rule-based policy inference. It also makes full use of domain-specific knowledge for policy rule learning. Through experiments conducted with virtual dynamic manufacturing logistics environments using NVIDIA's Isaac simulator, we show the effectiveness and superiority of the proposed system.