• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.8-11
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• 1996

In impedance control for contact force tracking it is well known that the reference trajectory of the robot is calculated from known environment stiffness. The accuracy of estimating the environment stiffness determines the performance of the resulting force tracking. Here we present a simple technique, called the trajectory modification technique(TMT), of determining the reference trajectory under the condition that the environment stiffness is unknown. Computer simulation studies have shown that force tracking using the proposed technique is excellent for unknown environment with time varying stiffness.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.132-140
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• 1999

This paper treats the estimation of human impedance and their application to human-robot collaboration work. Initially, we perform an experiment at which the human becomes a slave and the robot behaves like a master having F/T sensor on its end. The human impedance expressed in terms of mass, damping, and stiffness properties are estimated based on the force data measured by F/T sensor and the commanded position data of the robot. To show the effectiveness of the estimated human impedance, we perform the second experiment at which the roles of the human and the robot are reversed. It is shown that the robot using the estimated human impedance follows the trajectory commanded by human very smoothly.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.11
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• pp.1096-1101
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• 2009

In this paper, an embedded system has been designed for force control application to interact between a robot arm and a human operator. Force induced by the human operator is converted to the desired position information for the robot to follow. For smooth operations, the impedance force control algorithm is utilized to represent interaction between the robot and the human operator by filtering the force. To improve the performance of position control of the robot arm, a velocity term has been obtained and tested by several filters. A PD controller for position control has been implemented on an FPGA as well. Experimental studies are conducted with the ROBOKER to test the functionality of the designed hardware.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.552-557
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• 2011

This paper presents experimental results on the energy-bounding approach to a rate-mode bilateral teleoperation control that can guarantee the robust system stability in variable time-delayed telecommunication environments. Previously, rate-mode energy bounding approach [15] was proposed and verified with experimental results using the simulated remote slave model. In this paper, a real experimental setup using an industrial robot (Denso) as a remote slave robot composed and conducted similar experiments with previous paper. In order to guarantee stability of the Denso when contacting with high impedance wall, velocity based impedance control modified by position based is used. Experimental results show that the rate-mode energy bounding approach can guarantee stable bilateral teleoperation system in the free and contact motion with variable time delay.

• The Journal of Korea Robotics Society
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• v.17 no.1
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• pp.48-57
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• 2022

In this paper, we propose a legged landing platform for the quadcopter taking off and landing in the ship environment. In the ship environment with waves and winds, the aircraft has risks being overturned by contact impact and excessive inclination during landing on the ship. This landing platform has four landing legs under the quadcopter for balancing and shock relief. In order to make the quadcopter balanced on ships, the position of each end effector was controlled by PID control. And shocks have mainly happened when quadcopter contacts the ship's surface as well as legs move fast. Hence, impedance control was used to cope with the shocks. The performance of the landing platform was demonstrated by a simulation and a prototype in three sea states based on a specific size of a ship. During landing and tracking the slope of the ship's surface, oscillations of rotation and translation from the shock were mitigated by the controller. As a result, it was verified that transient response and stability got better by adding impedance control in simulation models and prototype experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.786-795
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• 2000

In this paper, a new impedance force control method for deburring and polishing process is proposed. The proposed method is robust to deal with unknown environment stiffness as unknown well as environment location. An adaptive technique is used to minimize the force error occurred due to unknown environment surface profile. A robust position control algorithm based on time-delayed information is used to cancel out uncertainties in robot dynamics. A three link robot manipulator is used to demonstrate performances of the proposed control on deburring and polishing tasks. Stability analysis for the adaptive control is presented and its results are confirmed by simulations.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.440-445
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• 1994

An application of H$_{\infty}$ synthesis to contact control of a manipulator is suggested. Based on computed torque linearization of a manipulator, a target dynamics for contact motion control is defined and used as a reference model. The target dynamics relates position and force errors through free motion impedance and force error compensators. The H$_{\infty}$ control synthesis is adopted to find an optimum the compensator for position tied force control in various directions of the end-effector. The optimization is performed on the augmented criteria, which trades off the sensitivity function of the errors and the input load at the joints. A design example of the compensator is provided that meets the design specifications.s.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.1-7
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• 1998

Robots utilized in the field of welfare or agriculture should be light in weight and flexible in structure. A pneumatic actuator has properties such that it is more powerful compared with a motor of same weight, and that it is flexible, clean and unexplosive. In this paper we propose a new structure of the pneumatic actuator with two-degree-of-freedom. By using proposed pneumatic actuators, we can easily construct multi-degree-of-freedom pneumatic manipulators. Here we constructed a fourteen-degree-of-freedom pneumatic dual manipulator. The performance of the dual manipulators is confirmed through experiments for ball-handling with impedance control. In the experiments several control schemes, including the decentralized control and the simple adaptive control (SAC), were used. The results show that a flexibility of the pneumatic actuator is appropriate to accomplish the coordinative motion of the right and left arms of the robot.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.1
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• pp.32-37
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• 2002

Applications of scaled telemanipulation into micro or nano world that shows many different features from directly human interfaced tools have been increased continuously. Here, we have to consider many aspects of scaling such as force, position, and impedance. For instance, what will be the possible range of force and position scaling with a specific level of performance and stability\ulcorner This knowledge of feasible staling region can be critical to human operator safety. In this paper, we show the upper bound of the product of force and position scaling and simulation results of 1DOF scaled system by using the Llewellyn's unconditional stability in continuous and discrete domain showing the effect of sampling rate.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.8
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• pp.585-591
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• 2003

A virtual force is generated and fed back to the operator to make the teleoperation more reliable, which reflects the relationship between a slave robot and an uncertain remote environment as a form of an impedance. In general, for the teleoperation, the teleoperated mobile robot takes pictures of the remote environment and sends the visual information back to the operator over the Internet. Because of the limitations of communication bandwidth and narrow view-angles of camera, it is not possible to watch certain regions, for examples, the shadow and curved areas. To overcome this problem, a virtual force is generated according to both the distance between the obstacle and the robot and the approaching velocity of the obstacle w.r.t the collision vector based on the ultrasonic sensor data. This virtual force is transferred back to the master (two degrees of freedom joystick) over the Internet to enable a human operator to estimate the position of obstacle at the remote site. By holding this master, in spite of limited visual information, the operator can feel the spatial sense against the remote environment. It is demonstrated by experiments that this collision vector based haptic reflection improves the performance of teleoperated mobile robot significantly.