• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.244-248
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• 1987

The force/torque sensor for robot is developed. The compliance algorithm for peg-in-hole insertion task using the forec/troque sensor is developed. The system consists of an IBM PC, robot, force/torque sensor, strain meter, A/D board, and interface board. The IBM PC functions as a main processor and the robot controller as a slave processor. The sensor is constructed to measure $T_x$, $T_y$, $F_z$ which are necessary to precisely execute a peg-in-hole insertion task by SCARA type assembly robot. The outputs of sensor are analyzed. On the basis of the analysis, compliance algorithm for peg-in-hole insertion task is developed. Some comments concerning the development of wrist force/torque sensor and compliance algorithm are given.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.101-108
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• 2004

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to obtain stable control performance. In this report, we applied disturbance estimation and compensation type robust control to all axes in a 3-link electro-hydraulic manipulator. From the results of experiment, it was confirmed that the performance of trajectory tracking and attitude regulating is greatly improved by the disturbance observer, which model is the same for each axis. On the other hand, for the autonomous assembly tasks, it is said that compliance control is one of the most available methods. Therefore we proposed compliance control which is based on the position control by disturbance observer for our manipulator system. To realize more stable contact work, the states in the compliance loop are feedback, where not only displacement but also velocity and acceleration are considered. And we applied this compliance control to Peg-in-Hole insertion task and analyzed mechanical relation between peg and hole. Also we proposed new method of shifting the position of end-effector periodically for the purpose of smooth insertion. As a result of using this method, it is experimentally confirmed that Peg-in-Hole insertion task with a clearance of 0.05［mm］can be achieved.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.7
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• pp.656-662
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• 2008

A cost-function based on manipulability and compatibility is designed to determine assembly motions of two cooperating manipulators. Assembly motions are planned along the direction maximizing performance indices to improve control performance of the two manipulators. This paper proposes bimanual task compatibility by defining cost functions. The proposed cost functions are applied and compared to the bimanual assembly task. The problem is formulated as a constrained optimization considering assembly constraints, position of the workpieces, and kinematics and redundancy of the bimanual robot. The proposed approach is evaluated with simulation of a peg-in-hole assembly with an L-shaped peg and two 3-dof manipulators.

• Journal of Korean Institute of Industrial Engineers
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• v.17 no.2
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• pp.75-86
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• 1991

This paper presents a methodology to enable the tolerances on mating parts of an assembly to be specified and be compatible to the precision of an assembly robot so as to achieve maximum system performance. The measure of performance is defined as the Probability of Successful Assembly (PSA). A typical loose fastener assembly, usually called peg-in-a-hole is investigated. The Geometric Tolerancing System is adopted to represent position tolerances of mating parts. Two models are presented by considering modifiers on a position tolerance, Regardless of Feature Size (RFS) and Maximum Material Condition (MMC). Using these models, it is analyzed how the Standard Limits and Fits recommended by ANSI influence the performance of an assembly robot. For this analysis, the Standard Limits and Fits are transformed to the representation scheme of the Geometric Tolerancing System. Due to low PSAs when the Standard Limits and Fits are taken into account, the effect of chamfers around a hole is also analyzed.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.1
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• pp.47-53
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• 2004

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is quite difficult to obtain stable control performance. We have applied a disturbance estimation and compensation type robust control to all the axes in a 6-link electro-hydraulic manipulator. It was confirmed that the performance of trajectory tracking and attitude regulating was greatly improved by the disturbance observer. For autonomous assembly tasks, it is said that compliance control is one of the most popular methods in contact task. We have proposed a compliance control based on the position control by a disturbance observer for our manipulator system. To realize more stable contact work, the states in the compliance loop are feedbacked, where not only displacement but also the velocity and acceleration are considered. We have also applied this compliance control to the Peg-in-Hole insertion task and proposed new methods of (1)rotating of the end-effector periodically in order to reduce the friction force, (2)random searching for the center of a hole and (3)trajectory modification to reduce the impact force. As a result of these new methods, it could be experimentally confirmed that the Peg-in-Hole insertion task with a clearance of 0.007 [mm] could be achieved.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1155-1160
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• 1991

Active part mating algorithm using 6-axis force sensor data for the assembly automation and/or teletobotics is presented and experimented. Parts to be mated are cylindrical and have no chamfers. There are basically two modes. One is the normal mode with only a positional error, the other is the tilted mode with an orientational error in addition to a positional error. The used algorithm distinguishes a contact external to the hole from that of internal to the hole in order to perform part-mating in spite of the relative tilt between the hole and the peg.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.31-35
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• 1986

Up to now, the most studies on the passive compliance system for assembly robot were only concerned about the device itself without through analysis of its concept. In this paper, we have tried to analyze a structural characteristics, in the case that the passive compliance system was used in simple assembly process like inserting a round shaft or peg into a round hole.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.427-431
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• 1996

A modeling of the dynamics of two cooperating robot manipulators doing assembly job such as peg-in-hole while coordinating the payload along the desired path is proposed. The system is uncertain due to the unknown mass and moment of inertia of the manipulators and the payload. To control the system, a robust control algorithm is proposed. The control algorithm includes fuzzylogic. By the fuzzy logic, the magnitude of the input torque of the manipulators is controlled not to go over the hardware saturation with keeping path tracking errors bounded.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.410-410
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• 2000

Impedance control is recognised as one of the most proper control scheme to carry out the assembly tasks, since it can control the dynamic relationship between the manipulator and environment directly. However, it is well known that the contact force cannot be controlled directly using the impedance control. Also impedance parameters should be properly defined depending on the task to be performed. We propose a new position based impedance control, which has self-adjusted impedance parameters and can control the contact force explicitly, Impedance parameters, as time-varying parameters, are adjusted automatically based on the measured contact force and the position error during the task. A proposed algorithm was implemented on the peg-in-hole task with the industrial manipulator. We shows the effectiveness of proposed control method experimentally.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.878-886
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• 2004

Uncertainties are inevitable in robotic assembly in unstructured environment since it is difficult to construct fixtures to guide motions of robots. This paper proposes an augmented Petri net and an algorithm to adapt the assembly model on-line during actual assembly process. The augmented Petri net identifies events using force and position information simultaneously. Unmodeled contact states are identified and incorporated into the model on-line. The proposed method increases the level of intelligence of the robot system by enhancing the autonomy. The proposed method is evaluated by simulation and experiments with L-type peg-in-hole assembly using a two-arm robot system.