• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.1013-1016
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• 1995

This paper deals with dynamics and control of a PRP6-DOF parallel manipulator. Dynamic modeling includes the effect of inertia of all links in the mechanism to increase modeling accuracy. Kinematic analysis about forward and inverse kinematics is also explained. Using Lagrange-D' Alambert method we get equations of motions in a link space which fully represent 6DOF motions of the manipulator.

• 한국정밀공학회지
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• 제11권5호
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• pp.88-97
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• 1994

We persent a method for kinematic calibration of open chain mechanisms based on the product of exponentials (POE) formula. The POE formula represents the forward kinematics of an open chain as a product of matrix exponentials, and is based on a modern geometric interpretation of classical screw theory. Unlike the kinematic parameters in the POE formula vary smoothly with changes in the joint axes;ad hoc methods designed to address the inherent singularities in the D-H parameters are therefore are therefore unnecessary. After introducing the POE formula, we derive a least-squares kinematic calibration algorithm for general open chain mechanisms. Simulation results with a 6-axis open chain are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.415-417
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• 2005

This paper proposes tracking control method using pseudo-backstepping control for wheeled mobile robots with nonholonomic constraints. First, the pseudo commands for forward linear velocity and angular velocity are chosen based on the kinematics. Then, the actual torque control inputs are designed to make the actual forward linear velocity and angular velocity follow the pseudo commands. Both semi-global practical posture(position and heading direction angle) stabilization and trajectory tracking are achieved for reference trajectories such as straight line and sinusoidal curve. The stability and performance analysed and numerical simulations are performed to confirm the effectiveness of the proposed scheme.

• 한국정밀공학회지
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• 제15권9호
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• pp.158-166
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• 1998

This paper presents a geometrical approach to the characteristic analysis of parallel mechanism with free joints intended for use as a planar task robot. Solution of the forward and inverse kinematic problems are described. Because the mechanism has only three degree-of-freedom output, constraint equations must be generated to describe the inter-relationship between actuated joints and free joints so as to describe the position and orientation of the moving platform. Once these constraints are incorporated into the kinematics model, a constrained Jacobian matrix is obtained. and it is used for the solution of the forward kinematic equations by Newton-Raphson technique. Another Jacobian matrix was derived to describe the interrelationship between actuated joints and moving platform. The stiffness, velocity transmission ratio, force transmission ratio and dexterity of the mechanism are then determined based on this another Jacobian matrix. The geometrical construction of the mechanism for the best performance was investigated using the characteristic analysis.

• 한국항공운항학회지
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• 제28권4호
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• pp.125-131
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• 2020

In order to study the correlation between the pilot's cognitive ability and recovery ability by applying a physical element that can cause spatial loss of position to the pilot, a turntable was installed on the top of the motion system to give a quantitative rotational error. We propose a method of simulating flight movement to reduce a difference in feeling and an intuitive method of forward kinematic analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.556-560
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• 2007

In this paper, the research results for the improvement of tracking performance of a hydraulic shaking table are presented. A servo-hydraulic shaking table is not only highly nonlinear but also has a lot of time delay. In addition, the shaking table, which consists of multi axial hydraulic actuators, is a MIMO system coupled by kinematics and dynamics of each other's actuators. And it is demanded for the shaking table to track arbitrary trajectories up to high frequency even at the extreme situations such as substantial external loads and large disturbances. For this purpose, an iterative feed-forward control based on the inverse of a measured frequency response function is used for the shaking table. To solve the dynamic coupling, a pressure feedback control as numerical damping is used. It is shown through numerical simulations that the tracking performance of shaking table is improved up to 100Hz.

• The Journal of Korean Physical Therapy
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• 제25권6호
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• pp.379-385
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• 2013

Purpose: The purpose of this study is to compare kinematics on lower limbs between stair walking with high heel and barefoot in healthy adult women. Methods: 18 healthy adult women were recruited in this study. The subjects performed stair ascent and descent with high heels and barefoot. The experiment was conducted in random order and repeated three times for each stair walking with high heels and barefoot. The movements of lower limb joints were measured and analyzed using a three-dimensional analysis system. Results: The ankle, knee, and hip flexion angles on the sagittal plane exhibited statistically significant differences between stair ascent and descent with high heels and barefoot. The pelvic forward tilt angles showed statistically significant differences only during stair ascent. The ankle inversion, hip abduction and pelvic lateral tilt angles on the frontal plane showed statistically significant differences between stair walking with high heels and barefoot. On the transverse plane, the hip rotation angles showed statistically significant differences between the high-heeled and barefoot gait during stair ascent and descent. However, the pelvic rotation angles showed no statistically significant differences. Conclusion: Therefore, wearing high-heeled shoes during stair walking in daily life is considered to influence lower limb kinematics due to the high heel, and thus poses the risks of pain, and low stability and joint damage caused by changes in the movement of lower limb joints.

• 한국해양공학회지
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• 제34권3호
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• pp.180-193
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• 2020

In this study, the end-effector tracking performance of a manipulator installed on a remotely operated vehicle (ROV) for autonomous underwater intervention is verified. The underwater manipulator is an ARM 7E MINI model produced by the ECA group, which consists of six joints and one gripper. Of the six joints of the manipulator, two are revolute joints and the other four are prismatic joints. Velocity control is used to control the manipulator with forward and inverse kinematics. When the manipulator approaches a target object, it is difficult for the ROV to maintain its position and posture, owing to various disturbances, such as the variation in both the center of mass and the reaction force resulting from the manipulator motion. Therefore, it is necessary to compensate for the influences and ensure the relative distance to the object. Simulations and experiments are performed to track the trajectory of a virtual object, and the tracking performance is verified from the results.

• 제어로봇시스템학회논문지
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• 제7권6호
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• pp.532-539
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• 2001

In robot teleoperation, much research has been carried out to control the slave robot from remote site. One of the essential devices for robot teleoperation is the masterarm, which is a path command generating device worn on human arm. In this paper, a new masterarm based on human kinematics is proposed. Its controller is based on the distributed controller architecture composed of two controller parts: a host controller and a set of satellite controllers. Each satellite controller measures the corresponding joint angle, while the host controller performs forward and inverse kinematics calculation. This distributed controller architecture can make the data updating faster, which allows to implement real-time implementation. The host controller and the satellited controllers are networked via three-wire daisy-chained SPI(Serial Peripheral Interface) protocol, so this architecture makes the electrical wiring very simple, and enhances maintenance. Analytical method for finding three additional unknown joint angles is derived using only three measured angles for each shoulder and wrist, which makes th hardware implementation very simple by minimizing the required number of satellite controllers. Finally, the simulation and experiment results are given to demonstrate the usefulness and performance of the proposed masterarm.

• 한국기계가공학회지
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• 제16권4호
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• pp.113-118
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• 2017

As the demand for industrial robots and Automated Guided Vehicles (AGVs) increases, higher performance is also required from them. Fuzzy controllers, as part of an intelligent control system, are a direct control method that leverages human knowledge and experience to easily control highly nonlinear, uncertain, and complex systems. This paper uses a $LabVIEW^{(R)}-based$ fuzzy controller with gain scheduling to demonstrate better performance than one could obtain with a fuzzy controller alone. First, the work area was set based on forward kinematics and inverse kinematics programs. Next, $LabVIEW^{(R)}$ was used to configure the fuzzy controller and perform the gain scheduling. Finally, the proposed fuzzy gain scheduling controller was compared with to controllers without gain scheduling.