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Joint Control (joint + control)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Joint control for flexible-joint robot with input-estimation approach and LQG method

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2008
Chien-Yu Ji
Abstract In this work, the input-estimation (IE) algorithm and the linear quadratic Gaussian (LQG) controller are adopted to design a control system. The combined method can maintain higher control performance even when the system variation is unknown and under the influence of disturbance input. The IE algorithm is an on-line inverse estimation method involving the Kalman filter (KF) and the least-square method, which can estimate the system input without additional torque sensor, while the LQG control theory has the characteristic of low sensitivity of disturbance. The design and analysis processes of the controller will also be discussed in this paper. The joint control of the flexible-joint robot system is utilized to test and verify the effectiveness of the control performance. According to the simulation results, the IE algorithm is an effective observer for estimating the disturbance torque input, and the LQG controller can effectively cope with the situation that the disturbance exists. Finally, higher control performance of the combined method for joint control of the robotic system can be further verified. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Proportional-Integral-Plus Control of an Intelligent Excavator

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 1 2004
Jun Gu
Previous work using LUCIE was based on the ubiquitous PI/PID control algorithm, tuned on-line, and implemented in a rather ad hoc manner. By contrast, the present research utilizes new hardware and advanced model-based control system design methods to improve the joint control and so provide smoother, more accurate movement of the excavator arm. In this article, a novel nonlinear simulation model of the system is developed for MATLAB/SIMULINK©, allowing for straightforward refinement of the control algorithm and initial evaluation. The PIP controller is compared with a conventionally tuned PID algorithm, with the final designs implemented on-line for the control of dipper angle. The simulated responses and preliminary implementation results demonstrate the feasibility of the approach. [source]

The role of M. popliteus in unpredictable and in self-initiated balance provocations

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2006
Ann-Katrin Stensdotter
Abstract The purpose of this study was to determine whether m. popliteus (POP) activity would contribute to the control of knee joint position in unpredictable and in self-initiated provocations of standing balance. Ten healthy women (age 25.2,±,4.5 years, means and SD) without known knee pathology were tested for postural reactions (1) to unpredictable support surface translations in anterior and posterior directions, and (2) in self-initiated balance provocations in a reaction time (RT) forward reach-and-grip task. Electromyographic activity was recorded from POP and other leg muscles plus the deltoid muscle. Three-dimensional kinematics were captured for the knee joint and the body centre of mass was calculated. POP was active first of all the muscles recorded, regardless of translation direction, and knee joint movements elicited were either knee extension or external rotation of the tibia. In the RT task, the POP was active after initiation of reaching movement, and there was little consistency in the kinematic response. POP activity was not direction specific in response to support surface translation, but appeared triggered from reactive knee joint movement. The response to the support-surface translation suggests that POP served to control knee joint position rather than posture. In the RT task, we could not deduce whether POP activity was attributed to knee joint control or to postural control. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:524,530, 2006 [source]