1,755 research outputs found
A TIME-DOMAIN INVERSE DYNAMIC TRACKING CONTROL OF A SINGLE-LINK FLEXIBLE MANIPULATOR
No full textA manipulator system with a large workspace volume and high payload capacity has greater link flexibility than do typical industrial robots and teleoperators. If link flexibility is significant, position control of the manipulator's end-effector exhibits nonminimum-phase, noncollocated, and flexible-structure system control problems. This paper addresses inverse dynamic trajectory planning issues of a single-link flexible manipulator. The inverse dynamic equation of a single-link flexible manipulator was solved in the time-domain. By dividing the inverse system equation into its causal part and anticausal part, the in verse dynamic method calculates the feed-forward torque and the trajectories of all state variables that do not excite structural vibrations for a given end-point trajectory. Through simulation and experiment with a single-link manipulator, the effectiveness of the inverse dynamic method in producing fast and vibration-free motion has been demonstrated
CONTACT CONTROL FOR ADVANCED APPLICATIONS OF LIGHT WEIGHT ARMS
No full textMany applications of robotic and teleoperated manipulator arms require operation in contact and noncontact regimes. This paper deals with both regimes and the transition between them with special attention given to problems of flexibility in the links and drives. This is referred to as contact control. Inverse dynamics is used to plan the tip motion of the flexible link so that the free motion can stop very near the contact surface without collision due to overshoot. Contact must occur at a very low speed since the high frequency impact forces are too sudden to be affected by any feedback generated torques applied to a joint at the other end of the link. The effects of approach velocity and surface properties are discussed. Force tracking is implemented by commands to the deflection states of the link and the contact force. This enables a natural transition between tip position and tip force control that is not possible when the arm is treated as rigid. The effects of feedback gain, force trajectory, and desired final force level are of particular interest and are studied. Experimental results are presented on a one-link arm and the system performance in the overall contact task is analyzed. Extension to multi-link cases with potential applications are discussed
In Vivo Study of Porcine Cholecystectomy using a Compact Laparoscopic Assistant Robot System KaLAR
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Highly efficient step-up dc–dc converter for photovoltaic micro-inverter
No full textThis paper presents a highly efficient step-up dc-dc converter for photovoltaic system. This converter is composed of an active resonant-clamp circuit and a resonant voltage doubler. The active resonant-clamp circuit limits the voltage stress and provides soft switching of the power switches. Also small value of a clamp capacitor employed to increase efficiency can reduce the conduction loss. Moreover, the resonant voltage doubler is used in the secondary side of the transformer to remove the reverse-recovery problem and clamp voltage stress of output diodes. Thus, the power losses of the proposed converter were minimized by the reducing switching power losses and conducting power loss. A 370 W prototype has been implemented to verify its performance. Experimental results prove the superiority of the proposed highly efficient step-up dc-dc converter for photovoltaic micro-inverter. (C) 2016 Elsevier Ltd. All rights reserved.1176sciescopu
Highly Efficient Asymmetrical PWM Full-Bridge Converter for Renewable Energy Sources
No full textThis paper presents a highly efficient asymmetrical pulse-width modulated (APWM) full-bridge converter for renewable energy sources. The proposed converter adopts full-bridge topology and asymmetric control scheme to achieve the zero-voltage switching (ZVS) turn-on of the power switches of the primary side and to reduce the circulating current loss. Moreover, the resonant circuit composed of the leakage inductance of the transformer and the blocking capacitor provides the zero-current switching (ZCS) turn-off for the output diode without the help of any auxiliary circuits. Thus, the reverse recovery problem of the output diode is eliminated. In addition, voltage stresses of the power switches are clamped to the input voltage. Due to these characteristics, the proposed converter has the structure to minimize power losses. It is especially beneficial to the renewable energy conversion systems. To confirm the theoretical analysis and validity of the proposed converter, a 400 W prototype is implemented with the input voltage range from 40 to 80 V.1184sciescopu
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