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Liu X.,Yanshan University | Zhao T.,Yanshan University | Bian H.,Yanshan University | Luo E.,CFHI Tianjin Heavy Equipment Engineering Research Co. | Yuan F.,Yanshan University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013

Based on the coupling dynamics characteristics of ship motions, the influence produced by coupling force/torque to performance of mechanism dynamics and modeling of dynamics of 3-SRR/SRU 3-DOF coupling parallel mechanism is analyzed, each branch is even borne by using actuation redundancy, the goal of using less-axis drivers to compensate multi-axis motions of the moving platform is achieved. By using the method of equivalent transform of parameters of coupling dynamics, the coupling force/torque of platform and branch are described in inertial coordinate frame. By the target of minimum input power, combined with rate-of-virtual work form of D'Alembert principle, the general equation of coupling dynamics is established. The numerical example shows that the coupling parallel mechanism with actuation redundancy is suitable for multi-axis compensation of stabilized platform. The index of dynamic performance of the system is also effectively improved. All these works lays a foundation to the further studies on the dynamics optimization and real-time control of the coupling parallel mechanism. ©2013 Journal of Mechanical Engineering. Source

Liu X.,Yanshan University | Zhao T.,Yanshan University | Luo E.,CFHI Tianjin Heavy Equipment Engineering Research Co. | Chen W.,Yanshan University | Pan Q.,Yanshan University
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2013

This article presents a coupling 3-PSR/PSU parallel mechanism for ship-based stabilized platform based on the coupling characteristics of the ship motions. With coupling characteristics, the goal of 3-axis drives and 5-axis compensation of the moving platform is achieved. From the screw theory, degrees-of-freedom and coupling kinematic characteristics of the mechanism are analyzed. A method for equivalent transformation of motion parameters is proposed. This presents a mapping relationship between the independent degrees-of-freedom and the coupling degrees-of-freedom. The investigations are further extended to the coupling dynamics characteristics of the mechanism. In particular, the effects produced by the coupling force/torque to the system are analyzed. Hence, taking minimum system driving force as the optimization goal, the coupling dynamic equation of the parallel mechanism is established. The numerical example reveals that this coupling parallel mechanism can be applied to the multi-axis compensation of ship-based stabilized platform. The study also enriches the application area of lower-mobility parallel mechanism. © IMechE 2012. Source

Zhao Y.-F.,Yanshan University | Zhao Y.-F.,CFHI Tianjin Heavy Equipment Engineering Research Co. | Cheng L.,Yanshan University | Cheng L.,CAS Shenyang Institute of Automation | And 3 more authors.
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2010

A new method for dynamic simulation of the process of cutting was proposed in order to forecast the performance of the parallel machine tool and ensure safety of the cutting process. Adding friction to all joints including screw joints realized the simulation model perfectly according with the real machine tool. Then, motion controlling model and cutting force model were created according to numerical control files and cutting parameters. Importing the instance simulation on the machining process of 5-UPS/PRPU parallel machine tool, the simulation results predict accurately the probable problems in the practical machining process. This methodology is easy, accurate, reliable and practical. Source

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