ln order to raise the tractive efficiency of a boat-typc tractor further, according to a point of view about reducing energy consumption by reducing the volume of thc blade cavity, an idea of four-footed walkiag boat-...ln order to raise the tractive efficiency of a boat-typc tractor further, according to a point of view about reducing energy consumption by reducing the volume of thc blade cavity, an idea of four-footed walkiag boat-type tractor is put forward. and a walking device with two feet and four small wheels is designed and manufactured. It can move on the rails of a paddy soil bin to simulate the tractive performance of a boat-type tractor in thc paddy field. Kinematics and dynam- ics of the walking device is analysed. Because it can ensure that the blade foot enters and leaves the soil vertically, and eliminates the functions of the soil compression and pick by the blade entirely, so the volume of the blade cavity can be reduced to a minimum and the efficiency of the walking sys- tem has been rasied considerably. Thus, it is feasible to adopt a four-footed walking mechanism in the boat-type tractor.展开更多
Faster response to orientation varying is one of the outstanding abilities of a parallel kinematic machine（PKM）.It enables such a system to act as a reconfgurable module employed to machine large components effcient...Faster response to orientation varying is one of the outstanding abilities of a parallel kinematic machine（PKM）.It enables such a system to act as a reconfgurable module employed to machine large components effciently.The stiffness formulation and analysis are the beforehand key tasks for its parameters design.A novel PKM with four degrees of freedom（DOFs）is proposed in this paper.The topology behind it is 2PUS-2PRS parallel mechanism.Its semianalytical stiffness model is frstly obtained,where the generalized Jacobian matrix of 2PUS-2PRS is formulated with the help of the screw theory and the stiffness coeffcients of complicated components are estimated by integrating fnite element analysis and numerical ftting.Under the help of the model,it is predicted that the property of system stiffness distributes within the given workspace,which features symmetry about a certain plane and is also verifed by performing fnite element analysis of the virtual prototype.Furthermore,key parameters affecting the system stiffness are identifed through sensitivity analysis.These provide insights for further optimization design of this PKM.展开更多
文摘ln order to raise the tractive efficiency of a boat-typc tractor further, according to a point of view about reducing energy consumption by reducing the volume of thc blade cavity, an idea of four-footed walkiag boat-type tractor is put forward. and a walking device with two feet and four small wheels is designed and manufactured. It can move on the rails of a paddy soil bin to simulate the tractive performance of a boat-type tractor in thc paddy field. Kinematics and dynam- ics of the walking device is analysed. Because it can ensure that the blade foot enters and leaves the soil vertically, and eliminates the functions of the soil compression and pick by the blade entirely, so the volume of the blade cavity can be reduced to a minimum and the efficiency of the walking sys- tem has been rasied considerably. Thus, it is feasible to adopt a four-footed walking mechanism in the boat-type tractor.
基金supported by the National Natural Science Foundation of China (Nos.51075295 and 51005164)Tianjin Research Program of Application Foundation and Advanced Technology (No.11JCYBJC05600)
文摘Faster response to orientation varying is one of the outstanding abilities of a parallel kinematic machine（PKM）.It enables such a system to act as a reconfgurable module employed to machine large components effciently.The stiffness formulation and analysis are the beforehand key tasks for its parameters design.A novel PKM with four degrees of freedom（DOFs）is proposed in this paper.The topology behind it is 2PUS-2PRS parallel mechanism.Its semianalytical stiffness model is frstly obtained,where the generalized Jacobian matrix of 2PUS-2PRS is formulated with the help of the screw theory and the stiffness coeffcients of complicated components are estimated by integrating fnite element analysis and numerical ftting.Under the help of the model,it is predicted that the property of system stiffness distributes within the given workspace,which features symmetry about a certain plane and is also verifed by performing fnite element analysis of the virtual prototype.Furthermore,key parameters affecting the system stiffness are identifed through sensitivity analysis.These provide insights for further optimization design of this PKM.
