Kinematic synthesis and simulation of a vegetable pot seedling transplanting mechanism with four exact task poses

To obtain a picking and planting integrated transplanting mechanism(PITM)with ideal trajectory shape,reasonable operating attitude,and compact structure for vegetable pot seedling transplanting,a symmetrical structural PITM composed of two planetary carriers and driven by a cam-noncircular gear combination mechanism was proposed in this paper.In accordance with the requirements of transplanting agronomy,the shape of the motion trajectory and the attitude of the end tip of the clamping claw at several specific positions(the starting and end points of picking seedling,the starting point of pushing seedling,and a special point on the return segment)were planned.To make the clamping claws of PITM pass through a set of prescribed positions,the mechanism was simplified to an open-chain 3R mechanism.An accurate four-position-based method for solving the open-chain mechanism model was adopted to obtain the curves of its fixed hinge point(central point)and dynamic hinge point(circle point).The ratio of adjacent bars’lengths was analyzed to determine the feasible interval of the central and circle point curves and the reasonable link length.A desired closed transplanting trajectory that goes through the given points and the corresponding transmission ratio model of the open-chain mechanism was established.After the transmission ratio of each stage of gear and cam pairs was calculated and distributed,the prototype of PITM was designed and manufactured.Lastly,the effectiveness and feasibility of the design were verified through a preliminary experiment of the prototype.

An Iteration Method Based on Homotopy Function for Solving Polynomial Systems and Application to Mechanisms Problems

A new iterating method based on homotopy function is developed in this paper. All solutions can be found easily without the need of choosing proper initial values. Compared to the homotopy continuation method, the solution process of the present method is simplified, and the computation efficiency as well as the reliability for obtaining all solutions is also improved. By application of the method to the mechanisms problems, the results are satisfactory.

Functional Design for Customizing Sit-To-Stand Assisting Devices

Standing up refers to the transition from the seating to the standing postures to perform a movement that involves several body segments and requires both voluntary action and equilibrium control during an important displacement of the body Centre of Gravity （COG）. This task can be considered very important for people with reduced mobility to achieve minimal independence in Activity of Daily Living （ADL）. In this paper, we propose solutions for the homecare of persons with reduced mobility, describing a functional design to customize assisting devices for the Sit-to-Stand （STS）. In particular, the support mechanism that generates the requested motion and sustains the body of a person can be synthesized ad-hoc according to the experimental data of the subject. Experimental tests carried out during the Sit-To-Stand are used to track and record point trajectories and the orientation of the trunk of an individual, and they are used to design a 1-DOF mechanism able to reproduce the assigned rigid-body motion. A four-bar linkage has been synthesized according to the desired features. Simulation results are reported to illustrate the engineering soundness of the proposed mechatronic solution.