Optimization Synthesis of Hybrid Six-Bar Mechanism With Non-Circular Gear Constraints

Abstract

A novel hybrid six-bar mechanism with non-circular gear constraints and its optimal synthesis method for complex multi-pose rigid body guidance tasks are proposed. An innovative optimization module is proposed to optimize the non-circularity and smoothness of non-circular gear pitch curves. The optimization synthesis of this mechanism is divided into two steps. The first step is to conduct multi-objective constraint optimization with pose error and non-circular gear pitch curve as optimization objectives to obtain the required diversified non-inferior solution set. Secondly, a set of solutions are selected from the solution set to construct the optimization function of non-circular gear pitch curves The non-circularity and smoothness of the pitch curve are optimized to the maximum extent, and the pose change is ensured to be small. Finally, the multi-pose picking and planting of vegetable pot seedlings were realized using the proposed mechanism and optimization synthesis method. The final optimization design results show that the error between the actual pose and the required pose of the compact hybrid mechanism is small. The optimization effect of non-circularity and smoothness of non-circular gear pitch curves is pronounced. The effectiveness of the mechanism is verified via kinematic simulation.

Rounding theory and method for the pitch curves of the variable center distance non-circular gear pair based on working conditions

“…In the research field of non-circular gear pair, most research and applications are focus on non-circular gear pair with fixed center distance, such as picking and planting mechanism, 31,32 silk reeling machine, 33 robot, 34–36 engine, 37 and etc. As a special case of the variable center distance non-circular gear pair, fixed center distance non-circular gear pair can surely be rounded by the method described in this research.…”

Design and Development of Rice Pot-Seedling Transplanting Machinery Based on a Non-Circular Gear Mechanism

“…By optimizing the non-circular gear parameters and structural parameters, the transplanting arm can achieve the characteristic trajectory and attitude required for rice pot transplanting, successfully performing the three actions of rice picking, conveying, and planting. The transplanting arm is a crucial component of the transplanting mechanism, being directly responsible for picking and pushing the rice seedlings [16]. Figure 3 illustrates the structure of the transplanting arm, which consists of a fixed cam (9) on the gearbox and a transplanting arm (7) on the planetary shaft.…”

“…The fork (8) is then reset through the cam (9) in preparation for the next seedling-clamping action. The transplanting arm is a crucial component of the transplanting mechanism, being directly responsible for picking and pushing the rice seedlings [16]. Figure 3 illustrates the structure of the transplanting arm, which consists of a fixed cam (9) on the gearbox and a transplanting arm (7) on the planetary shaft.…”