爬楼轮椅后腿机构优化设计

Optimal Design of the Rear Leg Mechanism of Climbing Wheelchair

爬楼轮椅后腿机构是典型的平面二自由度五杆机构,为了提高轮椅的运动性能,在对轮椅后腿运动学分析及对其关键点受力分析的基础上,以五杆机构中2连架杆和1连杆的杆长为设计变量,以并联机构的雅可比条件数均值为目标函数,给出约束条件,采用非线性遗传算法对轮椅后腿机构进行优化设计。之后在MATLAB中对五杆机构优化前后的运动轨迹及关键点的受力情况进行仿真分析,通过对比发现,优化后的雅可比条件数明显减小,五杆机构的活动空间更加紧凑,有效避免了机构的奇异位形,使轮椅后腿的位姿调节更加灵活;后腿机构关键点处受力明显减小,有效减少了工作过程中噪声的产生,使轮椅运行更加平稳。总之,优化设计使轮椅的各项性能得到了明显提升。

The rear leg mechanism of climbing wheelchair is the typical planar 2 degrees of freedom fivebar linkages,in order to improve the motion performance of the wheelchair,based on the kinematic analysis and the stress analysis on the key point of the rear leg,taking the length of two side links and one linkage of the five bar linkage as the design variable,the mean of the parallel mechanism Jacobian condition number as the objective function,the constraint conditions are given,and the nonlinear genetic algorithm are used to the optimization design of wheelchair rear leg mechanism.After that,the motion track before and after the optimization of five bar mechanism and the stress of the key point are simulated in the MATLAB.Through the comparison shows that,the optimal Jacobian condition number decreases obviously,the active space of five bar mechanism is more compact and the singular configuration of the mechanism is effectively avoided.The position and posture of the rear leg turn more flexible.The force at the key points of the rear leg mechanism is obviously reduced,the noise in the working process is effectively reduced and the wheelchair run more smoothly.In short,through the optimal design,the performance of the wheelchair is significantly improved.