针对四轮式机器人做非完整运动时系统的非完整性的问题，将四轮式机器人运动规划转化为非线性控制系统的优化问题。提出了对优化变量进行浮点数编码的改进遗传算法，使系统控制精度得到改善。同时将改进的遗传算法采用最优个体保留策略，设计交叉参数和自适应变异参数，确保算法具有良好的收敛性。通过数字仿真实验，证明了该方法的对四轮式机器人非完整运动规划问题具有可操作性。The optimal motion planning problem of four wheeled mobile robot systems, due to the nonholonomic constraints, is usually transformed into an optimal control problem of nonlinear system. The ameliorated genetic algorithm of optimal control for motion planning is presented with encoding the optimized variables with float-point number. The strategy the best individual to be reserved in the ameliorated genetic algorithm operation is applied. With appropriate crossover parameter and self-adaptive aberrance factor, the convergence of the algorithm is improved and the system’s motion precision is leveraged. The numerical simulation indicates the effectiveness of the algorithm for motion control of four wheeled mobile robot systems.