改进末端跟随运动的超冗余蛇形臂机器人运动学逆解

Inverse Kinematics of Hyper-Redundant Snake-Arm Robots with Improved Tip Following Movement

针对超冗余蛇形臂机器人运动学逆解中计算量大、超关节极限和位形偏移量大的问题,提出了一种改进末端跟随运动的逆解算法.在末端跟随法中引入蛇形臂弯曲角度的约束,调整关节位置的更新方式,使关节在蛇形臂轴线上运动.通过依次更新关节的空间位置,将超冗余多节蛇形臂的运动学逆解转化为2自由度单节蛇形臂的运动学逆解.仿真分析了蛇形臂机器人在基座移动和基座固定条件下的轨迹跟踪效果,对比了同一目标位置下不同方法的性能.结果表明,改进后的算法能保证蛇形臂的弯曲角度不超过给定范围,关节的运动量从末端到基座依次减小,机器人的运动更协调;与基于雅可比矩阵的数值法和现有启发式方法相比,该方法运算量降低,机器人整体位形偏移量减小,能用于蛇形臂机器人的实时控制.

An inverse kinematics algorithm with improved tip following movement is proposed to solve the problems of expensive computational cost,exceeding joint limits and large configuration deviation for the inverse kinematics of hyperredundant snake-arm robots.Constraints on the bending angles of snake arm are introduced to the tip-following method.And the update mode of the joint position is adjusted to make joints locate on the axis of the snake arm.By updating the spatial position of joints successively,the inverse kinematics of the hyper-redundant multi-section arm is converted into the inverse kinematics of a single-section arm with 2 degree-of-freedoms.Finally,the trajectory tracking effects of the snakearm robot with the base moving,and also with the base fixed,are analyzed by simulation,and the performances of different methods under the same target position are compared.Results show that the improved algorithm can ensure that the bending angles do not exceed the given range and the amount of joint movement is diminishing from the tip to the base,yielding a more concordant movement.Compared with the Jacobian-based numerical method and the existing heuristic methods,the computational cost is decreased and the generated configuration deviation of the whole robot is reduced using the proposed method,which is more applicable for the real-time control of a snake-arm robot.