The invention relates to a
motion planning method for additional shafts in working units of a gantry hoisting
robot. On the basis of addition of the gantry external linear additional shafts, redundant working units linked with six joints of the
industrial robot, and a fixed working platform, two of a section of
machining path points monotonously changing along a
motion direction of each slide table which is fixedly connected with a
robot base on the corresponding additional shaft are manually selected as end points of a preferred interval. A movable
initial point of each slide table is obtained through a
projection principle of a straight line from a point to a space. A movable middle point and a movable termination point of each slide table are obtained through setting a step length of the slide table, that is, distances from movable positions corresponding to the
machining path points in the corresponding preferred interval, of each slide table, to a zero point of the corresponding additional shaft, are obtained. Movements of the slide tables are in preference to motions of the joints of the
robot when the robot machines the path points in the preferred intervals. The method is capable of reducing the change amplitudes of the joints of the robot, so that the motion of the robot is continuous and stable; and the method is suitable for
machining the continuous and dense path points by the robot.