Abstract: In order to investigate the controllability for trajectory of hopping robot applied in complex terrain, an intermittent hopping robot which adopts six-bar geared metamorphic mechanism is designed. Through altering the topology structure of the metamorphic mechanism, the designed robot shows ability to store energy, lock and release energy, change the amplitude of stored energy and adjust attitude angle. In addition, the ground reaction force that acts on the foot of the robot has bionic character. According to the structure features of the robot, a righting mechanism that makes the robot roll and right itself in the case of falling down is designed. The simulation tests based on theoretical model analyses are conducted so as to invest the effect of changing the amplitude of stored energy and adjusting the attitude angle on hopping trajectory. A prototype is developed, and the simulation tests are verified by hopping motion experiments. Results indicate that it is of feasibility for mechanism design and controllability for horizontal and vertical jump distance. The controllability for horizontal jump distance is achieved by altering the amplitude of stored energy; In the case of the same stored energy, the controllability for vertical jump distance is achieved by adjusting the attitude angle. The investigation gives an alternative scheme for designing intermittent hopping robot that needs motion planning.

Key words: Attitude angle adjustment, Intermittent hopping robot, Mechanism design, Rolling and righting, Stored energy change