Biped Walking Of A Robot With Six Degrees Of Freedom

With high mobility, excellent adaptability to environments, and special ability to move ondiscrete terrains, biped robots have been attracting much attention. Active biped walking robotshave strong locomotion ability, but they have in general a lot of DoFs (degrees of freedom),and hence their structure and walking control are very complex. In contrast, passive or semi-passive walking robots have less DoFs, but their mobility is relatively poor. To combine theadvantages of active and passive biped walking robots and remove their disadvantages, a novelbiped walking robot has been developed, and its stability, walking gaits and walking patterngeneration have been studied deeply and systematically in this dissertation. Specifically, themain contributions are as follows.(1) A novel active biped walking robot with only 6-DoFs, which is called Bibot-U6, isdesigned and implemented with a modular method. Its kinematics and dynamics are analyzedwith the POE method and the Featherstone method, respectively.(2) Walking stability with frictional constraint is investigated. The stability criterion isextended by taking account not only the ZMP for evaluating the possibility of tipping-over butalso the friction between the feet and the ground for evaluating the possibility of slippage. Tothis end, the contact between the feet and the ground is modeled. The stability criterion isapplicable not only to Bibot-U6 with turning-around gait, but also to humanoid robots walkingwith high speed, or small friction on ?oors.(3) According to the configuration of Bibot-U6 robot, the turning-around gait, side-steppinggait, ?ipping-over gait and foot-wheel hybrid gait are presented. The corresponding walkingpattern and motion are planned in the case of level ground. A vertical moment compensationmethod is proposed to prevent the robot from possible rotational slippage when it walks withturning-around gait.(4) The walking pattern and motion are then extended to the cases where the robot walkson a slope and steps on and down a stair. A method to measure the slope angle with the robot’sinternal encoder and six-axis force/torque sensor is presented. In addition, the walking abilityof Bibot-U6 robot is analyzed, which is useful to the design of similar biped robots. Walkingsimulations and experiments are carried out to verify the e?ectiveness of the presented walkinggaits, stability analysis, and to illustrate the features of this novel biped robot.