On The Bipedal Walking Theory Research And Stability Analysis Based On Bionics And Passive Walking

Biped walking robot is similar to humans and can do a lot of work instead of humans,so many scholars pay attention to it. After half a century’s development, research onfully-actuated biped walking robot has made brilliant achievements, but the high energyconsumption, low efficiency and unnatural gait limit its application. The propose ofpassive dynamic walking principle by McGeer opened another line of thought for people,but the passive biped robot has very single walking environment and poor stability, cannotbe applied to practice. On this basis, a quasi-passive biped walking robot theory arises at thehistoric moment, it has efficient, high-speed and stable gait. In this paper, a semi-passivebiped robot walking mechanism and stability were studied. Mainly include the followingaspects:Usually, the function of the robot’s upper body is ignored, and the torso is replacedby a mass point on the hip in theoretical research, this is not conducive to the expansion ofthe functions of the robot. In this article we add a torso to the compass-like mass pointmodel, the torso and the legs form a linkage. Then we let the model walk down along a5°slope with its own gravity and inertia. In the simulation analysis, we set the torso’s qualityand length as0, and compare its limit cycle with the compasses-like robot, obtain thelinkage’s effect to the system. Then we change the quality and the length of the torso, paintthe angles change curve changing with time and the distance between the two feet curvechanging with time, get the influence to robot walking cycle, the step distance and theaverage walking speed, the final conclusion is accord with the characteristics of humans,can be used to guide the parameter selection of torso in the future.Then, we remove the linkage mechanism’s limit to the compasses-like robot so that thetorso and legs can move independently, and we deduce the new kinetic equation, and set twomovement patterns to the torso, and add control laws to the two models. The relation of thetorso’s angle’s selection range and control gain K, when K=1, the torso’s angle is limitedto0.012rad, and the range increases along with K’s value; Respectively, for the twomovement patterns, we get the curves of the walking cycle、the angle of two legs、averagewalking changing with the torso angle and control gain, and make comparison of them, sothat we can select torso movement patterns and control gain according to our requirement inthe future.Stability analysis is the emphasis and difficulty of walking robot research, all stabilitycriterions we widely use now have their defects. ZMP stability criterion can be only used toanalysis fully-actuated biped walking robot with flat feet, the calculate of the Poincareregression mapping fixed point is too complex and it’s only suitable for small disturbance stability analysis. This article divides the robot’s walking process into a series of invertedpendulum’s swing process, we construct a function for stability measurement through theanalysis of the robot’s COM, and analyze the relationship between the function and theangular momentum of the COM、the position of the COM and so on. At last, we constructthe function for stability measurement of the compasses-like robot with torso, then establishthe relationship between the robot’s state variables and the function, lay the foundation forthe future research.