Study On Humanoid Gait Planning And Stability Of Biped Robot

Biped robot is more capable of avoid-obstacle walking, and can walk on allkinds of complicated terrains, so it has wide application prospects in the industryof humanoid biped robot technology. There is very important theoreticalsignificance and practical value in the studying the humanoid gait of biped robot,and making it suitable of humanoid walking satbly and fast.This paper mainly study the key technology in the gait of humanoid walkingof humanoid biped robot. And this dissertation makes the study through theresearch of bionic mechanism of biped robot, the stablity of biped waiking gait,the planning of humanoid gait and the control method of it.This paper makes analysis of the freedom distribution and the driving modeof joint in human's low limbs, and has disigned the biped robot HEUBR₁ withbionic mechanism of 14 DOF. Based on the mechanism of human's ankle jointmovement, this paper disigned a new kind of parallel mechanism with 2 DOF, andapplied it in the design of joint in the biped robot. Considering the imbalancecharacter of series ankle motion, this dissertation optimized the design withparallel ankle joint mechanism in the biped robot, and made the motion velocityand the peak value of driving powerot of the parallel ankle joint mechanism in thebiped robot more stable. Through the analysis of simulation experiment in theADAMS, this paper studied the motion performance of the optimized parallelankle joint mechanism.This paper analyzes the relationship between Zero Moment Point(ZMP) andCenter Of Pressure(COP), and makes the conclusion that the ZMP of biped robotis the COP of biped robot under the condition that there is no viscous force andadsorption force between the biped robot and horizontal ground. According to thedifferences of the supporting surface in the gait of humanoid walking, this paperproposes description method of supporting surface, fulfills the region descriptionsof support polygon under the condition of multipoint contact; based on thecomprehensive consideration of the position of ZMP/COP and COG in thesupporting surface, this paper proposes criterion for comprehensive stabilitywhich is based on the consideration of ZMP/COP and COG, and the result ofsimulation experiment shows that this method is better than traditional criterionfor comprehensive stability in the evaluation of the gait's stability. This paper analyzes several kinds of human's walking gaits, then proposesthe 6 different kinds of biped robot's gait under different walking velocity, andanalyzes the rotation angle of joint, angular velocity, driving torque, the change ofsupporting surface footplate and the stability margin under the 6 different gaits.And this paper analyzes the corresponding energy consumption ratio of waikingof different walking gait, then compares scope of application, advantages anddisadvantages of different gaits. Comparing to the non-toe genuflex gait oftraditional biped robot, this paper proposes the planning method of humanoid gait,and plans the key parameter of gait in 3 dimensions, then uses the cubic splinefitting method to abtain the continuous path corresponding to certain parameters.By adjusting the length of leg and the angle of foot, it can simulate several kindsof human's walking gait. By adjusting the angle of ankle joint under key attitude,it can make sure that the biped robot walk stably.This paper analyzes the traditional methods of gait control, such as trackingthe COG trajectory and tracking the ZMP trajectory, then compares the stablewalking character of human's walking. Based on these reseaches, this paperproposes an inverted pendulum model with the charater of mobile and scalable,and analyzes the relationship between the movement of ZMP and COG inconstraint plane. Besides, this paper proposes a new control strategy which needsno accurate tracking of the expected ZMP trajectory but should actively adjust theZMP to track the COG trajectory in effective stable range. This paper presents anew method to fulfill the control of gait compensation by using the driving forceof telescopic handle in the inverted pendulum model with the charater of mobileand scalable to compensate the driving torque of joint in the multi-bar model.Based on the experimental platform of biped robot HEUBR₁, this paperimplements stable walking of different gait under different stride frequency, thecompares the angle of knee joint, angular velocity, driving torque, the change oftoe joint's angle, plantar pressure and stability margin of the gait of three differentgaits. The results show that there is big improvement in the walking of biped robotwhen using the parallel ankle joint with 2 DOF, and more accurate criterion forthe comprehensive stability of different gait, then prove feasibility of planning forhumanoid gait and control method.