Walking Machanism Analysis For A Heavy-load Hydraulic Hexapod

In recent decades,the number of researches on le gged robots have been increasing rapid ly.A lot of fle xible and adaptive robots infiltrated into every aspect of our lives.With the applicatio n fie lds of legged robots being enlarged now and then,further comple x requireme nts are proposed by contemporary practices inc luding heavier load and better adaptabilit y to extreme walk ing terrain etc.Based on a hexapod model equipped wit h series paral le l legs,this paper mainly focused on the walking mechanis m characterist ics inc lud ing single leg a nd pose k ine mat ics,terrain adaptab ility under a certain stabilit y index a nd power require ments under logical load distr ibut ion methods.This paper consulted the designs and characterist ics of he xapo d in or abroad of C hina,built a heavy-load hexapod model w ith a p lanar pantograph drove by hydraulic system as the walk ing mecha nis m,ana lyzed the forward and inverse kine mat ics and plotted the working space,deduced the equations between the pose vector and the joints' motions after the coordination relationship among the joints' motions was carried out.This paper carried out the stabilit y margin equatio ns in different gaits and discussed the influence produced by var iat ion of some parameters inc lud ing leg extensio n in vert ical d irection,deviatio n of the center of horizonta l trave l and angle between t he speed vector and the Maximum grad ient vector.The bionic princ ip le was proved mat hemat ica lly that robots become more stable when t heir centers of gravit y become lower.The optima l couples of parameters were plotted and the wa lking-path optimizat ion under a certain slope angle and arbitrary direction o f destinat ion was comp leted based on t he model parameters.As a result,the slope and walk ing directio n ranges were limited.This paper discussed not only t he foot-terrain force distr ibut io n princ iple under force control w hich ensures the hor izontal interaction e liminated but also the passive force distr ibut ion amo ng mult i-le gs wit hout real-time force control based on stiffness model,deduced the driving forces of transferr ing legs by t he Lagrange equat ions.Wit h the foot-terrain force distr ibuted and the reaction of transferring legs calculated the ranges of joints' driving forces of supporting legs were carried out and the hydraulic syste m of vert ical driving joint is designed.