SLIP-Based Control of Bipedal Walking Based on Two-Level Control Strategy

Abstract

SUMMARYIn this research, we propose a two-level control strategy for simultaneous gait generation and stable control of planar walking of the Assume The Robot Is A Sphere (ATRIAS) biped robot with unlocked torso, utilizing active spring-loaded inverted pendulum (ASLIP) as reference models. The upper level consists of an energy-regulating control calculated using the ASLIP model, producing reference ground reaction forces (GRFs) for the desired gait. In the lower level controller, PID force controllers for the motors ensure tracking of the reference GRFs for ATRIAS direct dynamics. Meanwhile, ATRIAS torso angle is controlled stably to make it able to follow a point mass template model. Advantages of the proposed control strategy include simplicity and efficiency. Simulation results using ATRIAS’s complete dynamic model show that the proposed two-level controller can reject initial condition disturbances while generating stable and steady walking motion.

Feasible speeds for two optimal periodic walking gaits of a planar biped robot

“…The solution r 2 opt = [r 2x opt r 2y opt ] ⊤ found with (19), minimizes Γ ⊤ Γ without constraints. Remark: For r 2 opt the constraints of no take-off and no slipping in double support can be satisfied or not.…”

“…Simulation results show that a two-level control strategy for simultaneous gait generation and stable control of planar walking of the ATRIAS biped can reject initial condition disturbances, while generating stable and steady walking motion. 19 Despite all these interesting studies on walking motions with finite time double support phases, there is a lack of knowledge about the role of the feet during the finite time double support phase regarding on the speed of the biped robot. Several questions on this issue are still open, such as:…”

A heuristic gait template planning and dynamic motion control for biped robots

“…Similarly, the spring-loaded inverted pendulum model is also used [17]. However, using these simplified models results in the algorithm requiring the robot centroid to considerably upwards [18], which is challenging to satisfy this requirement for some biped robots due to their ability needs. With the development of nonlinear optimization in trajectory planning, trajectory optimization based on the whole-body model of a biped robot has been studied [19,20].…”