Two-element control for the active SLIP model

Abstract

Abstract-The Spring Loaded Inverted Pendulum has been extensively studied and used as an inspiration to the study of legged locomotion. Biological data suggest that legs regulate energy production and removal via muscle activation, and therefore the conservative SLIP model cannot fully explain the robustness of many legged animals during running and hopping gaits. In this work we consider the active SLIP model, an energetically non-conservative version of the SLIP model with series actuation. In particular, we propose a strategy for actuator displacement to add/remove energy from the system, and to analytically solve part of its dynamics. Additionally, we develop a control strategy for online actuator displacement to drive the system to a desired state, even in the presence of terrain perturbation.

Learning from outside the viability kernel: Why we should build robots that can fall with grace

“…Various control policies have been proposed for SLIP models, often emphasizing deadbeat control [23] [34] or some form of optimality [20] [35]. At its simplest, even a linear controller is able to stabilize any of the limit cycles, even if not in an optimal manner.…”

Extending the lossy Spring-Loaded Inverted Pendulum model with a slider-crank mechanism

“…Similarly, Approximate analytical solution † Note that subscripts represent the system parameters at critical times such as y td , y b , and y lo represent the leg position at touchdown, bottom and liftoff events, respectively. linear actuators are also used for energy regulation purposes in vertical hopping robot models [10], [11].…”

“…However, such actuation methods are infeasible when the horizontal speed of the COM is small and can not even satisfy a rhythmic hopping when the locomotion is constrained to the vertical direction. An ad-hoc solution for this problem is to use linear actuators in series with the compliant leg to supply additional energy to the system [10], [11]. However, it requires extensive mechanical revisions on the robot platforms and has a non-negligible effect on system dynamics even if the motor is in the idle mode.…”

ATRIAS: Design and validation of a tether-free 3D-capable spring-mass bipedal robot

“…Further, the spring-mass model has been widely studied in the dynamics and control literature. The results include self-stabilizing techniques (Seyfarth and Geyer, 2002), step-planning methods (Piovan and Byl, 2013), and dynamic gait speed changes (Ernst et al, 2012). As such, ATRIAS has the potential to be controlled by implementing the same policies, or structurally similar policies (Martin et al, 2015; Rezazadeh et al, 2015), as those developed in the literature.…”