Stair Climbing using the Angular Momentum Linear Inverted Pendulum Model and Model Predictive Control

A new control paradigm using angular momentum and foot placement as state variables in the linear inverted pendulum model has expanded the realm of possibilities for the control of bipedal robots. This new paradigm, known as the ALIP model, has shown effectiveness in cases where a robot's center of mass height can be assumed to be constant or near constant as well as in cases where there are no non-kinematic restrictions on foot placement. Walking up and down stairs violates both of these assumptions, where center of mass height varies significantly within a step and the geometry of the stairs restrict the effectiveness of foot placement. In this paper, we explore a variation of the ALIP model that allows the length of the virtual pendulum formed by the robot's stance foot and center of mass to follow smooth trajectories during a step. We couple this model with a control strategy constructed from a novel combination of virtual constraint-based control and a model predictive control algorithm to stabilize a stair climbing gait that does not soley rely on foot placement. Simulations on a 20-degree of freedom model of the Cassie biped in the SimMechanics simulation environment show that the controller is able to achieve periodic gait

Wound Healing potential of Grandiflorenic Acid Isolated from Wedelia trilobata Linn.

The ethyl acetate fraction from ethanolic extract of W. trilobata leaves displayed antibacterial and fibroblast stimulatory activities thereby suggesting potential wound healing properties. Ethyl acetate fraction was further subjected to bioassay guided fractionation, which afforded isolation of grandiflorenic acid (GA). GA exhibited potential in vitro wound healing activity due to fibroblast stimulation and inhibiting inflammatory phase of wound healing, evident by reduced levels of inflammatory cytokines from macrophage RAW 264.7 cells. The aim of the present study was to evaluate wound healing activity of GA formulated in ointment base (0.5% and 1.0% w/w) using excision, incision and dead space wound models in experimental rats. Treatment of wound with isolated grandiflorenic acid 1.0% w/w topically exhibited significant (p<0.01) wound healing activity in all three models as compared to control groups. High rate of wound contraction, decrease in period of epithelialisation, high tensile strength, increase in dry granulation tissue weight