This work addresses the question whether active impedance control is key to a breakthrough for legged robots. In this paper, we will talk about controlling the mechanical impedance of joints and legs with a focus on stiffness and damping control. In contrast to passive elements like springs, active impedance is achieved by torque-controlled joints allowing real-time adjustment of stiffness and ...

Recent developments on the optimization and parameter estimation in hybrid active-passive composite sandwich structures are presented. For this purpose, a mixed layerwise finite element model has been formulated, by considering a higher order shear deformation theory to represent the displacement field in the viscoelastic core and a first order theory for the displacement fields of the adjacent...

This study proposed a novel algorithm to tune and coordinate power system stabilizers (PSSs) in multi-machine power systems. For a multi-machine power system, the coordination of the PSS parameters is generally formulated as an objective function with constraints including the damping ratio and damping factor. A novel hybrid particle swarm optimization (PSO) with the passive congregation algori...

Flying animals exhibit remarkable capabilities for both generating maneuvers and stabilizing their course and orientation after perturbation. Here we show that flapping fliers ranging in size from fruit flies to large birds benefit from substantial damping of angular velocity through a passive mechanism termed flapping counter-torque (FCT). Our FCT model predicts that isometrically scaled anima...

Congruent coordinate transformations are used to convert second-order models to a form in which the mass, damping and stiffness matrices can be interpreted as a passive mechanical system. For those systems which can be constructed from interconnected mass, stiffness and damping elements, it is shown that the input-output preserving transformations can be parameterized by an orthogonal matrix wh...

A magnetorheological knee prosthesis is presented that automatically adapts knee damping to the gait of the amputee using only local sensing of knee force, torque, and position. To assess the clinical effects of the user-adaptive knee prosthesis, kinematic gait data were collected on four unilateral trans-femoral amputees. Using the user-adaptive knee and a conventional, non-adaptive knee, gait...

Piezoelectric tube scanners are the actuators of choice in scanning probe microscopy. These nanopositioners exhibit a dominant first resonant mode that is excited due to harmonics of the input scan signal. This introduces errors in the scan obtained. The presence of this resonant mode limits the upper bound of a triangular scan rate to around 1/100th of the first mechanical resonance frequency....

Malaysians were reported to have the most number of Facebook friends, spend more time on Facebook and might be addicted to Facebook as well. This paper explored Facebook usage pattern, motivations and psycho logical/behavioural factors affecting the users. A focus group study was first conducted to explo re motives to use Facebook and symptoms related to excessive Facebook usage. The themes eme...

Dynamic hazards present a challenge to the structural designer. Structural control devices offer one effective approach to protect structures during these dynamic hazards. Various classes of control systems have been explored in recent years and have been demonstrated to be effective for reducing structural responses to extreme events. However, the design of advanced damping systems has not bee...

This paper presents the modeling and simulation of a magnetorheological damper based semiactive suspension using variable structure controllers. Passive suspension systems tend to limit the trade-off between passenger comfort and road handling. But Semiactive suspensions can reduce this trade-off margin and dynamically respond to the damping requirements. Active suspensions provide the best res...