9 accepted papers
For robotic transtibial prosthesis control, the global tibia kinematics can be used to monitor gait cycle progression and command smooth and continuous actuation. In this work, these global tibia kinematics define a phase variable impedance controller (PVIC), which is implemented as the nonvolitiona…
Phase variable control based on global tibia kinematics holds promise for predicting gait cycle progression to continuously control robotic transtibial prostheses. Calibration of the phase variable is critical to ensure its monotonic behavior, to approach a linear relationship with gait percentage,…
Realizing the potential of active lower-limb pros-theses to increase user mobility and efficiency requires safe, reliable, stable, and intuitive control strategies. The two prevailing classes of lower-limb prosthesis control can be categorized as volitional and non-volitional. Volitional control str…
This paper employs velocity decomposition of underactuated mechanical systems to determine the degree of dynamic coupling in the gaits of a two-link biped model. The degree of coupling between controlled and uncontrolled directions quantifies the control authority the system has over its unactuated…
This paper shows how CasADi’s state-of-the-art implementation of algorithmic differentiation can be leveraged to formulate and efficiently solve gait optimization problems, enabling rapid gait design for high-dimensional biped robots. Comparative studies on a 7-DOF planar biped show that CasADi gene…
This paper introduces a new gait switching approach for underactuated biped walkers. The switching condition relies on a reduced region of attraction - that of the unactuated dynamics - which is shown to be sufficient to predict falls. A gait transition is accordingly stable (as in “the robot does n…
This letter extends the use of the velocity decomposition metric for underactuated mechanical systems to the design of an enhanced hybrid zero dynamics (HZD)-based controller for biped robots. The metric has been used to quantify the control authority of underactuated planar bipeds by measuring the
The reaction wheel stabilizer (RWS) concept for bipedal stabilization consists of a wheel that can be accelerated in order to impart a reaction torque on the rest of the biped. The beneficial effects of such a device (or emulation of such a device through limb motion) on transient body motions are n…
While a number of controllers exist for dynamic humanoid walking over known uneven terrain, the ability to negotiate moderate changes in ground height without environment perception is still lacking. Such capability would mitigate problems caused by inaccurate sensing and reduce online terrain-depen