Houman Dallali

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We are interested in understanding the mechanisms behind and the character of the sway motion of healthy human subjects during quiet standing. We assume that a human body can be modelled as a single-link inverted pendulum, and the balance is achieved using linear feedback control. Using these assumptions, we derive a switched model which we then(More)
Keeping balance is the main concern for humanoids in standing and walking tasks. This paper endeavors to acquire optimal ankle stabilization methods for humanoids with passive and active compliance and explain ankle balancing strategy from the compliance regulation perspective. Unlike classical stiff humanoids, the compliant ones can control both impedance(More)
This paper describes the design of an ankle-foot robotic prosthesis controllable in the sagittal and frontal planes. The prosthesis was designed to meet the mechanical characteristics of the human ankle including power, range of motion, and weight. To transfer the power from the motors and gearboxes to the ankle-foot mechanism, a Bowden cable system was(More)
This paper presents the design of a novel compliant joint for high performance mobility. The design principle of the joint is based on an asymmetric compliant antagonistic scheme which is actuated by two motors of different power capability and efficiency. Torques from the two motors are transmitted to the joint through two elastic elements of different(More)
This paper focuses on developing a robust tracking control scheme for a compliant humanoid, COMAN. Passive compliance in COMAN offers many advantages in terms of safe interaction with the environment and users. In the case of light tasks and soft interaction, classical PD motor control is sufficient. However, the compliance poses some challenges in(More)
This paper introduces the design tuning of a recently introduced compliant actuation scheme that was developed to provide large energy storage capacity and demonstrate energetic efficient operation. The joint is based on an asymmetric compliant antagonistic actuation scheme where torques from two motors are transmitted to the joint through two elastic(More)
This paper studies the effect of passive and active impedance for protecting jumping robots from landing impacts. The theory of force transmissibility is used for selecting the passive impedance of the system to minimize the shock propagation. The active impedance is regulated online by a joint-level controller. On top of this controller, a reflex-based leg(More)
In ZMP trajectory generation using simple models, often a considerable amount of trials and errors are involved to obtain locally stable gaits by manually tuning the gait parameters. In this paper a 15 degrees of Freedom dynamic model of a compliant humanoid robot is used, combined with reinforcement learning to perform global search in the parameter space(More)
This paper focuses on the development of a dynamic model-free whole-body controller for a humanoid robot with high kinematic redundancy. The proposed controller is based on force-level operational-space control framework, which computes joint torques for the required forces of prioritized multiple tasks. While typical approaches based on this framework(More)