Kevin H. Ha

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This paper presents a method for providing volitional control of a powered knee prosthesis during nonweight-bearing activity such as sitting. The method utilizes an impedance framework, such that the joint can be programmed with a given stiffness and damping that reflects the nominal impedance properties of an intact joint. Volitional movement of the knee(More)
This paper presents an assessment of a lower limb exoskeleton for providing legged mobility to people with paraplegia. In particular, the paper presents a single-subject case study comparing legged locomotion using the exoskeleton to locomotion using knee-ankle-foot orthoses (KAFOs) on a subject with a T10 motor and sensory complete injury. The assessment(More)
This paper describes the design and implementation of a cooperative controller that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton to provide enhanced hip extension during the stance phase of walking in persons with paraplegia. The controller utilizes two sources of actuation: the electric motors of the powered(More)
Toxoplasmosis caused by the protozoan parasite Toxoplasma gondii is a widespread disease affecting primarily immunocom-promised and pregnant individuals [1]. Atovaquone is a recently introduced anti-malarial compound with broad spectrum activity against various apicomplexan parasites [2–5] including T. gondii [6]. Approved by the FDA in 1995, this drug is a(More)
This paper describes a hybrid system that combines a powered lower limb exoskeleton with functional electrical stimulation (FES) for gait restoration in persons with paraplegia. The general control structure consists of two control loops: a motor control loop, which utilizes joint angle feedback control to control the output of the joint motor to track the(More)
This paper describes a means of controlling the knee movement of a powered knee prosthesis during non-weight-bearing activity such as sitting, by utilizing surface EMG from the quadriceps and hamstring muscle groups in the residual limb. The method was implemented on a powered prosthesis on three amputee subjects, and experimental results are presented(More)
This paper presents a control approach for a lower-limb exoskeleton intended to facilitate recovery of walking in individuals with lower-extremity hemiparesis after stroke. The authors hypothesize that such recovery is facilitated by allowing the patient rather than the exoskeleton to provide movement coordination. As such, an assistive controller that(More)
This paper describes a novel controller, intended for use in a lower-limb exoskeleton, to aid gait rehabilitation in patients with hemiparesis after stroke. The controller makes use of gravity compensation, feedforward movement assistance, and reinforcement of isometric joint torques to achieve assistance without dictating the spatiotemporal nature of joint(More)
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