Shortcomings of human-in-the-loop optimization of an ankle-foot prosthesis emulator: a case series.

Human-in-the-loop optimization allows for individualized device control based on measured human performance. This technique has been used to produce large reductions in energy expenditure during walking with exoskeletons but has not yet been applied to prosthetic devices. In this series of case studies, we applied human-in-the-loop optimization to the control of an active ankle-foot prosthesis used by participants with unilateral transtibial amputation.

The effects of ground-irregularity-cancelling prosthesis control on balance over uneven surfaces.

Over half of individuals with a lower-limb amputation are unable to walk on uneven terrain. Using a prosthesis emulator system, we developed an irregularity-cancelling controller intended to reduce the effect of disturbances resulting from uneven surfaces. This controller functions by changing the neutral angles of two forefoot digits in response to local terrain heights.

Teleoperation of an Ankle-Foot Prosthesis With a Wrist Exoskeleton.

Objective: We aimed to develop a system for people with amputation that non-invasively restores missing control and sensory information for an ankle-foot prosthesis.

Methods: In our approach, a wrist exoskeleton allows people with amputation to control and receive feedback from their prosthetic ankle via teleoperation. We implemented two control schemes: position control with haptic feedback of ankle torque at the wrist; and torque control that allows the user to modify a baseline torque profile by moving their wrist against a virtual spring.

An Ankle-Foot Prosthesis Emulator Capable of Modulating Center of Pressure.

Objective: Several powered ankle-foot prostheses have demonstrated moderate reductions in energy expenditure by restoring pushoff work in late stance or by assisting with balance. However, it is possible that center of pressure trajectory modulation could provide even further improvements in user performance. Here, we describe the design of a prosthesis emulator with two torque-controlled forefoot digits and a torque-controlled heel digit.

Design and Validation of an Instrumented Uneven Terrain Treadmill.

Studying human and animal locomotion on an uneven terrain can be beneficial to basic science and applied studies for clinical and robotic applications. Traditional biomechanical analysis of human locomotion has often been limited to laboratory environments with flat, smooth runways and treadmills. The authors modified a regular exercise treadmill by attaching wooden blocks to the treadmill belt to yield an uneven locomotion surface.

Biomechanics and energetics of running on uneven terrain.

In the natural world, legged animals regularly run across uneven terrain with remarkable ease. To gain understanding of how running on uneven terrain affects the biomechanics and energetics of locomotion, we studied human subjects (N=12) running at 2.3 m s(-1) on an uneven terrain treadmill, with up to a 2.

Biomechanics and energetics of walking on uneven terrain.

Walking on uneven terrain is more energetically costly than walking on smooth ground, but the biomechanical factors that contribute to this increase are unknown. To identify possible factors, we constructed an uneven terrain treadmill that allowed us to record biomechanical, electromyographic and metabolic energetics data from human subjects. We hypothesized that walking on uneven terrain would increase step width and length variability, joint mechanical work and muscle co-activation compared with walking on smooth terrain.

Structural and functional evidence for discrete exit pathways that connect the canine sinoatrial node and atria.

Surface electrode recordings cannot delineate the activation within the human or canine sinoatrial node (SAN) because they are intramural structures. Thus, the site of origin of excitation and conduction pathway(s) within the SAN of these mammals remains unknown. Canine right atrial preparations (n=7) were optically mapped.