Enhancing Voluntary Motion with Modular, Backdrivable, Powered Hip and Knee Orthoses.

Mobility disabilities are prominent in society with wide-ranging deficits, motivating modular, partial-assist, lower-limb exoskeletons for this heterogeneous population. This paper introduces the Modular Backdrivable Lower-limb Unloading Exoskeleton (M-BLUE), which implements high torque, low mechanical impedance actuators on commercial orthoses with sheet metal modifications to produce a variety of hip- and/or knee-assisting configurations. Benchtop system identification verifies the desirable backdrive properties of the actuator, and allows for torque prediction within ±0.

Optimally Biomimetic Passivity-Based Control of a Lower-Limb Exoskeleton Over the Primary Activities of Daily Life.

Task-specific, trajectory-based control methods commonly used in exoskeletons may be appropriate for individuals with paraplegia, but they overly constrain the volitional motion of individuals with remnant voluntary ability (representing a far larger population). Human-exoskeleton systems can be represented in the form of the Euler-Lagrange equations or, equivalently, the port-controlled Hamiltonian equations to design control laws that provide assistance across a continuum of activities/environments by altering energetic properties of the human body. We previously introduced a port-controlled Hamiltonian framework that parameterizes the control law through basis functions related to gravitational and gyroscopic terms, which are optimized to fit normalized able-bodied joint torques across multiple walking gaits on different ground inclines.

Design Principles for Compact, Backdrivable Actuation in Partial-Assist Powered Knee Orthoses.

This paper presents the design and validation of a backdrivable powered knee orthosis for partial assistance of lower-limb musculature, which aims to facilitate daily activities in individuals with musculoskeletal disorders. The actuator design is guided by design principles that prioritize backdrivability, output torque, and compactness. First, we show that increasing the motor diameter while reducing the gear ratio for a fixed output torque ultimately reduces the reflected inertia (and thus backdrive torque).

Overhead throwing biomechanics in cricketers: The effect of a run-up approach.

Overhead throwing by cricketers when fielding with different approaches has been described using two-dimensional analysis. Currently, the three-dimensional kinematic and kinetic characteristics of an overhead throw performed by cricketers following a run-up are unknown. Fifteen South African cricketers performed six overhead throws, from a stationary position and with a run-up over 15-20 m prior to fielding a ball, respectively.

The association between gird and overhead throwing biomechanics in cricket.

The development of GIRD is a well-documented adaptation associated with repetitive overhead throwing in numerous sports. In occurrence with total rotational range of motion deficit, GIRD is considered pathological and increases shoulder injury risk. While cricketers demonstrate these deficits in rotational range; the association between GIRD and overhead throwing has yet to be explored.

Overhead throwing in cricketers: A biomechanical description and playing level considerations.

This study aimed to describe stationary overhead throwing biomechanics in South African cricketers, considering playing level, and relative to baseball. Kinematics and ground reaction forces were collected during throwing trials. Inverse dynamics was used to calculate joint kinetics.

A Phase Variable Approach for Improved Rhythmic and Non-Rhythmic Control of a Powered Knee-Ankle Prosthesis.

Although there has been recent progress in control of multi-joint prosthetic legs for rhythmic tasks such as walking, control of these systems for non-rhythmic motions and general real-world maneuvers is still an open problem. In this article, we develop a new controller that is capable of both rhythmic (constant-speed) walking, transitions between speeds and/or tasks, and some common volitional leg motions. We introduce a new piecewise holonomic phase variable, which, through a finite state machine, forms the basis of our controller.

Design and Validation of a Partial-Assist Knee Orthosis with Compact, Backdrivable Actuation.

This paper presents the mechatronic design and initial validation of a partial-assist knee orthosis for individuals with musculoskeletal disorders, e.g., knee osteoarthritis and lower back pain.

A Phase Variable Approach to Volitional Control of Powered Knee-Ankle Prostheses.

Although there has been recent progress in control of multi-joint prosthetic legs for periodic tasks such as walking, volitional control of these systems for non-periodic maneuvers is still an open problem. In this paper, we develop a new controller that is capable of both periodic walking and common volitional leg motions based on a piecewise holonomic phase variable through a finite state machine. The phase variable is constructed by measuring the thigh angle, and the transitions in the finite state machine are formulated through sensing foot contact together with attributes of a nominal reference gait trajectory.

Biomechanical analysis of gait waveform data: exploring differences between shod and barefoot running in habitually shod runners.

The aim of this study was to utilise one-dimensional statistical parametric mapping to compare differences between biomechanical and electromyographical waveforms in runners when running in barefoot or shod conditions. Fifty habitually shod runners were assessed during overground running at their current 10-km race running speed. Electromyography, kinematics and ground reaction forces were collected during these running trials.

Habitual Minimalist Shod Running Biomechanics and the Acute Response to Running Barefoot.

The aim of the study was to determine whether habitual minimalist shoe runners present with purported favorable running biomechanithat reduce running injury risk such as initial loading rate. Eighteen minimalist and 16 traditionally cushioned shod runners were assessed when running both in their preferred training shoe and barefoot. Ankle and knee joint kinetics and kinematics, initial rate of loading, and footstrike angle were measured.

Neurophysiological, behavioural and perceptual differences between wrist flexion and extension related to sensorimotor monitoring as shown by corticomuscular coherence.

Objective: To investigate the effects of neurophysiological, behavioural and perceptual differences between wrist flexion and extension movements, on their corticomuscular coherence (CMC) levels.

Methods: CMC was calculated between simultaneously recorded electroencephalography (EEG) and electromyography (EMG) measures from fifteen healthy subjects who performed 10 repetitions of alternating isometric wrist flexion and extension tasks at 15% of their maximum voluntary contraction (MVC) torque levels. Task precision was calculated from torque recordings.