A Wearable Upper Extremity Rehabilitation Device for Inducing Arm Swing in Gait Training.

This paper presents the design and validation of a proof-of-concept prototype for a wearable rehabilitation device to incorporate arm swing during gait rehabilitation. Unlike current stationary exoskeletons used for rehabilitation of upper limbs' function, assisting arm swing during gait requires inducing faster arm flexion/extension movements while maintaining the users' arms unconstrained in other directions. We developed a portable and underactuated system with features such as a large workspace and backdrivability to induce arm swing. Its wide workspace allowed the wearers to easily move their arms in different directions without any constraints. A modified double parallelogram linkage (mDPL) is proposed to allow the device to mimic the natural workspace of an arm. Additionally, a pulley drive and weight compensation system were created to place the motor on the users' back reducing the hindering weight of the actuators on their arms. Our experiments demonstrated this arm-swing rehabilitator could successfully induce arm movements at different arm configurations with low (0.67 Hz) and high (1.1 Hz) frequencies corresponding to slow and fast walking.

Investigating the efficacy of a tactile feedback system to increase the gait speed of older adults.

The objective of this study was to determine (1) if a novel haptic feedback system could increase the walking speed of older adults while it is being employed during overground walking and (2) whether the frequency at which this feedback was presented would have a differential impact on the ability of users to change walking speed while it was present. Given that peak thigh extension has been found to be a biomechanical surrogate for stride length, and consequently gait speed, vibrotactile haptic feedback was provided to the participants' thighs as a cue to increase peak thigh extension while the effect on gait speed was monitored. Ten healthy community-dwelling older adults (68.4 ± 4.1 years) participated. Participants' peak thigh extension, cadence, normalized stride length and velocity, along with their coefficients of variation (COV) were compared across baseline normal and fast walking (with no feedback) and three different frequency of feedback conditions. The findings indicated that, compared to self-selected normal and fast walking speeds, peak thigh extension was significantly increased when feedback was present and after it was withdrawn in a post-test. An increase in thigh extension led to an increase in stride length and, consequently, an increase in stride velocity compared to normal speed. There were no significant differences in the gait parameters as a function of feedback frequency during its application. In conclusion, while present, the haptic feedback system increased thigh extension and walking speed in older adults regardless of the feedback frequency and when the feedback was withdrawn, participants could maintain an increase in those parameters.

Modulation of Arm Swing Frequency and Gait Using Rhythmic Tactile Feedback.

Due to the neural coupling between upper and lower limbs and the importance of interlimb coordination in human gait, focusing on appropriate arm swing should be a part of gait rehabilitation in individuals with walking impairments. Despite its vital importance, there is a lack of effective methods to exploit the potential of arm swing inclusion for gait rehabilitation. In this work, we present a lightweight and wireless haptic feedback system that provides highly synchronized vibrotactile cues to the arms to manipulate arm swing and investigate the effects of this manipulation on the subjects' gait in a study with 12 participants (20-44 years). We found the developed system effectively adjusted the subjects' arm swing and stride cycle times by significantly reducing and increasing those parameters by up to 20% and 35%, respectively, compared to their baseline values during normal walking with no feedback. Particularly, the reduction of arms' and legs' cycle times translated into a substantial increase of up to 19.3% (on average) in walking speed. The response of the subjects to the feedback was also quantified in both transient and steady-state walking. The analysis of settling times from the transient responses revealed a fast and similar adaptation of both arms' and legs' movements to the feedback for reducing cycle time (i.e., increasing speed). Conversely, larger settling times and the time differences between arms' and legs' responses were observed due to feedback for increasing cycle times (i.e., reducing speed). The results clearly demonstrate the potential of the developed system to induce different arm-swing patterns as well as the ability of the proposed method to modulate key gait parameters through leveraging the interlimb neural coupling, with implications for gait training.