Development and Evaluation of Dorsiflexion Support Unit Using Elastomer Embedded Flexible Joint

In our previous study, we developed a walking support shoe with an elastomer-embedded flexible joint (EEFJ) to assist the function of tibialis anterior (TA) in initial stances (IC) and swing phases (SW). However, its usability and supporting effect have not been sufficiently evaluated. Therefore, in this study, we developed a dorsiflexion support unit (DSU) using the EEFJs with consideration on the usability for frail persons. Their needs were investigated in hearings at community centers. With reference to their comments, we proposed a three-phased scenario in which pre- / post-activities were considered as important factors of its product design of the DSU. We designed the DSU for better usability in the pre- / post-activities. Its basic function and mechanical properties were also investigated in experiments. According to the mechanical tests, the supporting torque was around 10% of the activation of TA in IC. In addition, the results of gait tests show reductions of ankle rotations by 17% and 11% in IC and SW, respectively, without significant increases of TA activations.

MotorSkins-a bio-inspired design approach towards an interactive soft-robotic exosuit

The work presents a bio-inspired design approach to a soft-robotic solution for assisting the knee-bending in users with reduced mobility in lower limbs. Exosuits and fluid-driven actuators are fabric-based devices that are gaining increasing relevance as alternatives assistive technologies that can provide simpler, more flexible solutions in comparison with the rigid exoskeletons. These devices, however, commonly require an external energy supply or a pressurized-fluid reservoir, which considerably constrain the autonomy of such solutions. In this work, we introduce an event-based energy cycle (EBEC) design concept, that can harvest, store, and release the required energy for assisting the knee-bending, in a synchronised interaction with the user and the environment, thus eliminating any need for external energy or control input. Ice-plant hydro-actuation system served as the source of inspiration to address the specific requirements of such interactive exosuit through a fluid-driven material system. Based on the EBEC design concepts and the abstracted bio-inspired principles, a series of (material and process driven) design experimentations helped to address the challenges of realising various functionalities of the harvest, storage, actuation and control instances within a closed hydraulic circuit. Sealing and defining various areas of water-tight seam made out of thermoplastic elastomers provided the base material system to program various chambers, channels, flow-check valves etc of such EBEC system. The resulting fluid-driven EBEC-skin served as a proof of concept for such active exosuit, that brings these functionalities into an integrated 'sense-acting' material system, realising an auto-synchronised energy and information cycles. The proposed design concept can serve as a model for development of similar fluid-driven EBEC soft-machines for further applications. On the more general scheme, the work presents an interdisciplinary design-science approach to bio-inspiration and showcases how biological material solutions can be looked at from a design/designer perspective to bridge the bottom-up and top-down approach to bio-inspiration.

Long-Term Effects of a Soft Robotic Suit on Gait Characteristics in Healthy Elderly Persons

As a walking assistive device for elderly persons, one of the major aims should be to improve and rehabilitate gait characteristics after long-term repeated use of the device. However, most of the existing research on walking assistive devices only emphasize their immediate effects, and there is limited research indicating the long-term effects. To address this gap, this paper experimentally validates the effects of our soft wearable robotic suit on gait characteristics of elderly persons after repeated use of the device for six weeks. Experimental results on four elderly subjects (age = 74.8 ± 5.0 year) show that, after six weeks of gait rehabilitation training by the robotic suit, the gait characteristics of the subjects were improved, leading to an increased walk ratio with an average of 9.8% compared with the initial state. The results of this research will benefit the potential use of the robotic suit in gait training and rehabilitation for elderly persons and also will be useful to the establishment of practical guidelines that maximize the training and rehabilitation effectiveness of the robotic suit.

Influence of a Soft Robotic Suit on Metabolic Cost in Long-Distance Level and Inclined Walking

Metabolic cost during walking is positively linked to exercise intensity. For a walking assistive device, one of the major aims should be the maximization of wearers' metabolic benefits for different walking situations. Toward this goal, this paper experimentally evaluates the influence of an authors' soft robotic suit, which has been developed to assist hip flexion for energy-efficient walking of elderly persons in daily life activities, on metabolic cost reduction in the long-distance level and inclined walking. Experiment results show that, for a 79-year-old healthy male subject, the robotic suit significantly reduced metabolic cost in the condition of the robotic suit worn and powered on compared with the condition of worn but powered off.

A Soft Wearable Robotic Suit for Ankle and Hip Assistance: a Preliminary Study

As a walking assistive device, one of major goals should be reduce wearer's metabolic cost as much as possible. Toward this goal, this paper presents the preliminary study on a new soft wearable robotic suit for ankle and hip assistance for daily life activities. The presented robotic suit is lightweight, and it almost does not restrict the lower limb motion range. In addition, its structure is simple, and thus wearers can easily take the device on and off by themselves. Experimental results on two young subjects show that the robotic suit reduced metabolic cost with averaged reductions of 10.2 % and 6.8 %, respectively, by not drastically disrupting the normal walking biomechanics of the subjects.

Experimental Evaluation of Energy Efficiency for a Soft Wearable Robotic Suit

This paper presents a new soft wearable robotic suit for energy-efficient walking in daily activities for elderly persons. The presented robotic suit provides a small yet effective assistive force for hip flexion through winding belts that include elastic elements. In addition, it does not restrict the range of movement in the lower limbs. Moreover, its structure is simple and lightweight, and thus wearers can easily take the device on and off by themselves. Experimental results on nine elderly subjects (age = 74.23.7 years) show that the robotic suit worn and powered on (PON) significantly reduced energy expenditure by an average of 5.9 % compared with the condition of worn but powered off (POFF). Furthermore, compared with the POFF condition, there was a significant improvement in gait characteristics in the PON condition for all subjects.

Development of Expanded Periodical Input Control for Periodic Motion with Multiple Frequency Components

<div class=""abs_img""><img src=""[disp_template_path]/JRM/abst-image/00260006/03.png"" width=""300"" />Frequency entrainment by EPIC</div> The semi-active assist mechanism proposed as a soft, flexible power assist device consists of an elastomer and actuator. Assist force is controlled by the actuator. in previous study, skill assist using periodical input control (PIC) had a motion-correction effect in motion for a single frequency. However, there is a problem by energy control in periodical input control for motion with multiple frequency components. In this study, we propose expanded PIC for motion with multiple frequency components. We verified the effect of skillassist considering multiple frequency components of human motion. </span>

Walking-Assistance Apparatus as a Next-Generation Vehicle and Movable Neuro-Rehabilitation Training Appliance

We have developed a prototype for a walkingassistance apparatus that serves as a next-generation vehicle or a movable neuro-rehabilitation training appliance for the elderly or motor palsy patients. Our prototype uses a novel spatial parallel link mechanism with a weight-bearing lift. The flat steps of the apparatus move in parallel with the ground; the apparatus supports complete leg alignment, including the soles of the feet, and assists walking behavior at the ankle, knee, and hip joints simultaneously. To estimate the walking phase of each leg of the user, pressure sensors were attached under the thenar eminence and the heel of the sole and the pressure variation at each sensing point was measured. To determine the direction in which the user is walking, a pressure sensor was attached to the flexible crural link. To adapt to the variations in the user’s walking velocity, the stride length and walking cycle while walking with the apparatus were compensated for using the concept of the walking ratio (the stride length times the walking cycle is constant). The apparatus can therefore be controlled in response to the user’s intent. We developed a control method for the apparatus by using impedance control, taking into account the dynamics of the apparatus and the user’s legs, as well as the assist ratio for the user. By adjusting the natural angular frequency of the desired dynamic equation for the user, our apparatus assists walking according to the user’s desired response. Motor palsy patients and those with weak muscles can walk with the assistance of the apparatus. Patients who have ambulation difficulty can also use the apparatus with a weight-bearing lift that we developed. Using the apparatus with this lift helps prevent stumbling and enables walking movement to be input to the brain’s motor area. The validity of the weightbearing lift is confirmed from the results of measured %Maximum Voluntary Contraction (%MVC).