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The evolutionarily novel ability to keep ones body upright while standing or walking, the human balance, deteriorates in old age or can be compromised after accidents or brain surgeries. With the aged society, age related balance problems are on the rise. Persons with balance problems are more likely to fall during their everyday life routines. Especially in elderly, falls can lead to bone fractures making the patient bedridden, weakening the body and making it more prone to other diseases. Health care expenses for a fall patient are often very high. There is a great deal of research being done on exoskeletons and power assists. However, these technologies concentrate mainly on the amplifications of human muscle power while balance has to be provided by the human themself. Our research has been focused on supporting human balance in harmony with the human's own posture control mechanisms such as postural reflexes. This paper proposes an artificial balancer that supports human balance through acceleration of a flywheel attached to the body. Appropriate correcting torques are generated through our device based on the measurements of body deflections. We have carried out experiments with test persons standing on a platform subject to lateral perturbations and ambulatory experiments while walking on a balance beam. These experiments have demonstrated the effectiveness of our device in supporting balance and the possibility of enhancing balance-keeping capability in human beings through the application of external torque.

Introduction/Background For stroke patients with hemiplegia, walking exercise are conventionally practiced using orthoses. For severe hemiplegic patients, knee-ankle-foot orthoses (KAFO) are frequently used to prevent giving way in the stance phase. However, it is very difficult to swing paralytic leg with KAFO. As a result, walking exercise with KAFO requires a high level of assistance and raise low exercise intensity. To solve these problems, we developed Welwalk, which has a motor on the knee joint with KAFO-like framework. Welwalk can extend and flex the knee in appropriate timing. This time, we examined whether subacute stroke patients with hemiplegia using Welwalk show early improvement in walking independence compared to patients using KAFO. Material and method Fourteen patients who satisfied the following criteria were included: patients with hemiplegia caused by primary supratentorial intracerebral hemorrhage or cerebral infarction, within 60 days after onset, aged 20 to 75 years, Functional Independence Measure (FIM) walking score ≤ 3, Stroke Impairment Assessment Set (SIAS) lower extremity total score ≤ 6, and use of KAFO. Rehabilitation was conducted for a maximum of 3 hours a day, including 40 minutes of walking exercise using Welwalk. A historical control group was selected from among patients admitted to the ward for intensive inpatient rehabilitation at Nanakuri Memorial Hospital. One control patient matching the criteria of each subject was selected, with a total of fourteen in the control group. The primary outcome measure was the improvement in efficiency of FIM-walk, defined as the gain in FIM walking score from the baseline to supervised walking divided by the number of weeks required. Results The mean improvement in efficiency of FIM- walk was 0.9 in the Welwalk group and 0.5 in the control group, and was significantly higher in the GEAR group (P Conclusion Walking exercise using Welwalk may facilitate early improvement in walking independence.