We have been developing the robotic wear curara as both a welfare device and rehabilitation robot that assists the elderly and disabled. curara is aimed at user friendliness. We have, thus, chosen a non-exoskeleton structure made of a plastic so that the robot is as light in weight as possible and to minimize the restraining stress against natural human movement. We verified the assistance effect of curara on 15 hemiplegic patients with stroke by comparing gait parameters (i.e., velocity, step length, cadence, and symmetry of joint angles) among three conditions. The conditions were "without assistance" (i.e., a control mode that cancels frictional resistances in actuators), Condition A (where joint angles are enlarged but there is no change in gait cycle), and Condition B (where there is no change in joint angles but the gait cycle is shortened). curara improved the walking velocity by 19% and 27% under Conditions A and B, respectively. Improvements in step length and cadence were, respectively, 11% and 7% under Condition A and 14% and 11% under Condition B. Moreover, the two assistance conditions reduced the difference in joint angles between unaffected and paralyzed legs. We consider that curara will facilitate the rehabilitation of stroke patients.

Planetary exploration requires rovers to perform a variety of challenging tasks autonomously. In order to complete relevant scientific mission, these rovers need to overcome difficulty for rough terrain traversing by "online methods". This paper discusses an idea that utilizes a rover mobile center of mass in order to aid in traversing rough terrain. According to vehicle pitch angle and contact angles, the rover recalculates the optimal position for the center of mass to minimize the indicator defined by two factors : the wheel driving force over the wheel normal force (adhesion coefficient) and tip-over stability angle (stability coefficient). Two innovative approaches are developed in this paper. The first one is that the authors defines easily comprehensible two factors, adhesion and stability coefficients for traversability indicator and proposes a method to calculate optimal center of mass position. The second one is that in the case of four-wheels drive, the relation between the front wheel and the rear wheel adhesion coefficient is easily solved and the best case for giving the driving forces can be solved as force making the front and the rear wheel adhesion coefficient equal. The authors call this "optimal force distribution method". Finally, this paper shows some simulation results for traversing rough terrain that compute the optimal center of mass while traversing the terrain.

BackgroundSpinocerebellar degeneration (SCD) mainly manifests a cerebellar ataxic gait, leading to marked postural sway and the risk of falling down. Gait support using a wearable robot is expected to be an effective solution to maintaining the status quo and/or delaying symptom progression. The aim of this study was to evaluate the effects of gait support in patients with SCD by using a wearable robotic system called curara ®; while undergoing walking tests.MethodsThe curara system assists both the hip and knee joints and supports the wearer’s rhythmic gait using a synchronization control based on a central pattern generator. The system reflects the wearer’s intended motion in response to the gait support by detecting an interactive force that is generated from slight movements of the wearer. The degree of coordinated motion between the robot and the wearer can be adjusted by modifying the synchronization gain. In this study, we provided gait support using three high-gain conditions (A, B, C) to more easily follow the wearer’s movement in each joint. The synchronization gains for both the hip and knee joints (i.e., Ch and Ck) were set at 0.5 for condition A and at 0.4 for condition B. Condition C had different gains for the hip and knee joints (i.e., Ch=0.4 and Ck=0.5). With the walking test, we assessed the effects of the gait support provided by the curara system on walking smoothness (measured using the harmonic ratio: HR) and spatiotemporal parameters (gait speed, stride length, cadence) in SCD patients (n=12). We compared the performance between the three high-gain conditions and without assistance from the robot.ResultsUnder condition C, the HRs in the anteroposterior, mediolateral, and vertical directions (HR-AP, HR-ML, and HR-V) were especially high compared with those under conditions A and B. The results of the statistical analyses using repeated measures analysis of variance followed by Tukey’s test showed that gait support with condition C results in a statistically significant increase in the HR-AP (2.04 ±0.52; p=0.025) and HR-V (2.06 ±0.37; p=0.032) when compared with walking without assistance from the system. In contrast, the gait speed, stride length, and cadence under condition C were no major changes in most patients, compared with the patient’s walking without assistance.ConclusionsThe significantly increased HR indicates that gait support under condition C achieved smoother walking than when not wearing the power unit of the system. Consequently, we suggest that gait support using the curara system has the potential to improve walking smoothness in patients with SCD.

Background We have developed a wearable rehabilitation robot, “curara®,” and examined its immediate effect in patients with spinocerebellar degeneration and stroke, but its rehabilitative effect has not been clarified. The purpose of this study was to examine the effect of this device on gait training in stroke patients. Methods Forty stroke patients were enrolled in this study. The participants were divided randomly into two groups (groups A and B). The participants assigned to group A received RAGT with curara® type 4, whereas those in group B received conventional therapist-assisted gait training. The clinical trial period was 15 days. The participants performed 10 sessions of gait training (5 times per week) each lasting 30 ± 5 min per day. The 10-m walking time (10mWT), and 6-minute walking distance (6MWD) were evaluated as the main outcomes. Timed up and go and Berg Balance Scale (BBS) were also examined. Gait parameters (stride duration and length, standard deviation of stride duration and length, cadence, ratio of the stance/swing phases, minimum/maximum knee joint angle, and minimum/maximum hip joint angle) were measured using a RehaGait®. The items other than BBS were measured on days 0, 7, and 14, whereas BBS was measured on days 0 and 14. The improvement rate was calculated as the difference of values between days 14 and 0 divided by the value on day 0. The improvement rates of the 10mWT and 6MWD were set as the main outcomes. Results The data of 35 participants were analyzed. There was no significant difference in the main outcomes between both groups at the end of gait training. As for intragroup changes, gait speed, stride length, stride duration, and cadence were improved significantly between days 0 and 14 in each group. When examining the interaction effect between the day of measurement and group, stride duration (p = 0.006) and cadence (p = 0.012) were more significantly improved in group A than in group B. Conclusions This novel wearable powered robot may have the potential to improve gait speed of individuals in stroke rehabilitation. Trial registration Japan Registry of Clinical Trials (jRCTs032180163). Registered on February 22, 2019; https://jrct.niph.go.jp/en-latest-detail/jRCTs032180163. UMIN Clinical Trials Registry (UMIN000034237) Registered on September 22, 2018; https://center6.umin.ac.jp/cgi-open-bin/icdr/ctr_view.cgi?recptno=R000038939.

This paper aimed to verify the effectiveness of the wearable robotic system "curara" for patients with spinocerebellar degeneration (SCD) by evaluating walking smoothness. The curara system supports the wearer's gait using a synchronization control method that uses a neural oscillator based on a central pattern generator network. The system reflects the motional intention by adjusting the synchronization gains. This modifies the degree of interactive coordinated motion between the curara and the wearer. As a feasibility study, we evaluated the waking smoothness of 10 patients with SCD using three gain condition settings. Harmonic ratio (HR), which has been used extensively to quantify the smoothness during walking, was used to assess their walking. The results show that most HRs in the medio-lateral, anterior-posterior, and vertical directions using the three gain conditions were higher than those for patients not wearing the system. In particular, the increasing rates of the HR in all directions during the gait support were 11.1%, 23.4%, and 23.2% compared with unassisted walking, when the gain condition settings of hip and knee joints are set at 0.4 and 0.5, respectively. Consequently, these results verified the effectiveness of the curara system for patients with SCD.