# A Motion Control of Soft Gait Assistive Suit by Gait Phase Detection Using Pressure Information
## 6 Conclusions  
The conclusions are as follows:  
1. We developed the soft gait assistive suit actuated by the PARMs. The target task is to assist the trainee's forward walking on the treadmill, and the PARMs are placed on the anterior and posterior surfaces of the thigh and the calf. The proposed gait assistive suit consists of the attachment unit and the control unit, and these units are separated physically and only connected by air tubes. The attachment unit has a lightweight soft structure, and the unique feature of the unit is that it has no electrical devices. Because electrical sensors are not needed to be attached to the trainee, and the suit is soft and lightweight, it has the advantage of being easy and safe to use. 2. We proposed the novel phase detection method using pressure and pressure derivative in the PARMs. The novel detection method is more robust to the signal noise compared with the conventional method since the pressure information is utilized which is smoother than the pressure derivative. Also, since the non-detection time is not required, the trainee can walk with a high walking rate. 3. We proposed the calculation method of the gait cycle time from the assist timing. The average gait cycle time is calculated from the assist timing, and the proper pressure input time is obtained from the calculation result. The pressurized timing and duration in each PARM are given from the EMG activation time in each muscle near the PARM. 4. We confirmed that the proposed gait assistive suit and its control method works correctly in the experiment. The phase detection accuracy and the change of the pressure input time were confirmed by comparing with the conventional control method. 1 trainee wore the gait assistive suit and walked 100 steps of 50 cycles on the treadmill with its speed of 3.0 km/h in each trial. We measured the two different gaits with their walking rate of 90 and 140 BPM by using a metronome. The total 100 walking steps were measured, and the success rate of the phase detection was counted in each case. In the case of 90 BPM walking, the conventional and the proposed control methods achieved 100% success rate. On the other hand, in the case of 140 BPM, the proposed control method achieved 100% detection, and the success rate of the conventional control method was 72%. As a result, it was confirmed that the regular and precise phase detection can be achieved in an arbitrary walking rate by using the proposed control method. 5. We verified whether the gait assistive suit is effective for decreasing activity in the trainee's muscles. We measured and compared the muscular activities of the assisted walking and walking without the suit. 5 healthy males in their 20 s and 30 s walked on the treadmill. EMG signals were recorded by EMG sensors, and their %\(MVC\) values were calculated. The trainee walks on the treadmill 40 steps of 20 cycles with its speed of 5.0 km/h in each trial. The average %\(MVC\) values with assist were less than or equal to the values without assist. This tendency was observed in all subjects. The results quantitatively confirmed that the suit can reduce muscular activity. We consider that the proposed suit is applicable to underwater training. The underwater training has an effect that the weight is canceled by water's buoyancy. Therefore, this training is popular as a training method for elder persons and persons in rehabilitation, etc. [39; 40]. The conventional assistive devices, which contain many electrical parts, will be difficult to apply for the underwater training from the waterproof point of view. On the other hand, our proposed suit has an advantage for the underwater application since it has no electrical parts on its attachment unit. As a preliminary step, the prototype suit was applied for the underwater walking experiment, and the experimental result demonstrated the applicability of our suit in the underwater situation [41]. As a future work, we will try to expand the application of the proposed suit, for example, underwater walking, swimming, etc.