Pneumatic generator


We presents a novel pneumatic generator based on the catalytic decomposition of hydrogen peroxide for producing the pressurized gas for mobile robotic systems driven by pneumatic actuators, thus replacing portable air compressors driven by electric motors. By adopting a pressure-feedback mechanism, hydrogen peroxide is autonomously self-injected into the catalytic reactor without the use of additional injection mechanisms such as electric micropumps. Additionally, the dynamic behavior of pressure generation is illustrated by both an analytic model and experiments. It is experimentally demonstrated that the proposed system has a considerably higher power density than a battery and electrical motor system. 


[1] Kim, Kyung-Rok, et al. "Design of a Compact Pneumatic Power Generator With a Self-Regulating Mechanism for Mobile Application." IEEE/ASME Transactions on Mechatronics 22.5 (2017): 1983-1991.
[2] Hong, Yun-Pyo, et al. "A novel pneumatic generator with pressure-feedback mechanism for self-injection of hydrogen peroxide." IEEE/ASME Transactions on Mechatronics (2017).

Soft Gait

When designing a lower-limb assisting robot with body-weight support (BWS), it is important to achieve high force fidelity to support body weight at standing phase. Low impedance operation at swing phase is also required not to disturb leg motions for users. The SoftGait is designed to achieve both performances with a simple mechanical structure based on a pneumatic actuator and low cost sensor development. The SoftGait generates large force for body-weight-supporting in squatting mode corresponding to user's body weight. In fact, in walking mode, it enables a user to experience more comfortable walking with support from intrinsic compliance walking with support from intrinsic compliance. The SoftGait uses two pneumatic linear actuators. Two different types of force sensors are designed to measure forces from both the seat and the pneumatic actuators. Two magnetic encoders attached to hip joints are designated to differentiate between a standing mode and a walking mode. In addition, two force sensing resistor (FSR) sensors are positioned in one shoe molded out of silicon for detecting gait phases in a walking mode and its availability as a gait phase detector is verified. A control strategy is established to operate the device using three modes: standing, walking and squatting. Mode transitions are conducted by using information from the sensors. All the modes are controlled by a simple PD controller while their target references are set to be different among modes. Experimental results tested with a healthy user show its effectiveness as a body-weight-support device targeting rehabilitation for the old and the obese.


[1] Hong, Yun-Pyo, et al. "The softgait: A simple and powerful weight-support device for walking and squatting." Intelligent Robots and Systems (IROS), 2015 IEEE/RSJ International Conference on. IEEE, 2015.

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