In previous research, a novel portable pneumatic power source, called a Dry Ice Power Cell, was proposed. In this paper, a novel pneumatic power assisted lower limb is developed by using a Dry Ice Power Cell as its power source. For those people whose muscle and balance remains in good condition but who have joint pain (hip or knee joint) in their leg and are unable to walk outdoors for long, the developed device can partially lift the patient in a comfortable way by pneumatic cylinder when the affected leg touches the floor, reducing the loads to which it is subject as well as the pain joint forces, thus relieving pain during walking. The developed device has the characteristics of a simple structure, low weight, easy to put on and take off and with sufficient capability to bear about 40% of the body weight during about 1000 steps of outdoor walking, using the power of the Dry Ice Power Cell. The developed device can assist with outdoor walking not only over flat ground but also sloped and stair areas. In this paper, the structure, and function and experiments involving the developed pneumatic power assisted lower limb are described in detail.

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In recent years, two types of variable valve actuators, electromagnetic and electro-hydraulic, have been developed for cam-less engines. The issue of these actuators is how to attain reliable control of the valve landing-velocity deceleration without any electronic position sensor. With this in mind, the former type of actuator is not so resistant to gas-pressure change, while the latter has issues of power waste and limited speed for quick motion control. The authors developed a sensor-less electro-hydraulic valve actuator (EHVA), with a hydro-mechanical position feedback mechanism in 2002 by using a 2-port switching valve. It operated in 24ms for positioning 12mm in stroke. This paper presents acceleration technology for working at an engine speed of 2100rpm and total valve opening time of 19ms, by applying a 3-port switching valve to the EHVA. The parameters of the EHVA were optimized using the bond graphs simulation program, and it succeeded in completing the valve lift motion within 19ms in a full stroke.

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