Pneumatic demultiplexer for controlling multiple assistive technology devices

摘要

A pneumatic demultiplexer that allows a person with a disability to control multiple assistive technology devices by the use of a single sip-and-puff tube. The devices to be controlled are operated by a single pneumatic or electrical switch input. The pneumatic demultiplexer is under the control of a microprocessor. In a scan stage the user selects the target device via scrolling LED indicators. When a specific device is chosen, the corresponding solenoid valve is activated to connect the input sip-and-puff port to the pneumatic output port. In the activation stage, the input sip-and-puff tube controls the target device directly via the pneumatic demultiplexer. The microprocessor monitors the line activity via a sip-or-puff switch. A watchdog timer is implemented by the microprocessor. After there is a lack of activity for preprogrammed time period, the system switches from the activation stage back to the scan stage.