A New Input Device for Spastics Based on Strain Gauge

This article presents a new sensor for use by people with spastic disorders and similar conditions and enables them to steer and control medical devices such as electric powered wheelchairs. As spastic patients often suffer from cramping of their extremities, which can then no longer be controlled, using a standard joystick while operating a powered wheelchair can lead to dangerous situations. To prevent this, we designed a sensor based on strain gauges, which is shaped like a flat disc that can be operated using any body part. By shifting weight along the x- and y-axis, the disc tilts in all directions thereby generating proportionate output signals. The disc can also be pressed downward (z-axis), for example, to open a wheelchair’s menu. Thanks to the sensor’s flat disc-like construction and the option of mounting it into a control panel, users are not in danger of becoming stuck on the disc during spastic episodes. In the event of a spasm, body parts simply slide over the disc reducing risk of unintended actions. The sensor is adaptive and adjustable enabling it to fit a user’s range of strength and motion at any time. It was developed to ensure users can operate sensitive systems safely.