Conventional joy-stick controls for wheelchairs rely on potentiometers to provide the stick position siqnals. The disadvantages of using potentiometers include, friction wear, and continual re-calibration maintenance. The modified joy-stick uses light-emitting diodes -LED's-and photo-resistive detectors to provide signals related to the position of a disc mounted on the inner end of the joy-stick. Four sets of LED and detectors are mounted at 90 deq intervals around the base of the control assembly and the output of each set is determined by the shading caused by the disc in that 90 deg. sector. The joy-stick is normally held in the centre position by a ring-shaped spring which acts on the shaft, just below the ball-joint.
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