Patent ID: 7637690
Filing Date: 2009-12-29
Classification: B63C

Abstract:
1. A programmable boatlift system having a single motor, comprising: a) a single first cable extending up from one end of a first boatlift cradle, and down to an opposite end of the first boatlift cradle, the single first cable being attached to a shaft therebetween, the shaft being attached to the motor; b) a collar having a plurality of holes for the transmission of light, said collar fixed concentrically to said shaft and to the axis of said shaft, and rotating in unison with said shaft; c) a quadrature encoder having two pairs of IR transmitters and IR receivers, said encoder placed over said collar, said two pairs of IR transmitters and IR receivers being set apart about 165 degrees relative to the axis of said shaft; d) said IR transmitters transmitting infra red light through the holes in said collar and said IR receivers receiving said infra red light so that said encoder produces an electronic output signal in proportion to the number of rotations of said collar, and in proportion to the distance the single first cable travels; and e) an electronic control circuit having a microcontroller, an in-circuit programming header, and a motor control circuit, said control circuit programmable to use said output signal to infer the exact position of the single first cable and the boatlift cradle without the requirement of a limit switch.