Sensor-less position control system for memory seat

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Sensor-less position control system for memory seat

Ishikawa, H. / Kanie, H. / Katoh, H. / Kimura, N.

A sensor-less memory seat system was developed that requires no position sensors such as Hall ICs etc. The memory seat is a seat system memorizing each users position and automatically returning the seat to several previously set seat positions. This system has been used for high-class automobiles as a highly functional seat system. However, due to its high cost, such system has not been used for the family type or economy cars, which are most needed. Under such circumstances, it has been tried to increase the installation rate of the system by spreading the use to the economy cars by reducing the system cost. The reduction of cost, however, had a limit with the current system which uses an expensive rotation sensor. By this development it was made this time, realized and commercialized a new sensor-less memory seat system which does not use the expensive rotation sensors, the cost of which is significantly large among the entire system. The sensor-less system detects the rotation of DC motor by current ripple signals in motor operating current. The developed Sensor-less position control system can attenuate a wide frequency variation of Motor current noise which varies depending on motor condition and convert small current ripples to Pulse signals in proportion to the rotation of DC motor. A low cost and compact size circuit was realized by developing a ripple detection IC. An example of the circuit operation waveform is shown. Noises have been removed from the ripple amplification waveform after SCF and ripples became accurate pulses. Even the motor rotation was changed similar waveform was obtained.