Abstract: Image processing parameters of an imaging chip in a vision-based occupant sensing system are adjusted for each frame based on ambient illumination responsive information obtained in the idle period preceding that frame. The same sensing data is also used to determine if active illumination is needed to supplement existent ambient illumination during the ensuing image acquisition interval. The inter-frame ambient illumination is detected with an external light sensor or with selected pixels of the imaging chip, and the information is used to calculate and set the gain and integration time of the imaging chip. In applications where the resolution of the imaging chip significantly exceeds the resolution required for occupant sensing, intensity data from one or more otherwise inactive pixels is averaged with the intensity data from the normally active pixels to adapt the sensitivity of the imaging chip to changing ambient illumination.

Abstract: The capacitance of a shielded capacitive load cell is determined so as to minimize the effect of stray or parasitic capacitance between the load cell and other objects including the shield. The load cell conductors are coupled across input and output terminals of an operational amplifier that is tied to a reference voltage. A constant current is applied to the load cell, and the resulting rate of change in voltage at the amplifier output is measured as a representation of the load cell capacitance. In a vehicle seat sensor application including an electromagnetic interference shield between the load cell and the seating surface, the amplifier output is coupled to the load cell electrode furthest from the shield, the amplifier maintains the other load cell electrode at a virtual reference voltage, and the shield is tied to the reference voltage.

Abstract: A circuit powering an electrical device based on a commanded current signal is provided. The circuit includes a linear current amplifier which sets a desired current flow. The circuit also dynamically controls a supply voltage in order to minimize power dissipation of the linear current amplifier. The circuit may also include a voltage drop measurement amplifier, a voltage shaping amplifier, and a switching power supply. The circuit is useful for controlling electrical devices requiring precise current control and minimal power dissipation, for example, driving light-emitting diodes (LEDs) that provide illumination inside the passenger compartment of a vehicle for an imaging occupant detection system.

Abstract: A spark timing control system for an uneven firing engine utilizes a microprogrammed engine controller which produces a spark timing control system based on internal calculations using spark advance and dwell variables supplied by a microcomputer. A crankshaft position transducer produces a reference signal having alternate long and short pulses from which the firing cycle may be determined. The microcomputer is interrupted at each falling edge of the reference signal and based on a determination of the existing firing cycle, calculates and supplies appropriate spark advance and dwell numbers to the controller.