Sensor lag compensation

An apparatus for approximation of a present value of a measured automotive control parameter, variations in the value of said parameter being substantially describable by means of a dominant time constant, comprising:

• sensing means for sensing the value of the parameter;
• rate of variation estimating means for estimating the rate of variation of the parameter;
• means for approximating the dominant time constant of the parameter;
• and
• present value determining means for determining the present value of said parameter, based on the sensed value, the rate of variation of the sensed value, and the dominant time constant of the parameter.

An apparatus for approximation of a present value of engine manifold absolute pressure comprising:

• sensing means for sensing the value of engine manifold absolute pressure;
• rate of variation estimating means for estimating the rate of variation of manifold absolute pressure, comprising (a) means for storing a predetermined number of the most recent sensed values of manifold absolute pressure, (b) means for estimating the first order relationship between said stored values, and (c) means for determining the rate of change in the value of said first order relationship;
• means for approximating the present value of the dominant time constant of the manifold absolute pressure, comprising (a) means for sensing engine throttle position, and (b) means for approximating the present value of the dominant time constant based on said sensed engine throttle position;
• and
• present value determining means for determining the present value of engine manifold absolute pressure by summing the sensed value of engine manifold absolute pressure and a value based on the rate of change in the value of said first order relationship and the present value of the dominant time constant.