Transmission grade sensor rationality and trim algorithm

A system for conducting a rationality check of at least one transmission grade sensor of a vehicle having an engine and a multi-ratio transmission, comprising:

• at least one controller connected to the at least one transmission grade sensor and to at least one of the engine and the multi-ratio transmission, and;
• at least one barometric pressure sensor and at least one vehicle speed sensor each connected to the at least one controller;
• the at least one controller being configured to calculate a first vehicle change in elevation over a time interval by determining an initial barometric pressure and a final barometric pressure from the data provided by the at least one barometric pressure sensor, by determining an ambient temperature, and by applying a hypsometric formula;
• the at least one controller being configured to calculate a second vehicle change in elevation over the time interval by multiplying:
• the sine of an average grade determined from data reported by the at least one transmission grade sensor;
• and
• a distance travelled calculated from the length of the time interval and an average speed determined from data reported by the at least one vehicle speed sensor;
• the at least one controller being configured to compare the second vehicle change in elevation to the first vehicle change in elevation;
• the at least one controller being configured, if the discrepancy between the second vehicle change in elevation and the first vehicle change in elevation meets or exceeds a preset minimum threshold, to calculate a grade correction factor based on a difference between:
• a grade calculated by taking the inverse sine of the first vehicle change in elevation divided by the distance travelled;
• and
• the average grade determined from the data reported by the at least one transmission grade sensor;
• the at least one controller being configured to modify at least one of shift logic and a shift schedule of the multi-ratio transmission based on the average grade determined from data reported by the at least one transmission grade sensor and on the grade correction factor;
• and
• the at least one controller being further configured to verify the grade correction factor by calculating an adjusted vehicle change in elevation over the time interval by multiplying the distance traveled by the sine of the sum of the grade correction factor and the average grade determined from data reported by the at least one transmission grade sensor, adjusted by the grade correction factor, and on the distance travelled, and by comparing the result to the first vehicle change in elevation based on the change in barometric pressure reported by the at least one barometric pressure sensor.

A method for conducting a rationality check of at least one transmission grade sensor of a vehicle having an engine and a multi-ratio transmission, comprising the steps of:

• connecting at least one controller to the at least one transmission grade sensor and to at least one of the engine and the multi-ratio transmission;
• connecting at least one barometric pressure sensor and at least one vehicle speed sensor to the at least one controller;
• configuring the at least one controller to:
• determine an average grade from data reported by the at least one transmission grade sensor;
• determine an average speed from data reported by the at least one vehicle speed sensor;
• calculate a distance travelled from the length of a time interval and the average speed;
• determine a change in barometric pressure from data reported by the at least one barometric pressure sensor;
• calculate a first vehicle change in elevation over the time interval based on the change in barometric pressure, by determining an ambient temperature, and by applying a hypsometric formula;
• calculate a grade from the first vehicle change in elevation and the distance travelled;
• calculate a second vehicle change in elevation over the time interval by multiplying the sine of the average grade by the distance travelled;
• compare the second vehicle change in elevation to the first vehicle change in elevation;
• if the discrepancy between the second vehicle change in elevation and the first vehicle change in elevation meets or exceeds a preset minimum threshold, calculate a grade correction factor based on a difference between:
• the grade calculated by taking the inverse sine of the first vehicle change in elevation divided by the distance travelled;
• and
• the average grade determined from the data reported by the at least one transmission grade sensor;
• modify at least one of shift logic and a shift schedule of the multi-ratio transmission based on the average grade determined from data reported by the at least one transmission grade sensor and on the grade correction factor;
• and
• configuring the at least one controller to verify the grade correction factor by:
• calculating an adjusted vehicle change in elevation over the time interval by multiplying the sine of the sum of the average grade determined from data reported by the at least one transmission grade sensor and the grade correction factor, and the distance travelled, and
• comparing the adjusted vehicle change in elevation to the first vehicle change in elevation based on the change in barometric pressure reported by the at least one barometric pressure sensor.