Method and apparatus to monitor an output speed sensor during operation of an electro-mechanical transmission

Method to detect a fault in a sensor and target wheel adapted to monitor rotational speed of an output shaft of an electro-mechanical transmission, comprising:

• monitoring rotational speed of a wheel operatively connected to a driveline operatively connected to the output of the electro-mechanical transmission;
• determining a first expected output of the transmission based upon the rotational speed of the wheel;
• determining a second expected output of the transmission based upon a rotational speed of a torque-generative device operatively connected to the transmission;
• comparing an output of the sensor with the first and second expected outputs of the transmission;
• and
• identifying a fault in the output of the sensor when the first and second expected outputs of the transmission differ by less than a predetermined threshold, and, the output of the sensor differs from an average of the first and second expected outputs of the transmission by greater than a predetermined threshold.

Method to control operation of a powertrain adapted to transmit power to a wheel via a driveline, the powertrain comprising an internal combustion engine operatively connected to an electro-mechanical transmission selectively operative in one of fixed gear and continuously variable operating modes, the method comprising:

• monitoring rotational speed of the wheel operatively connected to the driveline operatively connected to an output of the transmission;
• determining a first expected output of the transmission based upon the rotational speed of the wheel;
• determining a second expected output of the transmission based upon a rotational speed of a torque-generative device operatively connected to the transmission;
• comparing the first and second expected outputs and an output of a sensing system adapted to monitor rotational speed of the output of the transmission;
• identifying a fault in the sensing system adapted to monitor the rotational speed of the electro-mechanical transmission when the output of the sensing system differs from an average of the first and second expected outputs of the transmission by less than a predetermined threshold;
• and,
• controlling operation of the transmission based upon the first expected output of the transmission when a fault is identified.