Vehicle diagnostic control system

A method for controlling a vehicle equipped with a drive system, a controller means for regulating the operating speed of the drive system and a diagnostic means for sensing a plurality of drive system operating parameters, comprising the steps of:

• sensing a plurality of the parameter signals;
• comparing the value of each parameter signal to a corresponding predetermined fault value;
• classifying each parameter signal within one of a plurality of fault class levels as a function of said step of comparing;
• calculating a hierarchy between fault class levels, each class level being a function of the probability that faults within that level will cause vehicle damage, a highest class level including faults having the greatest probability of causing vehicle damage and the lowest class level including faults having the lowest probability of causing vehicle damage;
• calculating the highest fault class level in which a parameter signal has been classified;
• and
• limiting the maximum speed of the vehicle in response to the highest fault class level, whereby the maximum vehicle speed decreases as the fault class level increases.

An apparatus for a vehicle equipped with a drive system and a controller means for regulating the operating speed of the drive system, comprising in combination:

• at least one sensor means for sensing a vehicle parameter, said sensor producing a parameter signal in response to the sensed parameter;
• diagnostic means for receiving the parameter signal, comparing the parameter signal to a predetermined fault value, classifying the parameter signal in one of a plurality of fault class levels as a function of said comparison with said fault value, and responsively producing a fault level signal;
• wherein said plurality of fault class levels includes a hierarchy in which a highest fault class level includes parameter signals indicating the highest risk of vehicle damage for continued vehicle operation, and a lowest fault class level includes parameter signals indicating the lowest risk of vehicle damage for continued vehicle operation;
• wherein the controller means receives the fault level signal and limits the maximum speed of the vehicle in response to the fault level signal, whereby the maximum allowable vehicle speed decreases as the fault class level signal increases.

An apparatus for a vehicle equipped with a drive system and a controller means for regulating the operating speed of the drive system, comprising:

• a plurality of sensor means for sensing vehicle parameters and responsively producing respective parameter signals;
• diagnostic means for receiving the parameter signals, comparing the parameter signal to a fault value, classifying the parameter signal in one of a plurality of fault class levels as a function of the comparison between said parameter signal and said fault value, and producing a fault level signal corresponding to a fault class level of said parameter signal, said fault class levels being prioritized according to a probability that parameter signals within that fault class level will damage the vehicle;
• and
• wherein the controller means receives the fault level signal and limits the maximum speed of the vehicle as a function of said fault level signal, whereby the controller means decreases a maximum allowable vehicle speed in response to sensing parameter signals in fault class levels that have increasing probability of vehicle damage.

An apparatus for a vehicle equipped with a hydrostatic drive system, the drive system including first and second hydrostatic transmissions, each hydrostatic transmission including a fluid pump driven by an engine and being responsive to a respective control signal to provide pressurized fluid in proportion thereto and a hydraulic motor connected to the pump and being driven by the pressurized fluid, the drive system further including controller means for producing the control signals, said apparatus comprising:

• a plurality of sensor means for sensing vehicle parameters and responsively producing respective parameter signals;
• diagnostic means for receiving the parameter signals, comparing the parameter signal to a fault value, classifying the parameter signal in one of a plurality of fault class levels as a function of the comparison between said parameter signal and said fault value, and producing a fault level signal corresponding to a fault class level of said parameter signal, said fault class level being prioritized according to a plurality that parameter signals within that fault class level will damage the vehicle;
• and
• wherein the controller means receives the fault level signal and limits the magnitude of the control signals as a function of the fault level signal, whereby the maximum allowable value of the control signal decreases as the value of the fault level signal increases.

An apparatus for a vehicle equipped with a hydrostatic drive system, the drive system including first and second hydrostatic transmissions, each hydrostatic transmission including a fluid pump driven by an engine and being responsive to a respective control signal to provide pressurized fluid in proportion thereto and hydraulic motor connected to the pump and being driven by the pressurized fluid, the drive system further including a controller means, said apparatus comprising:

• a plurality of sensor means for sensing vehicle parameters and responsively producing respective parameter signals;
• diagnostic means for receiving the parameter signals, comparing the parameter signal to a fault value, classifying the parameter signal into one of a preselected number of hierarchical fault class levels, determining the highest fault class level in which a parameter signal is classified and producing a fault level signal corresponding to the highest detected fault class level;
• and
• wherein the controller means receives the fault level signal and limits the magnitude of the control signals in response to the fault level signal, whereby the maximum allowable value of the control signal decreases as the value of the fault level signal increases.