Vehicle brake-by-wire diagnostic system and method

A vehicle brake-by-wire diagnostic system, the vehicle brake-by-wire diagnostic system comprising:

• a vehicle brake-by-wire unit having a vehicle brake clamp force sensor;
• a vehicle controller in electrical communication with the vehicle brake-by-wire unit, wherein the vehicle controller is programmed to:
• determine a first expected clamp force based at least in part on a requested clamp force value and an end-to-end characteristic transfer function, wherein the end-to-end characteristic transfer function models nominal overall system dynamics of the vehicle brake-by-wire unit;
• determine a second expected clamp force based at least in part on an actuator displacement value and a mechanical characteristic function, wherein the mechanical characteristic function models nominal mechanical dynamics of the vehicle brake-by-wire unit;
• determine a first clamp force deviation between the first expected clamp force and a measured clamp force value measured by the vehicle brake clamp force sensor;
• determine a second clamp force deviation between the second expected clamp force and the measured clamp force value measured by the vehicle brake clamp force sensor;
• determine a performance of the vehicle brake-by-wire unit based at least in part on the first clamp force deviation and the second clamp force deviation;
• and
• perform a diagnostic action based at least in part on the performance of the vehicle brake-by-wire unit, wherein the diagnostic action includes limiting a maximum speed of the vehicle in response to identifying a diagnostic trouble code (DTC).

A method for diagnostic monitoring of a vehicle brake-by-wire system, the method comprising:

• recording a reference excitation profile of a reference brake-by-wire unit, wherein the reference brake-by-wire unit is a known healthy brake-by-wire unit, and wherein the reference excitation profile includes a requested clamp force versus time, a corresponding requested actuator displacement versus time, and a measured clamp force versus time;
• determining an end-to-end characteristic transfer function based at least in part on the requested clamp force versus time and the measured clamp force versus time;
• determining a mechanical characteristic function based at least in part on the requested actuator displacement versus time and the measured clamp force versus time;
• determining a performance of a vehicle brake-by-wire unit based on the end-to-end characteristic transfer function and the mechanical characteristic function;
• performing a diagnostic action based at least in part on the performance of the vehicle brake-by-wire unit, wherein the diagnostic action includes providing a diagnostic trouble code (DTC) based at least in part on the performance of the vehicle brake-by-wire unit;
• and
• limiting a maximum speed of the vehicle based at least in part on the DTC.