Online sensor calibration for electrohydraulic valves

A method for identifying a recalibration reference sensor in a hydraulic system comprising the steps of:

• (a) providing an electro-hydraulic system comprising a control system, a system pump, a system pump pressure sensor, a first valve having a first pressure sensor in fluid communication with a first side of a first actuator, a second valve having a second pressure sensor in fluid communication with a second side of the first actuator, a third valve having a third pressure sensor in fluid communication with a first side of a second actuator, and a fourth valve having a fourth pressure sensor in fluid communication with the second side of the second actuator;
• (b) setting the pump to a predetermined pressure;
• (c) commanding the first and third valves to open to the system pump and recording pressures sensed at the system pump pressure sensor, first, and third pressure sensors;
• (d) closing the first and third valves;
• (e) commanding the second and fourth valves to open to the system pump and recording pressures sensed at the system pump pressure sensor, second, and fourth pressure sensors;
• and
• (f) analyzing the recorded pressures against predefined condition data stored in the control system.

An online method for reconfiguring pressure sensors in a hydraulic system comprising the steps of:

• (a) providing an electro-hydraulic system comprising a control system, a system pump, a system pump pressure sensor, and a plurality of control valves wherein each of the valves has at least one corresponding pressure sensor in fluid communication with an actuator;
• (b) detecting at least one of a sensor drift condition, a recalibration request, and an unisolated fault condition;
• (c) verifying that the system pump pressure sensor or another pressure sensor can be trusted as a master reference sensor;
• (d) measuring and recording a first pressure reading at the master reference sensor and first voltage readings associated with the plurality of pressure sensors at a first pump pressure set point;
• (e) measuring and recording a second pressure reading at the master reference sensor and second voltage readings associated with the plurality of pressure sensors at a second pump pressure set point;
• and
• (f) computing a new gain and offset for each of the plurality of pressure sensors based on a comparison of the recoded first and second pressure readings with respect to the master reference sensor and the recorded first and second voltage readings.