Hysteresis compensation control of an actuator

A method of hysteresis compensation for a system including at least one actuator configured to receive a control input, the method comprising:

• defining a plurality of response curves, each response curve indicating a system output value expected to be generated for the system in response to providing each of a plurality of input values to the at least one actuator under a different one of a plurality of state conditions,
• defining a reference curve indicating a target system output value corresponding to each of the plurality of input values regardless of the state condition,
• receiving an indicated input value, identifying the target system output value corresponding to the indicated input value on the reference curve,
• determining whether a state transition has occurred when the indicated input value is received,
• determining a compensated input value in response to determining that no state transition has occurred by identifying an input value on a first response curve corresponding to a system output value equal to the identified target system output value, wherein the first response curve is a response curve of the plurality of response curves corresponding to a current state condition, and
• defining the compensated input value based on a difference between the indicated input value and the identified input value on the first response curve, generating a transition response curve in response to determining that a state transition has occurred,
• wherein the transition response curve extends from an origin point on the first response curve to an end point on a second response curve,
• wherein the first response curve corresponds to a state condition before the detected state transition and the second response curve corresponds to a state condition after the detected state transition, and
• wherein the transition response curve is generated based on a transition response curve length indicating a difference between an input value at the origin point of the transition response curve and an input value at the end point of the transition response curve,
• determining the compensated input value in response to determining that the state transition has occurred by identifying an input value on the transition response curve corresponding to the system output value equal to the identified target system output value, and
• defining the compensated input value based on a difference between the indicated input value and the identified input value on the transition response curve, and
• controlling an operation of the at least one actuator by transmitting the determined compensated input value as a control input to the at least one actuator.

A hysteresis compensation system comprising a controller configured to:

• define a rising response curve indicating an expected system output value for each of a plurality of different input values when applied as an input to at least one actuator of a system as part of an increasing sequence of input values;
• define a falling response curve indicating the expected system output value for each of the plurality of different input values when applied as input to the at least one actuator of the system as part of a decreasing sequence of input values;
• receive a new indicated input value;
• model a transition response curve in response to determining that the new indicated input value is a decreasing input value received after a received sequence of increasing input values, wherein the transition response curve extends from an origin point on the rising response curve to an end point on the falling response curve, wherein the origin point corresponds to a last indicated input value in the received sequence of increasing input values, wherein modelling the transition response curve includes
• applying a first input value as a control input to the at least one actuator of the system, wherein the first input value is less than a most recent previous input value applied to the at least one actuator,
• measuring an actual system output value generated by the system in response to applying the first input value as input to the at least one actuator,
• calculating a difference ΔOp between the measured actual system output value and the output value on the rising response curve for the applied first input value,
• calculating a difference ΔO between the output value on the falling response curve for the applied first input value and the output value on the rising response curve for the applied first input value,
• calculating a difference ΔIp between the applied first input value and the input value at the origin point of the transition response curve,
• estimating a difference ΔI between an input value at the origin point and an input value at the end point based on the calculated difference ΔOp, the calculated difference ΔO, and the calculated difference ΔIp for the applied first input value and the measured actual system output value based on a proportional relationship defined by
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• modelling the transition response curve by defining additional points on the transition response curve for input values between the input value of the origin point and the input value of the end point based on the estimated difference ΔI, a determined difference ΔO for the additional point, a determined difference ΔIp for the additional point, and the defined proportional relationship;
• receive a subsequent new indicated input value;
• determine a compensated input value based on the subsequent new indicated input value using the modelled transition response curve when the subsequent new indicated input value is between the input value of the origin point and the input value of the end point of the transition response curve;
• and
• control an operation of the one or more actuators of the system by transmitting the determined compensated input value as the control input to the one or more actuators.