Automatic characterization of an actuator based on capacitance measurement

An actuator driving method, comprising:

• receiving a control code at an actuator controller representing a desired position of an actuator within its range of movement, the control code having a value between predetermined maximum and minimum code values,
• converting the control code to a driving code with reference to limit codes stored in the actuator controller, the limit codes derived from a driving test performed on the actuator, and
• driving the actuator with a driving signal derived from the driving code,
• wherein the driving test comprises:
• incrementally, until a measured capacitance of the actuator indicates the actuator has moved from a first stop position to a first endpoint:
• applying the drive signal toward a second stop position,
• measuring capacitance of the actuator, and
• comparing the measured capacitance of the actuator to a first threshold to determine whether the actuator has moved to the first endpoint;
• storing a code associated with the drive signal that moved the actuator to the first endpoint as a first limit code as a first end of a response curve for the actuator;
• incrementally, until the measured capacitance of the actuator indicates the actuator has moved from the first endpoint to a second endpoint:
• applying the drive signal toward the second stop position,
• measuring capacitance of the actuator, and
• comparing the measured capacitance of the actuator to a second threshold to determine whether the actuator has moved to the second endpoint;
• storing a code associated with the drive signal that moved the actuator to the second endpoint as a second limit code as a second end of the response curve for the actuator.

An integrated circuit, comprising:

• control logic configured to:
• driving an actuator to a first stop position by a driving signal;
• incrementally, until a measured capacitance of the actuator indicates the actuator has moved from the first stop position to a first endpoint:
• applying the drive signal toward a second stop position,
• measuring capacitance of the actuator, and
• comparing the measured capacitance of the actuator to a first threshold to determine whether the actuator has moved to the first endpoint;
• storing a code associated with the drive signal that moved the actuator to the first endpoint as a first end of a response curve for the actuator;
• incrementally, until the measured capacitance of the actuator indicates the actuator has moved from the first endpoint to a second endpoint:
• applying the drive signal toward the second stop position,
• measuring capacitance of the actuator, and
• comparing the measured capacitance of the actuator to a second threshold to determine whether the actuator has moved to the second endpoint;
• storing a code associated with the drive signal that moved the actuator to the second endpoint as a second end of the response curve for the actuator.