# US 8,786,138 B2 · Systems, methods, and apparatus for controlling actuator drive current using bi-directional hysteresis control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,138 B2 - Document ID: US8786138B2 - Status: Granted - Kind: B2 - Application number: 12/784,638 - Filed: 2010-05-21 - Published: 2011-11-24 - Granted: 2014-07-22 - Earliest claimed: 2010-05-21 - Assignees: General Electric Company - Applicants: Roy Anthony Carter; Ravindra Mahavir Desai - Inventors: Roy Anthony Carter; Ravindra Mahavir Desai - Web page: https://patentgrep.com/patent/US8786138B2 ## CPC - G05B 19/33: using an analogue measuring device - G05B 2219/41086: Bang bang control - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract Certain embodiments of the invention may include systems, methods, and apparatus for controlling actuator drive current. According to an example embodiment of the invention, a method is provided for controlling actuator drive current. The method may include receiving a reference signal, determining a feedback signal based at least in part on the drive current, determining a conditioned feedback signal based at least in part on the feedback signal, comparing the reference signal to the conditioned feedback signal, and controlling the drive current based on the comparison of the reference signal and the conditioned feedback signal. Certain embodiments of the method may include manipulating one or more devices to establish at least one positive current path and at least one negative current path through an actuator via hysteresis control. ## Claims ### Claim 1 A method for controlling actuator drive current comprising: receiving, by a power amplifier, a reference signal, wherein the reference signal includes a pulse width modulation (PWM) signal; generating, by the power amplifier, a drive signal based at least in part on the reference signal; driving an actuator drive based at least in part on the drive signal; obtaining, by a first feedback circuit, a first feedback signal based at least in part on a drive current; generating, by the first feedback circuit, a first conditioned feedback signal based at least in part on the first feedback signal; obtaining, by a second feedback circuit, a second feedback signal based at least in part on a position of the actuator drive, wherein the second feedback signal differs from the first feedback signal; generating, by the second feedback circuit, a second conditioned feedback signal based at least in part on the first feedback signal; and controlling, by a controller, the PWM signal based on the first conditioned feedback signal and the second conditioned feedback signal. ### Claim 2 (depends on 1) The method of claim 1, wherein determining the feedback signal comprises sensing drive current through the actuator by measuring a voltage drop. ### Claim 3 (depends on 1) The method of claim 1, wherein generating the first conditioned feedback signal comprises adding parallel capacitance to the actuator. ### Claim 4 (depends on 1) The method of claim 1, wherein determining a conditioned feedback signal comprises amplifying the feedback signal. ### Claim 5 (depends on 1) The method of claim 1, wherein determining a conditioned feedback signal comprises delaying the feedback signal and filtering the feedback signal, wherein determining a conditioned feedback signal is further based at least in part on the filtered feedback signal. ### Claim 6 (depends on 1) The method of claim 1, wherein generating the first conditioned feedback signal comprises modifying the time constant of the feedback signal. ### Claim 7 (depends on 6) The method of claim 6, wherein modifying the time constant is based at least in part on one or more of the following: resistance and capacitance. ### Claim 8 A system for controlling drive current comprising: a controller; an actuator; a power amplifier operatively connected to the actuator and the controller, the power amplifier configured to receive a reference signal from the controller, generate a drive signal based at least in part on the reference signal, and supply the drive signal to the actuator, wherein the reference signal includes a PWM signal; a first feedback circuit operatively connected to the actuator and the controller, the first feedback circuit configured to obtain a first feedback signal based at least in part on a drive current and generate a first conditioned feedback signal based at least in part on the first feedback signal; a second feedback circuit operatively connected to the actuator and the controller, the second feedback circuit configured to obtain a second feedback signal based at least in part on a position of the actuator drive and generate a second conditioned feedback signal based at least in part on the first feedback signal; and wherein the controller is configured to manipulate the PWM signal based on the first conditioned feedback signal and the second conditioned feedback signal. ### Claim 9 (depends on 8) The system of claim 8, wherein the conditioned feedback signal is determined based at least in part on determining drive current through the actuator. ### Claim 10 (depends on 9) The system of claim 9, wherein the drive current is determined by measuring a voltage drop across a series sense resistor. ### Claim 11 (depends on 8) The system of claim 8, wherein the first feedback signal is based at least in part on a drive current passing through the actuator and through a capacitor in parallel with the actuator. ### Claim 12 (depends on 8) The system of claim 8, wherein the conditioned feedback signal comprises an amplified feedback signal. ### Claim 13 (depends on 8) The system of claim 8, wherein the conditioned feedback signal comprises a delayed filtered feedback signal. ### Claim 14 (depends on 8) The system of claim 8, wherein the first conditioned feedback signal comprises a delayed feedback signal based at least in part on modifying a time constant of the first feedback signal. ### Claim 15 (depends on 14) The system of claim 14, wherein modifying the time constant comprises modifying series resistance. ### Claim 16 (depends on 14) The system of claim 14, wherein modifying the time constant comprises modifying parallel capacitance. ### Claim 17 An apparatus for controlling actuator drive current comprising: a power amplifier operatively connected to an actuator and a controller, the power amplifier configured to receive a reference signal from the controller, generate a drive signal based at least in part on the reference signal, and supply the drive signal to the actuator, wherein the reference signal includes a PWM signal; a first feedback circuit operatively connected to the actuator and the controller, the first feedback circuit configured to obtain a first feedback signal based at least in part on a drive current and generate a first conditioned feedback signal based at least in part on the first feedback signal; a second feedback circuit operatively connected to the actuator and the controller, the second feedback circuit configured to obtain a second feedback signal based at least in part on a position of the actuator drive and generate a second conditioned feedback signal based at least in part on the first feedback signal; and wherein the controller is configured to manipulate the PWM signal based on the first conditioned feedback signal and the second conditioned feedback signal. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the first feedback signal is based at least in part on a drive current through the actuator. ### Claim 19 (depends on 17) The apparatus of claim 17, wherein the first feedback signal is based at least in part on a drive current passing through the actuator and through a capacitor in parallel with the actuator, and wherein the first feedback signal is delayed based at least in part on modifying the time constant of the first feedback signal. ### Claim 20 (depends on 19) The apparatus of claim 19 wherein the time constant of the first feedback signal is modified by modifying one or more of series resistance or parallel capacitance.