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US 2021/0175831 A1Published application
Low-Latency Impedance Estimation for Controlling a Reluctance Motor
AssigneeApple Inc.
InventorsDenis G. Chen, Juil Lee, Hari Vasudevan, Riccardo Tarelli, Darya Amin-Shahidi
Life of this patent
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Abstract
A haptic system includes a haptic engine in which a reluctance motor is driven by a driver controller operated in conjunction with an impedance-estimator that uses amplitude-modulated calibration signals. An enveloped-calibration signal is superimposed on a haptic-drive signal to quickly, and accurately, estimate the driving coil's impedance, while minimizing power penalty.
Claims24
A haptic system comprising:
- an impedance-estimator module configured to
- communicate with a haptic engine and with a driver controller;
- receive, from the driver controller, a drive signal comprising a pre-warm portion followed by a playback portion, and, from the haptic engine, a monitoring voltage signal and a monitoring current signal;
- and
- supply a modified driver signal to the haptic engine,
- while receiving the pre-warm portion, estimate values of resistance and inductance of a driving coil of the haptic actuator, and
- supply the values of the resistance and the inductance to the driver controller for adjusting at least the playback portion of the drive signal,
- wherein the impedance-estimator module comprises
- a) signal-generator circuitry configured to
- generate an amplitude-modulated calibration signal comprising one or more tones, wherein each tone is a signal having a respective frequency;
- modify the drive signal by adding the amplitude-modulated calibration signal to the drive signal, wherein the amplitude-modulated calibration signal has
- a first amplitude when the amplitude-modulated calibration signal is added to the pre-warm portion of the drive signal,
- a second amplitude smaller by a predetermined factor than the first amplitude when the amplitude-modulated calibration signal is added to the playback portion of the drive signal, and
- zero, one or more other amplitudes that (i) differ from the first and second amplitudes, and (ii) depend on a drive amplitude of the drive signal;
- b) down-converter circuitry configured to, for each tone of the amplitude-modulated calibration signal, down-convert the current signal and the voltage signal based on the tone;
- c) phasor-constructor circuitry configured to, for each tone of the amplitude-modulated calibration signal, obtain a corresponding complex impedance phasor as a ratio of the down-converted voltage signal and the down-converted current signal, and
- d) modeler-circuitry configured to compute the resistance and the inductance of the driving coil by fitting the one or more impedance phasors to a frequency-dependent model of impedance of the driving coil.
14 more elements
(canceled)
(canceled)
A device comprising:
- the haptic system of any one of the previous claims;
- and
- a host processor is configured to provide a target signal to the driver controller,
- wherein the driver controller is configured to produce the driver signal based on the target signal and the values of the resistance and the inductance supplied by the impedance-estimator module.
1 more element
(canceled)
A method comprising:
- generating an amplitude-modulated calibration signal comprising one or more tones, wherein each tone is a signal having a respective frequency;
- receiving, from a driver controller, a drive signal comprising a pre-warm portion followed by a playback portion;
- modifying the drive signal by adding the amplitude-modulated calibration signal to the drive signal, wherein the amplitude-modulated calibration signal has
- a first amplitude when the amplitude-modulated calibration signal is added to the pre-warm portion of the drive signal, and
- one or more second amplitudes that are smaller by respective predetermined factors than the first amplitude when the amplitude-modulated calibration signal is added to the playback portion of the drive signal, where the one or more second amplitudes of the calibration signal depend on a drive amplitude of the drive signal;
- supplying the modified drive signal to a haptic actuator;
- while receiving the pre-warm portion, determining resistance and inductance of a driving coil of the haptic actuator by
- receiving, from the haptic actuator, a current signal through, and a voltage signal across, the driving coil;
- for each tone of the amplitude-modulated calibration signal,
- down-converting the current signal and the voltage signal based on the tone, and
- obtaining a corresponding impedance phasor as a ratio of the down-converted voltage signal and the down-converted current signal;
- computing the resistance and the inductance of the driving coil by fitting the one or more impedance phasors to a frequency-dependent model of impedance of the driving coil;
- and
- providing the resistance and the inductance of the driving coil to the driver controller for adjusting at least the playback portion of the drive signal.
11 more elements
24-35. (canceled)
Dependencies are inferred from the claim text.