Closed-loop control of linear resonant actuator using back EMF data and hall sensing

A method of controlling a linear resonant actuator, the method comprising:

• driving, by drive electronics, a mass into motion along a movement axis using one or more coils;
• obtaining, from a magnetic field sensor a magnetic field sensor signal that varies in response to a magnetic field that is generated by the one or more coils when the mass is driven into motion;
• receiving, from a channel coupling the magnetic field sensor to a system processor, an analog output signal;
• receiving measurements of actuator current and actuator voltage from the drive electronics;
• receiving a temperature signal indicating a temperature of the magnetic field sensor;
• calculating a first estimate of mass position using the magnetic field sensor signal, actuator current, and a magnetic model;
• calculating an estimate of coil resistance based on the temperature signal, the actuator current, the actuator voltage and a thermal model;
• calculating a second estimate of mass position and an estimate of mass velocity based on the first estimate of mass position, the actuator current, the actuator voltage and the estimated coil resistance;
• calculating an actuator control signal based on the second estimate of mass position and the estimate of mass velocity;
• and
• providing the actuator control signal to the drive electronics, the actuator control signal configured to cause the drive electronics to adjust the drive current provided to the one or more coils.

A system comprising:

• a linear resonant actuator including a mass, one or more coils and a magnetic field sensor;
• drive electronics coupled to the linear resonant actuator and configured to drive the one or more coils in response to an actuator control signal;
• a system processor coupled to the drive electronics and the linear resonant actuator, the system processor configured to:
• drive, by the drive electronics, the mass into motion along a movement axis using the one or more coils;
• obtain, from the magnetic field sensor, a magnetic field sensor signal that varies in response to a magnetic field that is generated by the one or more coils when the mass is driven into motion;
• receive, from a channel coupling the magnetic field sensor to a system processor, the magnetic field sensor signal;
• receiving measurements of actuator current and actuator voltage from the drive electronics;
• receive a temperature signal indicating a temperature of the magnetic field sensor;
• calculate a first estimate of mass position using the magnetic field sensor signal, actuator current and a magnetic model;
• calculate an estimate of coil resistance based on the temperature signal, the actuator current, the actuator voltage and a thermal model;
• calculate a second estimate of mass position and an estimate of mass velocity based on the first estimate of mass position, the actuator current, the actuator voltage and the estimated coil resistance;
• calculate the actuator control signal based on the second estimate of mass position and the estimate of mass velocity;
• and
• provide the actuator control signal to the drive electronics, the actuator control signal configured to cause the drive electronics to adjust the drive current provided to the one or more coils.