Power assist device, and vehicle equipped with said power assist device

A signal processing module comprising:

• a memory storing information of a parameter defining a transfer function that interrelates a total torque to be input to an electrically assisted vehicle which includes a motor and a wheel and a rotational speed of the wheel, and an inverse transfer function thereof;
• and
• a signal processor connected to the memory, wherein,
• when incorporated in the electrically assisted vehicle, the signal processor is connected to a sensor to output a signal which is in accordance with the rotational speed of the wheel and to a driving circuit for the motor, and is configured to:
• (0) receive the signal which is output from the sensor, and determines a detected value of rotational speed of the wheel,
• (1) read information of the parameter from the memory, and, based on the inverse transfer function defined by the parameter, determines an estimated value of the total torque from the detected value of rotational speed of the wheel,
• (2) from the driving circuit, acquire information representing an operating state of the motor, and, based on the information, determines an estimated value of a motor torque that is being generated by the motor,
• (3) determine, as an estimated value of a pedal torque, a value which is obtained by subtracting the estimated value of a motor torque from the estimated value of the total torque,
• (4) determine a command value for motor torque based on the estimated value of first torque, and inputs the command value for the motor torque to the driving circuit, and
• (5) update at least a portion of the information of the parameter stored in the memory so that an error between the detected value of rotational speed of the wheel and an estimated value of rotational speed of the wheel that is determined from a given torque value based on the transfer function defined by the parameter is reduced.

A power assist device for use in estimating a pedal torque to be applied to a vehicle mechanism of an electrically assisted vehicle by using a system parameter of the vehicle mechanism, calculating a torque for a motor from the estimated pedal torque, and driving the electrically assisted vehicle with the estimated pedal torque and the torque of the motor, wherein,

• the system parameter of the vehicle mechanism is updated at a moment absent of the estimated pedal torque,
• wherein the system parameter of the vehicle mechanism defines a transfer function and an inverse transfer function of the transfer function;
• the transfer function receives an overall torque input to the vehicle mechanism and outputs a rotational speed of a wheel, the overall torque including the estimated pedal torque and the torque of the motor;
• the inverse transfer function receives the rotational speed of the wheel and outputs an estimated overall torque, the estimated overall torque including the estimated pedal torque and an estimated torque of the motor;
• the estimated overall torque is obtained by using the inverse transfer function and the rotational speed of the wheel;
• the estimated torque of the motor is obtained on a basis of a rotation control technique to be applied to the motor;
• and
• the estimated pedal torque is obtained by subtracting the estimated torque of the motor from the estimated overall torque.