Acura NSX 1997 Service Manual page 546

Main Menu
System Description
Function and Operation (cont'd)
EPS Control Unit
The control unit receives input signals from the vehicle speed sensors, torque sensor. It performs a multitude of control
functions, including a circuit which can detect troubles in each functional part of the system and the control unit itself. The
control unit operates the system while the engine is in the process of starting, on receipt of voltage generated by the alter-
nator. The system remains operational if the engine stalls with the ignition switch in ON (II) position.
Basic Control
(1) Travelling speeds are compiled into data, receiving input signals from the vehicle's speed sensors.
(2) The magnitude and direction of torque are compiled into data, receiving input signals from the torque sensor.
(3) The rotational speed and direction of steering are compiled into data, receiving calculated data.
(4) Determination of motor torque data from the prescribed assisting force map, based on the vehicle speed data, steer-
ing rotational speed data and the steering torque data.
(5) Changeover of control modes based on data on vehicle speed, direction of torque and rotational direction of steering.
Normal Control Mode:
The rotational direction of motor is determined after changing over to the left/right steering mode in accordance with
torque direction data. The mode is switched to the straight ahead mode when the output data is zero.
Return Control Mode:
According to torque direction data and steering rotational direction data, the mode is changed over to the return control
mode to improve the steering return characteristic.
Damper Control Mode:
According to vehicle speed data, torque value data and steering rotational speed data, the mode is changed over to the
damper control mode to improve the convergence property of the steering.
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