Vehicle Steering Device

Patent metadata

Field	Value
Publication number	US-2017183032-A1
Application number	US-201615379937-A
Country	US
Kind code	A1
Filing date	Dec 15, 2016
Priority date	Dec 24, 2015
Publication date	Jun 29, 2017
Grant date	—

Abstract

A vehicle steering device includes a driver torque estimation unit that includes a driver torque estimation observer, a low-pass filter, and a hands-on/off determination unit. The driver torque estimation observer estimates driver torque applied to a steering wheel by a driver on the basis of a detected value that includes at least torsion bar torque detected by a torque sensor and the rotational angle of an electric motor detected by a rotational angle sensor. The low-pass filter performs a low-pass filtering process on the estimated driver torque. The hands-on/off determination unit determines whether in a hands-on state or a hands-off state on the basis of the driver torque after being subjected to the low-pass filtering process.

First claim

What is claimed is:

1 . A vehicle steering device comprising:
a steering wheel; an input shaft to which the steering wheel is coupled; an output shaft coupled to the input shaft via a torsion bar; an electric motor coupled to the output shaft via a speed reduction mechanism; a torque detector that detects torsion bar torque applied to the torsion bar; a rotational angle detector that detects a rotational angle of the electric motor; and a steering wheel operation state determination device, wherein: the steering wheel operation state determination device includes:
a driver torque estimation observer that estimates driver torque applied to the steering wheel by a driver using a detected value that includes at least the torsion bar torque detected by the torque detector and the rotational angle of the electric motor detected by the rotational angle detector;
a low-pass filter that performs a low-pass filtering process on the driver torque estimated by the driver torque estimation observer; and
a hands-on/off determination unit that determines whether in a hands-on state or a hands-off state on a basis of the driver torque after being subjected to the low-pass filtering process by the low-pass filter.

2 . The vehicle steering device according to claim 1 , wherein:
the speed reduction mechanism includes a worm gear rotationally driven by the electric motor, and a worm wheel coupled so as to be rotatable together with the output shaft and rotationally driven by the worm gear; and the driver torque estimation observer is configured to estimate the driver torque on a basis of a rotational angle and an angular velocity of the worm wheel computed on a basis of the rotational angle of the electric motor detected by the rotational angle detector, and the torsion bar torque.

3 . The vehicle steering device according to claim 1 , further comprising:
a current detection unit that detects a motor current that flows through the electric motor, wherein the driver torque estimation observer is configured to estimate the driver torque on a basis of a motor torque of the electric motor computed on a basis of the current detected by the current detection unit, the rotational angle of the electric motor detected by the rotational angle detector, and the torsion bar torque.

4 . The vehicle steering device according to claim 1 , wherein
a cut-off frequency of the low-pass filter is 4 [Hz] or more and 6 [Hz] or less,

Assignees

• Jtekt Corp

Inventors

• Wilhelm Frederic
• Tamura Tsutomu
• Fuchs Robert
• Moreillon Maxime

Classifications

• G01L3/10

  involving electric or magnetic means for indicating · CPC title

• B62D6/10 Primary

  characterised by means for sensing {or determining} torque · CPC title

• B62D3/12

  of rack-and-pinion type · CPC title

• B62D5/0409

  Electric motor acting on the steering column · CPC title

• B62D5/0466 Primary

  for returning the steering wheel to neutral position · CPC title