Control apparatus

Patent metadata

Field	Value
Publication number	US-2016159389-A1
Application number	US-201514956172-A
Country	US
Kind code	A1
Filing date	Dec 1, 2015
Priority date	Dec 3, 2014
Publication date	Jun 9, 2016
Grant date	—

Abstract

A control apparatus controls a motor of an electric power steering system including: an input shaft connected to a steering member; a column shaft connected to the input shaft; a turning device that includes a rack and pinion mechanism, and turns a wheel; and the motor. The control apparatus includes a reliability computation portion that computes a reliability according to an abnormality detection state regarding at least one of a current sensor, a torque sensor, and a rotational angle sensor; a steering-shaft load estimation portion that estimates a steering shaft load, a torque corresponding value, and a rotational angle corresponding value; and a weight changing portion that changes a weighting of the current corresponding value, the torque corresponding value, or the rotational angle corresponding value according to the reliability.

First claim

What is claimed is:

1 . A control apparatus controlling a motor of an electric power steering system including: an input shaft that is connected to a steering member turned by a driver; a column shaft that is connected to the input shaft at a position opposite to the steering member; a turning device that includes a rack and pinion mechanism converting a rotational motion of the column shaft into a reciprocating motion, and turns a wheel; and the motor that generates assist torque assisting turning of the steering member, the control apparatus comprising:
a reliability computation portion that computes a reliability according to an abnormality detection state for at least one of
a current sensor detecting an energization current to the motor,
a torque sensor detecting a steering torque, and
a rotational angle sensor detecting a rotational angle of the motor;
a steering-shaft load estimation portion that estimates a steering shaft load using
a current corresponding value corresponding to a detection value from the current sensor,
a torque corresponding value corresponding to a detection value from the torque sensor, and
a rotational angle corresponding value corresponding to a detection value from the rotational angle sensor; and
a weight changing portion that, according to the reliability, changes a weighting of three values including
the current corresponding value,
the torque corresponding value, and
the rotational angle corresponding value,
the weighting of the three values corresponding to a sensor, whose abnormality is detected, the weighting being used for estimation of the steering shaft load.

2 . The control apparatus according to claim 1 , wherein:
during a period of time from when the abnormality of at least one of the current sensor, the torque sensor, and the rotational angle sensor is detected until the abnormality is confirmed as a malfunction,
according to the reliability, the weight changing portion gradually decreases the current corresponding value, the torque corresponding value, or the rotational angle corresponding value that corresponds to a sensor, the abnormality of which is detected and is used for estimating the steering shaft load.

3 . The control apparatus according to claim 1 , wherein:
when the abnormality of at least one of the current sensor, the torque sensor, and the rotational angle sensor is detected, when a predetermined amount of time elapses without malfunction being confirmed, and when the at least one of the current sensor, the torque sensor, and the rotational angle sensor returns to a normal state,
the weight changing portion gradually increases the current corresponding value, the torque corresponding value, or the rotational angle corresponding value within a range up to a normal value, the current corresponding value, the torque corresponding value, or the rotational angle corresponding value corresponding to a sensor that has the abnormality detected but is not confirmed as malfunctioning and being used for estimating the steering shaft load.

4 . The control apparatus according to claim 1 , wherein:
the current corresponding value represents an assist torque detection value computed based on a detection value from the current sensor.

5 . The control apparatus according to claim 1 , wherein:
the current corresponding value represents a last value of an assist torque command value.

6 . The control apparatus according to claim 1 , wherein:
the torque corresponding value represents a steering torque detection value obtained by the torque sensor.

7 . The control apparatus according to claim 1 , wherein:
the torque corresponding value represents a last value of a steering torque command value.

8 . The control apparatus according to claim 1 , wherein:
the motor is connected to the column shaft; and the rotational angle corresponding value represents a detection value of a rotational angular speed of the column shaft, the detection value being computed based on an other detection value from the rotational angle sensor.

9 . The control apparatus according to claim 1 , further comprising:
an assist torque command value computation portion that computes an assist torque command value for driving of the motor based on the steering shaft load.

10 . The control apparatus according to claim 1 , further comprising:
a steering torque command value computation portion that computes a steering torque command value based on the steering shaft load; and an assist torque command value computation portion that computes an assist torque command value for driving of the motor based on the steering torque command value and the steering torque.

11 . The control apparatus according to claim 9 , wherein:
the reliability computation portion determines whether at least one of the current sensor, the torque sensor, and the rotational angle sensor is in the abnormality detection state; the reliability computation portion receives a detection value from the current sensor, the torque sensor, and the rotational angle sensor; the estimated steering shaft load, which is estimated by the steering-shaft load estimation portion, is outputted to the assist torque command value computation portion; and the motor is controlled based on the assist torque command value.

Assignees

• Denso Corp

Inventors

• Kuramitsu Shuji

Classifications

• B62D5/0484 Primary

  for reaction to failures, e.g. limp home · CPC title

• B62D5/0442

  Conversion of rotational into longitudinal movement · CPC title

• B62D5/049

  detecting sensor failures · CPC title

• B62D5/0403

  characterised by constructional features, e.g. common housing for motor and gear box · CPC title

• B62D5/0409

  Electric motor acting on the steering column · CPC title