Steering control unit

Patent metadata

Field	Value
Publication number	US-10703407-B2
Application number	US-201815938651-A
Country	US
Kind code	B2
Filing date	Mar 28, 2018
Priority date	Apr 3, 2017
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

When a steering angle reaches a first value close to a second value that defines a boundary of the maximum physical range of operation of a steering wheel, an ECU calculates a virtual end controlled variable that sharply increases a steering torque. The ECU calculates a second limit on the virtual end controlled variable and calculates a final limit (upper and lower limits) on an assist controlled variable by taking into account the second limit. When performing virtual end control, the ECU calculates the final limit on the assist controlled variable by using, as a first limit corresponding to the steering torque, a previous value held by upper and lower limit holders, instead of a present value calculated in accordance with the steering torque in a present calculation cycle.

First claim

What is claimed is:

1. A steering control unit comprising;
an assist controller that calculates an assist controlled variable on the basis of a plurality of kinds of state quantities including a steering torque and a steering angle, the assist controlled variable being used to control power supply to a motor that generates an assist force to be supplied to a steering mechanism of a vehicle;
a correction controller that performs, when the steering angle reaches a first value close to a second value that defines a boundary of a physical range of operation of a steering wheel that is included in the steering mechanism, correction control that calculates a correction quantity that corrects the assist controlled variable to sharply increase the steering torque;
a limit calculator that sets first limits individually for each of the plurality of kinds of state quantities, each of the first limits being used to limit a variation range of the assist controlled variable in accordance with a corresponding one of the plurality of kinds of state quantities, the limit calculator being configured to calculate a final limit on the assist controlled variable by adding together all the first limits; and
a limit processor that limits the variation range of the assist controlled variable on the basis of the final limit calculated by the limit calculator, wherein
the limit calculator sets a second limit that limits the correction quantity in accordance with the steering angle, and calculates the final limit by taking into account the second limit, and when the correction control is performed, the limit calculator calculates the final limit by using the first limit that corresponds to the steering torque immediately before the correction control is performed.

2. The steering control unit according to claim 1 , wherein
the limit calculator includes a holder and a switcher,
each time the first limit corresponding to the steering torque is used, the holder holds the used first limit corresponding to the steering torque, and
the switcher switches, in accordance with whether the correction control is performed, the first limit that corresponds to the steering torque and that is to be used to calculate the final limit, between a present value and a previous value, the present value being calculated in a present calculation cycle, the previous value being calculated in a previous calculation cycle and held by the holder.

3. The steering control unit according to claim 1 , wherein
the correction controller sets a value of a flag in accordance with whether the correction control is performed, and
the limit calculator recognizes, on the basis of the value of the flag, whether the correction control is performed.

4. The steering control unit according to claim 1 , wherein
the limit calculator includes a steering angle-sensitive calculator,
the steering angle-sensitive calculator includes a first calculator, a second calculator, and a third calculator,
the first calculator calculates the first limit corresponding to the steering angle in accordance with the steering angle,
the second calculator calculates the second limit in accordance with the steering angle, and
the third calculator calculates a final individual limit corresponding to the steering angle by adding together the first limit calculated by the first calculator and the second limit calculated by the second calculator.

5. The steering control unit according to claim 1 , wherein
the limit calculator includes a plurality of state quantity-sensitive calculators and a final limit calculator,
the state quantity-sensitive calculators calculate the first limits on the assist controlled variable in accordance with the plurality of kinds of state quantities,
the final limit calculator calculates the final limit on the assist controlled variable by adding together all the first limits calculated by the state quantity-sensitive calculators,
the state quantity-sensitive calculators include a first steering angle-sensitive calculator and a second steering angle-sensitive calculator,
the first steering angle-sensitive calculator calculates the first limit corresponding to the steering angle in accordance with the steering angle, and
the second steering angle-sensitive calculator calculates the second limit in accordance with the steering angle.

6. The steering control unit according to claim 1 , wherein
the limit calculator includes a steering angle-sensitive calculator that calculates the first limit corresponding to the steering angle on the basis of a map that defines a relationship between the steering angle and the first limit corresponding to the steering angle, and
the first limit defined in the map is set by taking into account the correction quantity.

Assignees

• Jtekt Corp

Inventors

• Maeda Shingo

Classifications

• B62D5/0469 Primary

  End-of-stroke control · CPC title

• B62D5/0493

  detecting processor errors, e.g. plausibility of steering direction · CPC title

• B62D5/0463 Primary

  calculating assisting torque from the motor based on driver input · CPC title

• B62D6/10 Primary

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