JP2011051378A - Electric power steering device having automatic steering function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device allowing safe parking of a vehicle by ensuring the safety when starting the vehicle while setting the position of a steering wheel automatically to be steered, to the intention of a driver. <P>SOLUTION: Information on the position of a steering wheel by a steering-without-driving changing switch installed in a driver's seat is incorporated in a controller of an electric power steering device, the vehicle stop state and the non-steering state are determined, and the vehicle is automatically operated to the position of the steering wheel set by the steering-without-driving changing switch. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus that can be automatically steered when a vehicle is stopped.

  Conventionally, in an electric power steering apparatus, there has been a problem of eliminating the need for the driver to check the turning angle of the wheel when starting the vehicle.

  As a prior art for improving this portion, there is one disclosed in Japanese Patent Application Laid-Open No. 2007-145248, which determines a vehicle stop state based on a vehicle speed signal and a non-steer state due to a torque signal being smaller than a specified value. When both are judged, the steering angle signal and the steering angular velocity signal are read, and the steering wheel is returned to the neutral position at a prescribed speed.

  However, in this prior art, since the microcomputer in the controller of the electric power steering automatically determines the vehicle state and starts the automatic steering, for example, the vehicle with the driver consciously turning off the steering wheel Even when the vehicle is stopped, there is a problem that the steering wheel is automatically returned to the neutral position.

JP 2007-145248 A

  The problem to be solved by the present invention is to provide an electric power steering apparatus that performs an appropriate operation in response to a driver's instruction.

  In order to solve the above problems, the present invention takes in steering wheel position command information from a changeover switch installed in a driver's seat into a controller of an electric power steering device, determines a vehicle stop state and a non-steering state, and changes the changeover switch. It is characterized in that it is automatically operated to the steering wheel position set in.

  According to the present invention, since the position of the steering wheel that is automatically steered can be matched with the driver's intention, it is not necessary to perform troublesome stationary steering, ensuring safety when starting the vehicle, There is an effect that the vehicle can be parked safely.

The schematic diagram of the electric power steering device concerning the present invention is shown. The figure which shows an example of the operation system of the electric power steering apparatus which concerns on this invention is shown. The block diagram which shows the function structural example of the control apparatus of the electric power steering apparatus which concerns on this invention is shown. The flowchart figure which shows an example of this invention is shown. An example of a reference neutral command value is shown. An example of a reference left end command value is shown. An example of a reference right end command value is shown.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, where SM is a steering mechanism. This steering mechanism SM has a steering shaft 2 having an input shaft 2a to which a steering force applied from a driver is transmitted to the steering wheel 1 and an output shaft 2b connected to the input shaft 2a via a torsion bar (not shown). It has. The steering shaft 2 is rotatably mounted on the steering column 3, one end of the input shaft 2a is connected to the steering wheel 1, and the other end is connected to a torsion bar (not shown).

  The steering force transmitted to the output shaft 2b is transmitted to the intermediate shaft 5 via the universal joint 4 composed of the two yokes 4a and 4b and the cross connecting portion 4c for connecting them, It is transmitted to the pinion shaft 7 through a universal joint 6 composed of yokes 6a and 6b and a cross connecting portion 6c for connecting them. The steering force transmitted to the pinion shaft 7 is converted into a straight movement in the vehicle width direction by the steering gear mechanism 8 and transmitted to the left and right tie rods 9, and the steered wheels WL and WR are steered by these tie rods 9.

  A steering assist mechanism 10 for transmitting a steering assist force to the output shaft 2b is connected to the output shaft 2b of the steering shaft 2. The steering assist mechanism 10 includes a speed reduction mechanism 11 connected to the output shaft 2b, and an electric motor 12 composed of, for example, a brushless motor as an electric motor that generates a steering assist force connected to the speed reduction mechanism 11. .

  A steering torque sensor 14 as a steering torque detecting means is disposed in a housing 13 connected to the steering wheel 1 side of the speed reduction mechanism 11. The steering torque sensor 14 detects a steering torque applied to the steering wheel 1 and transmitted to the input shaft 2a. For example, a torsion bar (not shown) in which the steering torque is interposed between the input shaft 2a and the output shaft 2b. The torsional angular displacement is converted into a torsional angular displacement, and this torsional angular displacement is detected by a non-contact magnetic sensor.

  The steering torque detection value T output from the steering torque sensor 14 is input to the controller 15 as shown in FIG. In addition to the torque detection value T from the steering torque sensor 14, the controller 15 includes a vehicle speed Vs detected by a vehicle speed sensor (not shown), motor currents Iu to Iw flowing through the electric motor 12, a rotation angle sensor 18 constituted by an encoder, and the like. The rotation angle θ of the steering shaft 2 detected in step 3 is also input. The rotation angle sensor may be a resolver type sensor built in the electric motor 12.

  Since the controller 15 uses the battery 16 as a power source and inputs power via the IGN switch 17, the entire electric power steering system is started / stopped by turning on / off the IGN switch 17. The power source of the battery 16 may be directly input to the controller 15, and a relay (not shown) may be driven by the IGN switch 17 to input the power source.

  Further, the controller 15 switches the steering wheel 1 in three stages, neutral, right end, and left end, by a changeover switch 19 provided within a reachable range during the driving operation, and sets the positions of the steered wheels WL and WR. It is possible to select a straight traveling state, a right cutting state, or a left cutting state. As the changeover switch, a toggle switch, a button switch, a touch sensor or the like is used.

  FIG. 3 is a control block diagram of the controller 15 of the present invention. In the controller 15, a current command for causing the electric motor 12 to generate a steering assist force according to the torque detection value T and the vehicle speed detection value Vs input from the steering torque sensor 14. The value is calculated by the steering assist command value calculation unit 31, the compensation values of the phase compensation unit 32, the differential compensation unit 33, the convergence control unit 34, and the inertia compensation unit 35 are calculated, and the steering assist torque command value Iref is calculated. Further, the steering assist torque command value Iref is subjected to PI control 36 and PWM control 37, and a current control value E is calculated. The current control value E is input to the inverter 38, and the inverter 38 drives and controls the electric motor 12 based on the current control value E.

The motor rotation angle θ detected by the rotation angle detection unit 39 calculates the motor angular velocity ω by the angular velocity calculation unit 40, and further calculates the motor angular acceleration α by the angular acceleration calculation unit 41, together with the vehicle speed Vs, the convergence control unit 34, inertia The compensation unit 35 compensates the steering assist torque command value Iref to improve the steering performance of the electric power steering.
The stationary steering switch calculating unit 50 inputs the motor rotation angle θ and the selector switch information SW, executes a control flowchart described later, and outputs an output value K.

  The detected torque value T is input to the steering determination unit 44. When the detected torque value T is smaller than the arbitrary torque T1, the control value 1 is output, and when the detected torque value T is larger than the arbitrary torque T1, the control value 0 is output. The output value is multiplied by the output value K of the stationary steering switch calculating unit 50 by the multiplier 51, and can be operated only when the steering is not performed. In addition, when the arbitrary torque T1 is exceeded during operation, it is possible to stop it.

  The vehicle speed Vs is input to the vehicle speed determination unit 43. When the vehicle speed Vs is 0, a control value 1 is output, and when it is not 0, a control value 0 is output. The output value is multiplied by the output value K of the stationary steering switch calculating unit 50 by the multiplier 52, and can be operated only when the vehicle is stopped.

  The motor angular velocity ω is input to the stationary steering gain calculation unit 49, and the gain G is output so that the steering velocity ω1 is arbitrarily set. The gain G is expressed by the following equation: G = − (| ω | / ω1) +1, and the multiplier 53 multiplies the output value K of the stationary steering switch calculating unit 50 by the multiplier 53. This makes it possible to operate the steering wheel safely at a constant speed while preventing the steering wheel from rotating suddenly due to the reaction force of the tire caused by disturbances such as road surface conditions such as grooves and saddles when the vehicle is stopped, and impact on the tire. it can.

  The output value K output from the stationary steering switching calculation unit 50 is obtained as a stationary command value S via a multiplier 51, a multiplier 52, and a multiplier 53, and is fed back to the steering assist torque command value Iref to provide a motor. 12 is controlled.

Here, an example of a flowchart relating to the stationary steering switching calculation unit 50 is shown in FIG.
First, in step S1, the motor rotation angle θ is read, and in step S2, switch information SW of the changeover switch 19 is read. Next, in step S3, it is determined whether or not the changeover switch 19 has been selected to be neutral. If it has been selected, the process proceeds to step S4.

In step S4, it is determined whether or not the steering angle is in the neutral position based on the motor rotation angle θ. If it is determined that the rudder angle is not near neutral, the process proceeds to step S5.
If it is determined in step S4 that the position is neutral, the control is terminated.

  In step 5, it is determined whether or not the steering angle is a right steering angle based on the motor rotation angle θ. If the steering angle is determined to be a right steering angle, the process proceeds to step S6 to output a left turn command value and is not determined to be a right steering angle. In this case, the process proceeds to step S7 and a right turn command value is output. After step S6 and step S7, the process returns to step S1, and the determination of the motor rotation angle θ and the switch information SW is repeated, and the execution of the control is terminated by the neutral position determination of step S4.

  If the changeover switch 19 is not selected to be neutral in step S3, the process proceeds to step S8. In step S8, it is determined whether or not the changeover switch 19 has been selected as the left end. If selected, the process proceeds to step S9, and if not, the process proceeds to step S11.

  In step S9, it is determined whether or not the steering angle is at the left end based on the motor rotation angle θ. If it is determined that the steering angle is other than the left end, the process proceeds to step S10 and a left turn command value is output. If it is determined in step S9 that the position is the left end position, the control is terminated. After step S10, the process returns to step S1, and the determination of the motor rotation angle θ and the switch information SW is repeated, and the execution of the control is terminated by the left end position determination in step S9.

  If the changeover switch 19 is not selected as the left end in step S8, the process proceeds to step S11. In step S11, it is determined whether or not the changeover switch 19 is selected to the right end. If it is selected, the process proceeds to step S12, and if it is not selected, the execution of the control is terminated.

  In Step S12, it is determined whether or not the steering angle is at the right end based on the motor rotation angle θ. If it is determined that the steering angle is other than the right end, the process proceeds to Step S13 and a right turn command value is output. If it is determined in step S12 that the position is the right end position, the control is terminated. After step S13, the process returns to step S1, and the determination of the motor rotation angle θ and the switch information SW is repeated, and the execution of the control is terminated by the right end position determination in step S12.

  FIG. 5 shows an example of the reference neutral command value 45 when the changeover switch 19 selects neutral. When the steering position based on the motor rotation angle θ is determined to be the right steering angle, a left turn command value is output. When approaching the neutral position, the command value is gradually decreased to stop. When the steering position is determined to be the left steering angle, a right turn command value is output, and when approaching neutral, the command value is gradually decreased and stopped. When the steering position is near neutral, the steering command value is not output.

  FIG. 6 shows an example of the reference left end command value 46 when the changeover switch 19 selects the left end. When the steering position based on the motor rotation angle θ is determined to be the right steering angle, the left turn command value is Output and stop at the left end position. When it is determined that the steering position is the left steering angle and it is not at the left end position, the left turn command value is output in the same manner and the vehicle stops at the left end position. When the steering position is the left end position, the steering command value is not output.

  FIG. 7 shows an example of the reference right end command value 47 when the changeover switch 19 selects the right end. When the steering position based on the motor rotation angle θ is determined to be the left steering angle, the right turn command value is Output and stop at the right end position. When the steering position is determined to be the right steering angle and not at the right end position, the right turn command value is output in the same manner and the vehicle stops at the right end position. When the steering position is the right end position, the steering command value is not output.

  As described above, according to the present invention, the electric power steering capable of aligning the automatically steered steering wheel position with the driver's intention, ensuring the safety at the time of starting the vehicle, and safely parking the vehicle. Providing the device.

  The present invention is applicable not only to the electric power steering device but also to the steer-by-wire in which the steering unit including the steering wheel and the steering gear mechanism are mechanically separated, for example, when the power supply system is stopped due to an abnormality and then returns to an abnormal state. It is also possible to adapt to the returning operation of recognizing the mutual steering angle position of the steering unit and the steering gear mechanism.

  The present invention can be suitably used for an electric power steering device or the like.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Steering column 4 Universal joint 5 Intermediate shaft 6 Universal joint 7 Pinion shaft 8 Steering gear mechanism 9 Tie rod 10 Steering assist mechanism 11 Deceleration mechanism 12 Electric motor 13 Housing 14 Torque sensor 15 Controller 16 Battery 17 IGN switch 18 Rotation angle sensor 19 changeover switch 31 steering assist command value calculation unit 32 phase compensation unit 33 differential compensation unit 34 convergence control unit 35 inertia compensation unit 36 PI control unit 37 PWM control unit 38 inverter 39 rotation angle detection unit 40 angular velocity calculation unit 41 Angular acceleration calculation unit 42 Motor current detection unit 43 Vehicle speed determination unit 44 Steering determination unit 45 Reference neutral steering command value 46 Reference left end steering command value 47 Reference right end Steering gain calculation unit outright laid steering command value 49 50 stationary steering steering switch operation unit

Claims (3)

  A motor that applies a steering assist force to the steering system of the vehicle, a torque sensor that detects a steering force that acts on the steering wheel, and a steering angle detection means that detects the steering angle of the steering wheel in the previous period, the vehicle stops. Electric power with a stationary steering switch that recognizes the state in which the steering assist force is not applied, and allows the driver to select the neutral, left end, and right end of the steering wheel and automatically operate the steering wheel Steering device.   The electric power steering apparatus according to claim 1, wherein a gain is set based on an angular velocity of the motor and a steering speed is controlled to be constant.   The electric power steering apparatus according to claim 1 or 2, wherein the steering is stopped when a steering force that is automatically steered exceeds a set value.

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