JP2005112024A - Steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering control device capable of enhancing the operational responsiveness when starting to turn a steering wheel or performing a sudden steering without degrading the steering feeling during the regular steering. <P>SOLUTION: A steering wheel 1 and a rack and a pinion 4 are connected to each other via a transmission ratio variable mechanism 7, and a first electric motor 5 as a turning actuator is provided on an output shaft 14 side of the transmission ratio variable mechanism 7. A second electric motor 9 is provided on a transmission ratio operation unit of the transmission ratio variable mechanism 7. The rotational angle on the input/output sides of the transmission ratio variable mechanism 7 are detected by first and second steering angle sensors 33 and 34, and the target transmission ratio and the target actual steering angle are operated based on the detected values, and both motors 5 and 9 are feedback-controlled. A torque sensor 42 is provided on the output shaft 14 side, and addition-correction is performed according to the detected value of a torque sensor 42 in determining the target transmission ratio and the target actual steering angle. The motor control quantity is increased only when the steering wheel 1 is started to turn or suddenly steered. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The invention of this application relates to a steering control device that controls a steering actuator in accordance with an input of a steering input means such as a steering wheel.

  As a conventional steering control device, a device as described in Patent Document 1 has been devised.

  In this steering control device, a steering wheel as a steering input means is linked to a rack and pinion as a steering operation mechanism via a transmission ratio variable mechanism, and the transmission ratio of the transmission ratio variable mechanism is controlled by a transmission ratio operation motor. In addition, the output shaft side of the transmission ratio variable mechanism is controlled and driven by a steering motor. In the transmission ratio operating motor, the target transmission ratio corresponding to the input side steering angle is determined by the controller so that the actual transmission ratio calculated from the detected steering angle on the input side and the output side approaches the target transmission ratio. Feedback control. In addition, the steering motor determines the target actual steering angle according to the target transmission ratio and the detected steering angle on the input side by the controller, and feeds back the detected steering angle on the output side to the target actual steering angle. To be controlled.

Here, the target transmission ratio is basically determined according to the steering angle on the input side, and the target actual steering angle is determined to reflect the determined value of the target transmission ratio. If the target actual rudder angle is determined as it is according to the steering angle on the input side, the responsiveness at the start of turning of the steering wheel or at the time of sudden steering is lowered. For this reason, in this steering control device, in determining the target transmission ratio and the target actual steering angle, the second target value corresponding to the steering angular velocity on the input side is set to the first target value corresponding to the steering angle. Addition correction to be added is performed. Therefore, at the start of turning the steering wheel or sudden steering, the target transmission ratio and target actual steering angle are corrected to reflect the steering speed of the steering wheel, enabling quick steering according to the driver's steering intention. Become.
JP 2001-138936 A

  However, in the case of this conventional steering control device, when the target transmission ratio and the target actual steering angle are determined, addition correction is performed according to the steering angular velocity on the input side. Although sometimes it becomes possible to obtain a large steering speed by the addition correction, the addition correction is also performed when the steering wheel is turned at a constant speed if the steering wheel is rotating. It will be broken. For this reason, it is difficult to set a sufficient control gain to improve the operation response at the start of turning of the steering wheel or abrupt steering, and if the control gain is set to a large value, the amount of addition correction performed during normal steering is also large. As a result, the steering feeling is deteriorated.

  Therefore, the invention of this application is to provide a steering control device capable of improving the operation responsiveness at the start of turning of the steering wheel or at the time of sudden steering without causing deterioration of the steering feeling at the time of normal steering. is there.

  As a means for solving the above-described problem, the invention according to claim 1 is directed to determining a target transmission ratio for controlling the transmission ratio operating actuator and a target actual steering angle for controlling the steering actuator. Addition correction according to was performed.

  In the case of the present invention, in determining the target transmission ratio and the target actual steering angle, the correction value corresponding to the steering torque is added to the target calculation value, so that the steered wheels are operated at a speed according to the steering intention of the driver. Can do.

  According to the second aspect of the present invention, in determining the target transmission ratio for controlling the transmission ratio operating actuator and the target actual steering angle for controlling the steering actuator, an addition correction according to the steering angular acceleration on the input side To do.

  In the case of this invention, in determining the target transmission ratio and the target actual steering angle, the correction value corresponding to the steering angular acceleration on the input side is added to the target calculation value, so that the steered wheels are driven at a speed according to the driver's steering intention. Can be operated.

  In the invention of this application, when the target transmission ratio and the target actual rudder angle are determined, the addition correction according to the input torque or the steering angular acceleration is performed. The operating speed of the steered wheels can be increased only under conditions that actually require a large steered speed. Therefore, it is possible to reliably prevent the deterioration of steering feeling during normal steering.

  Embodiments of the invention of this application will be described below with reference to the drawings.

  First, a first embodiment shown in FIGS. 1 to 4 will be described.

  FIG. 1 schematically shows a steering control device according to the first embodiment. As shown in the figure, this steering control device includes a steering upper shaft 2 (hereinafter referred to as “upper shaft 2”) connected to a steering wheel 1 of a vehicle as steering input means, and a steered wheel 3. A rack and pinion 4 that is a steering operation mechanism for operation, a first electric motor 5 as a steering actuator that drives the rack and pinion 4, and a steering lower that is coupled to the pinion shaft of the rack and pinion 4 A shaft 6 (hereinafter referred to as “lower shaft 6”), a transmission ratio variable mechanism 7 that connects the upper shaft 2 and the lower shaft 6 so that the transmission ratio can be adjusted, and the transmission ratio variable mechanism 7 for transmission ratio control. The second electric motor 9 serving as a transmission ratio operation actuator that applies the operating force of A controller 10 as control means for, and a.

  The upper shaft 2 has one end connected to the steering wheel 1 and the other end connected to the input shaft 11 of the transmission ratio variable mechanism 7. On the other hand, the lower shaft 6 includes a main body shaft 12 connected to the rack shaft of the rack and pinion 4, a plurality of connecting shafts 13 connecting the output shaft 14 of the transmission ratio variable mechanism 7 and the main body shaft 12 via a universal joint. It is constituted by. The rack and pinion 4 includes a rack bar 17 linked to the left and right steered wheels 3 via a tie rod 15 and a knuckle arm 16, and a pinion gear 18 that meshes with the rack bar 17.

  The first electric motor 5 that drives the rack and pinion 4 is linked to the pinion shaft via a worm gear 19 so as to be able to transmit the drive, and is driven to rotate in forward and reverse directions under the control of the controller 10.

  On the other hand, as shown in FIGS. 1 and 4, the variable transmission ratio mechanism 7 includes first and second planetary gear mechanisms 20 and 21 having substantially the same configuration arranged in series in a housing 22, and both gear mechanisms 20 and 21. Planetary carriers are constituted by a common synchronizing shaft 23. A plurality of similar shafts 23 are provided, and both gear mechanisms 20 and 21 are connected to each other via the plurality of synchronization shafts 23.

  In the first planetary gear mechanism 20, an input shaft 11 is provided on a sun gear 24, a planetary gear 25 rotatably supported on one end side of each of the synchronization shafts 23 is meshed with the sun gear 24, and the outer peripheral side of the sun gear 24 is coaxial. The ring gear 26 that meshes with the planetary gear 25 is integrally coupled to the housing 22.

  On the other hand, in the second planetary gear mechanism 21, the output shaft 14 is provided on the sun gear 27, and the planetary gear 28 supported on the other end of each synchronization shaft 23 is engaged with the sun gear 27, and is arranged on the coaxial outer peripheral side of the sun gear 27. The ring gear 29 thus engaged is further meshed with each planetary gear 28. A worm wheel 30 is formed on the outer peripheral surface of the ring gear 29, and a worm shaft 31 connected to the rotating shaft of the second electric motor 9 is engaged with the worm wheel 30. Therefore, the second electric motor 9 is linked to the ring gear 29 through the worm gear 32 including the worm wheel 30 and the worm shaft 31 so as to be able to transmit the drive, and is driven to rotate in the forward and reverse directions by the control of the controller 10. Yes.

And when the number of teeth of each gear element corresponding to the two planetary gear mechanisms 20 and 21 is set to the same number, and the ring gear 29 of the second planetary gear mechanism 21 is stopped similarly to the first planetary gear mechanism 20, The input shaft 11 and the output shaft 14 rotate synchronously at a 1: 1 rotation ratio. In other words, the planetary gears 25 and 28 of the planetary gear mechanisms 20 and 21 are always revolved at the same speed via the synchronous shaft 23. Therefore, if both the ring gears 26 and 29 are stopped, of course, The sun gears 24 and 27 rotate at the same speed. As a result, the input shaft 11 and the output shaft 14 rotate at a 1: 1 rotation ratio. Further, the transmission ratio variable mechanism 7 is configured as described above. Therefore, when rotation is applied from the second electric motor 9 to the ring gear 29 of the second planetary gear mechanism 21, the rotation is added to the sun gear 27 and the output shaft 14 via the planetary gear 28. That is, when rotation in the same direction as the revolution direction of the planetary gear 28 is applied from the second electric motor 9 to the ring gear 29, the speed is increased so that the rotation ratio of the input shaft 11 and the output shaft becomes larger than 1: 1, and vice versa. When the rotation of the second electric motor 9 is applied to the ring gear 29 in the reverse direction, the speed is reduced so that the rotation ratio becomes smaller than 1: 1. The transmission ratio of the transmission ratio variable mechanism 7 is adjusted by current control of the second electric motor 9 by the controller 10 described later.

Further, as shown in FIG. 1, a first steering angle sensor 33 and a second steering angle sensor 34 for detecting these rotation angles are provided on the input shaft 11 and the output shaft 14 of the transmission ratio variable mechanism 7, respectively. Signals of these detected steering angles θ _h and θ _w are input to the controller 10.

  On the other hand, a torque sensor 42 is provided on the lower shaft 6. The torque sensor 42 includes a torsion bar 43 interposed in the middle of the lower shaft 6 and an electromagnetic or optical torsion detection unit 44 that detects a torsion amount of the torsion bar 43. The detected detection value T is input to the controller 10 as a parameter indicating the torque of the transmission system.

In addition to these detected steering angles θ _h and θ _w and torque T, a vehicle state quantity signal indicating a vehicle operating state such as a vehicle speed and a yaw rate is input to the controller 10. In the following description, it is assumed that only the vehicle speed V is input as the vehicle state quantity signal.

The controller 10 is constituted by a microcomputer or the like, as a basic function, the target transfer ratio of the transmission ratio variable mechanism 7 determined from the detected steering angle theta _h of the vehicle speed V and the input side as compared to the actual transmission ratio feedback operation, the target actual steering angle of a function of outputting a command value, the lower shaft 6 determined from the detected steering angle theta _h and the target transmission ratio (pinion shaft) to the results driving circuit of the second electric motor 9 the detected actual steering angle as compared to the theta _w feedback operation, and a function of outputting the result as a command value to the drive circuit of the first electric motor 5.

Specifically, the controller 10 includes a target transmission ratio calculation means 35 for determining a target transmission ratio R _* of the detected steering angle theta _h from the transmission ratio variable mechanism 7 of, as shown in FIG. 2 and the current vehicle speed V input side, The actual transmission ratio calculating means 36 for obtaining the current transmission ratio R of the transmission ratio variable mechanism 7 from the detected steering angle θ _h on the input side and the detected actual steering angle θ _w on the output side, the target transmission ratio calculating means 35, and the actual transmission ratio Transmission ratio operation actuator command value calculation means 37 (hereinafter referred to as “command value calculation means 37”) that receives the calculation results R _* and R of the calculation means 36 and calculates and outputs the command value of the second electric motor 9; Target actual steering angle calculation means 38 for determining the target actual steering angle θ _{w *} of the lower shaft 6 from the product of the target transmission ratio R _* obtained by the target transmission ratio calculation means 35 and the detected steering angle θ _h , and target actual steering angle calculation finger of the first electric motor 5 receives the detected actual steering angle theta _W operation result theta _{w *} and the output side of the means 38 A steering actuator command value calculation means 39 (hereinafter referred to as “command value calculation means 39”) that calculates and outputs a command value is provided.

A major feature of the control of the steering control device is a calculation process of the target transmission ratio R _* in the target transmission ratio calculation means 35 and a series of processes for receiving the calculation result. Hereinafter, a specific processing flow in the target transmission ratio calculation means 35 will be described with reference to the flowchart of FIG.

That is, the target transmission ratio calculating means 35 first reads the input and output side steering angles θ _h and θw, the vehicle speed V, and the steering torque T, and then in step 101, the transmission ratio corresponding to the steering angle θ _h. Is obtained by calculation or based on a map stored in advance, and then in step 102, the first correction coefficient corresponding to the vehicle speed V is similarly obtained by calculation or map, and the transmission ratio obtained in step 101 Multiply the first correction coefficient.

  Next, in step 103, the second correction coefficient corresponding to the current steering torque T is similarly obtained by calculation or map, and the value obtained in step 102 is further multiplied by the second correction coefficient. The relationship between the second correction coefficient and the steering torque is as illustrated in the column of step 103, for example, when the map is used. In this map, the second correction coefficient is 1 when the steering torque is close to 0, and the second correction coefficient gradually increases from 1 as the steering torque increases. Therefore, multiplying the transmission ratio obtained in steps 101 and 102 by the second correction coefficient means that an addition correction corresponding to the steering torque T is performed on the calculated value of the transmission ratio obtained in the previous step. It becomes.

Assuming that the calculation value obtained in step 103 is called a basic target calculation value, in the next step 104, it is determined whether or not the current steering speed of the steering wheel 1 exceeds a threshold value, and the steering speed is reduced. When the threshold value is not exceeded, the basic target calculation value is output as the target transmission ratio R _* , and when the threshold value is exceeded, correction is made to reduce the transmission ratio value with respect to the basic target calculation value. Output as target transmission ratio R _* .

  In the process of step 104, for example, a relationship map between the steering speed and the maximum allowable transmission ratio as shown in the column of step 104 (the actual maximum transmission ratio of the transmission ratio variable mechanism 7 at a steering speed not exceeding the threshold value). When the value of the basic target calculation value obtained in step 103 exceeds the maximum transmission ratio corresponding to the steering speed at that time, the basic target calculation value is displayed on the diagram of the relationship map. You may make it restrict | limit to the value projected on. The steering speed threshold value is a limit steering speed value at which the operation of the first electric motor 5 may not be able to follow the control when the basic target calculation value obtained in step 103 is output as it is. Say that. Therefore, the process in step 104 is a process for causing the first electric motor 5 to follow the control with certainty.

The target transmission ratio R _* calculated by the target transmission ratio calculating means 35 as described above is reflected in the control of the second electric motor 9 through the processing of the command value calculating means 37, as shown in FIG. This is reflected in the control of the first electric motor 5 through the processing of the target actual steering angle calculation means 38 and the command value calculation means 39. Since the target transmission ratio R _* calculated by the target transmission ratio calculating means 35 is added and corrected to a value corresponding to the steering torque in the above-described step 103, the operating speeds of the first and second electric motors 5 and 9 ( The control amount is controlled to increase as the steering torque increases.

Therefore, in the case of this steering control device, at the start of turning of the steering wheel 1 where the steering torque becomes large or when the steering is suddenly performed, as a result of the target actual steering angle θw _* being increased by the addition correction, quick steering control is performed, On the other hand, during a normal steering operation in which the steering wheel is turned off at a constant speed, addition correction is not performed (or the correction amount is reduced), so that normal steering control is performed.

  In addition, since friction exists in each part of the operation part of the steering control device, torque due to the friction acts even when the steering wheel 1 is not steered rapidly. Therefore, as shown in the map shown in Step 103 of FIG. 3, if the second correction coefficient is set not to be larger than 1 in a region (torque region) where only the torque corresponding to the friction is generated. The addition correction amount when the steering wheel 1 is operated at a constant speed can be completely reduced to zero.

  In the first embodiment described above, the electric motor 5 is directly used as the steering actuator. However, as in the second embodiment shown in FIG. 5, the hydraulic cylinder mechanism 50 operated by the electric motor 5 is used as the steering actuator. You may make it use as. Hereinafter, other embodiments including the second embodiment will be described. However, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

  The hydraulic cylinder mechanism 50 is a reversible pump 51 such as a gear pump that is driven forward and backward by the electric motor 5 and a hydraulic cylinder 52 that is fixedly installed on the vehicle body and moves the rack bar 17 of the rack and pinion 4 forward and backward by supplying and discharging hydraulic pressure. The driving force of the electric motor 6 is once converted into hydraulic pressure via the reversible pump 51, and the rack bar 17 is moved forward and backward by the hydraulic pressure.

  Therefore, in the steering control device of this embodiment, the driving force of the electric motor 5 operates the rack bar 17 via the hydraulic cylinder mechanism 50, but controls the electric motor 5 as in the first embodiment. The same effect can be obtained. However, in the case of this embodiment, since the driving force of the electric motor 5 is once converted into hydraulic pressure, a larger turning force is easily generated, which is advantageous when applied to a large vehicle or the like.

  Next, a third embodiment shown in FIGS. 6 and 7 will be described.

  The basic configuration of the steering control device of this embodiment is substantially the same as that of the first embodiment, but there is no torque sensor 42 on the lower shaft 6 connected to the pinion shaft of the rack and pinion 4. The addition correction processing by the target transmission ratio calculation means 35 shown in FIG. 2 is different from that of the first embodiment.

For the treatment of the target transmission ratio calculating section 35, as shown in the flowchart of FIG. 7, after obtaining the transmission ratio corresponding to the steering angle theta _h of input at step 101, the according to the vehicle speed V at step 102 The process up to the point where the correction coefficient of 1 is multiplied by the transmission ratio is the same as in the first embodiment. However, in the subsequent step 203, the second correction coefficient corresponding to the current steering angular acceleration is calculated instead of the steering torque. The value is obtained from the map, and the value obtained in step 102 is multiplied by the second correction coefficient. In this case, the current steering angle acceleration is as determined by a calculation differentiating twice a steering angle theta _h of the input side, the second correction coefficient becomes 1 in the vicinity of the steering angular acceleration is 0, the steering angular acceleration The value is set to increase to 1 or more in accordance with the increase. That is, in step 203, addition correction according to the steering angular acceleration is performed on the value obtained in step 102.

The next step 104 is the same as that of the first embodiment. When the steering speed does not exceed the threshold value with reference to the current steering speed of the steering wheel 1, the basic target calculation value obtained in step 203 is directly used. The target transmission ratio R _* is output. When the threshold value is exceeded, the basic target calculation value is limited and corrected, and the value is output as the target transmission ratio R _* .

In the case of the steering control device of this embodiment, the target transmission ratio R _* calculated by the target transmission ratio calculating means 35 is added and corrected to a value corresponding to the steering angular acceleration of the steering wheel 1 by the processing of step 203. The operating speeds (control amounts) of the first and second electric motors 5 and 9 that reflect the value of the target transmission ratio R _* are controlled according to the state of the steering angular acceleration. Therefore, also in this steering control device, when the steering wheel 1 is started to be turned or when the steering is suddenly performed, the target actual steering angle θw _* is increased and quick turning control is executed, and the steering wheel 1 is turned at a constant angular acceleration. During normal steering operation, normal steering control is executed.

  Also in this embodiment, if the second correction coefficient is set so as not to be larger than 1 in the region of the steering angular acceleration corresponding to the generated friction of the operating part of the steering control device, the steering wheel 1 at a constant speed. The addition correction amount when operating the can be completely reduced to zero.

In this embodiment, the steering angular acceleration is obtained by differentiating the detected steering angle θ _h on the input side twice, and addition correction according to the steering angular acceleration is performed. There is no need to provide a torque sensor as in the embodiment, and there is an advantage that the device configuration can be simplified correspondingly. However, in the case of the apparatus of the first embodiment, since the process of performing differentiation twice with respect to the detected steering angle θ _h is not performed as in the second embodiment, noise is less likely to be included in the calculated value. As a result, there is another advantage that the control accuracy is increased.

Also, as in this embodiment, when the control target value (R _* , θw _* ) is added and corrected in accordance with the steering angular acceleration of the steering wheel 1, as in the fourth embodiment shown in FIG. The hydraulic cylinder mechanism 50 can be used as a steering actuator. The configuration of the hydraulic cylinder mechanism 50 is the same as that of the second embodiment shown in FIG.

  The embodiments of the present invention are not limited to those described above. For example, in each of the above embodiments, a planetary gear mechanism is used as a transmission ratio variable mechanism. However, a differential gear mechanism is used instead of the planetary gear mechanism. Etc. can also be adopted. Further, the steering input means is not limited to the steering wheel, and a mechanism such as a lever can be used.

  Next, inventions other than the invention described in the claims that can be grasped from the contents of the above-described embodiment will be described together with the effects thereof.

  (A) The steering control device according to claim 2, wherein the steering angular acceleration is obtained by differentiating the steering angle on the input side detected by the first steering angle sensor twice.

  In this case, since the first steering angle sensor that detects the steering angle on the input side can be used to detect the steering angular acceleration, it is possible to reduce the number of components and downsize the device.

The schematic block diagram of the steering control apparatus which shows 1st Embodiment of invention of this application. The control block diagram of the controller of the embodiment. The flowchart which shows the flow of control of the target transmission ratio calculation in the controller of the embodiment. The expanded sectional view of the transmission ratio variable mechanism of the embodiment. The schematic block diagram of the steering control apparatus which shows 2nd Embodiment of invention of this application. The schematic block diagram of the steering control apparatus which shows 3rd Embodiment of invention of this application. The flowchart which shows the flow of control of the target transmission ratio calculation in the controller of the embodiment. The schematic block diagram of the steering control apparatus which shows 4th Embodiment of invention of this application.

Explanation of symbols

1 ... Steering wheel (steering input means)
3 ... steered wheel 4 ... rack & pinion (steering operation mechanism)
5 ... 1st electric motor (steering actuator)
7. Transmission ratio variable mechanism 9. Second electric motor (transmission ratio operation actuator)
10 ... Controller (control means)
33 ... 1st steering angle sensor 34 ... 2nd steering angle sensor 42 ... Torque sensor 50 ... Hydraulic cylinder mechanism (steering actuator)

Claims (2)

Steering input means for inputting a steering force from the driver;
A steering operation mechanism for operating the steered wheels;
A steering input means on the input side and a steering operation mechanism on the output side, respectively, and a transmission ratio variable mechanism that connects the steering input means and the steering operation mechanism so that the transmission ratio can be adjusted,
A steering actuator for applying a driving force to the output side of the transmission ratio variable mechanism;
A transmission ratio operation actuator for applying an operation force for transmission ratio control to the transmission ratio variable mechanism;
A first rudder angle sensor for detecting a rotation angle on the input side of the transmission ratio variable mechanism;
A second steering angle sensor for detecting a rotation angle on an output side of the transmission ratio variable mechanism;
Based on the rotation angle on the input side detected by the first steering angle sensor and the rotation angle on the output side detected by the second steering angle sensor, the target transmission ratio of the transmission ratio variable mechanism and the target actuality of the steering actuator are determined. Control means for determining the rudder angle;
In a steering control device with
In determining the target transmission ratio and the target actual rudder angle, an addition correction according to a steering torque is performed. Steering input means for inputting a steering force from the driver;
A steering operation mechanism for operating the steered wheels;
A steering input means on the input side and a steering operation mechanism on the output side, respectively, and a transmission ratio variable mechanism that connects the steering input means and the steering operation mechanism so that the transmission ratio can be adjusted,
A steering actuator for applying a driving force to the output side of the transmission ratio variable mechanism;
A transmission ratio operation actuator for applying an operation force for transmission ratio control to the transmission ratio variable mechanism;
A first rudder angle sensor for detecting a rotation angle on the input side of the transmission ratio variable mechanism;
A second steering angle sensor for detecting a rotation angle on an output side of the transmission ratio variable mechanism;
Based on the rotation angle on the input side detected by the first steering angle sensor and the rotation angle on the output side detected by the second steering angle sensor, the target transmission ratio of the transmission ratio variable mechanism and the target actuality of the steering actuator are determined. Control means for determining the rudder angle;
In a steering control device with
In determining the target transmission ratio and the target actual steering angle, an addition correction according to the steering angular acceleration on the input side is performed.

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