Patent Publication Number: US-2006011003-A1

Title: Operating position select device for automatic transmission

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an operating position select device for an automatic transmission by which a driver can select by operating a select lever one of select mode positions corresponding to a plurality of operation modes of the automatic transmission.  
      2. Description of the Related Art  
      An operating position select device for an automatic transmission of this kind is disclosed in Japanese patent laying-open publication (Tokkaihei) No. 9-323559. This select device includes a select lever unit disposed near a driver&#39;s seat in a passenger compartment and a mode shift unit mounted on an automatic transmission. The select lever unit has a select lever manually operated by a driver and is connected with the mode shift unit by a connecting mechanism, such as a control cable, or a connecting linkage, which transmits an operating force applied on the select lever by the driver to the mode shift unit to shift operation modes of the automatic transmission.  
      The conventional art, however, has a problem that the select lever unit needs a long select lever in order to operate it without a large operating force of the driver, which reduces design freedom concerning an installation location of the select lever unit and/or a layout of a passenger compartment.  
      This reason comes from the fact that a length of the select lever is determined so that a driver can easily operate the select lever and its operating torque must overcome frictional resistance of the connecting mechanism and the like. Namely, the operating torque, generated by the operating force on the select lever, has to be larger than torque caused by the sum of the frictional resistance in the connecting mechanism and resistance generated when a detent pin, which moves with the select lever, gets over a cam top portion of a detent plate during select operation, although the operating force of the driver is limited to a certain extent. Accordingly, to satisfy both of the above requirements the select lever needs to be longer than a certain length, typically to be 350 mm.  
      Another operating position select device for an automatic transmission of this kind is disclosed in Japanese patent laying-open publication (Tokkai) No. 2003-97694. This select device is, what is called, a shift-by-wire type one. It has a select lever manually operated by a driver, a select position detector for detecting a position of the select lever, a mode shift unit mounted on an automatic transmission for shifting its operation modes, an electric motor for driving a mode shift unit, and a control unit for controlling the electric motor based on an output signal from the detector.  
      This select device is suitable for shortening a length of the select lever and expanding design freedom for its installation location and/or layout of a passenger compartment, while the select device lacks a mechanical connection between the select lever and the mode shift unit. This lack of the mechanical connection results in a problem that the mode shift unit can not be sifted despite of operating the select lever in case of electrical failure such that an electric wire is broken, or the select position detector or the control unit fails.  
      It is, therefore, an object of the present invention to provide an operating position select device for an automatic transmission which overcomes the foregoing drawbacks and can expand design freedom concerning layout of a passenger compartment and/or an installation location of a select lever unit, and drive a mode shift unit despite of electric failure of the operating position select device, with providing favorable select-lever operating feeling in a select operation.  
     SUMMARY OF THE INVENTION  
      According to the first aspect of the present invention there is provided an operating position select device for an automatic transmission whose operation modes are shiftable, the operating position select device comprising: a select lever unit having a select lever that is operated by a driver between a plurality of select positions corresponding to the operation modes; an operating position sensor that detects an operating position of the select lever and outputs an operating position signal; an operating force sensor that detects operating force applied to the select lever and outputs an operating force signal; a mode shift unit mounted on the automatic transmission to shift operation modes of the automatic transmission; a mechanically connecting means that mechanically connects the select lever and the mode shift unit with each other; an assist actuator that is arranged between the select lever and the mode shift unit and supplies assist force to the shift lever; and a control unit that controls the assist actuator, the control unit including an improper-halt judging part that judges an improper halt of the select lever between the adjacent select positions based on the operating position signal and outputs an improper-halt signal, a basic target reaction-force setting part that sets a basic target reaction-force based on the operating position signal and outputs a basic target reaction-force signal, a target reaction-force compensating part that computes a reaction-force compensation-amount based on the improper-halt signal and the operating position signal and outputs a reaction-force compensation-amount signal, a target reaction-force computing part that computes a target reaction-force based on the basic target reaction-force signal and the reaction-force compensation-amount signal and outputs a target reaction-force signal, and an assist force computing part that computes an assist force of the assist actuator based on the target reaction-force signal and the operating force signal.  
      According to the second aspect of the present invention there is provided an operating position select device for an automatic transmission whose operation modes are shiftable, the operating position select device comprising: a select lever unit having a select lever that is operated by a driver between a plurality of select positions corresponding to the operation modes; an operating position sensor that detects an operating position of the select lever and outputs an operating position signal; an operating force sensor that detects operating force applied to the select lever and outputs an operating force signal; a mode shift unit mounted on the automatic transmission to shift operation modes of the automatic transmission; a mechanically connecting means that mechanically connects the select lever and the mode shift unit with each other; an assist actuator that is arranged between the select lever and the mode shift unit and supplies assist force to the shift lever; and a control unit that controls the assist actuator, the control unit including an improper-halt judging part that judges an improper halt of the select lever between the adjacent select positions based on the operating position signal and outputs an improper-halt signal, an input operating-force compensating part that computes an operating-force compensation-amount based on the improper-halt signal and the operating position signal and outputs an operating-force compensation-amount signal, a second operating-force computing part that computes a second operating-force based on the operating force signal and the operating-force compensation-amount signal and outputs a second operating-force signal, and an assist force computing part that computes an assist force of the assist actuator based on the target reaction-force signal and the second operating-force signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The objects, features and advantages of the present invention will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a schematic diagram showing a structure of an automatic transmission with an operating position select device of a first embodiment according to the present invention;  
       FIG. 2  is an enlarged perspective view showing an assist actuator that is used in the operating position select device shown in  FIG. 1 ;  
       FIG. 3  is an enlarged perspective view showing a mode shift unit that has a detent mechanism and is used in the operating position select device shown in  FIG. 1 ;  
       FIG. 4  is a control bock diagram of a control unit and its peripheral equipment that are used in the operating position select device shown in  FIG. 1 ;  
       FIG. 5  is a flowchart of an assist control executed in the control unit shown in  FIG. 4  for controlling the assist actuator during a select operation;  
       FIG. 6  is a characteristic diagram showing relationships of operating reaction force acting on a select lever and a cam profile of a detent mechanism with respect to an operating angle of the select lever, when the select lever is shifted from a position P to a position R without assist force outputted from the assist actuator;  
       FIG. 7  is a characteristic diagram showing a relationship between the operating angle and target reaction force;  
       FIG. 8  is a target select-position table that is provided in a target select-position computing part of the control unit;  
       FIG. 9  is a flowchart of an improper-halt preventing control executed by the control unit;  
       FIG. 10  is a time chart showing a state of an operating position and operating force during a select operation from the position P to the position R with an improper halt of the select lever;  
       FIG. 11  is a control bock diagram of a control unit and its peripheral equipment that are used in an operating position select device of a second embodiment according to the present invention;  
       FIG. 12 a  flowchart of an assist control executed in the control unit shown in  FIG. 11  for controlling an assist actuator during a select operation;  
       FIG. 13  is a flowchart of an improper-halt preventing control executed by the control unit; and  
       FIG. 14  is a time chart showing a state of an operating position and operating force during a select operation from the position P to the position R with an improper halt of the select lever. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Throughout the following detailed description, similar reference characters and numbers refer to similar elements in all figures of the drawings, and their descriptions are omitted for eliminating duplication.  
      An operating position select device of a first preferred embodiment according to the present invention will be described with reference to the accompanying drawings.  
      Referring to  FIG. 1  of the drawing, there is shown an automatic transmission  19  and an operating position select device  100  to control the transmission  19 .  
      The automatic transmission  19  is a conventional multi-speed transmission with a plurality of planetary gear sets, not shown, and is operatable among a plurality of operation modes, for example, a parking mode, a reverse drive mode, a neutral mode, a forward drive mode, and a forward low gear drive mode.  
      The automatic transmission  19  is provided with the operating position select device  100 , which shifts the operation modes to a desired operation mode by manually selecting a select lever  2  of the select device  100 .  
      The operating position select device  100  includes a select lever unit  1  manually operated by a driver, a mode shift unit  300  mounted on the automatic transmission  19 , a first and second control cables  8  and  18  connecting the select lever  2  to the mode shift unit  300 , an operating angle sensor  200  for detecting an operating angle of the select lever  2 , an assist actuator  9  for assisting operating force inputted from the select lever  2  by the driver, an operating torque sensor  21  for detecting actual operating force applied to the select lever  2 , and a control unit  22  for controlling the assist actuator  9 .  
      The select lever unit  1  is arranged, for example, at a center console  3  beside a driver&#39;s seat and has the select lever  2  operated by the driver, a bracket  5  fixed to a vehicle body, a supporting shaft  5   a  fixed on the bracket  5  so as to swingably support the select lever  2 , a knob  4  mounted on the top of the select lever  2  so as to be held by a hand of the driver, and a checking mechanism, not shown, for ensuring the select lever  2  to be kept in a selected mode position.  
      The select lever  2  is set to be approximately 100 mm in length in this embodiment, which is shorter by approximately 250 mm than a conventional type select lever. The lever  2  is operatable by the driver swingably in a first direction toward a P position as indicated by an arrow  
      B P  and in a second direction, opposite to the first direction, toward an L position as indicated by an arrow B L .  
      The select lever  2  can be positioned in one of select positions: the P position corresponding to the parking mode of the automatic transmission  19 , an R position corresponding to the reverse drive mode, an N position corresponding to the neutral mode, a D position corresponding to the forward drive mode, and the L position corresponding to the forward low geared drive mode.  
      The assist actuator  9 , as shown in  FIGS. 1 and 2 , includes an electric motor  15  with reduction gears for reducing rotation speed of an output shaft of the motor  15 , a worm  16  formed on the outer peripheral surface of the output shaft, and a worm wheel  14  meshing with the worm  16  and integrally united to the coupling shaft  12  for coupling the first and second control cables  8  and  18 .  
      The worm wheel  14  is provided on its upper surface with an electric terminal  24  contacting to a carbon resistor  25 , indicated by a dashed line in  FIG. 2 , that is printed on a substrate fixed to a case of the assist actuator  9 . The electric terminal  24  and the carbon resistor  25  constitute the operating angle sensor  200  for detecting an operating angle of the select lever  2  to output an operating angle signal to the control unit  22 .  
      The electric terminal  24  is movable together with and around the coupling shaft  12  to change its position with respect to the carbon resistor  25  that is immobile, so that the operating angle sensor  200  can detect a rotating angle of the coupling shaft  12  and output the operating angle signal that is, for example, proportional to the operating angle of the select lever  2 . The operating angle signal is set to increase as the select lever  2  moves toward the L position, in the second direction B L . The operating angle sensor  200  acts as an operating position sensor of the present invention, and the operating angle signal corresponds to an operating position signal of the present invention.  
      There is provided the operating torque sensor  21  attached to the coupling shaft  12  so as to detect the operating force applied to the select lever  2 . Since the operating force is proportional to operating torque applied to the coupling shaft  12 , the torque sensor  21  detects the operating force based on relative torsion amount between the upper and lower portions of the coupling shaft  12  and outputs an operating force signal to the control unit  22 . The operating force signal, for example, increases with the operating force applied to the select lever  2 . The torque sensor  21  acts as an operating force sensor of the present invention.  
      The mode shift unit  300  shifts the operation modes of the automatic transmission  19  according to an operated position of the select lever  2 . Referring to  FIGS. 1 and 3  of the drawings, the mode shift unit  300  has a manual plate lever  20  and a detent mechanism  350  for keeping the manual plate lever  20  in a position selected by the select lever  2 .  
      The manual plate lever  20  is integrally fixed in its intermediate portion with a rotary shaft  26 , and connected at its one end portion with the second control cable  18  so as to be rotated on the shaft  26  with respect to a transmission case of the transmission  19  according to a select operation of the select lever  2 . The rotary shaft  26  is fixed to a detent plate  27  of the detent mechanism  350 .  
      The detent mechanism  350  includes the detent plate  27  with a cam  270 , a detent pin  29  to be pressed onto the cam  270 , and a spring plate  28  acting its spring force on the detent pin  29 .  
      The detent plate  27  is mechanically connected with a valve spool  310  of a manual valve disposed in a control valve unit  400  of the automatic transmission  19  so as to move the spool  300  according to a select position. The detent plate  27  is formed on its upper portion with the cam  270  having top portions  27   a  and bottom portions  27   b . Each bottom portion  27   b  is arranged between the adjacent top portions  27   a  and corresponds with one of the five operation modes of the automatic transmission  19 .  
      The cam  270  is pressed by the detent pin  29  that is urged by the spring plate  28 . The spring plate  28  is mounted at its one end portion on the control valve unit  400  and supports the detent pin  29  at its other end portion. The spring plate  28  presses the detent pin  29  onto the cam  270  of the detent plate  27  so that the detent pin  29  is positioned in one of the bottom portions  27   b  to detain the valve spool  310  of the manual valve in the selected position.  
      The detent plate  27  is coupled at its cam side portion with a parking rod  30  having a wedge  30   a  that can press a parking pawl  31 . The wedge  30   a  is movable along the rod  30  and presses the parking pawl  31  by spring force of a coil spring  30   b  so that the pawl  31  engages with a parking wheel  32  united to an output shaft of the automatic transmission  19  when the select lever  2  is shifted to the P position. This engagement of the pawl  31  and the wheel  32  results in locking drive wheels, not shown, for parking a motor vehicle.  
      The mode shift unit  300  is mechanically connected with the select lever  2  through the first and second control cables  8  and  18 , and others. As shown in  FIGS. 1 and 2 , the first control cable  8  connects at its one end portion with a bottom portion of the select lever  2  through a first joint  7  and at the other end portion with one end portion of an input lever  10  through a second joint  11 . The other end portion of the input lever  10  is connected with a top portion of a coupling shaft  12 , whose bottom portion is connected with one end portion of an output lever  13 . The other end portion of the output lever  13  is connected with one end portion of the second control cable  18  through a third joint  17 . The other end portion of the second control cable  18  is, as shown in  FIGS. 1 and 3 , connected with the manual plate lever  20 .  
      The first and second control cables  8  and  18 , the first to third joints  7 ,  11 , and  17 , the input and output plates  10  and  13 , and the coupling shaft  12  act as a mechanically connecting means of the present invention.  
      The control unit  22  is electrically connected to a power supply PS, ground GND, the operating angle sensor  200 , and the torque sensor  21 . The control unit  22  receives the operating angle signal from the operating angle sensor  200  and the operating force signal from the torque sensor  21  so as to compute target assist current based on these signals, and drives the electric motor  15  under pulse width modulation (PWM) control based on the target assist current.  
       FIG. 4  shows a control block diagram of the control unit  22  and its related units. When the select lever  2  is shifted by a driver, the select lever  2  moves and changes its operating angle, and operating force applied to the lever  2  by the driver is transmitted to the mode sift unit  300  through the first and second control cables  8  and  18 , and the coupling shaft  12 .  
      The first control cable  8  rotates the coupling shaft  12 , so that the terminal  24  on the worm wheel  14  united with the shaft  12  moves with respect to the carbon resistance  25  to change a relative angle between them. This relative angle, corresponding to an operating angle of the select lever  2 , is detected by the operating angle sensor  200 , which outputs an operating angle signal to the control unit  22 .  
      Operating force applied to the select lever  2  is transmitted through the first control cable  8  to the coupling shaft  12  and twists it, so that torsion occurs between the upper and lower portions of the shaft  12 . This torsion, corresponding to operating force applied to the select lever  2 , is detected by the torque sensor  21 , which outputs an operating force signal to the control unit  22 .  
      The control unit  22  includes an improper-halt judging part  33 , a target reaction-force compensating part  34 , a basic target reaction-force setting part  35 , a target reaction-force computing part  36 , an assist-force computing part  37 , and a motor drive control part  38 .  
      The improper-halt judging part  33  is electrically connected to the operating angle sensor  200  and judges an improper-halt (IH) of the select lever  2  based on an operating angle signal from the operating angle sensor  200  to output an improper-halt signal. The judgment part  33  judges the lever  2  to be in an improper-halt position when an operating position, corresponding to an operating angle, deviates from a select position P, R, N, D, or L and the lever  2  is kept halted for more than a predetermined period. This predetermined period is set to be a few seconds for example.  
      The target reaction-force compensating part  34  includes an improper-halt position computing part  341 , a target select-position computing part  342 , and a reaction compensation-amount computing part  343 .  
      The improper-halt position computing part  341  is electrically connected to the improper-halt judging part  33  and the operating angle sensor  200  to receive the improper-halt signal and the operating angle signal, respectively. The position computing part  341  computes an improperly halted operating position PIH obtained at time when an improper-halt is judged by the improper-halt judging part  33 , and outputs an improperly halted operating position signal.  
      The target select-position computing part  342  receives the improperly halted operating position signal from the improper-halt position computing part  341  and determines a target select-position P T  to output a target select-position signal. The target select-position is set based on the improperly halted operating position P IH  by using a target select-position table shown in  FIG. 8 , which will be described in detail later.  
      The reaction compensation-amount computing part  343  receives the target select-position signal from the target select-position computing part  342  and the operating angle signal from the operating angle sensor  200  and computes a reaction compensation-amount ΔR for reducing a difference between the target select-position and the operating position to output a reaction compensation-amount signal.  
      The basic target reaction-force setting part  35  is electrically connected to the operating angle sensor  200  and sets a basic target reaction-force F tb , by using a basic target reaction-force table having data on a characteristic of ideal reaction force as shown in  FIG. 7 , to output a basic target reaction-force signal.  
      The target reaction-force computing part  36  receives the basic target reaction-force signal from the basic target reaction-force setting part  35  and the reaction compensation-amount signal from the reaction compensation-amount computing part  343  and adds them to each other to obtain a target reaction-force F t , then outputting a target reaction-force signal.  
      The assist force computing part  37  receives an operating force signal from the torque sensor  21  and the target reaction-force signal from the target reaction-force computing part  36  and computes an assist force F A  based on an operating force F and the target reaction-force F t , then outputting an assist force signal. An assist force (F A ) value iFa is computed by the following equation, for example. 
 
 iFa=kp ( rFs−tFs )+ ki ∫( rFs−tFs ) dt  
 
 where tFs is a target reaction-force (F t ) value, rFs is an operating force (F) value, kp is a proportional gain, and Ki is an integral gain. 
 
      The motor drive control part  38  receives the assist force signal from the assist force part  37  and outputs motor drive current determined based on the assist force signal to the motor  15  so that the motor  15  generates assist force under Power Width Modulation (PWM) control. Accordingly, the motor  15  applies motor torque to the coupling shaft  12  to assist the operating force. In stead of the PMW control, the motor  15  may be driven under other controls, such as current control or armature voltage control.  
      In the select device  100 , when the operating position select unit  100  fails electrically because of a broken electric wire for example, the operating force of the select lever  2  is directly transmitted from the lever  2  to the mode shift unit  300  mechanically through the first and second control cables  8  and  18 , the input and output levers  10  and  13  and the others. Accordingly, the mode shift unit  300  is driven to shift the modes of the automatic transmission  19 , although its operating force becomes larger than that in a normal state.  
       FIG. 5  shows a flowchart of an assist process executed in the control unit  22  in order to control the assist actuator  9  when the select lever  2  is operated by a driver.  
      At step S 1 , the assist force computing part  37  receives an operating force signal from the torque sensor  21  to read operating force F, and then the flow goes to step S 2 .  
      At the step S 2 , the improper-halt judging part  33 , the target reaction-force compensating part  34 , and the basic target reaction-force setting part  35  receives an operating angle signal from the operating angle sensor  200  to read an operating angle A OP . Then, the flow goes to step  3 .  
      At the step S 3 , the basic target reaction-force setting part  35  sets basic target reaction-force F tb  based on the operating angle A OP  and outputs a basic target reaction-force signal to the target reaction-force computing part  36 . Then, the flow goes to step S 4 .  
      At the step S 4 , the improper-halt judging part  33  receives the operating angle signal and judges whether or not the select lever  2  is improperly halted based on the operating position P O  and time T M  counted by a not-shown timer, which will be described in detail later. It outputs an improper-halt signal when it judges an improper-halt. Then, the flow goes to step S 5 .  
      At the step S 5 , the target reaction-force compensating part  34  receives the improper-halt signal from the improper-halt judgment part  33  and the operating angle signal from the operating angle sensor  200  and sets a reaction compensation-amount ΔR, outputting a reaction compensation-amount signal. Then, the flow goes to step S 6 .  
      At the step S 6 , the target reaction-force computing part  36  receives the basic target reaction-force signal from the basic target reaction-force setting part  35  and the reaction compensation-amount signal from the reaction compensation-amount computing part  343  and sets a target reaction-force F t , outputting a target reaction-force signal. Then, the flow goes to step S 7 .  
      At the step S 7 , the assist force computing part  37  receives an operating force signal from the torque sensor  21  and the target reaction force signal from the target reaction-force computing part  36  and sets an assist force F A , outputting an assist force signal. Then, the flow goes to step S 8 .  
      At the step S 8 , the motor drive control part  37  outputs motor drive electric current, determined based on the assist force signal, to the motor  15 , thereby the motor  15  applying assist force to the select lever  2 , and then the flow ends.  
       FIG. 6  is a basic target reaction-force table used by the basic target reaction-force setting part  35  and shows characteristic relationships of operating reaction force Fm acting on the select lever  2 , and a cam profile of the detent mechanism  350  with respect to the operating angle A OP , respectively, during the select operation from the P position to the R position.  
      The operating reaction force Fm is calculated by using operating select torque detected by the torque sensor  21  in a case where the motor  15  is not driven in the select operation from the Position to the R position. The reaction force Fm is generated by resultant force from the sum of friction force caused by the first and second cables  8  and  18 , inertia force of the motor  15 , spring force of the detent mechanism  350 , and others.  
      The reaction force Fm increases in a direction opposite to the operating direction of the lever  2  as a function of the operating angle A OP  and reaches its peak Fma before the detent pin  29  reaches the top portion  27   a  of the cam  270  formed on the detent plate  27  as shown in  FIG. 6 , and then decreases with increasing the angle A OP  in this pullback zone.  
      Specifically, in the pull-back zone, the reaction force Fm acts on the select lever  2  against the operating force inputted by the driver until the neutral position, because the detent plate  27  is biased by the spring force of the spring plate  28  in a direction opposite to the operating direction. The larger the deformation amount of the spring plate  28  becomes in the pull-back zone, the further the select lever  2  moves in the operating direction. Note that the operating force in the opposite direction is affected by not only the deformation amount of the spring plate  28 , but also the cam profile. The above-described decrease of the resistance force Fm results from a slight slope of the cam  270 .  
      In the pull-back zone, the operating force inputted from the select lever  2  needs to overcome the reaction force Fm generated by the spring force of the spring plate  28  and the cam profile, in order to move the select lever  2  in the operating direction.  
      In a neutral position where the detent pin  29  is on the peak of the cam  270 , the reaction force Fm acting on the select lever  2  becomes zero due to its cam profile, although the spring plate  28  is deformed to the maximum degree.  
      After the detent pin  29  passes over the peak, the spring plate  28  starts to reduce its deformation amount until the pin  29  reaches the bottom of the cam  270  corresponding to the R position.  
      In this pull-in zone, the detent plate  27  is pressed by the spring plate  28  in the operating direction, so that the lever  2  is assisted to move forward by the reaction force Fm. Accordingly, the select lever  2  is propelled by the reaction force Fm, increasing at first and then decreasing, in such a way that the lever  2  is pulled into the bottom portion  27   b  corresponding to the R position.  
      Therefore, the operating force to be applied from the select lever  2  needs to be larger than and overcome the reaction force Fm shown in  FIG. 6  in order to manually move the select lever  2  for an select operation without assist force of the motor  15 .  
       FIG. 7  is a schematic diagram showing a relationship between basic target reaction-force Ftb and an operating angle A OP  when the select lever  2  is shifted from the P position to the R position. This basic target-reaction force Ftb is idealistic reaction force and set as shown in  FIG. 7  so as to bring a favorable operationality to a driver by providing nice click-feeling during the select operation.  
      When the select lever  2  is moved from the P position to the R position for example, the basic target reaction-force Ftb is set to have a pull-back zone where the basic target resistance-force Ftb acts against the operating direction of the lever  2 , indicated by a line over a horizontal axis of the operating angle in  FIG. 7 , a neutral poison on the horizontal axis, and a pull-in zone where the basic target resistance-force Ftb acts in the operating direction, indicated by the line under the horizontal axis. In the pull-back zone and pull-in zone, the basic target reaction-force Ftb increases at first and then decreases, although their acting directions are different from each other.  
      In the operating position select device  100  of the first embodiment, the assist control is executed so that assist force added from the motor  15  and operating force inputted by a driver overcome the resistance force Fm shown in  FIG. 6  and the driver receives the basic target resistance-force Ftb shown in  FIG. 7 .  
      The assist force is generated under proportional plus integral (PI) feedback control by using the equation of iFa=kp(rFs−tFs)+ki∫(rFs−tFs)dt.  
      This control brings the favorable operationality to the driver. When the driver shifts the select lever  2  from a select position to another select position, there is a possibility that he or she thinks the select lever  2  is completely shifted to a desired select position and stops its select operation, although the lever  2  is actually positioned at an improper position, such as an intermediate position between select positions.  
      In order to resolve the above improper-halt of the lever  2 , a flowchart, shown in  FIG. 9 , of an improper-halt preventing control is executed by the control unit  22  in this embodiment.  
      At step S 11 , corresponding to the steps  1  and  2  of  FIG. 5 , the control unit  22  receives the operating angle signal from the operating angle sensor  200  and the operating force signal from the torque sensor  21   d  to read the operating position P O  (corresponding to an operating angle A OP ) and the operating force F, and then the flow goes to step S 12 .  
      At the step S 12 , the improper-halt judging part  33  detects whether or not a flag FLG-IH of an improper halt is OFF (its value being zero for example). If YES, the flow goes to step S 13 , while, if NO, it goes to step S 17 .  
      At the step S 13 , the judgment part  33  judges whether or not a current operating position P O1  of the lever  2  is equal to a last operating position P O2  and deviates from a select position P TA  (P, R, N, D, or L). If YES, the flow goes to step S 14 , while, if NO, it goes to step S 21 .  
      At the step S 14 , the timer is incremented so that its count time T M  becomes zero, and then the flow goes to step S 15 .  
      At the step S 15 , the judging part  33  judges whether or not the count time T M  of the timer exceeds a predetermined time T 0 . The predetermined time T 0  is set to be, for example, a few seconds in this embodiment. If YES the flow goes to step S 16 , while, if NO, it goes to step S 21 .  
      At the step S 16 , the timer is cleared and the flag FLG-IH is set ON (its value being one for example), and then the flow goes to step S 17 .  
      At the step S 17 , the judgment part  33  judges whether or not the last flag FLG-IH is OFF and the current flag FLG-IH is ON. If YES, the flow goes to step S 18 , while, if NO, it goes to step S 24 .  
      At the step S 18 , the an improper-halt position computing part  341  sets the operating position P O  to be an improperly halted operating position P IH , and then the flow goes to step S 19 .  
      At the step S 19 , the target select-position computing part  342  sets a target select-position P T  based on the improperly halted operating position P IH , with referring to the target select-position table shown in  FIG. 8 , and then the flow goes to step S 20 .  
      At the step S 20 , the reaction compensation-amount computing part  343  computes a reaction compensation-amount ΔR based on the operating position P O  and the target select-position P T , and then the flow goes to step S 21 .  
      At the step S 21 , the basic target reaction-force setting part  35  sets a basic target reaction-force F tb  based on the operating position P O  and the target select position P T , and then the flow goes to step S 22 .  
      At the step S 22 , the target reaction-force computing part  36  computes a target reaction-force F t  by adding the basic target-reaction force F tb  and the reaction compensation-amount ΔR to each other, and then the flow goes to step S 23 .  
      At the step S 23 , the assist-force computing part  37  computes assist force F A  based on the target reaction-force Ft and the operating force F. The motor drive control part  38  receives the assist force signal and outputs motor drive current to drive the motor  15 , and the flow ends.  
      On the other hand, at the step S 24 , the improper-halt judging part  33  judges whether or not the operating position P O  reaches the target select-position P T . If YES, the flow goes to step S 25 , while, if NO, it goes to the step S 19 .  
      At the step S 25 , the judgment part  33  sets the flag FLG-IH to be zero and clears the target reaction force compensation amount ΔF to zero.  
      As understood from the above flowchart, when the select lever  2  is positioned at an improper position, such as an intermediate position between select positions (adjacent two of P, R, N, D, and L) due to a lever-shift halfway operation, the improper-halt judging part  33  judges the improper-halt when the lever  2  is kept halted at the improper position for more than the predetermined period. The improper-halt position computing part  341  holds its improperly halted operating position P IH  at time when the improper halt is judged by the improper-halt judging part  33 .  
      Then, the target select-position computing part  342  refers to the target select-position table shown in  FIG. 8  based on the improperly halted operating position PIH, and determines a target select-position P T .  
       FIG. 8  shows the target select-position table, which has data on relationship between a target select-position P T  and an improperly halted operating position P IH . In the table, a data value is set larger as the select position shifts from the position P to the position L. A target select-position is determined, for example in this embodiment, such that it is set to be a select position near to the select mode position P of the adjacent select mode positions between which the lever  2  is halted when the improperly halted operating position P IH  is less than a half angle between adjacent select mode positions, while it is set to be a select position near to the position L thereof when the position P IH  is equal to or more than the half angle.  
      After the target select-position is determined, the reaction compensation-amount computing part  343  computes a reaction compensation-amount R so that a difference between the target select position and the operation position P O  is reduced to zero. This reaction compensation-amount (ΔR) value tFs_h is computed by the equation of tFs_h=kp2(rPm−tPm)+ki2∫(rPm−tPm)dt, where rPm is an improperly halted operating position (P IH ) value, tPm is a target select position (P T ) value, kp2 is a proportional gain and kj2 is an integral gain.  
      Then, the target reaction-force computing part  36  adds a basic target reaction force F tb  obtained from the basic target reaction-force setting part  35  and the compensation-amount ΔR obtained from the target reaction-force computing part  36  to each other so as to obtain a target reaction-force F t .  
      The target assist-force computing part  37  computes an assist force FA based on an inputted operating force F and the target reaction force P T .  
       FIG. 10  shows an example of improper-halt preventing control executed when the lever  2  is halted improperly between the select positions P and R during a select operation from the position P to the position R.  
      As shown in  FIG. 10 , when the select lever  2  starts to shift from the position P to the position R by a driver&#39;s operation as shown in the upper part of  FIG. 10 , the target reaction-force F t , indicated a heavy full in the lower part of  FIG. 10 , increases and then decreases when the lever  2  is moved by operating force F of a driver and assist force of the assist actuator  9 , where the operating force F, indicated by a dashed line, also increases and then decreases similarly to the target reaction-force F t , but with larger values than the target reaction-force F t .  
      However, in this case, the driver stops shifting the lever  2  for the predetermined period before reaching the position R as shown in the upper part of  FIG. 10 , causing the improper-halt judging part  33  to judge an improper-halt of the lever  2 . The improper-halt operating position computing part  341  holds an improperly halted operating position P IH . Then, the target select-position computing part  342  determines that a target operation position P T  is set to be the position R, because the operating position P IH  exceeds a half angle between the positions P and R.  
      Note that the target reaction-force Ft is reduced in order to prevent this improper-halt in this embodiment. Specifically, the basic target reaction force setting part  35  sets a basic target reaction-force F tb , and the target reaction force-computing part  36  computes a target reaction-force F t  as shown in the lower part of  FIG. 10 , and thereby the assist actuator  9  applies its assist force to the lever  2  so as to move it surely to the position R, as shown in the lower part of  FIG. 10 , although the driver does not apply operating force to the lever  2 . This assist control gives the driver a feeling that the lever  2  is moved to the position R due to its inertia.  
      This operating position select device  100  of the first embodiment has many advantages described below.  
      The select lever  2  can be shorter than a conventional one by approximately 150 mm at its portion projecting from a center console toward a passenger compartment without increasing an operating force applied to the select lever  2  so much. This brings a design freedom concerning an installation location of the select lever and/or a layout of a passenger compartment to be broadened.  
      When operating the select lever  2 , assist torque from the electric motor  15  is applied to the coupling shaft  12  of the mechanically connecting mechanism so as to reduce the operating force applied to the select lever  2 . When the operating position select unit  100  fails electrically, a driver can shift the mode shift unit  300  by operating the select lever  2  because the select lever  2  and the mode shift unit  300  are mechanically connected by the mechanically connecting mechanism, such as the first and second control cables  8  and  18  and the others.  
      When a driver stops shifting the lever  2  at an improper position for the predetermined period, the assist actuator  9  can move it to a select mode position so as to prevent it from being positioned at the improper position between select mode positions.  
      The target select-position computing part  342  determines a target select-position based on the improperly halted operating position P IH  and the assist actuator  9  applies its assist force to the lever  2 , which can ensure the lever  2  to move in a select direction where there is a select position most like the driver&#39;s desired select position.  
      When the select lever  2  is halted improperly, it is moved by the actuator  9  based on an assist force signal determined based on operating force F and a target reaction-force F t , where the target reaction-force F t  is computed based on a basic target reaction-force F tb  and a reaction compensation-amount ΔR obtained by a target select position P T  and an operating position PO (corresponding to an operating angle A OP ) of the lever  2 , which enables the lever  2  to approach the driver&#39;s desired select position.  
      Next, an operating position select device of a second embodiment according to the present invention will be described with reference to the accompanying drawings of FIGS.  11  to  14 .  
      This operating position select device is constructed similarly to that of the first embodiment shown in FIGS.  1  to  4  except a control unit  22 . The control unit  22  of the second embodiment lacks the basic target reaction-force setting part  35 , the target reaction-force computing part  36 , and the target reaction-force compensating part  34  of the first embodiment, while it has an input operating-force compensating part  41 , a target reaction-force setting part  42 , and a second operating-force computing part  43 .  
      The input operating force-compensating part  41  includes an improper-position computing part  411 , a target select-position computing part  412 , and an operating-force compensation-amount computing part  413 .  
      The improper-halt position computing part  411  is electrically connected to an improper-halt judging part  33  and an operating angle sensor  200  to receive an improper-halt signal and an operating angle signal, respectively. The position computing part  411  computes an improperly halted operating position P IH  obtained when an improper-halt of a select lever is judged by the improper-halt judging part  33 , and outputs an improperly halted operating position signal.  
      The target select position computing part  412  receives the improperly halted operating position signal from the improper-halt position computing part  441  and determines a target select-position P T  by using a target select-position table shown in  FIG. 8  to output a target select-position signal.  
      The operating-force compensation-amount computing part  413  receives the target select position signal from the target select position computing part  412  and the operating angle signal from the operating angle sensor  200  and computes an operating-force compensation-amount ΔF for reducing a difference between the target select position and the operating position, corresponding to an operating angle obtained by the operating angle sensor  200 , to output an operating-force compensation-amount signal. The operating-force compensation-amount (ΔF) value rFs_h is calculated by an equation of rFs_h=kp3(tPm−rPm)+Ki3∫(tPm−rPm)dt, where rPm is an improper-halt position (P IH ) value, tPm is a target select position (P T ) value, kp3 is a proportional gain, and Ki3 is an integral gain.  
      The target reaction-force setting part  42  is electrically connected to the operating angle sensor  200  to receive an operating angle signal and set a target reaction-force F t , outputting a target reaction-force signal. The target reaction-force setting part  42  of the second embodiment corresponds to the basic target reaction-force setting part  35  of the first embodiment, and uses a target reaction-force table similar to the basic target reaction-force table of  FIG. 7 . Note that in the second embodiment the target reaction-force is not compensated such as that of the first embodiment.  
      The second operating-force computing part  43  is electrically connected to a torque sensor  21  and the operating-force compensation-amount computing part  413  to receive an operating force signal and the operating-force compensation-amount signal, respectively, and compute second inputted operating-force, outputting a second operating-force signal to an assist force computing part  44 .  
      The assist force computing part  44  is electrically connected to the target reaction-force setting part  42  and the second operating-force computing part  43  to receive the target reaction-force signal and the second operating-force signal, respectively, and compute assist force, outputting an assist force signal to a motor drive control part  38 .  
      The other parts of the operating position select device of the second embodiment are similar to those of the first embodiment.  
       FIG. 12  is a flowchart of the assist control executed by the control unit  22  in order to control the assist actuator  9  when the select lever is operated by a driver.  
      At step S 31 , the assist force part  37  receives an operating force signal from the torque sensor  21  to read operating force F, and then the flow goes to step S 32 .  
      At the step S 32 , the improper-halt judging part  33 , the target operating-force compensating part  41 , and the target operating-force setting part  42  receives an operating angle signal from the operating angle sensor  200  to read an operating angle A OP . Then, the flow goes to step  33 .  
      At the step S 33 , the target reaction-force setting part  42  sets a target reaction-force F t  based on the operating angle A OP  and outputs a target reaction-force signal to the assist-force computing part  44 . Then, the flow goes to step S 34 .  
      At the step S 34 , the improper-halt judging part  33  receives the operating angle signal and judges an improper-halt of the select lever based on the operating angle and time counted by a not-shown timer, similarly to the first embodiment, to output an improper-halt signal when the judging part  33  detects the improper-halt. Then, the flow goes to step S 35 .  
      At the step S 35 , the input operating-force compensating part  41  receives the improper-halt signal from the improper-halt judgment part  33  and the operating angle signal from the operating angle sensor  200  and sets an operating-force compensation-amount ΔF, outputting an operating-force compensation-amount signal. Then, the flow goes to step S 36 .  
      At the step S 36 , the second operating-force computing part  43  receives operating force signal from the torque sensor  21  and the operating-force compensation-amount signal from the operating-force compensation-amount computing part  413  and sets a second operating-force F 2 , outputting a second operating-force signal. Then, the flow goes to step S 37 .  
      At the step S 37 , the assist force computing part  44  receives a target reaction-force signal from the target reaction-force setting part  42  and the second operating-force signal from the second operating-force computing part  413  and sets an assist force F A , outputting an assist force signal. Then, the flow goes to step S 38 .  
      At the step S 38 , the motor drive control part  37  outputs motor drive electric current, determined based on the assist force signal, to the motor  15 , thereby the motor  15  applying assist force to the select lever, and then the flow ends.  
       FIG. 13  is a flowchart of an improper halt preventing control executed in the control unit  22 .  
      At step S 41 , corresponding to the steps  31  and  32  of  FIG. 12 , the control unit  22  receives the operating angle signal from the operating angle sensor  200  and the operating force signal from the torque sensor  21  to read the operating position P O  (corresponding to an operating angle A OP ) and the operating force F, and then the flow goes to step S 42 .  
      At the step S 42 , the improper-halt judging part  33  detects whether or not an improper-halt flag FLG-IH is OFF (its value being zero for example). If YES, the flow goes to step S 43 , while, if NO, it goes to step S 47 .  
      At the step S 43 , the judgment part  33  judges whether or not a current operating position P O1  of the lever is equal to a last operating position P O2  and deviates from a select position P TA  (P, R, N, D, or L). If YES, the flow goes to step S 44 , while, if NO, it goes to step S 51 .  
      At the step S 44 , the timer is incremented so that its count time T M  becomes zero, and then the flow goes to step S 45 .  
      At the step S 45 , the judging part  33  judges whether or not the count time T M  of the timer exceeds a predetermined time T 0 . The predetermined time T 0  is set to be, for example, a few seconds in this embodiment. If YES the flow goes to step S 46 , while, if NO, it goes to step S 51 .  
      At the step S 46 , the timer is cleared and the flag FLG-IH is set ON (its value being one for example), and then the flow goes to step S 47 .  
      At the step S 47 , the judgment part  33  judges whether or not the last flag FLG-IH is OFF and the current flag FLG-IH is ON. If YES, the flow goes to step S 48 , while, if NO, it goes to step S 54 .  
      At the step S 48 , the an improper-halt position computing part  411  sets an operating position P O  to be an improperly halted operating position P IH , and then the flow goes to step S 49 .  
      At the step S 49 , the target select-position computing part  412  sets a target select-position P T , and then the flow goes to step S 50 . The target select position P T  is set based on the improperly halted operating position P IH  with referring to a target select-position table shown in  FIG. 8  similarly to the first embodiment.  
      At the step S 50 , the operating-force compensation-amount computing part  413  computes an operating-force compensation-amount ΔF based on the target select position P T  and the operating position P O , and then the flow goes to step S 51 .  
      At the step S 51 , the target reaction-force setting part  42  sets target reaction-force Ft based on the operating position P O  and then the flow goes to step S 52 .  
      At the step S 52 , the second operating-force setting part  43  sets a second operating-force F 2  based on the operating force F and the operating-force compensation-amount ΔF and outputs a second operating-force signal, and then the flow goes to step S 53 ,  
      At the step S 53 , the assist force computing part  44  computes assist force F A  based on the target reaction-force F t  and the second operating-force F 2  and outputs an assist force signal. The motor drive control part  38  receives the assist force signal and outputs motor drive current to drive the motor  15 , and the flow ends.  
      At the step S 54 , the improper-halt judging part  33  judges whether or not the operating position P O  reaches the target select position P T . If YES, the flow goes to step S 55 , while, if NO, it goes to the step S 49 .  
      At the step S 55 , the judgment part  33  sets the flag FLG-IH to be OFF and clears the target operating-force compensation-amount ΔF to zero.  
      In this second embodiment, when the improper-halt judging part  33  judges an improper-halt, the operating-force compensating part  413  computes an operating-force compensation-amount ΔF capable of reducing a difference between a target select position and an operating position of the select lever.  
      This compensation-amount ΔF is added to the operating force F by the second operating-force computing part  43 , and its additional value is outputted as second operating-force to the assist force computing part  44 . The computing part  44  computes assist force based on a difference between the second operating force F 2  and the target reaction force F t  and outputs an assist force signal to the motor drive control part  38 .  
       FIG. 14  shows an example of improper-halt preventing control executed when the lever is halted improperly between the positions P and R during a select operation from the position P to the position R.  
      As shown in  FIG. 14 , when the select lever starts to shift from the position P to the position R by a driver&#39;s operation as shown in the upper part of  FIG. 14 , the target reaction-force F t , indicated a light full in the lower part of  FIG. 14 , increases and then decreases when the lever is moved by operating force F of a driver and assist force of the assist actuator  9 , where the operating force F, indicated by a dashed line, also increases and then decreases similarly to the target reaction-force F t , but with larger values than the target reaction-force F t . When the lever moves, the operating force becomes equal to the second operating-force, because the operating-force compensation-amount AF is zero.  
      However, in this case, the driver stops shifting the lever for the predetermined period before reaching the position R as shown in the upper part of  FIG. 14 , causing the improper-halt judging part  33  to judge an improper-halt. The improper-halt operating position computing part  411  holds an improperly halted operating position P IH . Then, the target select-position computing part  412  determines that a target operation position P T  is set to be the position R, because the operating position P IH  exceeds a half angle between the positions P and R.  
      Note that the second operating-force F 2  is increased in order to prevent this improper-halt in this embodiment. Specifically, the operating-force compensation-amount computing part  413  computes an operating-force compensation-amount ΔF for adding it to the operating force F as shown in the lower part of  FIG. 14 . Accordingly, the assist actuator  9  applies its assist force to the lever so as to move it surely to the position R, although the driver does not apply operating force to the lever. This assist control gives the driver a feeling that the lever is moved to the position R due to its inertia.  
      The advantages of the operating position select device of the second embodiment will be described.  
      The select lever can be shorter than a conventional one by approximately 150 mm at its portion projecting from a center console toward a passenger compartment without increasing an operating force applied to the select lever so much. This brings a design freedom concerning an installation location of the select lever and/or a layout of a passenger compartment to be broadened.  
      When operating the select lever, assist torque from an electric motor  15  is applied to a mechanically connecting mechanism so as to reduce the operating force applied to the select lever. When the operating position select unit fails electrically, a driver can shift a mode shift unit  300  by operating the select lever because the select lever and the mode shift unit  300  are mechanically connected by the mechanically connecting mechanism, such as first and second control cables  8  and  18  and the others.  
      The target select-position computing part  412  determines a target select-position based on the improperly halted operating position P IH  and the assist actuator  9  applies its assist force to the lever, which can ensure the lever to move in a select direction where there is a select position most like the driver&#39;s desired select position.  
      When the select lever is halted improperly, it is moved by the actuator  9  based on an assist force signal determined based on a target reaction-force Ft and a second operating-force F 2 , where the second operating-force F 2  is computed based on operating force F and an operating-force compensation-amount ΔF obtained by a target select position P T  and an operating position P O  (corresponding to an operating angle A OP ) of the lever. Therefore, the select lever can be controlled to approach the driver&#39;s desired select position.  
      While there have been particularly shown and described with reference to preferred embodiments thereof, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.  
      For example, the operating force F may be detected based on an estimate from supply current to the motor  15  and its rotational speed in stead of using the torque sensor  21 .  
      The operating position can be detected by the displacement amount of the select lever  2  or the mechanically connecting mechanism  400  that connects the select lever  2  and the mode shift unit  300  with each other instead of the operating angle of the select lever  2 .  
      The mechanically connecting mechanism may be rods or linkage instead of the first and second control cables  8  and  18  in the above embodiments. The select lever may be of a shape different from the above embodiments.  
      The select lever  2  may have a configuration different from that of the first embodiment shown in  FIG. 1 , for example, a finger-controable one.  
      The configuration of the cam of the detent mechanism may be formed arbitrarily to have different target reaction force.  
      The entire contents of Japanese Patent Application (Tokugan) No. 2004-207726 filed Jul. 14, 2004 is incorporated herein by reference.