JP2008157184A - Start control device for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate operation of an acceleration pedal in starting or crawling on a manual transmission vehicle, and to restrict response delay or the like when high-torque starting operation (relatively quick clutch releasing operation) is carried out by a driver. <P>SOLUTION: The start control device for an automobile is provided with a target rotational speed correction unit. As a driver's demand for starting or drawing according to an operation state to a manual transmission and a clutch is detected, a target rotational speed based on the stroke position of the clutch, and a target rotational speed based on the stroke speed of the clutch are respectively determined. In a prescribed control subject zone set between a clutch disconnected state and a clutch imperfectly connected state, when it is detected that the stroke speed of the clutch reaches a prescribed speed range, the target rotational speed correction unit uses the larger one of the target rotational speed corrected based on the stroke position and the target rotational speed corrected based on the stroke speed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle start control device, in particular, in a range from a clutch disengaged state to a predetermined control end stroke point by detecting a driver's start or slow speed travel request by the operation state of a manual transmission and a clutch. The present invention relates to a vehicle start control device having a function of controlling an engine speed to a target speed larger than an idling speed.

In Patent Document 1, when the vehicle speed is below a certain level, the throttle opening is below a certain level, the starting speed or the slow speed driving condition such as shifting to a predetermined gear and brake not being operated is satisfied, the engine speed is idled according to the clutch position. An automobile start and slow speed running control device having a function of controlling to a target rotational speed higher than the number is disclosed. According to this slow speed control device, when the start or slow speed conditions are satisfied, the engine speed is increased according to the clutch position, the vehicle speed, and the throttle opening (particularly when the low vehicle speed and the clutch position are at the intermediate position). It is said that the delicate operation of the accelerator pedal at the time of starting or slow running is not required.
JP 2001-263138 A

  However, the above-described conventional technique has a problem in that it cannot correct the engine speed that correctly reflects the driver's intention to operate because the clutch operating speed is not taken into consideration. For example, even if the clutch pedal operation amount is the same, if a fast clutch pedal operation is performed, engine speed correction may not be in time for a sudden increase in clutch transmission torque, and engine stalls may occur. If the engine speed is set high to cope with this, the engine speed becomes unnecessarily high when a slow pedal operation is performed.

  The present invention has been made in view of the above-described circumstances, and the object of the present invention is to make it possible to omit the operation of the accelerator pedal at the time of starting or traveling at a low speed, and correctly reflects the driver's intention to start. An object of the present invention is to provide a vehicle start control device capable of performing engine speed control.

  According to the first aspect of the present invention, the clutch is disengaged from the clutch disengaged state to the half-clutch state and the clutch engaged state by stroking the transmission amount of the driving force from the engine to the tire. A clutch that adjusts by transitioning to a stroke, a stroke detection unit that detects the stroke of the clutch, an engine control unit that controls the engine speed to a target speed, and detected by the stroke detection unit when the vehicle starts. The stroke speed is calculated based on the stroke of the clutch, and the target rotational speed is idled based on the stroke speed of the clutch in a predetermined control target section set from the clutch disengaged state to the half-clutch state. Having a target rotational speed correction unit that increases more than the number of Vehicle start control device is provided to symptoms.

  According to a second aspect of the present invention, in the above-described vehicle start control device, the target rotational speed correction unit obtains the target rotational speed from the idling rotational speed, and the target based on the stroke position of the clutch. There is provided an automobile start control device characterized in that a target rotational speed based on a rotational speed and a stroke speed of the clutch is calculated and the larger target rotational speed is adopted.

  According to the present invention, it is possible to reduce the burden on the driver at the time of starting or traveling at a low speed, in particular, the burden on a delicate accelerator operation for obtaining a start with less shock.

  Next, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a vehicle system including an automobile start control device according to a first embodiment of the present invention.

  Referring to FIG. 1, an engine 101 controlled by an electronically controlled throttle valve 102 that adjusts an engine intake flow rate, and a clutch unit (clutch) 105 that is stroked to be connected / disconnected by a clutch pedal 107 via a hydraulic circuit 115 A manual transmission 106 is shown. The clutch unit 105 is disposed between the engine 101 and the tire 116, and the torque output as the driving force of the automobile from the engine according to the driver's intention to start (manipulation) is manually transmitted via the clutch unit 105. This is transmitted to the tire 116 via the transmission 106, and as a result, the vehicle can be started. The operation of the clutch unit 105 will be described in detail. The clutch unit 105 moves forward and backward by operating a flywheel and a clutch cover fixed to the output shaft of the engine 101, a clutch disk splined to the manual transmission 106, and a clutch pedal 107. Consists of release bearings. The clutch cover includes a diaphragm spring and a pressure plate that is pressed by the diaphragm spring. The pressure plate is pressed by a diaphragm spring whose posture has been changed by the advancement and retraction of the release bearing, and the clutch disk is frictionally held between the pressure plate and the flywheel to transmit the torque of the engine 101 to the input shaft of the manual transmission 106. . Further, the pressure plate moves in conjunction with the operation of the clutch pedal 107 via the hydraulic circuit 115. When the clutch pedal 107 is depressed to the back of the vehicle floor, the pressure plate is separated from the flywheel to bring the clutch unit 105 into the clutch disengaged state. When the clutch pedal 107 is not depressed, the pressure plate removes the clutch disc. When the clutch unit 105 is engaged and the clutch pedal 105 is depressed to a middle position by friction between the flywheel and the clutch, and the clutch plate 107 is depressed to the middle, the pressure plate causes friction while causing the clutch disk to slip between the flywheel and the flywheel. The clamping clutch unit 105 is set to a half-clutch state. That is, the clutch unit 105 adjusts torque, which is a driving force transmitted from the clutch disengaged state to the half-clutch state and the clutch engaged state, as the clutch pedal 107 depressed by the driver is released. The clutch unit 105 actually strokes the pressure plate, but the stroke position of the pressure plate is called the clutch stroke position, and the stroke speed of the pressure plate is called the clutch stroke speed.

  Further, in this vehicle system, the ISC valve 104 for keeping the idle speed at an optimum value, the clutch pedal position sensor 108 for detecting the clutch pedal position, the shift position sensor 109 for detecting the gear shift position, and the accelerator opening degree are detected. An accelerator opening sensor 110, a vehicle speed sensor 111 for detecting the vehicle speed, an engine rotation sensor 112 for detecting the engine speed, and a brake sensor 113 for detecting the state of the brake are provided. Then, the output from the clutch pedal position sensor 108 is substituted as the stroke position and stroke speed values of the clutch unit 105 in accordance with the operation position and operation speed of the clutch pedal 107. The method using the clutch pedal position sensor is that the existing clutch pedal position sensor 108 can be used (no additional sensor for detecting the stroke position of the pressure plate or the like is required), and even if there is a need for additional, This is advantageous in that it can be arranged not near the clutch unit with a small space margin but near the clutch pedal with a relatively large space.

  The engine control unit 103 is configured to include a control circuit (target rotational speed correction unit) 114, and controls the throttle valve 102 based on the detection signals input from the above-described sensors, thereby setting the engine rotational speed to the target rotational speed. Control and adjust to drive.

  Basically, an intended vehicle behavior can be realized by the driver shifting the manual transmission 106 to an arbitrary gear and operating the clutch pedal 107 and the accelerator, but the control circuit of the engine control unit 103 (Target rotational speed correction unit) 114 starts engine rotational speed control, which will be described later, when a start or slow speed traveling condition described later is satisfied.

  FIG. 2 is a flowchart showing an example of an engine speed control routine by the control circuit (target speed correction unit) 114. Referring to FIG. 2, first, the control circuit (target rotational speed correction unit) 114 sequentially checks the following items (1) to (5).

(1) Whether the shift position is a predetermined gear (eg, 1st or Rev) (step S201)
(2) Whether or not the accelerator pedal opening is within a predetermined (small) range (step S202)
(3) Whether the vehicle speed is within a predetermined (low speed) range (step S203)
(4) Whether the brake is not operating (step S204)
(5) The actual throttle opening is equal to or less than the target throttle opening (step S205).

  When all of the above items (1) to (5) are satisfied, the control circuit (target rotational speed correction unit) 114 determines that the driver has requested start or slow speed travel, and the step The engine speed control starting from S206 is started. The determination item (5) is provided for switching from the following engine speed control to engine control according to the operation amount of normal accelerator pedal operation when an accelerator pedal operation of a predetermined amount or more is performed. It is. As a condition for starting the engine speed control in step S206 and subsequent steps, not only the clutch pedal position but also the time after the clutch pedal is operated may be set as the control start condition.

[Engine speed control]
First, the control circuit (target speed correction unit) 114 calculates the clutch pedal position Cp0 at which the input speed of the manual transmission 106 starts to increase. When the clutch pedal position Cp0 at which the input rotation speed starts increasing has already been obtained, it is not necessary to calculate the clutch pedal position Cp0 every time, and this step can be omitted as appropriate.

  Subsequently, the control circuit (target speed correction unit) 114 calculates the clutch stroke speed based on the output of the clutch pedal position sensor, and sets the target engine speed NEv based on the clutch stroke speed (clutch pedal operating speed). A target engine speed NEp based on the clutch stroke position (clutch pedal position) is calculated (steps S207 and S208).

  The target engine speed NEv based on the former clutch stroke speed (clutch pedal operating speed) is calculated with reference to a target engine speed NEv calculation map (see FIG. 3) prepared in advance, for example. According to FIG. 3, when the clutch is not moving (clutch pedal operating speed Pv = 0), the target engine speed NEv is equivalent to the idling speed, and the clutch stroke speed (clutch pedal operating speed) Pv becomes high. Accordingly, the map is such that the target engine speed NEv increases.

  Further, a target engine speed NEv calculation map as shown in FIG. 4 may be used instead of the target engine speed NEv calculation map of FIG. According to FIG. 4, the map is such that the target engine speed NEv increases stepwise as the clutch stroke speed (clutch pedal operating speed) Pv exceeds a certain threshold value. In addition to the target engine speed NEv calculation map of FIGS. 3 and 4, additional correction based on the accelerator opening and the vehicle speed can be added.

  Similarly, the target engine speed NEp based on the stroke position (clutch pedal position) of the latter clutch is calculated with reference to a target engine speed NEp calculation map (see FIG. 5) prepared in advance. According to FIG. 5, when the clutch is disengaged, the target engine speed NEp becomes a predetermined number of speeds higher than the idling speed, and as the clutch stroke position (clutch pedal position) Pp moves to the engagement side, The map is such that the engine speed NE increases (however, the upper limit threshold NEp_MAX is the upper limit). As for the target engine speed NEp based on the clutch stroke position (clutch pedal position), as shown in Patent Document 1, in addition to the target engine speed NEv calculation map of FIG. It is also possible to add corrections.

  Subsequently, in the control circuit (target rotational speed correction unit) 114, the clutch stroke speed (clutch pedal operation speed) calculated from the detection signal from the clutch pedal position sensor 108 is within a predetermined speed range (TH_LOW to TH_HIGH). It is confirmed whether or not (step S209).

  The lower limit (TH_LOW) and upper limit (TH_HIGH) of the predetermined speed range determine whether or not to adopt the engine speed NEv based on the clutch stroke speed (clutch pedal operating speed), and a very slow clutch operation is performed. When it is being performed or when a very fast clutch operation is being performed, the target engine speed NEv based on the stroke speed (clutch pedal operating speed) of the clutch is not adopted (No in step S209). In this case, the target engine speed NEp based on the clutch stroke position (clutch pedal position) is adopted as the target engine speed.

  Subsequently, the control circuit (target rotational speed correction unit) 114 determines that the current clutch stroke position (clutch pedal position) position Cp indicated by the detection signal from the clutch pedal position sensor 108 is the control start point (Cp0-α). ) To determine whether the clutch is on the clutch engagement side (step S210). In this embodiment, the starting point of the engine speed control target range is set to the clutch disengagement side by a predetermined amount α from the clutch stroke position (clutch pedal position) Cp0 at which the input speed starts to increase.

  The clutch stroke speed (clutch pedal operating speed) is within a predetermined range (TH_LOW to TH_HIGH) (Yes in step S209), and the current clutch stroke position (clutch pedal position) Cp is the control start point (Cp0). -Α) When the clutch is on the clutch engagement side (Yes in step S210), the control circuit (target rotational speed correction unit) 114 is configured such that the target engine rotational speed NEv based on the clutch stroke speed (clutch pedal operating speed) The target engine speed NEp based on the clutch stroke position (clutch pedal position) is compared (step S211).

  If the target engine speed NEv based on the clutch stroke speed (clutch pedal operating speed) is larger as a result of the comparison in step S211, the target engine speed is set based on the clutch stroke speed (clutch pedal operating speed). The engine speed NEv is set (step S212).

  On the other hand, if the target engine speed NEp based on the clutch stroke position (clutch pedal position) is equal to or lower than the target engine speed NEv based on the clutch stroke speed (clutch pedal operating speed), the target engine speed NEv The target engine speed NEp based on the stroke position (clutch pedal position) is set (step S213).

  The above engine speed control is continued until the actual engine speed NE matches the input speed (step S214).

  FIG. 6 is a diagram for explaining the vehicle behavior realized by the present invention when the driver makes a quick clutch engagement operation with the intention of starting at a relatively high torque. 302 in FIG. 6 represents an engine speed control start point (Cp0-α).

  When the driver operates the clutch pedal quickly, engine rotation control based on the clutch stroke speed (clutch pedal operation speed) is not performed between the clutch disengagement position 301 and the engine speed control start point 302, and the target engine The target engine speed NEp calculated mainly based on the clutch stroke position (clutch pedal position) is adopted as the speed NE (see “target engine speed (pedal position)” in the upper dashed-dotted line in FIG. 6). .

  When the clutch stroke position (clutch pedal position) passes the engine speed control start point 302, the target engine speed NEp calculated based on the clutch stroke position (clutch pedal position) and the clutch stroke speed (clutch pedal) Control based on a comparison of the target engine speed NEv calculated based on the operating speed is started. In the example of FIG. 6, NEv> NEp is established between the engine speed control start point 302 and the intermediate position 303 because the clutch stroke speed (clutch pedal operation speed) is fast, and the target engine speed NE is set. The target engine speed NEv calculated based mainly on the stroke speed of the clutch (clutch pedal operating speed) is adopted (see “target engine speed (pedal operating speed)” in the upper broken line in FIG. 6). For this reason, the actual engine speed is increased so as to follow the target engine speed NEv (see “actual engine speed (with control)” in the upper thick solid line in FIG. 6).

  Thereafter, when the clutch stroke position (clutch pedal position) passes the intermediate position 303, the clutch stroke position (clutch pedal position) shifts to the engagement side, the relationship between NEv and NEp is reversed, and NEv ≦ NEp is satisfied. When established, the target engine speed NEp calculated mainly based on the stroke position (clutch pedal position) of the clutch is employed as the target engine speed NE.

  As described above, according to the present invention, when a fast clutch pedal operation is performed, a higher target engine speed can be increased from an early stage. It can be avoided.

  Further, in the present embodiment, the engine speed can be increased by a necessary amount when necessary, so that the advantage that the engine target speed by the clutch stroke position (clutch pedal position) can be set low is also achieved. ing.

  FIG. 7 is a diagram for explaining the vehicle behavior realized by the present invention when the driver performs a slow clutch engagement operation with the intention of starting at a relatively low torque. When the driver operates the clutch pedal slower than a certain value (lower limit TH_LOW of the speed region), engine rotation control based on the clutch stroke speed (clutch pedal operation speed) is not performed, and the clutch stroke position ( The target engine speed NEp calculated based on the clutch pedal position) is employed (see “target engine speed (pedal position)” in the upper dashed line in FIG. 7).

  In the present embodiment, as described above, the target engine speed NEp calculated based on the stroke position (clutch pedal position) of the clutch is adopted when the moving speed of the clutch pedal is outside the predetermined speed range. Unnecessary increase in engine speed is also avoided.

  Subsequently, a second embodiment of the present invention in which the calculation of the target engine speed NEp based on the clutch stroke position (clutch pedal position) in the first embodiment of the present invention is omitted will be described. Since the present embodiment can be realized with the same configuration as the first embodiment described above, the following description will focus on the differences.

  FIG. 8 is a flowchart showing an example of a routine for engine speed control by the control circuit (target speed correction unit) 114 according to the second embodiment of the present invention. Steps S301 to S306 in FIG. 8 are the same as steps S201 to S206 in FIG.

  In step S307, the control circuit (target speed correction unit) 114 calculates a target engine speed NEv based on the stroke speed of the clutch (clutch pedal operation speed) (step S307).

  The target engine speed NEv based on the clutch stroke speed (clutch pedal operating speed) is calculated using, for example, a target engine speed NEv calculation map shown in FIG. 9 or FIG. The difference from the target engine speed NEv calculation map shown in FIG. 3 and FIG. 4 is that an upper limit threshold NEv_MAX that determines the upper limit of the target engine speed NEv is determined, and that the clutch operating speed Pv is the upper limit value. When (TH_HIGH) is exceeded, the engine speed is set so as not to increase when the speed is high.

  Subsequently, the control circuit (target rotational speed correction unit) 114 determines that the current clutch stroke position Cp indicated by the detection signal from the clutch pedal position sensor 108 is the clutch stroke position Cp0 at which the input rotational speed starts increasing. Whether or not the clutch is on the clutch engagement side is confirmed (step S308). Here, when the current clutch stroke position Cp is closer to the clutch engagement side than Cp0, control for maintaining the current engine speed NE is started (step S309).

  When the current clutch stroke position Cp is on the clutch disengagement side from Cp0, the control circuit (target speed correction unit) 114 sets the target engine speed NEv based on the clutch stroke speed (clutch pedal operating speed) to the target engine. The rotation speed is determined (step S310).

  The above engine speed control is continued until the actual engine speed NE matches the input speed (step S311).

  As described above, it is possible to realize a smooth running even at the target engine speed NEv based only on the stroke speed of the clutch (clutch pedal operating speed).

  Subsequently, a third embodiment of the present invention in which a function for correcting the engine speed according to the road surface gradient is added to the first and second embodiments of the present invention will be described. Since the present embodiment can be realized with the same configuration as the first embodiment described above, the following description will focus on the differences.

  In the present embodiment, the engine control unit 103 is further connected to road surface gradient detecting means. The road surface gradient can be obtained from information from a vehicle height sensor provided between each wheel and the vehicle body, which is used for optical axis correction of the head ride.

  The basic operation is the same as that of each of the above-described embodiments, but the target engine speed NEv based on the clutch stroke speed (clutch pedal operation speed) in step S207 in FIG. 2 (step S307 in FIG. 8) or in FIG. In the step of calculating the target engine speed NEp based on the clutch stroke position (clutch pedal position) in step S208, each map is corrected based on the detected road surface gradient.

  FIG. 11 shows a target engine speed NEv line (solid line) before correction and a target engine speed NEv line (broken line) after correction, and FIG. 12 shows a target engine speed NEp line before correction. It is a figure showing (target line) NEp line (dashed line) after correction (solid line) and amendment.

  The lower broken line in FIG. 11 (FIG. 12) represents an example of the target engine speed NEv (NEp) line when the road surface gradient is a negative value (downhill road). It is possible to suppress the correction amount based on the speed (clutch stroke position) and suppress the engine speed.

  On the other hand, the upper broken line in FIG. 11 (FIG. 12) represents the target engine speed NEv (NEp) line when the road surface gradient is a positive value (climbing road), and on the uphill, the stroke speed of the clutch It is possible to increase the amount of correction by (clutch stroke position) and more reliably avoid engine stop.

  Although the third embodiment of the present invention has been described above, various modifications such as changing the correction amount of the target engine speed NEv (NEp) line and the correction method (translation, inclination increase / decrease) according to the magnitude of the road surface gradient. It is possible to make changes.

  Next, a description will be given of a fourth embodiment of the present invention in which an engine stall occurrence suppression function is added to the first to third embodiments of the present invention. Since the present embodiment can be realized with the same configuration as the first embodiment described above, the following description will focus on the differences.

  In the present embodiment, the engine control unit 103 is further provided with an engine history storage means such as a flag for storing the presence or absence of engine stall at the time of the previous start, and when the engine stall occurs, the engine history record is written into the engine engine history storage means. Done.

  The basic operation is the same as that of each of the embodiments described above, but the target engine speed NEv based on the clutch stroke speed in step S207 in FIG. 2 (step S307 in FIG. 8) and the clutch stroke in step S208 in FIG. In the step of calculating the target engine speed NEp based on the position, each map is corrected based on the written engine history.

  For example, if an engine stall has occurred at the time of the previous start, the target engine speed NEv (NEp) line is corrected as indicated by the upper broken line in FIG. 11 (FIG. 12). Thereby, it is possible to more reliably avoid a situation in which engine stall occurs repeatedly due to insufficient correction of the engine speed.

  Although the embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the description of the embodiments described above, and various modifications may be made according to the specifications of the vehicle to be applied. Can be added.

  For example, in the first embodiment described above, the target engine speed NEv based on the stroke speed of the clutch and the target engine speed NEp based on the stroke position of the clutch are calculated, and the larger one is adopted. As described above, the same effect can be achieved by increasing the target engine speed NEp based on the clutch stroke position with a correction factor (correction width) corresponding to the clutch stroke speed.

  In the above-described embodiment, the clutch pedal position sensor 108 is used to detect the clutch stroke position and the clutch stroke speed. However, the position of the pressure plate is determined by a position sensor provided in the clutch unit or the like. It is also possible to adopt a configuration that detects and detects the stroke position of the clutch and the stroke speed of the clutch.

It is a figure showing the composition of the vehicle system containing the starting control device of the car concerning a 1st embodiment of the present invention. It is a flowchart showing an example of a routine of engine speed control by the control circuit (target speed correction unit) according to the first embodiment of the present invention. It is an example of the target engine speed NEv calculation map used in the first embodiment of the present invention. It is another example of the target engine speed NEv calculation map used in the first embodiment of the present invention. It is an example of the target engine speed NEp calculation map used for calculation of the target engine speed NEp based on the clutch position by the control circuit (target speed correction unit) according to the first embodiment of the present invention. It is a figure for demonstrating the vehicle behavior implement | achieved by this invention when a driver | operator intends the start with a comparatively high torque and performs quick clutch engagement operation. It is a figure for demonstrating the vehicle behavior implement | achieved by this invention when a driver | operator performs slow clutch engagement operation aiming at starting by comparatively low torque. It is a flowchart showing an example of a routine of engine speed control by a control circuit (target speed correction unit) according to a second embodiment of the present invention. It is an example of the target engine speed NEv calculation map used in the second embodiment of the present invention. It is another example of the target engine speed NEv calculation map used in the 2nd Embodiment of this invention. It is a figure for explaining the 3rd and 4th embodiment of the present invention. It is a figure for explaining the 3rd and 4th embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Engine 102 Throttle valve 103 Engine control unit 104 ISC valve 105 Clutch unit 106 Manual transmission 107 Clutch pedal 108 Clutch pedal position sensor 109 Shift position sensor 110 Accelerator opening sensor 111 Vehicle speed sensor 112 Engine rotation sensor 113 Brake sensor 114 Control circuit ( Target rotation speed correction unit)
115 Hydraulic circuit 116 Tire

Claims (4)

A clutch that is arranged between the engine and the tire and adjusts by shifting the clutch disengaged state from the clutch disengaged state to the half-clutch state and the clutch engaged state by stroking the transmission amount of the driving force from the engine to the tire;
A stroke detection unit for detecting a stroke of the clutch;
An engine control unit for controlling the engine speed to a target speed;
When the vehicle starts, the stroke speed is calculated based on the stroke of the clutch detected by the stroke detection unit, and the clutch stroke is determined in a predetermined control target section set from the clutch disengaged state to the half-clutch state. Comprising a target rotational speed correction unit for increasing the target rotational speed from the idling rotational speed based on speed;
A vehicle start control device.   The vehicle start control device according to claim 1, wherein the predetermined control target section is defined by a stroke position or a stroke time of the clutch. The target rotational speed correction unit calculates a target rotational speed based on the clutch stroke position and a target rotational speed based on the clutch stroke speed, respectively.
Adopting the larger target rotational speed among the target rotational speed calculated based on the stroke position of the clutch and the target rotational speed calculated based on the stroke speed of the clutch;
The start control device for an automobile according to claim 1 or 2.   4. The vehicle start control device according to claim 1, wherein the clutch stroke is substituted by an output from a stroke sensor of a clutch pedal operated by a driver.

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