JP2016013217A - Automatic transport vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform accurate moving distance measurement regardless of a variation in a driving wheel diameter.SOLUTION: An automatic transport vehicle 10 includes two driving wheels 13 and 14 provided in different positions in a right and left direction of a vehicle body (a frame 11), and the steering is performed by a difference in rotational speeds of the two driving wheels 13 and 14. The automatic transport vehicle 10 includes moving distance measurement wheels 17 and 18 provided separately from the driving wheels 13 and 14, which are provided so that rotational shafts 17a and 18a can move relatively in a pressing direction with respect to a travelling surface in a state of being pressed on a travelling surface side by pressing means irrespective of an attitude variation of the vehicle body, and rotary encoders 24 and 25 for detecting the number of rotations of the moving distance measurement wheels 17 and 18. The automatic transport vehicle 10 includes calculation means (a control device 26) for calculating a moving distance of the vehicle body based on a detection signal of the rotary encoders 24 and 25.

Description

  The present invention relates to an automatic conveyance vehicle, and more particularly to an automatic conveyance vehicle suitable for a case where a person is carried and automatically travels on a preset route.

  2. Description of the Related Art Conventionally, an electric wheelchair that is capable of self-propelling using a differential caster is known as a moving means for elderly people and disabled persons (for example, see Patent Document 1). In the electric wheelchair, the passenger operates the operation lever provided on the armrest of the seat so that the differential caster is rotationally driven to be self-propelled. The differential caster includes a steering shaft supported rotatably about a vertical axis, and a pair of drive wheels provided at the lower end of the steering shaft and supported rotatably about a horizontal axis. Each drive wheel is driven independently by an electric motor built in the drive wheel.

  That is, the conventional electric wheelchair has a configuration in which a passenger changes the traveling direction by operating an operation lever. For example, when the electric wheelchair is turned right, the operation lever is tilted to the right. The control unit is configured so that the rotational speed of the electric motor of the differential caster on the left side of each differential caster becomes a predetermined rotational speed corresponding to the inclination angle of the operation lever, and the differential caster on the right side. The rotation speed and the rotation ratio are calculated so that the rotation speed of the electric motor of the caster is zero or smaller than the rotation speed of the electric motor of the left differential caster. Then, both electric motors are driven so as to achieve the rotational speed, and the electric wheelchair turns to the right due to the difference in the rotational speed between the left and right drive wheels.

JP 2012-74139 A

  In a conventional electric wheelchair, when the traveling direction is changed, a traveling direction change (curve traveling) operation is performed due to the difference in the rotational speeds of the left and right drive wheels, but the rider operates the operation lever to change the traveling direction. The passenger operates the operation lever while confirming the traveling state. Therefore, if the amount of operation of the control lever is different from the turning radius at the time of turning, there is no major problem because the passenger operates and corrects the operating lever. However, an operation for correction is required or meandering occurs. .

  On the other hand, in an automated guided vehicle that automatically travels along a preset route, the passenger is not involved in changing the traveling direction of the automated guided vehicle, and the automated guided vehicle follows a preset route from the departure point to the destination point. The drive wheels are controlled to move. And the control part of an automatic conveyance vehicle calculates a moving speed and a travel distance from the diameter and rotation speed of a driving wheel, and adjusts the rotation speed of the right and left driving wheels in a curve according to the curvature of the curve.

  If the diameter of the drive wheel is constant, there is no problem, but the travel distance per rotation of the wheel fluctuates due to changes in the structure of the drive wheel (solid, hollow), deflection due to material, or changes in wheel diameter due to wear, etc. Thus, accurate distance measurement cannot be performed. As a result, it is impossible to accurately move to the destination point.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an automatic transport vehicle capable of performing accurate movement distance measurement regardless of fluctuations in drive wheel diameter.

  An automatic transport vehicle that solves the above problem is an automatic transport vehicle that has at least two drive wheels provided at different positions in the left-right direction of the vehicle body and that is steered by the difference in rotational speed between the two drive wheels. Further, the travel distance measurement is provided separately from the drive wheel, and the rotation shaft is relatively movable in the pressing direction with respect to the traveling surface and is pressed by the pressing means on the traveling surface side regardless of the posture variation of the vehicle body. A wheel, a rotation speed detection means for detecting the rotation speed of the movement distance measurement wheel, and a calculation means for calculating the movement distance of the vehicle body based on a detection signal of the rotation speed detection means.

  According to this configuration, the moving distance of the vehicle body is calculated from the diameter and the rotational speed of the moving distance measuring wheel provided separately from the driving wheel. The movement measuring wheel is provided in a state in which the rotation shaft is relatively movable in the pressing direction with respect to the traveling surface and is pressed by the pressing means on the traveling surface side regardless of the posture variation of the vehicle body. The ratio of bearing is small, and wear due to pressing force is small. Moreover, since the movement measuring wheel always moves in contact with the traveling surface, the moving distance per rotation does not vary. Therefore, accurate travel distance measurement can be performed regardless of fluctuations in the drive wheel diameter.

  Two drive wheels are provided symmetrically in a state where the drive shaft is located on the same straight line extending in the left-right direction of the vehicle body. It is preferable to be provided on a vertical plane including the drive shaft. According to this configuration, when driving on a curve, the difference in the number of revolutions per unit time of both driving wheels is the same if the curvature of the curve is the same and the diameters of both driving wheels are the same regardless of whether the vehicle bends left or right. Since it becomes the same, control of a driving wheel becomes easy. Even if the amount of wear of the drive wheels is different, fine adjustment is sufficient.

  It is preferable that the moving distance measuring wheel is provided outside the both driving wheels. The distance between the moving distance measuring wheels when the both moving distance measuring wheels are provided outside the both driving wheels is larger than that when the both moving distance measuring wheels are provided inside the both driving wheels. For this reason, the difference in the number of rotations of the both travel distance measuring wheels becomes large during curve traveling with the same curvature, and control is easy.

  According to the present invention, accurate travel distance measurement can be performed regardless of fluctuations in the drive wheel diameter.

(A) is a schematic side view of an automatic conveyance vehicle, (b) is a side view which shows the support structure of a movement distance measurement wheel. The bottom view of an automatic conveyance vehicle. The block diagram which shows the structure of a control part. (A) is a schematic side view which shows the support state of the movement distance measurement wheel of another embodiment, (b) is the top view.

Hereinafter, an embodiment in which the present invention is embodied in an automated guided vehicle for transporting a passenger such as a patient in a hospital will be described with reference to FIGS.
As shown in FIG. 1A, the automatic guided vehicle 10 includes a frame 11 as a vehicle body and a seat 12 provided on the frame 11. As shown in FIG. 2, the frame 11 includes a beam member 11a extending in the left-right direction of the automatic guided vehicle 10, a beam member 11b extending in the front-rear direction, and a plate 11c provided on the beam member 11b.

  As shown in FIG. 2, the automated guided vehicle 10 has two drive wheels 13 and 14 on the rear side and two driven wheels 15 and 16 on the front side. Both drive wheels 13 and 14 are configured to be independently driven by electric motors M1 and M2, respectively. Both drive wheels 13 and 14 are provided symmetrically with the drive shafts 13a and 14a positioned on the same straight line extending in the left-right direction of the frame 11. Hollow tires are used for the drive wheels 13 and 14 in order to improve the ride comfort of the passenger P.

  In addition to the drive wheels 13 and 14, movement distance measurement wheels 17 and 18 are provided on the frame 11 symmetrically. The moving distance measuring wheel 17 is provided at a position outside the driving wheel 13, and the moving distance measuring wheel 18 is provided at a position outside the driving wheel 14. Since the travel distance measuring wheels 17 and 18 are irrelevant to the ride comfort of the passenger P, they are made of a material that is difficult to be deformed or worn, for example, urethane resin.

  The travel distance measuring wheels 17 and 18 are provided in a state in which the rotation shafts 17a and 18a are relatively movable in the pressing direction with respect to the traveling surface S and are pressed by the pressing means 19 on the traveling surface S side regardless of the posture variation of the frame 11. ing. More specifically, as shown in FIGS. 1B and 2, the frame 11 extends in the left-right direction (perpendicular to the paper surface in FIG. 1B), and is larger than the outer diameter of the drive wheels 13 and 14. Are provided with two beam members 11a. A support bracket 20 is fixed to the end portions of both beam members 11a by bolts 21, and a support member 22 is supported on the support bracket 20 so as to be movable in the vertical direction below the support bracket 20.

  As shown in FIG. 2, the support member 22 is provided at a larger interval than the thickness of the movement distance measuring wheels 17, 18 and supports the rotary shafts 17 a, 18 a to be rotatable, and both ends of the support plate 22 a. And a pair of sliding shafts 22b provided so as to be slidable through the support bracket 20 in the vertical direction. Each sliding shaft 22b is provided with a spring as the pressing means 19 between the support bracket 20 and the support plate 22a. A retaining member 23 for preventing the sliding shaft 22b from being detached from the support bracket 20 is fixed to the upper end of each sliding shaft 22b, that is, the projecting end from the support bracket 20.

  Rotary encoders 24 and 25 as rotation speed detecting means for detecting the rotation speed of the moving distance measuring wheels 17 and 18 are connected to the rotation shafts 17a and 18a, respectively. The rotary encoders 24 and 25 are fixed to the support plate 22a via a bracket (not shown).

  As shown in FIG. 2, electric motors M <b> 1 and M <b> 2 that drive the drive wheels 13 and 14 and a control device 26 that controls the electric motors M <b> 1 and M <b> 2 are provided on the frame 11. The control device 26 includes a CPU and a memory (not shown).

  As shown in FIG. 3, the control device 26 receives detection signals from the rotary encoders 24 and 25, and controls the electric motors M1 and M2 based on the detection signals. The control device 26 also functions as calculation means for calculating the movement distance of the vehicle body (frame 11). The control device 26 calculates the moving distance of the moving distance measuring wheels 17 and 18 based on the rotation speed of the rotary encoders 24 and 25 and the diameter of the moving distance measuring wheels 17 and 18. The average value of the movement distances of the movement distance measuring wheels 17 and 18 is set as the movement distance of the vehicle body, that is, the movement distance of the automatic transport vehicle 10 in both the straight traveling and the curved traveling (curve traveling). Further, the latest driving wheel diameter is calculated from the information on the moving distance of the automatic conveyance vehicle 10 and the rotational speed information of the driving wheels 13 and 14. The memory of the control device 26 stores the relationship between the difference in the amount of movement of the travel distance measuring wheels 17 and 18 per unit time and the rotation radius of the vehicle body. The electric motors M1 and M2 are controlled based on the latest driving wheel diameter so that the difference in the movement amount per unit time of the distance measuring wheels 17 and 18 becomes the difference in the movement amount corresponding to the target curve traveling.

Next, the operation of the automatic guided vehicle 10 configured as described above will be described.
The automated guided vehicle 10 moves along a predetermined route in the hospital. In the memory of the control device 26, the state of the moving path from the beginning to the end of the path, that is, the linear moving distance of the plurality of linear moving units, and the movement of each curved moving unit (curved traveling unit) sandwiched between the linear moving units. The distance and the radius of curvature are stored as route data.

  When the passenger P gets on the automated guided vehicle 10 and instructs the destination, the control device 26 stores the position of the passenger P on the departure point as the departure point and the movement route to the instructed destination in the memory. The travel route from the departure point to the destination is determined from the route data. Then, both electric motors M1, M2 are controlled so as to adjust the rotational speeds of the left and right drive wheels 13, 14 in accordance with the state of the movement path.

  Since hollow tires are used for the drive wheels 13 and 14, the amount of deflection of the drive wheels 13 and 14 varies depending on the weight difference and posture of the passenger P. Further, since the driving wheels 13 and 14 are easily worn, the wheel diameter changes depending on use. As a result, when the number of rotations of the drive wheels 13 and 14 is detected and the movement distance of the automatic transport vehicle 10 is measured based on a preset diameter, the movement distance per rotation of the drive wheels 13 and 14 is determined. It changes and the exact distance traveled cannot be measured.

  However, in this embodiment, the rotational speeds of the travel distance measuring wheels 17 and 18 are detected by the rotary encoders 24 and 25, and based on the rotational speed and the diameters of the travel distance measuring wheels 17 and 18 set in advance. Then, the moving distance of the automated guided vehicle 10 is measured. Unlike the driving wheels 13 and 14 and the driven wheels 15 and 16, the travel distance measuring wheels 17 and 18 do not have a function of supporting the weight of the automatic transport vehicle 10 or the passenger P, and depend on the weight of the automatic transport vehicle 10 or the passenger P. The amount of deflection does not change. In addition, since the travel distance measuring wheels 17 and 18 are irrelevant to the ride comfort of the passenger P and are formed of a material that is not easily deformed or worn, the diameter hardly changes, and the travel distance measuring wheels 17 and 18 rotate. The movement distance per rotation of the movement distance measurement wheels 17 and 18 measured based on the number and the diameter becomes accurate.

  For this reason, during linear movement, both electric motors M1, M2 are driven and controlled so that the rotational speeds of both movement distance measuring wheels 17, 18 are the same, and when moving a curve, both movement distance measuring wheels 17, The electric motors M1 and M2 may be driven and controlled so that the difference in the rotational speed of 18 corresponds to the rotational speed difference corresponding to the radius of curvature.

According to this embodiment, the following effects can be obtained.
(1) The automatic transport vehicle 10 has two drive wheels 13 and 14 provided at different positions in the left and right direction of the vehicle body (frame 11), and steering is performed by a difference in rotational speed between the drive wheels 13 and 14. It is an automated guided vehicle. And it is provided separately from the drive wheels 13 and 14, and the rotary shafts 17a and 18a are relatively movable in the pressing direction with respect to the traveling surface S and are pressed by the pressing means 19 on the traveling surface S side regardless of the posture variation of the vehicle body. And the rotational speed detection means (rotary encoders 24 and 25) for detecting the rotational speed of the travel distance measuring wheels 17 and 18. Moreover, the automatic conveyance vehicle 10 is provided with the calculating means (control apparatus 26) which calculates the moving distance of a vehicle body based on the detection signal of a rotation speed detection means. The travel distance measuring wheels 17 and 18 have a small proportion of the weight of the vehicle body and the passenger P, are less worn by the pressing force, and always move in contact with the traveling surface S. Therefore, the travel distance per rotation is small. Does not fluctuate. Therefore, accurate travel distance measurement can be performed regardless of fluctuations in the drive wheel diameter.

  (2) The drive wheels 13 and 14 are provided symmetrically with the drive shafts 13a and 14a positioned on the same straight line extending in the left-right direction of the vehicle body (frame 11). According to this configuration, when the vehicle travels on a curve, if the curve curvature is the same and the diameters of both drive wheels 13 and 14 are the same regardless of whether the vehicle bends in the left or right direction, both drive wheels 13 and 14 per unit time. Since the difference in the number of rotations is the same, the control of the drive wheels 13 and 14 is simplified. Even if the wear amounts of the drive wheels 13 and 14 are different, fine adjustment is sufficient. Further, even when an unspecified number of occupants with different physical conditions get on, meandering traveling due to an unbalanced load or the like can be suppressed, and a stable riding comfort can be realized.

  (3) The movement distance measuring wheels 17 and 18 are provided symmetrically on the outer sides of the drive wheels 13 and 14. The distance between the travel distance measurement wheels 17 and 18 when the travel distance measurement wheels 17 and 18 are provided outside the drive wheels 13 and 14 is the same as the travel distance measurement wheels 17 and 18. It becomes larger than the case where it is provided inside. For this reason, the difference in the rotational speeds of the both travel distance measuring wheels 17 and 18 becomes large during curve traveling with the same curvature, and control is easy. Further, even when the automated guided vehicle 10 travels along a route in which the curve continues, it can travel while drawing an accurate curve locus, so that the ride comfort is improved.

  (4) The movement distance measuring wheels 17 and 18 are supported by a support member 22 supported so as to be movable in the vertical direction with respect to the support bracket 20 fixed to the frame 11. The support member 22 is fixed to both ends of the support plate 22a that rotatably supports the rotary shafts 17a and 18a, and is slidable through the support bracket 20 in the vertical direction. A pair of sliding shafts 22b is provided. Each sliding shaft 22b is provided with a spring as the pressing means 19 between the support bracket 20 and the support plate 22a. According to this configuration, the rotation shafts 17 a and 18 a of the movement distance measuring wheels 17 and 18 can be pressed from the direction perpendicular to the traveling surface S.

The embodiment is not limited to the above, and may be embodied as follows, for example.
As a configuration in which the rotating shafts 17a and 18a can move the distance measuring wheels 17 and 18 in the pressing direction with respect to the traveling surface S and are pressed by the pressing means 19 toward the traveling surface S regardless of the posture variation of the vehicle body. It is good also as a structure shown to 4 (a) and (b). In this configuration, a substantially L-shaped bracket 30 on one side is rotatably supported on the frame 11 via a bearing 31 and a support shaft 32 on one end side, and the movement distance measuring wheel 17 is rotatably supported on the other end side. Has been. The bracket 30 is urged in a direction in which the travel distance measuring wheel 17 is pressed against the traveling surface S by a tension spring 33 as a pressing means provided between one end side and the frame 11. A rotary encoder 24 is connected to the rotating shaft 17 a of the moving distance measuring wheel 17. Although not shown, the movement distance measuring wheel 18 is also provided in the same manner.

  ○ Allowable diameters of the drive wheels 13 and 14 are set in advance in consideration of puncture, overload, or deflection due to uneven load, and the allowable diameters are stored in the memory. The allowable diameter is obtained through experiments. During traveling, the control device 26 determines from the moving distance of the automatic transport vehicle 10 calculated from the diameters of the moving distance measuring wheels 17 and 18 and the detection signals of the rotary encoders 24 and 25 and the rotational speeds of the driving wheels 13 and 14. The driving wheel diameter may be calculated, and an alarm may be issued when the driving wheel diameter exceeds the allowable diameter. The driving wheel diameter is calculated by the following formula: driving wheel diameter = movement distance / (π · rotational speed). As the number of revolutions, the number of revolutions of the electric motors M1, M2 commanded by the control device 26 is used.

  ○ When the driving wheel diameter calculated during traveling exceeds the allowable diameter, an alarm that can also guess the type of abnormality may be issued. For example, the drive wheel diameter corresponding to puncture, overload or unbalanced load is stored in the memory, and when the drive wheel diameter exceeds the allowable diameter, it is notified which abnormality is likely to correspond. Also good. In this case, if the alarm corresponds to puncture, it is confirmed whether or not the drive wheels 13 and 14 are punctured, and if punctured, the tire is replaced. If the alarm corresponds to an overload or an unbalanced load, the overload is eliminated or the unbalanced load is eliminated, that is, the user is seated at the correct position.

The both travel distance measurement wheels 17 and 18 are not limited to the configuration provided outside the both drive wheels 13 and 14 but may be provided inside the both drive wheels 13 and 14.
○ Both movement distance measurement wheels 17 and 18 are not limited to positions symmetrical with respect to the center of the frame 11, and either one of both movement distance measurement wheels 17 and 18 is provided outside the drive wheels 13 and 14. The other may be provided inside.

  The automatic transport vehicle 10 has at least two drive wheels 13 and 14 provided at different positions in the left and right direction of the vehicle body (frame 11), and steering is performed by the difference in rotational speed between the drive wheels 13 and 14. What is necessary is just an automatic conveyance vehicle. For example, the drive wheels 13 and 14 may not be positioned on a straight line extending in the left-right direction of the frame 11 but may be provided in a state shifted in the front-rear direction.

  The rotational speed detection means for detecting the rotational speed of the travel distance measuring wheels 17 and 18 is not limited to the rotary encoders 24 and 25. For example, a plurality of permanent magnets may be attached to the rotating shafts 17a and 18a, and a magnetic sensor such as a Hall element that detects the permanent magnets may be provided to face the moving path of the permanent magnets. In this case, the number of rotations of the travel distance measuring wheels 17 and 18 is detected from the number of pulses of a pulse signal per unit time output from the magnetic sensor as a permanent magnet detection signal.

  ○ As for the movement method of the automatic guided vehicle 10, the control device 26 determines the movement route from the starting position to the target position based on the route data stored in the memory, and the state of the movement route, that is, whether the movement route is a straight line. It is not limited to the method of controlling the electric motors M1 and M2 by determining whether the curve is a curve. For example, a display unit or an instruction unit that indicates the state of the movement route is provided near the boundary between the straight line portion and the curved portion of the movement route of the automatic guided vehicle 10, and the control device 26 determines whether the display unit displays or indicates the instruction unit. The electric motors M1 and M2 may be controlled by determining whether the vehicle travels in a straight line or a curve. The display unit displays a display indicating whether the tip is a straight line part or a curved part and a curvature part in the case of a curved part. For example, an IC tag is used as the instruction unit, and the IC tag stores data indicating whether the tip portion is a straight line portion or a curved portion, and in the case of a curved portion, a curvature is stored.

  ○ It is not essential for the automated guided vehicle 10 to have two travel distance measuring wheels 17 and 18, and even if there is only one travel distance measuring wheel, accurate travel distance measurement is possible regardless of fluctuations in the diameter of the drive wheel. It can be carried out. For example, two drive wheels 13 and 14 are provided symmetrically in a state in which the drive wheels 13 and 14 are positioned on the same straight line extending in the left and right direction of the vehicle body (frame 11), and the travel distance measurement wheel includes the drive shafts 13a and 14a. A configuration in which one piece is provided at a position equidistant from both drive wheels 13 and 14 in a state of being present on the vertical plane may be employed. In this case, it is possible to accurately measure the movement distance of the automatic transport vehicle 10 from the rotation speed detected by the rotation speed detection means and the diameter of the movement distance measurement wheel.

(Circle) the press means 19 is not restricted to a spring, For example, rubber | gum may be sufficient.
O The traveling route of the automatic guided vehicle 10 is not limited to indoors but may be outdoor.
The following technical idea (invention) can be understood from the embodiment.

  (1) The automated guided vehicle according to any one of claims 1 to 3 includes a memory that stores an allowable diameter of the drive wheel, and includes a moving distance of the vehicle body calculated by the calculation means, and a drive. A driving wheel diameter during traveling is calculated from the number of rotations of the wheel, and an alarm is issued when the calculated driving wheel diameter exceeds the allowable diameter.

  (2) In the invention described in the technical idea (1), based on the value of the driving wheel diameter exceeding the allowable diameter, the type of abnormality of the driving wheel is determined, and the type of abnormality is dealt with. Raise different alarms.

  DESCRIPTION OF SYMBOLS S ... Running surface, 10 ... Automatic conveyance vehicle, 11 ... Frame as vehicle body, 13, 14 ... Drive wheel, 13a, 14a ... Drive shaft, 17, 18 ... Moving distance measuring wheel, 17a, 18a ... Rotating shaft, 19 ... Press means, 26... Control device that also functions as calculation means, 33... Tension spring as press means.

Claims (3)

An automatic transport vehicle having at least two drive wheels provided at different positions in the left-right direction of the vehicle body, and being steered by a difference in rotational speed between both drive wheels
A travel distance measuring wheel provided separately from the drive wheel and provided so that the rotation shaft is relatively movable in the pressing direction with respect to the traveling surface and is pressed against the traveling surface by the pressing means regardless of the posture variation of the vehicle body; ,
Rotational speed detection means for detecting the rotational speed of the moving distance measuring wheel;
An automatic conveyance vehicle comprising: a calculation means for calculating a moving distance of the vehicle body based on a detection signal of the rotation speed detection means.   Two drive wheels are provided symmetrically in a state where the drive shaft is located on the same straight line extending in the left-right direction of the vehicle body. The automated guided vehicle according to claim 1, wherein the automatic transport vehicle is provided so as to exist on a vertical plane including the drive shaft.   The automatic guided vehicle according to claim 2, wherein the moving distance measuring wheel is provided outside the driving wheels.