JP3196279B2 - Driving control method for unmanned vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling control method for an unmanned vehicle traveling along a guide rail. Note that an unmanned vehicle means a vehicle that can automatically perform travel control.

[0002]

2. Description of the Related Art As an unmanned vehicle traveling along a guide rail, there is, for example, a type disclosed in Japanese Patent Application No. 2-25864.

FIG. 1 is a conceptual top view of an unmanned vehicle of this type. This unmanned vehicle travels along a guide rail 1 laid in a factory, warehouse, or the like. A pair of wheels 3 and 4 are provided at the center of the truck 2 of the unmanned vehicle, and free wheels 5 and 6 made of casters are provided at the front and rear of the truck 2 respectively.

Drive motors 7 and 8 are independently connected to the wheels 3 and 4, respectively.
A control circuit 9 is connected to 8. Further, a rail detection sensor 10 is connected to the control circuit 9, and the rail detection sensor 10 is attached to the front end 2 a of the carriage 2 so as to detect the guide rail 1.

[0005] An unmanned vehicle has a guide rail 1 having a straight section and a curved section.
When traveling on the upper side, the rail detection sensor 10 detects the guide rail 1 of the linear portion and the curved portion, and the rail detection sensor 1
The travel of the unmanned vehicle is controlled based on the detection data of 0.

An unmanned vehicle having such a structure has two wheels 3, 4
By making the peripheral speeds equal, the unmanned vehicle can bend in the direction of the wheel with a lower peripheral speed by making the peripheral speeds of both wheels different.

According to the prior art, such an unmanned vehicle is controlled, for example, as follows.

FIG. 2 is an elevational view of the unmanned vehicle and the guide rail 1 viewed from the traveling direction of the unmanned vehicle. In this figure, the free wheels 5, 6
Has been omitted.

The rail detection sensor 10 detects the distance D between the center 1a of the guide rail 1 and the center 2a of the wheels 3 and 4, and sends the data to the control circuit 9.

[0010] The control circuit 9 and the distance D, a distance between the centers 2W of both wheels 3 and 4, on the basis of the maximum velocity V _m of the velocity V, and the unmanned vehicle in the center of the unmanned vehicle, the rotation of both wheels 3 and 4 The speed is the peripheral speed V of the wheel with the larger deviation from the rail 1
_o and the peripheral speed V _i of the wheel with the smaller deviation from rail 1
Is controlled as follows. _{V o = V + AD ............... (} 1) V i = V-AD ............... (2) However, when the V + AD> V _{m is, V o = V m ............... (} 3) V i = V _m -2AD (4) Here, V _m is the maximum speed of the unmanned vehicle, and A is a proportional coefficient determined by friction between the wheel and the floor surface.

FIG. 3 shows the peripheral velocities V _o and V _i of the wheels 3 and 4,
5 is a graph showing AD as a variable. (1),
As can be seen from equations (2), (3), and (4), V _o >V> V
_Since it is _i , as shown in FIG. 4, it bends in the direction of the wheel whose deviation from the rail 1 is small.

When there is no slip between the floor and the wheels, the curvature of the locus of the unmanned vehicle is obtained as follows.

Assuming that the center of curvature of the locus of the center of the wheel is O, the radius of curvature is R, and the turning angle is θ, the following relationship is established.
Here, W is half the length of the axle spacing. (R + W) θ = V _o (9) (R−W) θ = V _i (10)

Eliminating the rotation angle θ yields the following relationship: _{R = W (V o + V} i) / (V o -V i) ............... (11)

The curvature κ = (dφ / ds), which is a quantity indicating the change dφ in the traveling direction per unit length ds measured along the center locus of the unmanned vehicle, is obtained as the reciprocal of R. κ = (1 / R) = (V o -V i) / W (V o + V i) ............... (12)

Therefore, the curvature radius R and the curvature κ at V + AD <V _m are (1), (2), (11), and (12).
It is obtained from the formula as follows. R = (WV) / (AD) (13) κ = (AD) / (WV) (14)

Similarly, the radius of curvature R when V + AD> V _m
And the curvature κ are obtained from the equations (3), (4), (11) and (12) as follows. R = W (V _m −AD) / (AD) (15) κ = (AD) / (W (V _m −AD)) (16)

FIG. 5 is a graph showing the curvature κ obtained based on the equations (14) and (16) using AD as a variable.

The straight line I (V) is a graph corresponding to the equation (14), and the curve II is a graph corresponding to the equation (16).
Curve II is a reciprocal function passing through the origin and diverging at AD = V _m , and a straight line I (V) is a straight line passing through the origin and changing its slope in proportion to the reciprocal of the velocity V. κ is AD <V _m −
When V, it is given by a straight line I (V), and when AD> V _m -V, it is given by a curve II. Intersection P of straight line I (V) and curve II
(V) moves depending on V. When V is large, it approaches the origin, for example, point Pa, and when V is small, it moves away from the origin, for example, point Pb.

As can be seen from FIG. 5, κ rapidly increases when AD becomes larger than V _m -V. That is, the traveling direction changes rapidly.

[0021]

FIG. 6 shows an unmanned vehicle in which the guide rail enters the curves C1 and C2 from the straight line L0 by linear motion when the straight portion L0 is connected to circular curves C1 and C2 having different radii. Gap d from the center guide rail
1 and d2 are schematically shown.

As can be seen from FIG. 6, the distances d1 and d2 change depending on the radii of the curves C1 and C2. Unmanned vehicle direction based on the distance d1, d2 is controlled, the distance d1, d2 as can be seen from FIG. 5 is a traveling direction becomes greater than V _m -V changes abruptly.

As a result, the unmanned vehicle may derail on a curve with a small radius, and the correction of the traveling direction may be delayed on a curve with a large radius, so that a hunting phenomenon in which the unmanned vehicle vibrates around the guide rail occurs. Sometimes.

FIG. 7 shows the case where the speed of an unmanned vehicle entering the curved portion C by the linear motion from the straight line L1 is different when the guide rail comprises the first straight portion L1, the curved portion C, and the second straight portion L2. The trajectories a1 and a2 of the unmanned vehicle and the trajectory a3 of the unmanned vehicle entering the second straight line portion L2 from the curved portion C are schematically shown.

As can be seen from FIG. 5, even when the distance D between the center of the unmanned vehicle and the guide rail is equal, when the speed V is large, the inclination of the straight line I (V) is small, so that even if the distance D is large. The correction of the direction tends to be delayed, and the unmanned vehicle moves along the locus a1 in FIG.
May derail like. On the other hand, when the speed V is small, the direction correction is large even if the interval D is small. Therefore, as shown by the locus a2 in FIG. 7, the unmanned vehicle may cause a hunting phenomenon that vibrates around the guide rail.

Further, when the unmanned vehicle that has made a circular motion along the curved portion C enters the second straight portion L2, the distance D between the center of the unmanned vehicle and the guide rail changes suddenly. a
As shown in FIG. 3, the unmanned vehicle tends to cause a hunting phenomenon in the second straight portion L2.

Further, when shifting from the straight line I (V) of FIG. 5 to the curve II, the traveling direction may change abruptly.

Therefore, when the conventional method of controlling an unmanned vehicle is used, strict conditions are imposed on the shape of the guide rail, the traveling speed of the unmanned vehicle, and the like, in order to drive the vehicle stably.

An object of the present invention is to propose a traveling control method capable of avoiding such a problem.

[0030]

The object of the present invention is to provide first and second wheels provided on both sides of a vehicle body, interval detecting means for detecting a gap between the center of both wheels and a guide rail, and interval detecting means. Rotation speed determining means for determining the rotation speeds of the first and second wheels based on the output of the first and second wheels, and first and second wheels respectively driving the first and second wheels at the rotation speeds determined by the rotation speed determination means.
And a driving control method for an unmanned vehicle having the second drive means, wherein the speed at the center of both wheels is V, and the maximum peripheral speed of both wheels is V
_m, D the spacing between the induction rail and the center of the both wheels, the floor conditions and the proportionality coefficient A depends on the load or the like, the circumferential speed V _o of the wheel deviation is large from the induction rail in both wheels the peripheral speed of the wheel deviation is small from the induction rail when the V _i, which is solved by the travel control method of an unmanned vehicle, characterized in that said control means V _o and V _i set based on the following formula . _{V o = V + (V m} -V) VAD / V m 2 V i = V- (V m + V) VAD / V m 2.

[0031]

In the traveling control method according to the present invention, the peripheral velocities of the outer wheel and the inner wheel are controlled so as to satisfy equations (17) and (18). _{V o = V + (V m} -V) VAD / V m 2 ......... (17) V i = V- (V m + V) VAD / V m 2 ......... (18)

Equations (17) and (18) are modified as follows, where the correction amounts of the second term are α and β. _{V o = V + α ......... (} 17a) V i = V-β ......... (18a) α = (1-V / V m) (V / V m) AD ......... (19) β = (1 + V / V _m ) (V / V _m ) AD (20)

FIG. 8 is a graph showing α and β with V / V _m as a variable when AD is constant.

As can be seen from FIG. 8, α and β are 2 of V / V _m
It becomes a quadratic function curve. As the correction amount alpha, beta is a quadratic function of the velocity V / V _m, so gradually changes, problems with rapid change of the correction amount in the related art does not occur.

When V / V _m = 1, α = 0 (21) β = 2AD (22), and the speed of the wheel whose deviation from the guide rail is large, that is, the speed of the outer ring far from the center of curvature, is as follows. Is zero. Therefore, the change in direction is only due to the deceleration of the inner wheel.

By substituting the equations (17) and (18) into the equation (12), if the slip with respect to the floor is ignored, the curvature κ of the locus of the unmanned vehicle can be obtained as follows. κ = V _m DA / W (V _m ² −AD) (23) where W is の of the center-to-center distance 2W between both wheels.

FIG. 9 shows that (V /
V _m ) as a parameter and (AD / V _m ) as a variable, W
6 is a graph showing the curvature κ when = 1.

As can be seen from FIG. 9, the curvature κ changes smoothly with respect to both V and D. Conversely, as V increases, the curvature κ increases. This means that the higher the speed, the greater the direction correction when away from the guide rail. In general, when the speed is high, the vehicle tends to derail immediately if the traveling direction is not correct. However, in the present invention, the direction is corrected more quickly as the speed is higher, so that the derailment can be reduced.

[0039]

FIG. 10 is a block diagram of an apparatus for implementing a traveling control method according to the present invention.

An image of the guide rail G provided on the floor F is formed using a lens L, and this image is formed by a light receiving element in which a plurality of photoelectric elements are arranged in a lateral direction with respect to the guide rail G. Is detected using a rail detection sensor S composed of

In the interval detecting means DD, the gap D between the center of the left and right wheels W1 and W2 of the unmanned vehicle and the guide rail G is determined based on the difference between the output of the rail detection sensor S and a preset reference value. Desired.

The output of the interval detecting means DD is sent to the rotational speed determining means RD.

The rotation speed determining means RD is input with constants such as the maximum peripheral speed V _m of both wheels and a proportional constant A in advance. When the floor is slippery, A is set larger than when the floor is not slippery, and when the load is large, A is set larger.

The speed of the unmanned vehicle, that is, the speed V at the center of the left and right wheels is set by speed setting means VS.
The set value V is sent to the rotation speed determining means RD.

The rotation speed determining means R includes a speed V, an interval D,
Based on the maximum peripheral velocity V _m and the proportional coefficient A, (17), (1
To calculate the V _o and V _i by using the 8).

Other control signals, such as a signal for starting the unmanned vehicle and a signal for stopping, are sent from the control unit CTR to the rotation speed determining means. However, control such as departure and stop of an unmanned vehicle is out of the scope of the present invention, and a description thereof will be omitted.

The rotation speed determining means RD further determines which of the right and left wheels is closer to the guide rail based on the output of the distance detecting means DD.

Based on this determination, the drive device (for example, the first drive device D1) for the wheel near the guide rail G is V
send _o signal, it sends a V _i signal to a driving device for distant wheels from the guide rail G (for example, the second driving device).

The first and second driving devices are arranged so that the peripheral speeds of the first and second wheels W1 and W2 are respectively equal to the rotational speed determining means RD.
The wheel is driven to rotate to the value sent from the vehicle.

[0050]

When the speed is high, the guide rail tends to deviate. However, in the present invention, the curvature increases as the speed increases, so that the direction is quickly corrected, the derailment is reduced, and the straight section is reduced. The running is stable both in the curve section and in the curve section.

Immediately after the transition from the curved portion to the straight portion or from the straight portion to the curved portion, the deviation from the guide rail is large, but in the present invention, the curvature increases smoothly as a function of the deviation D. Does not occur and follows the rail smoothly.

FIG. 11 shows an example of the trajectory T of an unmanned vehicle guided by a guide rail G to which two straight lines are connected via an arc.

In the present invention, the locus T of the unmanned vehicle also depends on the speed V of the unmanned vehicle. However, when the speed is high, the curvature increases and the direction is quickly corrected, so that the deviation from the guide rail is small, and since the curvature changes smoothly as a function of the deviation D, the unmanned vehicle draws a smooth trajectory.

This means that the occurrence of excessive or insufficient correction of the rotational speed of the wheel is reduced.

This means that the degree of freedom in designing the guide rail is increased.

[Brief description of the drawings]

FIG. 1 is a conceptual top view of an unmanned vehicle controlled by a traveling control method according to the related art and the present invention.

FIG. 2 is an elevational view of the lower part of the unmanned vehicle of FIG. 1 as viewed from the front.

[Figure 3] peripheral velocity V _o of the outer and inner rings in the travel control method according to the prior art, the V _i, expressed as a function of the deviation from the induction rail graph.

Figure 4 is an explanatory view for explaining the relationship between the radius of curvature R of the outer ring and the inner ring of the peripheral velocity V _o, V _i and unmanned vehicles.

FIG. 5 is a graph showing a curvature κ of a trajectory of an unmanned vehicle when a traveling method according to the related art is applied as a function of a product AD of a deviation D from a guide rail and a proportionality coefficient A.

[6] prior art running control method unmanned vehicle which strained facilities and by the straight line portion L ₀ from different radii curved portions C1, from the induction rail when entering the C2 deviation d1, d2 and for schematically showing , Top view of the guide rail.

FIG. 7 shows trajectories a1 and a2 of an unmanned vehicle to which a traveling control method according to the prior art has been applied at different speeds from a straight line portion L1 of a guide rail to a curved portion C, and to the guide rail. The top view of the guide rail for showing typically the locus a3 which entered into the linear part from the curved part.

[8] The present invention according to the travel control method outer and inner rings of the peripheral velocity V _o by the respective correction amounts relative to the speed V of the unmanned vehicle V _i alpha, the beta, the V / V _m as a variable, AD is constant Graph drawn under conditions.

FIG. 9 shows the curvature κ of the trajectory of an unmanned vehicle to which the traveling control method according to the present invention has been applied when there is no slip between the floor and the wheels.
Is a graph showing the product AD of the deviation D from the guide rail and the proportionality constant A as a variable, using the speed V of the unmanned vehicle as a parameter.

FIG. 10 is a block diagram of an example of a device for implementing the traveling control method of the present invention.

FIG. 11 is an example of a locus of an unmanned vehicle when the unmanned vehicle to which the traveling control direction of the present invention is applied passes through a curved portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Guide rail 2 Unmanned vehicle truck 3, 4 Wheels 5, 6 Freewheel 7, 8 Drive motor 9 Control circuit 10 Detection sensor 1a Center of guide rail 2a Center of wheels 3, 4 A Proportional coefficient D Center and wheel of guide rail peripheral speed of the distance O unmanned vehicle center of curvature R unmanned vehicle trajectory wheel near the velocity V _o induction rail radius of curvature V unmanned vehicle distant wheel peripheral speed V _i induction rail of track between the centers of 3,4 curvature distance ds minute length measured along the trajectory of the unmanned vehicle dφ unmanned vehicle is in the traveling direction of the change κ unmanned vehicle trajectory when traveling only ds between V _m maximum peripheral speed 2W wheels 3,4 of the wheels C1 , C2, C Curved portion of guide rail L0, L1, L2 Linear portion of guide rail d1, d2 Distance between center of guide rail and center of unmanned vehicle wheel a1, a2, a3 Example of locus of unmanned vehicle CTR and others Control section DD interval detecting means D1, D 2 First and second drive units F Floor surface G Guide rail L Lens RD Rotation speed determination means S Rail detection sensor VS Speed setting means

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05D 1/00-1/12

Claims (1)

(57) [Claims] 1. First and second wheels provided on both sides of a vehicle body, interval detecting means for detecting a deviation interval of the center of both wheels from a guide rail, and first and second wheels based on an output of the interval detecting means.
And a rotation speed determining means for determining the rotation speed of the second wheel, and first and second drive means for driving the first and second wheels at the rotation speed determined by the rotation speed determination means, respectively. In the traveling control method of the vehicle, the speed at the center of both wheels is V, the maximum circumferential speed of both wheels is V _m , the gap between the center of both wheels from the guide rail is D, the floor condition, the load amount, and the like. When the proportional coefficient is A, the peripheral speed of a wheel having a large deviation from the guide rail among both wheels is V _o , and the peripheral speed of a wheel having a small deviation from the guide rail is V _i , the control means is expressed by the following equation. A driving control method for an unmanned vehicle, wherein V _o and V _{i are} set based on the setting. _{V o = V + (V m} -V) VAD / V m 2 V i = V- (V m + V) VAD / V m 2.