JP2823324B2 - Self-driving car - Google Patents

Description

The present invention relates to an automatic traveling vehicle traveling on a predetermined traveling route.

(B) Conventional technology In recent years, in food vending machines, factories, and the like, automation related to article transportation is being performed. An example of such an article transport automation is an automatic traveling vehicle, and a traveling vehicle for transporting articles is used for transporting foods in vending machines, transporting assembly materials in factories, and the like.

In view of such a technical situation, the applicant of the present application has provided guide means only in a part of the traveling route, and when traveling on a part without the guide means, detects the number of revolutions of the wheels of the traveling vehicle by an encoder, and determines the current position from the result. The vehicle that travels after confirmation is proposed as Japanese Patent Application No. 1-269281.

(C) Problems to be Solved by the Invention However, in the configuration in which the number of revolutions of the wheels of the traveling vehicle is calculated to calculate the current position as described above, if a slip or the like occurs between the wheels and the road surface, the accurate current position is calculated. It was difficult to confirm.

A method of confirming a target by image processing and correcting the current position based on this information is conceivable. However, there is a problem that the processing takes too much time and the correction of the route tends to be delayed.

On the other hand, when the traveling vehicle travels by correcting the target position and orientation so as to approach the current position and orientation, the traveling vehicle can generally change its direction due to the difference in the movement amount of the left and right wheels. Therefore, if priority is given to correcting the direction, it is impossible for the traveling vehicle to move sideways, so it is necessary to turn the direction again to a direction different from the direction of the target position to approach the target position Come to occur,
Conversely, if priority is given to position correction, even if the vehicle reaches the target position, the traveling vehicle must be moved again to correct the direction, and finally the difference in the optimal route is considerably large. There is a problem in that a forced route must be taken.

The problem to be solved by the present invention is to control a traveling vehicle such that when the route of the actual traveling vehicle deviates from the optimal route, the target position and direction of the optimal route can be corrected with the minimum time and route. Is to provide a way to

(D) Means for Solving the Problems The present invention calculates an optimal route connecting two points, and in a traveling vehicle that autonomously travels along this route, a predetermined traveling direction of the traveling vehicle whose traveling direction is the X-axis direction. The deviation ΔY in the Y-axis direction of the current position from the target position at the time of sampling, and the deviation Δθ in the rotation direction of the traveling vehicle, and the deviation ΔY in the Y-axis direction.
In the range where Y is larger than the predetermined value, the correction amount in the Y-axis direction is relatively heavily weighted with respect to the correction amount in the rotation direction,
Further, in a range where the rotation direction deviation ΔY is smaller than a predetermined value, a gain function is set which weights the correction amount in the rotation direction relatively heavily with respect to the correction amount in the Y-axis direction as the deviation ΔY decreases. The shifts ΔY and Δθ are corrected.

(E) Function When the traveling vehicle is far away from the target position on the optimal route, the correction in the traveling direction is large and the correction in the rotation direction is conservative, and conversely, the correction in the rotation direction is large at the position close to the target position. To make the correction of the traveling direction conservative and gradually approach the target position and direction.

(F) Embodiment Hereinafter, the traveling vehicle of the present invention will be described in detail with reference to an embodiment of the drawings.

FIG. 1 is a schematic view of a traveling vehicle, and (a) and (b) of FIG.
(C) shows a case where different optimum routes are set. In the figure, reference numeral 1 denotes a traveling vehicle traveling along a preset optimal traveling route (shown by a broken line in the figure), and reference numerals 2 and 3 denote guide means provided near the starting point and the ending point of the preset traveling route. is there. The guide means 2 and 3 are specifically made of a magnetic tape attached to the floor surface.
At the start and end points of the vehicle. Reference numerals 4 and 5 denote stop position marks indicating stop positions of the traveling vehicle, which are made of a magnetic tape like the guide means 2 and 3. Here, the guide means 2, 3 are provided fixed to the traveling route.

FIG. 2 shows the lower surface of the traveling vehicle.
Is a drive wheel which is driven by a motor or the like and whose movement amount can be detected by an encoder or the like, and 8 is a rotatable caster. Reference numerals 9 and 10 denote guide means detectors for detecting the guide means 2 and 3, which are constituted by magnetic sensors, are arranged side by side in the direction perpendicular to the traveling direction with an interval in front and behind, and the guide means Based on the detection results of the detectors 9 and 10, the position and orientation of the traveling vehicle 1 are calculated as described later. Reference numeral 11 denotes a stop position detector for detecting the stop position marks 4, 5, which is also constituted by a magnetic sensor and is arranged in parallel with the traveling direction.

FIG. 3 is a perspective view of the traveling vehicle 1, in which 12 is a working manipulator provided on the upper portion of the traveling vehicle 1, and 61 and 71 are disposed near the drive wheels 6 and 7, and the amount of movement thereof is shown. Is a measuring wheel that can be detected by an encoder or the like.

FIG. 4 is a block diagram showing a control mechanism of the traveling vehicle 1. In the figure, reference numeral 14 denotes a traveling route creation unit which generates a traveling route that can travel from the starting point to the ending point based on the set position information of the starting point and the ending point; , The route selector that selects the best route
It consists of 16. Reference numeral 17 denotes a target position calculation unit that calculates a movement target position at the time of sampling of the traveling vehicle 1 per unit time based on the route information selected by the route selection unit 16 at the unit time interval.

Reference numeral 18 denotes a current position calculating unit, and the gate means detector,
And the present position of the traveling vehicle is calculated based on the detection data from the stop position detectors 9, 10, 11 or the measurement data (for example, encoder pulses) from the measurement wheels 61, 71 provided on the drive wheels 6, 7. . Here, the measurement wheels 61 and 71 are constantly pressed against the traveling surface so that the current position of the traveling vehicle 1 can be accurately grasped even when the drive wheels 6 and 7 slide. 19 is a target position correction unit for correcting the target position by comparing the information from the target value calculation unit 17 at the time of sampling with the information from the current position calculation unit 18, and 20, 21 are from the target position correction unit 19. A control amount calculating unit for calculating a control amount for controlling the driving wheels 6 and 7 so that the traveling vehicle 1 approaches the target position by the proportional integration method based on the data of FIG. Is a driver that drives each of the drive wheels 6 and 7 individually. Further, the drive data of the drive wheels 6 and 7 is fed back to the control amount calculation unit via feedback loops 24 and 25 to become position data for calculation of the control amount.

A method of controlling the traveling vehicle 1 having the above configuration will be described below.

[Current Position Calculation Method] The current position calculation method during travel of the traveling vehicle 1 is different between the autonomous travel section except the start point and the end point on the guide means 2, 3 and the guide travel section on the guide means 2, 3. ing.

Autonomous driving section current position calculation method In the autonomous driving section, the amount of change in the encoder pulse of the measuring wheels 61 and 71 is measured at each sampling time, and the current position (X _n , Y _n ) and attitude θ _n are calculated by the following equation. Ask.

_{X n = X n-1 +} ΔLcos (θ n-1 + Δθ / 2) ... ( Equation _{1) Y n = Y n-} 1 + ΔLsin (θ n-1 + Δθ / 2) ... ( Equation 2) θ _n = θ _{n- 1} + Δθ (Equation 3) Here, n is the number of times of sampling, ΔL, and Δθ are the amounts of change in the moving distance and the posture angle for each sampling time. The directions of X and Y are the traveling direction shown in FIG. 2 and the direction perpendicular thereto.

Method for Calculating Current Position of Guide Travel Section The guide travel section is a travel section when the two guide means detectors 9 and 10 before and after the drive wheels 6 and 7 are both on the guide means 2 and 3. In this guide traveling section, θ _n and Y _n are obtained from the detection values of the guide means detectors 9 and 10 by the following equations.

θ _n = tan ⁻¹ ｛(Sf−Sb) / W _s … (Equation 4) Y _n = Sfcosθ _n- (Ws / 2) sin θ (Equation 5) where Sf is the front guide means detector 10 Detection value, Sb
Is a detection value of the rear guide means detector 9, and Ws is an interval between the front and rear guide means detectors 9, 10. Note that _Xn is obtained by the above equation (1).

[Traveling Vehicle Position Correction Method] In FIG. 5, the current position of the traveling vehicle 1 at the time of predetermined sampling in the coordinate system [X, Y] based on the starting point is defined as (X _now , Y _now , θ _now ). The target position at the time (X
_ref , Y _ref , θ _ref ) and the target position at the next sampling is (X ′ _ref , Y ′ _ref , θ ′ _ref ). At this time, the deviation of the traveling vehicle 1 from the target value at a predetermined sampling time is calculated as follows using the target position information at the next sampling.

The target travel distances Ll and Lr of the left and right drive wheels 6 and 7 are
Using the correction amount S in the traveling direction and the correction amount R in the rotation direction with respect to the target position at the time of the predetermined sampling, L′ l and L′ r are corrected by the following equation.

L'l = Ll + PI (S ) + PI (R) ... ( Equation 6) L'r = Lr + PI (S) -PI (R) ... ( Equation 7) where, PI represents a proportional integral, S = e _x ... (equation 8) R = (φ-Δθ ref) × X ref / V max + (θ ref -θ now) ... ( equation _{9) (e x, φ,} Δθ ref, θ ref, θ now during Figure 5 ). V _ref / V _max is the ratio between the moving speed of the traveling vehicle 1 at the time of predetermined sampling and the maximum speed, and is a term provided to further reduce the correction of the rotation direction at low speed.

By the way, as shown in FIG. 6, the current position now _n has a deviation of ΔY in the Y-axis direction from the target position ref _n (the direction is the X-axis direction) at the time of the n-th sampling, and the direction is If such that theta _n, the correction amount at this time
P _n is given so as to approach ref _n in both the Y-axis direction and the θ direction. On the other hand, for the (n + 1) th target position ref _{n + 1} , the correction amount of the deviation in the Y-axis direction from the current position now _{n + 1} and the correction amount in the θ direction move in opposite directions. The corrected amount acts in a direction deviating from the optimum route as shown by a broken line in the figure. As a result, the traveling vehicle 1 delays converging to the target position and orientation of the optimal route.

Therefore, in the present invention, PI (R), PI
The coefficient term in the expression of (S) is a linear gain function as shown in FIG. 7, for example, and the deviation between the current position and the target position in the Y-axis direction is large (for example, ± 20 mm or more) in the Y-axis direction. The correction amount is weighted to be large, and conversely, as the deviation amount in the Y-axis direction is small and approaches the target position, the correction amount in the rotation (θ) direction is increased. In this way, the traveling vehicle 1 converges in the target city and direction of the optimal route, always following the route that approaches the optimal route without moving away from the optimal route from the current position to the target position.

The following control is performed during the actual traveling on the traveling route from the starting point, ie, the stop position mark 4 of the guide means 2, to the end point, ie, the stop position mark 5, of the guide means 3.

At the time of traveling near the starting point of the traveling route and where the guide means 2 can be detected by the guide means detectors 9 and 10,
Based on the detection results of the guide means detectors 9 and 10, the accurate current position of the traveling vehicle 1 is confirmed by the current position calculation method during the guide travel, and the vehicle is driven to approach a target position preset by the position correction method. The vehicle travels while controlling the amount of movement of the wheels 6,7.

When the vehicle is traveling near the middle of the travel route and cannot detect the guide means 2 and 3 by the guide means detectors 9 and 10, the vehicle travels by the current position calculation method of the autonomous travel section based on the detection results of the measurement wheels 61 and 71. After confirming the accurate current position of the vehicle 1, the vehicle 1 travels while controlling the amount of movement of the drive wheels 6, 7 so as to approach a target position set in advance by the position correction method. Since these drive wheels 6 and 7 are independently driven,
By appropriately adjusting the amount of each movement, it is possible to travel in all directions including front, rear, left and right. In addition, since the position correction method is calculated by using the target position information one point ahead, the target can be image-recognized by a CCD camera or the like, and can be processed much faster than the method of correcting the traveling trajectory based on this data.

When the traveling vehicle 1 reaches a position near the end point of the traveling route and at which the guide means 3 can be detected by the guide means detectors 9 and 10, the accurate current position and travel are again determined by the detection results of the guide means detectors 9 and 10. You can run while checking the speed. At the time of traveling near the middle of the traveling route where the guide means 2 and 3 cannot be detected, even if the traveling vehicle 1 slightly deviates from the traveling route, the traveling vehicle 1
When the vehicle reaches the position, the vehicle can travel by confirming the correct position by detecting the guide means 3. When the stop position detector 11 detects the stop position mark 5, the traveling is terminated and stopped, and the traveling vehicle 1 prepares for the next traveling.

(G) Effects of the Invention As described above, the present invention weights the correction amount in the Y-axis direction and the correction amount in the rotation (θ) direction,
At a position farther than a predetermined distance from the optimal route, Y
The priority is corrected by increasing the priority in the axial direction, and within a predetermined range from the optimum route, the priority is corrected by increasing the priority in the θ direction as the vehicle approaches the optimum route. It is possible to approach the shortest distance easily and reasonably, and it is possible to correct in an appropriate direction.

[Brief description of the drawings]

1 (a), 1 (b) and 1 (c) are diagrams showing different optimum traveling routes of the traveling vehicle of the present invention, FIG. 2 is a bottom view of the traveling vehicle, FIG. 3 is an external perspective view of the traveling vehicle, FIG. 4 is a block diagram showing a control mechanism of the traveling vehicle, FIG. 5 is a diagram showing a concept of a position correction method, FIG. 6 is a diagram showing a situation where the traveling vehicle approaches a target position from a current position by correction, and FIG. 7 (a) and 7 (b) are diagrams showing an embodiment of a function constituting a coefficient term of a PI control function in a traveling direction and a rotation direction. 1, traveling vehicle 2, 3, guiding means 6, 7, driving wheel 9, 10, guiding means detector 17, target position calculating unit 61, 71 measuring wheel 24, 25 ... Feedback loop.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05D 1/00

Claims (1)

(57) [Claims] 1. An optimum route connecting two points is calculated, and in a traveling vehicle that autonomously travels along this route, a current position of the traveling vehicle with respect to a target position at the time of predetermined sampling of the traveling vehicle having the traveling direction as an X-axis direction. The deviation ΔY in the Y-axis direction and the deviation Δθ in the rotation direction of the traveling vehicle,
In the range where Y is larger than a predetermined value, the correction amount in the Y-axis direction is relatively heavily weighted with respect to the correction amount in the rotation direction. In the range where the deviation ΔY in the rotation direction is smaller than a predetermined value, the deviation ΔY is small. An automatic traveling vehicle, wherein a gain function that weights the correction amount in the rotation direction relatively heavily with respect to the correction amount in the Y-axis direction as much as possible is set to correct the deviations ΔY and Δθ.