JP2556737B2 - Vehicle position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an automated guided vehicle that detects the vehicle body position using only the rolling distance detection values of the left and right measuring wheels of the vehicle body and performs control such as automatic steering. The present invention relates to a vehicle body position detecting device.

(Prior Art) A conventional vehicle body position detecting device of this type is the former vehicle body position detecting device that uses an encoder or the like to measure the rolling distances of the left and right wheels of the vehicle body on an axis on which the turning centers of the vehicle body are lined up. In order to detect the rolling distance or to detect the rolling distance, two dedicated left and right measuring wheels were individually attached.

In the latter vehicle body position detecting method, the rolling distance is detected by the vehicle body position detecting device described above, and the vehicle body position is calculated using the following equation (1).

However, in the equation (1), i is a sequential value for each minute unit time, x ⁱ , y ⁱ , θ ⁱ are vehicle body positions, Δl _L ⁱ , Δl _R ⁱ are rolling distance detection values of left and right measuring wheels, and w is The distance between the left and right measuring wheels is shown.

(Problems to be Solved by the Invention) The calculation by the equation (1) is based on the premise that the left and right measuring wheels 2 are accurately mounted on the shaft 3 where the turning centers of the vehicle body are aligned as shown in FIG. Therefore, each of the left and right measuring wheels 2 has a respective positional deviation u _L , u _R , v _L , v as shown in FIG. 2 with respect to the axis 3 on which the turning centers of the vehicle body 1 are arranged.
_{If R} and angle deviations α _L and α _R are generated and attached,
The vehicle body position calculation result by the above equation (1) includes an error.

Therefore, in the conventional method, in order to detect the vehicle body positions x ⁱ , y ⁱ , θ ⁱ with high accuracy, the left and right measurement wheels 2 must be on the shafts 3 on which the turning centers of the vehicle body 1 are aligned, and There was a problem that the mounting accuracy had to be improved.

(Means for Solving the Problems) In order to solve these problems, the present invention provides an unmanned guided vehicle in which a pair of drive wheels are provided in a vehicle body and the steering wheel is automatically steered and travels by the rotational speed difference between the pair of drive wheels. , A pair of measuring wheels for detecting a rolling distance is provided under the vehicle body of the automatic guided vehicle, separately from the driving wheels, and a measuring wheel shaft connecting the axle center of the driving wheels and the pair of measuring wheels. It was configured so that it would be attached so that its center matches.

(Embodiment) An embodiment will be described in detail below with reference to the drawings.

FIG. 2 shows the position deviations u _L , u _R , v _L , v _R and the angular deviation α _L from the state in which the measuring wheels 2 are accurately mounted on the shaft 3 on which the turning centers of the vehicle body 1 in FIG. 3 are lined up. , Α _R is generated.

The rolling distance Δl _L ⁱ of the left measuring wheel when the vehicle body 1 turns by the turning angle Δθ _t ^{i with the} point A as the turning center can be expressed by the following equation (2).

Based on the formula of Δl _L ⁱ obtained above, similarly, each quantity corresponding to the right measuring wheel 2 is represented with a subscript R, and Δl _L
^{When i} and Δl _R ⁱ are calculated and fitted to the equation (1), Δθ ⁱ and Δl ⁱ are calculated, and each error is included, and can be expressed by the following equation (3).

However, in the above formula (3), r ⁱ is the successive turning radius of the vehicle body 1, u _L , V _L , u _R , v _R , α _L , α _R are the mounting position deviations and angular deviations of the left and right measurement wheels 2, Δθ _t ⁱ , Δl _t ⁱ (= r ⁱ
• Δθ _t ⁱ ) is a true value. Here, when α _L = α _R = α, the above equation (3) is expressed as the following equation (4).

In the above formula (4), k ₁ , k ₂ , and k ₃ are constant terms.

Replace 1 / k ₁ , 1 / k ₂ and k ₃ / k ₂ with kθ, kl ₁ and kl ₂ (4)
When Δθ _t ⁱ and Δl _t ⁱ are obtained from the equation, the following equation (5) is obtained.

Substituting Δθ ⁱ and Δl ⁱ of equation (1) into equation (5),
If θ _t ⁱ and Δl _t ⁱ are replaced with Δθ ⁱ and Δl ⁱ again, the following equation (6) is obtained.

Therefore, if the constants kθ, kl ₁ and kl ₂ are properly selected and the values calculated by equation (6) are substituted into the equations for x ⁱ , y ⁱ , θ ⁱ in equation (1), the error in the vehicle body position calculation value will be Will not be included.

The condition of α _L = α _R = α, which is the condition of the equation (4), has an integrated structure in which the left and right measurement wheels 2 are connected by a shaft 5 as shown in FIG. This can be achieved by increasing the parallel accuracy in the rolling direction. In FIG. 1, the left and right measuring wheels 2 are freely rotatable with respect to the shaft 5 via bearings or the like (not shown), and encoders and the like for rolling distance detection are attached to the left and right individually.

The values of the constants kθ, kl ₁ and kl ₂ in equation (6) are the vehicle position x
Values obtained by calculating ⁱ , y ⁱ , θ ⁱ and the actual vehicle body position
It can be determined in advance by comparing X ⁱ , Y ⁱ and Θ ⁱ .

For example, kθ, kl ₁ and kl ₂ are values when there is no positional deviation or angular deviation in the mounting state of the measuring wheels, kθ = 1, kl ₁ = 1, k
With l ₂ = 0 set, first, the vehicle body 1 is turned to travel, and kθ is determined by the following equation (7) from the values of θ ¹ and θ ⁱ at that time.

Next, after setting kθ to a value determined by the equation (7), the vehicle body 1 travels straight in the x-axis direction, and kl ₁ is determined by the following equation (8) from the values of x ⁱ and X ⁱ at that time.

Next, set kl ₁ to the value determined by equation (8), and then set the vehicle body 1
Is turned with a constant radius, and kl ₂ is determined by the following equation (9) from the values of y ⁱ , θ ⁱ , and Y ⁱ at that time.

The calculation of the vehicle body position in the equations (1) and (6) is performed by the vehicle body 1
It is performed by a computer or the like (not shown) installed in the.

(Effects of the Invention) As described above, in an unmanned guided vehicle in which a pair of driving wheels are provided in the vehicle body and the steering speed is automatically steered / traveled by the difference in the rotational speeds of the pair of driving wheels, the rolling is performed at the lower part of the unmanned guided vehicle body. A pair of a pair of measuring wheels for detecting the distance is installed separately from the drive wheels and the axle center of the drive wheels and the center of a measurement wheel shaft connecting the pair of measurement wheels are attached to each other so as to match. By increasing the parallel accuracy of the left and right rolling directions when mounted on the vehicle body, the terms in the vehicle body position calculation formula that are caused by the mounting deviation amount with respect to the axis where the turning center of each vehicle body of the left and right measurement wheels are aligned are made constant. Therefore, if the constants are properly determined in advance, even if the mounting state of the left and right measurement wheels on the vehicle body is at any position where there is a positional deviation or angular deviation with respect to the axis where the turning center of the vehicle is aligned, Position It can be detected accurately.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing the structure of left and right measuring wheels applied to the vehicle body position detecting method of the present invention and the mounting state on the vehicle body. FIG. 2 is a positional deviation of the measuring wheels from the state shown in FIG.
FIG. 3 is an explanatory diagram showing a state in which an angular deviation is generated, and FIG. 3 is a configuration diagram showing a state in which left and right measuring wheels are attached to a vehicle body, which is required in a conventional vehicle body position detecting method. 1 ... Vehicle body 2 ... Left and right measuring wheels 3 ... Axes aligned with the center of turning of the vehicle body 4 ... Points for which the vehicle body position is calculated 5 ... Axis 6 ... Wheels

 ─────────────────────────────────────────────────── ─── Continued Front Page (56) References JP-A-55-10557 (JP, A) JP-A-61-274214 (JP, A)

Claims (1)

(57) [Claims] 1. An unmanned guided vehicle having a pair of driving wheels provided on a vehicle body and automatically steered and traveling by a rotational speed difference between the pair of driven wheels, wherein a pair of driving wheels are provided below the unmanned guided vehicle for detecting a rolling distance. A vehicle body position detecting device, characterized in that a pair of measuring wheels are mounted separately from the drive wheels, and an axle center of the drive wheels and a center of a measuring wheel shaft connecting the pair of measuring wheels are aligned with each other.