JPS6339923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to self-guided vehicles, and in particular to fork lift vehicles along a predetermined path that is not constrained by a fixed track. It concerns a self-guided vehicle suitable for moving trucks and other means of transport.

Here, “track-boundedness”
In a broad sense, this includes, for example, those laid by creating a groove in the floor, placing a conductor wire in the groove, and then filling the groove with cement to level the floor. This means that the vehicle must move along the track. Then, it senses the electromagnetic field from the conductor wire, which is supplied with an appropriate direct current, calculates the vehicle's position, and determines that the vehicle following the conductor is "track-bound."

[Prior Art] Vehicles restrained by "tracks" are known.
The general category of track-restrained vehicles includes not only rail-restrained vehicles, but also vehicles that are not mechanically forced to follow the track, for example by markings on the floor, or by the vehicle itself. It also includes vehicles that are configured to detect and follow a trajectory. One type of mark that has recently become commonplace on floors in factory buildings is an electromagnetic radiation radiating loop placed in the floor. There is a transducer inside the vehicle, which detects the position of the vehicle relative to the track, and uses the path defined by the track to manipulate the motion of the vehicle to follow that path.

An example of an advance in "track-bound" vehicles is described in the Swedish Patent Publication. The application specifically deals with the problem of following curved trajectories. Since vehicles of this type usually have four wheels, it is not immediately obvious what is the best way to steer the wheels in order to obtain the best following on curved tracks. As stated in the specification of the above application, the problem is
The solution is to drive the two wheels at different calculated speeds. In another solution, which is simpler in principle, the means for detecting the trajectory are installed in front of the front pair of wheels in the direction of travel.
Such a solution is described, for example, in U.S. Pat.
Discussed in issue 3757887.

Other configurations for automatically loading and unloading fork lift trucks are described in the Swedish Patent Publication. The sensor is in this case centrally located below the vehicle. It is stated that the fork lift truck is equipped with a mileage recorder to measure the distance traveled by the vehicle. The driving recorder consists of a toothed wheel fixed to one of the axles of the vehicle's wheels and a sensor (details omitted) that detects the tooth that passes in front of the sensor when the vehicle is moving. For example, in a rotary encoder consisting of a rotating disk with a number of slits and an optical sensor), the distance traveled is proportional to the number of teeth (or slits) passed in front of the sensor.

Practical experience gained from operating fork lift trucks and various types of vehicles that follow electrically looped tracks shows that conventional "track-bound" vehicle systems do not meet the demands for flexibility in running tracks, etc. It turns out that the system is good when the is low.
This track restrained vehicle system allows for the construction of a sophisticated system that saves both time and effort.

[Problem to be solved by the invention] However, to date, these systems have only been developed in areas where the conditions are clearly advantageous, i.e. where it is easy to lay electrical lines and where operating conditions rarely change. not being used. Such conditions do not always exist. In many cases, installing the cables that determine the trajectory is difficult and expensive. Also, for flexible systems or multiple vehicles, many different programmed movements are required. This requires a very extensive loop system and, in addition, it is difficult for the vehicle to maintain the desired trajectory among the various signals from the floor and not be confused with other signals. be.

The object of the invention is to provide a system in which such disadvantages are substantially avoided. With this in mind, the objective is to eliminate "track binding" in the broadest sense and force the vehicle to follow a predetermined path that exists as type-specific information within the vehicle itself.

[Means for Solving the Problems] The self-guided vehicle of the present invention uses “dead navigation”.
The vehicle is controlled using a combination of distance and direction data.
Here, "dead reckoning" is a technical term introduced from ship navigation technology. The navigator calculates the position of the ship from the sailing direction and the measured speed of the ship, and uses this to navigate along the desired route. This is called “dead reckoning.” The vehicle according to the invention uses a driving principle related to this concept of "dead reckoning". That is, the direction and speed (or distance traveled) of the vehicle are periodically measured, the current position of the vehicle is calculated, and the vehicle is moved along a predetermined route.
It controls the operation of the vehicle.

If you are using "dead reckoning" to guide you, you cannot expect perfect accuracy, and you will need to "fix" it periodically.

Here, periodic "fixing" means that when driving by "dead reckoning," an error inevitably occurs in the calculated position, but this error accumulates over time, so it is necessary to eliminate this error. Therefore, it means measuring the actual position on a regular basis.

In some parts of the route, the vehicle is on a “track”
It is also conceivable that the vehicle could be operated and driven by "dead reckoning" in other areas.

The advantages and objects of the invention are set out in the first claims.
This can be achieved by a self-guided vehicle having the characteristics described in Section 1.

Here, the traveling means described in claims 1 and 2 respectively means, for example, driving wheels, and the steering means means means for changing the traveling direction of the vehicle, such as steering wheels. The traveling means and the steering means may be provided separately or may be provided in combination. For example, driving and steering can be achieved by differentially driving two drive wheels. These embodiments are discussed below in the Examples section.

In addition, the measuring devices described in claims 1 and 2 respectively include two measuring wheels, a ball arranged in a roller receiver, and a single measuring wheel that can freely rotate. Any of these may be used, but these various embodiments will also be described later in the Examples section.

Furthermore, the means for calculating the sum described in claims 1 and 2, respectively, is, for example, a means for calculating according to formula (3) described later, but it may not be possible to use ordinary electronic computer means. , a microprocessor can be used.

The weighted coefficient described in claim 2 refers to, for example, the coefficient e in equation (3) described later.

[Operation] The operating principle of the vehicle will be briefly described below, but the present invention is not limited thereto.

A vehicle according to the invention having running means and steering means is provided, for example, with two freely rotating measuring wheels. The measuring wheels rotate along the floor, are preferably pivoted coaxially with the axle and are arranged on each side of the vehicle.

The measuring wheels, which do not have to carry a load, are each provided with a device for measuring the rotational distance of the measuring wheel (ie the product of the circumference of the measuring wheel and the rotational speed). If the vehicle drives straight ahead (the simplest case), the measured distances for both measuring wheels are the same. However, if the vehicle travels along a curved path, the measured values for each side of the measuring wheel will be different. This is because when the vehicle travels around a curve, the measuring wheel on the center side of the curve moves a smaller distance than the measuring wheel on the outside of the curve.

If the rotation distance data of both fixed wheels is continuously recorded, the actual position of the vehicle can be determined and calculated from this data.
Since the travel distance is measured at sufficiently short predetermined time intervals, the travel trajectory during each time interval can be accurately approximated as a circular arc. That is, the turning radius of the vehicle is determined from the difference in the rotational distances of the fixed wheels on both sides within the predetermined time interval. And within this time interval,
This can be approximated as a vehicle traveling on an arc with this radius.

Therefore, the radius of the circular arc that is approximated by the vehicle can be calculated for each measurement time interval.

This "dead reckoning" basically draws a travel trajectory that is approximately determined by connecting and adding arcs with different radii of curvature, and calculates the vehicle's position at each instant. Although it is possible to measure distances by means other than using two non-pivot wheels,
This will be described later, but first the operation of the above embodiment will be described.

While moving along the arc, the left measuring wheel of the vehicle rotates a distance ΔX _v , the right measuring wheel rotates a distance ΔX _h , and the distance between the two measuring wheels is a, then from the relationship of elementary geometry , the average radius r and the travel angle from the center of the arc are α [radians], then the length of the traveled arc is expressed as rα=ΔX _h +ΔX _v /2...(1), and the radius of curvature is expressed by the equation r =a/2・ΔX _h +ΔX _v /ΔX _h −ΔX _v ...(2).

There are several possible ways to maneuver a vehicle along a path. Since the position coordinates of the vehicle are determined by one coordinate system, the position and orientation of the vehicle can be expressed by another coordinate system by coordinate transformation. A command route or reference route that is determined in relation to the two-dimensional space of the floor by focusing on a point located at the front of the vehicle in the direction of movement of the vehicle, which is determined in relation to the coordinate system of the vehicle itself. (a predetermined route stored in the storage means) by calculating the deviation of the one point, and determining the angular position (steering angle) of the steering means based on the distance between the one point and the commanded route or the reference route; It uses a simple steering method. This steering method, commonly referred to as the thumb in the track, is also known when using "track" means with wires laid in the floor. The equation required for steering is very simple. The steering angle of the steering means is set to a value directly proportional to the calculated deviation between the position of a point fixed on the vehicle and the route to be followed.

Furthermore, in a particularly preferred steering method, two
Better use is made of the measurements obtained from the two measuring wheels, in particular the information regarding the "angular bearing" or "attitude" of the vehicle with respect to the commanded or reference path.

Here, the “angular bearing” of the vehicle (angular
"orientation", also called "attitude", is the direction in which the vehicle is facing; in other words, the direction in which the axis of symmetry of the vehicle is facing.

Let φ ₁ be the vehicle attitude at the beginning of a short measurement time interval in which the vehicle movement can be approximated as a circular arc, let φ _{2 be the vehicle attitude at the end, and let φ 2} be the attitude of the vehicle at the end of the short measurement time interval in which the vehicle movement can be approximated as an arc, and the command path and 2 at the start of the above measurement time interval. The distance from the midpoint between the two measurement wheels is S ₁ , the distance at the end is S ₂ , and the radius of the command path and the angle of the steering wheel at the end of the above measurement interval are the basic value δg. Assuming that they match, the new appropriate value δ (steering angle) of the steering means is given by the following equation.

δ=a・φ ₂ +b・φ ₂ −φ ₁ /Δt+c・S ₂ +d・S ₂ −S ₁ /Δt+e・φ ₂ +f・(δg−δa)……(3
) Here, if S ₂ and φ ₂ have the same sign, e=1,
Otherwise, e=0.

Note that a, b, c, d, e, and f are constants, Δt is a time interval, and δa is the actual value of the angle of the steering wheel.

As mentioned above, formula (3) excluding "+e·φ ₂ " is the content of the calculation in the means for calculating the sum described in the claims 1 and 2, respectively. It shows. As can be seen from this equation, the steering angle takes into account not only the deviation Sφ but also the differences S ₂ −S ₁ /Δt and φ ₂ −φ ₁ /Δt. (
This is in contrast to the conventional method, commonly referred to as trajectory thumb, which only considers deviations. ) The reason for taking this difference into consideration is to prevent large acceleration from occurring in the lateral direction of the vehicle, and the details will be described later.

As mentioned above, the term “+e·φ ₂ ” in equation (3) indicates the content of the operation in the means for increasing or decreasing the weighting coefficient described in claim 2. . Here, the coefficient corresponds to the coefficient e. If the vehicle is moving away from the predetermined route, it is automatically recognized that S ₂ and φ ₂ have the same sign.

That is, the vehicle is on the right side of the predetermined route (S ₂ >0), and the actual attitude of the vehicle is in a clockwise direction from the predetermined attitude on the predetermined route (φ ₂ >
0), or the vehicle is on the left with respect to the predetermined path (S ₂ <0), and the actual attitude of the vehicle is counterclockwise from the predetermined attitude on the predetermined path (φ ₂ <0), the vehicle is moving away from the predetermined path, and S ₂ and φ ₂ have the same sign. In other cases, the vehicle is parallel to or approaching the predetermined path, and S ₂ and φ ₂ have opposite signs.

By increasing/decreasing the weighting coefficient as described above, when the vehicle is moving away from a predetermined path, the steering angle can be greatly reduced to quickly return to the predetermined path, while when the vehicle is parallel or approaching In such cases, it is possible to gradually reduce the steering angle to prevent so-called overshoot.

If the constant in the above steering operation equation (Equation (3)) is an appropriate value, the normal trajectory can be stably followed by the steering operation based on Equation (3).

Usually, a commanded route or a reference route followed by a self-guided vehicle is configured as a series of straight lines and circular arcs. Based on the information continuously obtained by the two measuring wheels, the vehicle can guide itself along a predetermined path.
If the path is closed, a part of the path, preferably a straight part, may be suitable for providing markings in the floor, in a known manner, in order to "fix" or "update" the position coordinates of the vehicle. ing.

When determining a route, especially for curves with a relatively small radius of curvature, it is desirable not to choose a route that directly changes from a straight line to a curve with a predetermined radius of curvature. I mean,
This is because if the straight line section as described above changes directly to a curve with a small radius of curvature, lateral acceleration will suddenly occur and force will be applied to the vehicle and the loaded object, which is disadvantageous. Railroad rail designers are faced with problems corresponding to those mentioned above. Solutions found in the technical field of railway rails can be fully applied to trackless vehicles. The solution is the so-called “transition curve”.
curve)” is used between a straight line and a curved line.A transitional curve is a curve in which the change in the radius of curvature of the curve is constant, that is, a curve in which the radius of curvature changes directly.And, The solution to this problem is a solution to a third-order differential equation in the orthogonal Cartesian coordinate system.

For this solution, please refer to “Comprehensive Technology Dictionary”
(Lexikon der gesamtem Technik) 2nd edition,
“Railway Proportional Curves” published in 1904
(Krummungsverhaltnisse der Eisenbahnen)
It is described in.

Embodiment In an embodiment of the invention, the self-guided vehicle is a fork lift truck with means consisting of two measuring wheels and a steering wheel. Acts as a third, single steering wheel,
It consists of two wheels connected by a tie rod device. Both wheels are drive wheels and are pivotable by means of a steering arrangement. Since it actually has two steering wheels (Figs. 1 and 2)
When performing calculations (although one steering wheel is shown in Fig. 4 for convenience), instead of the actual steering angles of the two steering wheels, virtual steering angles placed at the same position on the vehicle are used. It is practically advantageous to use an ideal steering angle of a single steering wheel. Since the above theoretical steering angle corresponds to the actually recorded steering angle position, it is preferable to establish a simple variable conversion method. In an embodiment according to the present invention,
The conversion between the theoretical steering angle and the actual steering angle takes place by means of a function table already loaded into the control computer. However, variable transformations can also be carried out by means of nomographs or other similar methods, such as those used in simple mechanical engineering.

The measuring device which is a component of the present invention can be either two measuring wheels, a ball arranged in a roller receiver, or a single freely pivotable measuring wheel. Each will be described below.

It should be noted that the measuring wheel need not be a load-bearing wheel. The measuring wheel can be a completely independent free wheel. Also, the two measuring wheels do not need to have coaxial rotation axes. Rather, these measuring wheels are aligned in the primary forward direction (the
primary forward direction). Here, the primary forward direction means the forward direction of the vehicle and not the reverse direction. If the rotation axes of the two measuring wheels are each fixed in a fixed direction with respect to the vehicle and cannot turn, each measuring wheel may slip in a predetermined direction. The axes of the two measuring wheels need not be parallel to each other if the measuring wheels slip without rotating due to movement parallel to the axis of the respective measuring wheel. That is, firstly, the measuring wheels can be arranged in a manner other than side by side or on coaxial rotation axes. For example, the axes of the measuring wheels can be arranged shifted relative to each other in the longitudinal direction of the vehicle. Second
In addition, the measuring wheel is designed to rotate only in its direction of rotation if it is not loaded. And, if a ring angle occurs, the measuring axis is designed to slip. and,
In order to facilitate the above-mentioned slipping, it is suitable to provide the outer periphery of the measuring wheel with a roller or something similar, the axis of which is oriented in a predetermined direction of the circumference of the measuring wheel. Measuring wheels that slip in a predetermined direction while rotating in a direction perpendicular to this direction are known in planimeters.

Another method of measuring movement in two-dimensional space is to place the ball in a roller receiver with rollers. It is similar to the ball and ball holder of a ballpoint pen. When the vehicle moves, the ball rotates without slipping against the rollers. If a measuring wheel is provided that measures all the movements of the ball along two great circles relative to the ball receiver, without the ball slipping relative to the ball receiver, then the value of the displacement can be calculated in two different directions. can be asked about. If these two great circles are perpendicular to each other, movement can be recorded along mutually perpendicular X and Y coordinates.

Yet another method of keeping the vehicle along a predetermined path is to use, instead of two fixed measuring wheels, a single measuring wheel that is freely swivelable, and for which the angle at each moment is determined. It measures distance traveled as well as location. As will become clear from the description below, the measured values obtained by the measuring wheel are processed analogously.

The invention will now be explained in more detail with reference to the accompanying drawings, in which: FIG.

FIG. 1 shows a fork lift truck of essentially conventional type and therefore will not be described in detail here. Although the steering wheel 1 actually consists of two wheels placed close to each other and connected by tie rods (not shown), in principle the vehicle has three wheels. operates as a vehicle. The vehicle together with the steering wheel 1 is carried by two parallel non-driven measuring wheels 2, 3 with thick rubber tires.

The measuring wheels 2 and 3 are provided with toothed rims, which are not shown in this figure, but are sensed by a sensor 4. Furthermore, it is shown in FIG. 1 that the steering wheel 1 is actuated via a steering drive means having a gear 5 and a steering motor 6 acting on the gear.

The steering drive means are shown more clearly in FIG. It can be seen that the measuring wheels 2 and 3 have toothed rims 20 and 30, which rims rotate together with said wheels. Each toothed rim has a sensor 4, in this case magnetic, which is located on the vehicle. Naturally, optical sensors can be used as well. By detecting the number of teeth passing in front of the sensor per unit time and the direction in which the teeth pass, the measuring wheel 2
It is possible to calculate the moving direction and moving distance of each of the above and 3. Such measurements are widely used using rotary encoders.

Signals from the sensors corresponding to the direction and distance of travel are transmitted via conductor pairs 40 and 41, respectively, to the right and left steering wheel counting mechanisms, respectively. The counters are located within the central unit 8 and are numbered 9 and 10 in the diagram.
The calculation unit 11 performs calculations based on the above equations (1), (2) and (3), and also calculates how the angle of the steering wheel should be adjusted using the programmed path. Information regarding the angle to be taken by the steering wheel is calculated digitally in this embodiment, but is converted by the D/A converter 12.
The DC servo 14 provides a drive current to the steering motor 6 which is transmitted via conductor 80 to the DC servo 14 which rotates the steering wheel 1 to the appropriate angular position. In this embodiment, the steering motor and DC servo correspond to the steering operation means. The steering wheel 1 also has a driving force (not shown in FIG. 2) for propelling the vehicle.

The actual angular position of the steering wheel (steering angle) is detected by a digital sensor 7, which may be of the same general type as the device used for the measuring wheel, for example a rotary encoder.

The operation of the device shown in FIG. 2 is as follows.

When the vehicle moves, the front wheels rotate. Each wheel has a sensor 4 which generates a series of pulses indicating the direction and amount of movement. This series of pulses is sent to an 8-bit or 9-bit counter 9 which counts up for forward movement and counts down for backward movement.

The 8-bit counter covers the range of integers from 0 to 255 (decimal). Therefore, when the vehicle moves forward and the count value exceeds 255, an overflow occurs. At this time, the count value returns to 0 and counting begins. A similar shift occurs for backward movement.
That is, when the count reaches 0 and the movement continues to retreat, the next reading will be 255.

The counters are connected to the computer via 8-bit parallel inputs per counter or other suitable method. Through continuous readings, the computer detects and determines the movement of the wheels.

The weakness of this system is that the computer cannot ensure in which direction the wheels will rotate. For example, suppose the counter has a value of 0 during a certain reading. Suppose the value of the next reading is 100. In this case, the wheel moved forward and the counter counted 0, 1, 2...99, 100, or it moved backward and the counter counted 0, 255, 254,... 101, etc.
I guess he counted 100. By making frequent readings and appropriate resolution of the counter readings by the computer, the computer always makes the correct choice when asked to choose between the two possible cases mentioned above. , this problem is solved. The solution used in this case was to read very frequently and move the counter so that the difference between one read and the next read was no more than 1/2 of the integer area of the counter (128 for an 8-bit register). The measurement time interval is determined taking speed into consideration. That is, the moving distance in the measurement time interval is determined.

The following counting method was used.

X ₁ = Count value at the time of _reading X ₂ = Count value at the time of _reading ΔX = Wheel movement (positive indicates forward movement, _negative indicates backward _movement ) In the case of ΔX=X ₂ −X ₁ −256.

When |X ₂ −X ₁ |<128, ΔX=X ₂ −X ₁ .

When X ₂ −X ₁ <0 and |X ₂ −X ₁ |≧128, ΔX=+(X ₂ −X ₁ +256).

When |X ₂ −X ₁ |<128, ΔX=X ₂ −X ₁ .

...(4) The procedure for calculating the steering angle from the front wheel count data is as shown in the flowchart in Figure 6. The following variables are used in this flowchart:

XH1...Measuring value of the right measuring wheel in the previous reading XV1...Measuring value of the left measuring wheel in the previous reading XH2...Measuring value of the right measuring wheel in the current reading XV2...Measuring value of the left measuring wheel in the current reading Measured value R... Radius of the path arc (if linear motion, R = 0) d... Distance between the measuring wheel and the driving wheel a... Distance between the measuring wheels T1... Time at the previous reading T2... Time at the current reading KMIN…minimum distance that the center point between the measuring wheels must move before a new calculation of the steering angle is performed.

In addition to the above calculation program (FIG. 6), a program is required to output appropriate signals to the steering operating means via the D/A converter. This program is shown as a flowchart in FIG.

This program (Figure 7) should be executed in parallel with the calculation program (Figure 6),
It is a kind of software control.

Furthermore, the counters 9 and 10 described above do not clearly indicate the direction of tooth movement. However, it is desirable that the counters 9, 10 be able to display the number of tooth movements of the rims 20 and 30 as well as the direction in which the measuring wheels are rotated. Sensors with such a function are known, in which there are two sensor elements, which detect each tooth with a phase shift, so that the direction of rotation can be immediately obtained. In the above example
A commercially available sensor called Airpax 14-0002 was used.

Still another embodiment is shown in FIG. 3, in which instead of a structure with two non-pivot support wheels and one steering wheel, the drive and steering operations are carried out by two separate motors 105. and 1
This is done simultaneously by wheels 103 and 104 with 06. These two wheels simultaneously serve as measuring wheels and have toothed rims and sensors as in the previous embodiment. Two wheels 101 and 102 are provided at both ends of the vehicle 100,
They are simply pivot wheels that rotate freely.
This embodiment was originally intended to show that the present invention is also applicable to the case where the steering operation is performed by differentially driving two wheels on collinear axes.
In many cases, it is desirable to provide separate measuring wheels and drive wheels, taking into account the risk of slippage of the drive wheels and errors.

The computational functionality of the embodiment shown in FIG.
This is done by means of a counter, which is connected to a measuring wheel. In the embodiment shown in FIG. 3, the steering operation is performed by motors 105 and 10.
It must be carried out by differentially controlling 6.
For this control, motor drive units 109 and 1
10, respectively. Rotation of the vehicle is caused by different outputs to the two motors, and if the outputs are of opposite signs and of the same magnitude, then the vehicle 100 will rotate between wheels 103 and 10.
Rotate around the center point with 4.

FIG. 4 shows a further embodiment in which a pivot bearing ring 2' is provided with angle measuring means 30'. As in the previous embodiment, the measuring wheel is provided with a toothed rim 20' and a sensor for measuring the rotational distance. Processing unit 8' is for angle measurement 1
0' and a wheel counter 9'. It goes without saying that the functions of this arithmetic unit 11' are somewhat different, and will be explained in detail below with reference to FIG.

FIG. 5 schematically shows this measurement method. As can be seen from the above schematic showing the computer program, instead of ΔX _h and ΔX _v the values K, α
It is sufficient to use .beta. and .beta., which values are calculated from the two measured values obtained from the measuring wheel 2'.
That is, the rotation distance ΔS _M and the rotation angle γ in the time interval Δt
Calculated from.

It can be seen from FIG. 5 that the wheel 2' forms an angle α with the main axis of the wheel. In order to be able to use the same calculation system as for the two-wheel measurement method, a transformation of the coordinates is carried out to calculate the displacement of the wheel during the time interval Δt, stored as the values of ΔS _M and γ. , component K for the forward displacement of the vehicle, rotation β around the center of rotation O, and midpoint P between both wheels.
rotation angle α around (which is a fixed point on the vehicle)
must be expressed by. It can be seen from FIG. 5 that the following relationship holds true.

KΔS _M cosγ β=ΔS _n /R′=SΔ _M sinγ/l It can be seen that l, b and v are constants and depend on the position of wheel 2' relative to wheels 2 and 3, and that the above equations only apply to pivot bearing wheels. If you are familiar with this technical field,
In practice, the wheel 2' must have a pivot axis in the vehicle that does not intersect the axle, i.e., otherwise the wheel 2' will not follow the movement, and the It will be appreciated that the above calculations are somewhat more complicated because spacing has to be taken into account.

The most important feature of the present invention is to periodically calculate how the position and orientation of the vehicle (the angle between the center line of the vehicle and the reference coordinate axis) has actually changed;
This calculated value allows the vehicle to be steered. That is, the illustrated features are not intended to limit the invention. That is, many different types of steering control means and measuring means may be used in vehicles constructed in accordance with the principles of the present invention.

In the first embodiment, the distance between wheels 2 and 3 is 1.129 m and the distance between the line joining said wheels on the one hand and the steering wheel 1 on the other hand is
It was 1.435m. The appropriate constants for the steering angle equation (3) are determined by simulation on an analog computer, and for this example, a=
2.4, b=0.7, c=1.4, d=0.6, e=1.0, and f=0.6, and the units were meters.

Experiments have shown that the present invention provides practically sufficient steering accuracy. Total length approx.
A closed path consisting of several curves of 100 m was used. A target line is drawn at the location of the route,
Detected every round to update the computer. The error in the vehicle's position calculated by "dead reckoning" was at best about 30 cm, despite the large length of the path laid out on the factory floor, which was far from ideal.

The present invention differs from vehicles running on tracks such as rails by the fact that it takes into account not only the motion of the vehicle, but also its attitude.

[Brief explanation of the drawing]

FIG. 1 shows the type of forklift truck used. FIG. 2 shows a three-wheeled self-guided vehicle operating in accordance with the principles of the present invention.
Partially shown in flow sheet format. FIG. 3 shows another embodiment. FIG. 4 shows a further embodiment in which the movement of the vehicle is measured by a pivot wheel provided with angle measuring means. FIG. 5 is a diagram showing how the pivot wheels of FIG. 4 are used to calculate and determine the travel curve and distance of the vehicle. FIG. 6 is a flowchart showing a procedure (program) for calculating the steering angle.
FIG. 7 is a flowchart showing a procedure (program) for outputting an appropriate steering angle signal via a D/A converter. 1... Steering wheel, 2, 3... Measuring wheel, 4... Sensor, 5... Gear, 6... Steering motor,
7... Digital sensor, 8... Central unit, 9, 10... Counter, 11... Arithmetic unit, 12... D/A converter, 14... DC servo,
20, 30... Rim, 40, 41... Pair of conductors, 10
0... Vehicle, 101, 102, 103, 104... Wheels, 105, 106... Motor, 107... Arithmetic unit, 108... Differential unit, 109, 110... Drive unit.

Claims (1)

[Scope of Claims] 1. A traveling means, a steering means, a steering drive means for causing the steering means to follow a predetermined route stored in a storage means as described below, A self-guided vehicle having a measuring device that simultaneously measures the resulting displacement as a change in two positional coordinates to obtain a travel displacement measurement value, the vehicle comprising: a storage means for storing a predetermined route of the vehicle; , the lateral deviation S _i (i=0, 1, 2,
…) and the attitude deviation of the vehicle with respect to the path φ _i
(i = 0, 1, 2, ...) from the travel displacement measurement values, and the difference in lateral deviation at two consecutive measurement times S ₂ −S ₁ /Δt, that is, the lateral movement Means for calculating the difference in speed and attitude deviation at two consecutive measurement times, φ ₂ −φ ₁ /Δt, that is, the turning speed with respect to the path, the lateral deviation S ₂ calculated immediately before, and the difference S ₂ −S ₁ /Δt, attitude deviation φ ₂ , and the difference φ ₂ −φ ₁ /Δt to calculate the total sum; and according to the calculated total sum, the steering means follows the predetermined path. A self-guided vehicle characterized by comprising: control means for controlling the steering drive means by applying a steering angle signal to the steering drive means. 2. A traveling means, a steering means, a steering drive means for causing the steering means to follow a predetermined route stored in the storage means described below, and a steering means for controlling the displacement caused by the vehicle traveling with respect to the ground. A self-guided vehicle having a measuring device that simultaneously measures changes in position coordinates and obtains travel displacement measurements, the vehicle having a storage means for storing a predetermined route of the vehicle, and a measuring device that simultaneously measures changes in position coordinates and obtains travel displacement measurements, The vehicle's lateral deviation S _i (i=0, 1, 2,
…) and the attitude deviation of the vehicle with respect to the path φ _i
(i = 0, 1, 2, ...) from the travel displacement measurement values, and the difference in lateral deviation at two consecutive measurement times S ₂ −S ₁ /Δt, that is, the lateral movement Means for calculating the difference in speed and attitude deviation at two consecutive measurement times, φ ₂ −φ ₁ /Δt, that is, the turning speed with respect to the path, the lateral deviation S ₂ calculated immediately before, and the difference S ₂ −S ₁ /Δt, attitude deviation φ ₂ , and the difference φ ₂ −φ ₁ /Δt to calculate the total sum; and according to the calculated total sum, the steering means follows the predetermined path. control means for controlling the steering drive means by giving it a steering angle signal, and the attitude deviation φ ₂ for calculating the calculated sum when the vehicle is moving away from a predetermined route. A self-guided vehicle, characterized in that it includes means for increasing a weighting factor multiplied by the vehicle, while decreasing said factor when the vehicle is parallel to or approaching a predetermined path.