JP7509073B2 - Autonomous Vehicles - Google Patents

Description

The present invention relates to an autonomous moving body.

Conventionally, there is known technology for improving the accuracy of control results when an autonomous mobile body moves straight ahead (see, for example, Patent Document 1).

JP 2019-099141 A

In conventional technology, the assembly of the steering wheels and drive wheels in an autonomous vehicle can reduce the accuracy of the control results when the autonomous vehicle turns.

The autonomous mobile body that achieves the above-mentioned objective is characterized by comprising a machine base having either a front wheel or a rear wheel that is steerable, a drive unit that drives the steerable wheels, a turning angular velocity detection unit that detects the turning angular velocity of the machine base, a calculation unit that calculates a correction value based on an ideal turning angular velocity when the machine base travels along a target route and the turning angular velocity detected by the turning angular velocity detection unit, a determination unit that determines an induced angular velocity of the steerable wheels based on the correction value, and a drive control unit that controls the drive unit based on the induced angular velocity determined by the determination unit.

According to this configuration, the autonomous moving body calculates a correction value based on the rotation angular velocity detected during rotation, and determines an induced angular velocity based on the calculated correction value. Therefore, by rotating based on the determined induced angular velocity, it is possible to improve the accuracy of the control results when the autonomous moving body is rotating.

In the autonomous moving body, the calculation unit may calculate a ratio between the turning angular velocity and the ideal turning angular velocity as the correction value.
According to this configuration, the determination unit can determine the induced angular velocity such that the turning angular velocity matches the ideal turning angular velocity by using the correction value.

In the autonomous moving body, the calculation unit may calculate a difference between the turning angular velocity and the ideal turning angular velocity as the correction value.
According to this configuration, the determination unit can determine the induced angular velocity such that the difference between the turning angular velocity and the ideal turning angular velocity is eliminated by using the correction value.

The above-mentioned autonomous moving body may further include a speed detection unit that detects the moving speed of the vehicle, and the calculation unit may further calculate, as the ideal turning angular velocity, a value obtained by dividing the moving speed of the vehicle detected by the speed detection unit by the dimension of the wheelbase, which is the distance from the front wheel set to the rear wheel set, and multiplying the result by the tangent of the steering angle, and may calculate the correction value based on the calculated ideal turning angular velocity.

According to this configuration, the calculation unit can calculate the correction value by simple processing.
In the above autonomous moving body, the determination unit may determine, as the induced angular velocity, the sum of a value obtained by multiplying a first rotation angular velocity related to feedforward control of the base by the correction value and a second rotation angular velocity related to feedback control of the base.

According to this configuration, the accuracy of the feedforward control during turning of the autonomous moving body is improved, and the accuracy of the control results during turning can be improved.
In the above autonomous moving body, the determination unit may determine, as the induced angular velocity, a value obtained by multiplying the sum of a first rotation angular velocity associated with feedforward control of the base and a second rotation angular velocity associated with feedback control of the base by the correction value.

This configuration can improve the accuracy of feedforward control and feedback control during turning. This allows the autonomous moving body to improve the accuracy of the control results when turning.

In the above autonomous mobile body, the correction values include a left correction value used when turning the machine base to the left and a right correction value used when turning the machine base to the right, and the calculation unit calculates the left correction value based on the turning angular velocity detected by the turning angular velocity detection unit when the machine base is turning to the left, and calculates the right correction value based on the turning angular velocity detected by the turning angular velocity detection unit when the machine base is turning to the right, and the determination unit may determine the induced angular velocity based on the left correction value when the machine base turns to the left while traveling along the target path, and determine the induced angular velocity based on the right correction value when the machine base turns to the right while traveling along the target path.

According to this configuration, it is possible to improve the accuracy of the control results when the autonomous moving body turns both left and right.
In the above autonomous moving body, the drive control unit may calculate an induced steering angle of the steerable wheels based on the induced angular velocity, and control the drive unit so that the steering angle of the steerable wheels becomes the induced steering angle.

With this configuration, the drive control unit calculates the induced steering angle used to control the drive unit, so that the drive unit can be controlled without having a separate configuration for performing calculation processing of the induced steering angle.

The present invention can improve the accuracy of control results when turning.

FIG. 1 is a diagram showing an example of the configuration of an autonomous moving body. FIG. 2 is a diagram showing an example of the configuration of a control device. FIG. 4 is a diagram used to explain a second turning angular velocity. 6 is a flowchart showing an example of an operation of a control unit related to a process of determining a correction value. 5 is a flowchart showing an example of an operation of a control unit related to control during turning.

[Embodiment]
<Configuration of the Autonomous Moving Body 10>
An embodiment of an autonomous mobile body will be described below with reference to the drawings. As shown in FIG. 1, the autonomous mobile body 10 is, for example, an "automatic guided vehicle" (AGV). The autonomous mobile body 10 means, for example, a trackless vehicle that loads luggage manually or automatically onto the main body, autonomously travels to a specified location, and manually or automatically unloads the luggage. The autonomous mobile body 10 includes, for example, an unmanned towing vehicle and an unmanned forklift. A case where the autonomous mobile body 10 is an unmanned towing vehicle will be described below.

Note that the "autonomous" aspect of the autonomous mobile body 10 means that no human is required to steer the vehicle, and does not exclude the autonomous mobile body 10 transporting "people (e.g., people unloading cargo)."

As shown in FIG. 1, the autonomous moving body 10 includes a base 11, a pair of left and right front wheels 14, and a pair of left and right rear wheels 15. In this embodiment, the front wheels 14 serve as steering wheels and drive wheels. The front wheels 14 are an example of steerable wheels.

The autonomous mobile body 10 includes a steering motor 22 that adjusts the steering angle δ of the front wheels 14, a driving motor 23 that drives the front wheels 14, and a control device 24. The autonomous mobile body 10 performs driving operations based on the control of the control device 24.

[Configuration of control device 24]
2, the autonomous moving body 10 includes a front wheel potentiometer 31, a front wheel encoder 32, and a gyro sensor 33. The front wheel potentiometer 31, the front wheel encoder 32, the gyro sensor 33, the steering motor 22, and the traveling motor 23 are connected to the control device 24.

The front wheel potentiometer 31 detects the steering angle δ of the front wheel 14 and outputs information indicating the detected steering angle δ to the control device 24. The front wheel encoder 32 is provided on the front wheel 14 and detects the rotation speed of the front wheel 14. The front wheel encoder 32 converts the rotation speed of the front wheel 14 into the moving speed v of the machine base 11 and outputs information indicating the converted moving speed v to the control device 24. The front wheel encoder 32 is an example of a speed detection unit that detects the moving speed v of the machine base 11.

The gyro sensor 33 detects the turning angular velocity ωm of the machine base 11 during turning, and outputs information indicating the detected turning angular velocity ωm to the control device 24. The gyro sensor 33 also detects an attitude angle θ indicating the inclination of the machine base 11, and outputs information indicating the detected attitude angle θ to the control device 24. The gyro sensor 33 is an example of a turning angular velocity detection unit that detects the turning angular velocity ωm of the machine base 11 in the process of detecting the turning angular velocity ωm.

The control device 24 controls the steering motor 22 and the travel motor 23. In detail, the control device 24 drives the steering motor 22 to control the direction of the front wheels 14, which are steered wheels. The control device 24 controls the rotation of the front wheels 14, which are drive wheels, by controlling the travel motor 23. The steering motor 22 and the travel motor 23 are examples of a drive unit.

The control device 24 includes, for example, a control unit 100 and a storage unit 200. The control unit 100 is realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). In addition, some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware.

The storage unit 200 is realized, for example, by a storage device (a storage device with a non-transient storage medium) such as an HDD (Hard Disk Drive) or a flash memory, or a removable storage medium such as a DVD or a CD-ROM. In addition to a program that realizes the control unit 100, the storage unit 200 stores, for example, left correction value information 202 indicating a left correction value CVL used for correction when the machine base 11 turns left, and right correction value information 204 indicating a right correction value CVR used for correction when the machine base 11 turns right. In the following description, when there is no need to distinguish between the left correction value CVL and the right correction value CVR, they will simply be referred to as correction value CV.

The control unit 100 includes a calculation unit 101, a determination unit 102, and a drive control unit 103. The calculation unit 101 calculates a correction value CV based on an ideal turning angular velocity ωt when the machine base 11 (i.e., the front wheels 14) travels along a target route, and a turning angular velocity ωm detected by the gyro sensor 33. Details of the process by which the calculation unit 101 calculates the correction value CV will be described later.

The determination unit 102 corrects the ideal turning angular velocity ωt based on the correction value CV calculated by the calculation unit 101, and determines the induced angular velocity ωd of the machine base 11. Details of the process by which the determination unit 102 determines the induced angular velocity ωd will be described later.

The drive control unit 103 drives and controls the steering motor 22 and the travel motor 23 based on the induced angular velocity ωd determined by the determination unit 102. In detail, the drive control unit 103 calculates the induced steering angle θd of the front wheels 14 based on the induced angular velocity ωd determined by the determination unit 102, and drives and controls the steering motor 22 so that the steering angle δ of the front wheels 14 becomes the induced steering angle θd.

[Calculation process of correction value CV]
Returning to Fig. 1, the calculation process of the correction value CV will be described in detail. As shown in the plan view of Fig. 1, the front wheels 14, which are drive wheels, of the autonomous mobile body 10 are not provided at the center of the machine base 11 in the left-right direction indicated by the center line CL, but are provided at a position offset from the center line CL of the machine base 11 as indicated by a solid line in Fig. 1. In other words, the front wheels 14 are provided at a position offset in the left-right direction from the center line CL passing through the center of the machine base 11.

In the following, it is assumed that the steering mechanism of the autonomous mobile body 10 is realized by an Ackermann mechanism. In this case, the angles of the pair of left and right front wheels 14 tilted by steering are the same. For ease of explanation, the steering angle δ of the machine base 11 will be described as the angle between the center line CLh of the imaginary front wheel 14a that is located at the center of the pair of left and right front wheels 14 and on the center line CL of the machine base 11, and the center line CL of the machine base 11. The angle of the front wheels 14 tilted by steering and the angle of the imaginary front wheel 14a are both steering angles δ.

In the following description, the dimension of the wheelbase, which is the distance from the front wheel axle AX1 that connects the pair of left and right front wheels 14 to the rear wheel axle AX2 that connects the pair of left and right rear wheels 15, is also referred to as the wheelbase L. In the following description, the distance from the turning center CP to the machine base 11 during turning is also referred to as the turning radius R.

The autonomous moving body 10 performs a calibration run, for example, when the autonomous moving body 10 starts its operation. In the calibration run, the autonomous moving body 10 is controlled by the control device 24 to perform a steady circular turn. While the autonomous moving body 10 performs a steady circular turn by the calibration run, the steering angle δ and the moving speed v are maintained at constant values.

First, the calculation unit 101 calculates the ideal turning angular velocity ωt prior to calculating the correction value CV. When the autonomous mobile body 10 makes a steady circular turn, the calculation unit 101 calculates the ideal turning angular velocity ωt based on the moving velocity v detected by the front wheel encoder 32 and the steering angle δ detected by the gyro sensor 33. The ideal turning angular velocity ωt can be geometrically expressed by the following formula (1).

ωt = v / R = v / L × tan δ ... (1)
ωt: ideal turning angular velocity v: moving velocity R: turning radius L: wheelbase δ: steering angle As shown in equation (1), the calculation unit 101 calculates the ideal turning angular velocity ωt by dividing the moving velocity v by the wheelbase L and multiplying the result by the tangent of the steering angle δ.

Next, the calculation unit 101 calculates the ratio between the turning angular velocity ωm detected by the gyro sensor 33 and the calculated ideal turning angular velocity ωt as the correction value CV. In detail, the calculation unit 101 calculates the value obtained by dividing the ideal turning angular velocity ωt by the turning angular velocity ωm as the correction value CV, as shown in the following formula (2).

CV = ωt / ωm (2)
CV: correction value ωt: ideal turning angular velocity ωm: turning angular velocity As shown in formula (2), in this embodiment, when the ideal turning angular velocity ωt and the turning angular velocity ωm are the same, the correction value CV is 1. Furthermore, when the turning angular velocity ωm is larger than the ideal turning angular velocity ωt, the correction value CV is a value smaller than 1 and larger than 0, and when the turning angular velocity ωm is smaller than the ideal turning angular velocity ωt, the correction value CV is a value larger than 1.

The calculation unit 101 calculates a left correction value CVL based on the turning angular velocity ωm detected by the gyro sensor 33 when the machine base 11 is turning left, and stores the calculated left correction value CVL in the storage unit 200 as left correction value information 202. The calculation unit 101 also calculates a right correction value CVR based on the turning angular velocity ωm detected by the gyro sensor 33 when the machine base 11 is turning right, and stores the calculated right correction value CVR in the storage unit 200 as right correction value information 204.

The determination unit 102 determines the induced angular velocity ωd based on the first turning angular velocity ωf, the second turning angular velocity ωb, and the correction value CV. Here, the first turning angular velocity ωf is the turning angular velocity related to the feedforward control of the machine base 11 when traveling along the target route. The second turning angular velocity ωb is the turning angular velocity related to the feedback control of the machine base 11 when traveling along the target route. The control unit 100 performs normal feedforward control and feedback control to travel along the target route, and derives the first turning angular velocity ωf and the second turning angular velocity ωb. The determination unit 102 determines the sum of the first turning angular velocity ωf multiplied by the correction value CV and the second turning angular velocity ωb as the induced angular velocity ωd, as shown in the following formula (3).

ωd = CV × ωf + ωb ... (3)
ωd: induced angular velocity CV: correction value ωf: first turning angular velocity ωb: second turning angular velocity As shown in formula (3), the determination unit 102 does not change the first turning angular velocity ωf by multiplying the first turning angular velocity ωf by the correction value CV when the ideal turning angular velocity ωt and the turning angular velocity ωm are the same. Also, when the turning angular velocity ωm is larger than the ideal turning angular velocity ωt, the determination unit 102 performs a correction to reduce the first turning angular velocity ωf by multiplying the first turning angular velocity ωf by a correction value CV that is smaller than 1 and larger than 0. Also, when the turning angular velocity ωm is smaller than the ideal turning angular velocity ωt, the determination unit 102 performs a correction to increase the first turning angular velocity ωf by multiplying the first turning angular velocity ωf by a correction value CV that is larger than 1.

The second turning angular velocity ωb will be described in detail with reference to FIG. 3. The control device 24 performs feedback control to determine the second turning angular velocity ωb so that the separation distance LZ from the center M of the autonomous mobile body 10 to the target route TR is 0, and the attitude angle θ, which is the angle between the target route TR and the center line CL, is 0. In this case, the autonomous mobile body 10 has a means capable of identifying its own position and information indicating the position of the target route TR, and identifies the separation distance LZ. In this case, the autonomous mobile body 10 further has information indicating its own reference attitude when traveling on the target route TR, and the gyro sensor 33 identifies the inclination from the reference attitude as the attitude angle θ. When the autonomous mobile body 10 is traveling on the target route TR, the second turning angular velocity ωb is 0.

When the machine base 11 turns left while traveling along the target route TR, the determination unit 102 reads out left correction value information 202 from the storage unit 200 and determines the induced angular velocity ωd based on the left correction value CVL. When the machine base 11 turns right while traveling along the target route TR, the determination unit 102 reads out right correction value information 204 from the storage unit 200 and determines the induced angular velocity ωd based on the right correction value CVR.
[Operation flow]
The flowchart shown in FIG. 4 is executed, for example, when the autonomous moving body 10 starts to operate or when an instruction for calibration travel is given to the autonomous moving body 10. First, the drive control unit 103 starts the calibration travel and controls the steering motor 22 and the traveling motor 23 so that the autonomous moving body 10 turns in a steady circle (step S100). Next, the calculation unit 101 acquires information indicating the turning angular velocity ωm detected by the gyro sensor 33 during steady circular turning (step S102). Next, the calculation unit 101 calculates the correction value CV based on the acquired turning angular velocity ωm and the calculated ideal turning angular velocity ωt (step S104). For example, during steady circular turning, the calculation unit 101 acquires the moving velocity v detected by the front wheel encoder 32, acquires the steering angle δ from the front wheel potentiometer 31, and calculates the ideal turning angular velocity ωt.

The flowchart shown in FIG. 5 is executed, for example, when the autonomous mobile body 10 turns while traveling along the target route TR. First, the control unit 100 performs feedforward control to derive the first turning angular velocity ωf (step S200). Next, the control unit 100 performs feedback control to derive the second turning angular velocity ωb (step S202).

Next, the determination unit 102 determines the induced angular velocity ωd based on the correction value CV stored in the memory unit 200, the first turning angular velocity ωf, and the second turning angular velocity ωb (step S204). In this embodiment, the determination unit 102 determines the sum of the first turning angular velocity ωf multiplied by the correction value CV and the second turning angular velocity ωb as the induced angular velocity ωd. In step S204, when the autonomous mobile body 10 turns left, the determination unit 102 reads the left correction value information 202 from the memory unit 200 and determines the sum of the first turning angular velocity ωf multiplied by the left correction value CVL and the second turning angular velocity ωb as the induced angular velocity ωd. Furthermore, in step S204, when the autonomous mobile body 10 is turned to the right, the determination unit 102 reads the right correction value information 204 from the storage unit 200, and determines the sum of the first turning angular velocity ωf multiplied by the right correction value CVR and the second turning angular velocity ωb as the induced angular velocity ωd.

Next, the drive control unit 103 calculates the steering angle δ of the front wheels 14 based on the induced angular velocity ωd determined by the determination unit 102 (step S206). Next, the drive control unit 103 controls the drive of the steering motor 22 so that the steering angle δ of the front wheels 14 becomes the calculated induced steering angle θd (step S208).

[Effects of the autonomous moving body 10 according to the present embodiment]
According to the present embodiment described above in detail, the following effects are achieved.
(1) The calculation unit 101 calculates a correction value CV based on an ideal turning angular velocity ωt when the machine 11 travels along the target route TR and the turning angular velocity ωm detected by the gyro sensor 33. The determination unit 102 determines an induced angular velocity ωd of the front wheels 14 based on the correction value CV. The drive control unit 103 controls the steering motor 22 and the traveling motor 23 based on the induced angular velocity ωd determined by the determination unit 102.

According to this configuration, the autonomous mobile body 10 calculates the correction value CV based on the rotation angular velocity ωm detected by turning, and determines the induced angular velocity ωd based on the calculated correction value CV. Therefore, the autonomous mobile body 10 can improve the accuracy of the control results during turning by turning based on the determined induced angular velocity ωd.

(2) The calculation unit 101 calculates the ratio between the turning angular velocity ωm and the induced angular velocity ωd as the correction value CV.
According to this configuration, the determination unit 102 can determine the induced angular velocity ωd by using the correction value CV so that the turning angular velocity ωm coincides with the ideal turning angular velocity ωt.

(3) The autonomous mobile body 10 further includes a front wheel encoder 32 that detects the moving speed v of the platform 11. The calculation unit 101 further calculates, as the ideal turning angular velocity ωt, a value obtained by dividing the moving speed v of the platform 11 detected by the front wheel encoder 32 by the wheelbase L and multiplying the result by the tangent of the steering angle δ. The calculation unit 101 calculates the correction value CV based on the calculated ideal turning angular velocity ωt.

According to this configuration, the calculation unit 101 can calculate the correction value CV by simple processing based on the travel speed v, the wheel base L, and the steering angle δ.
(4) The determination unit 102 determines the sum of the first rotation angular velocity ωf related to the feedforward control of the machine base 11 multiplied by the correction value CV and the second rotation angular velocity ωb related to the feedback control of the machine base 11 as the induced angular velocity ωd.

With this configuration, the determination unit 102 corrects the first turning angular velocity ωf related to the feedforward control. This improves the accuracy of the feedforward control during turning, and improves the accuracy of the control results when the autonomous mobile body 10 turns.

(5) The correction value CV includes a left correction value CVL used when turning the machine base 11 left and a right correction value CVR used when turning the machine base 11 right. The calculation unit 101 calculates the left correction value CVL based on the turning angular velocity ωm detected by the gyro sensor 33 when the machine base 11 is turning left. The calculation unit 101 also calculates the right correction value CVR based on the turning angular velocity ωm detected by the gyro sensor 33 when the machine base 11 is turning right. The determination unit 102 determines the induced angular velocity ωd based on the left correction value CVL when the machine base 11 turns left while traveling along the target route TR, and determines the induced angular velocity ωd based on the right correction value CVR when the machine base 11 turns right while traveling along the target route TR.

According to this configuration, the determination unit 102 can improve the accuracy of the control results of the autonomous moving body 10 both when the autonomous moving body 10 turns left and when the autonomous moving body 10 turns right.
(6) The drive control unit 103 calculates the induced steering angle θd of the front wheels 14 based on the induced angular velocity ωd, and controls the steering motor 22 and the traveling motor 23 so that the steering angle δ of the front wheels 14 becomes the calculated induced steering angle θd.

Here, depending on the type of steering motor 22, it may be necessary to provide a steering angle as control information. With this configuration, the autonomous mobile body 10 can control the steering motor 22 without having a separate driver or the like that performs the calculation process of the induced steering angle θd, by the drive control unit 103 calculating the induced steering angle θd used to control the steering motor 22.

[When there is one correction value CV]
In the above description, the calculation unit 101 calculates the left correction value CVL and the right correction value CVR used when the autonomous mobile body 10 turns left and turns right, respectively, but this is not limited to the above. The left correction value CVL may be used, for example, when turning right, and the right correction value CVR may be used, for example, when turning left. In addition, when the same correction value CV is used when turning left and when turning right, the storage unit 200 may store either the left correction value information 202 or the right correction value information 204 instead of the configuration in which both the left correction value information 202 and the right correction value information 204 are stored. In addition, instead of or in addition to the configuration in which both the left correction value information 202 and the right correction value information 204 are stored, correction value information indicating the correction value CV used when turning both may be stored.

[Another Example of Determination Process of Induced Angular Velocity ωd]
In the above description, the determination unit 102 determines the sum of the first turning angular velocity ωf multiplied by the correction value CV and the second turning angular velocity ωb as the induced angular velocity ωd, but this is not limiting. The determination unit 102 may determine the sum of the first turning angular velocity ωf and the second turning angular velocity ωb multiplied by the correction value CV as the induced angular velocity ωd, as shown in the following formula (4).

ωd = CV(ωf + ωb) ... (4)
ωd: induced angular velocity CV: correction value ωf: first turning angular velocity ωb: second turning angular velocity As shown in formula (4), the determination unit 102 multiplies the sum of the first turning angular velocity ωf and the second turning angular velocity ωb by the correction value CV, and when the ideal turning angular velocity ωt and the turning angular velocity ωm are equal, the determination unit 102 does not change the sum of the first turning angular velocity ωf and the second turning angular velocity ωb. Also, when the turning angular velocity ωm is larger than the ideal turning angular velocity ωt, the determination unit 102 performs a correction to reduce the induced angular velocity ωd by multiplying the sum of the first turning angular velocity ωf and the second turning angular velocity ωb by the correction value CV that is smaller than 1 and larger than 0. In addition, when the turning angular velocity ωm is smaller than the ideal turning angular velocity ωt, the determination unit 102 performs a correction to increase the induced angular velocity ωd by multiplying the sum of the first turning angular velocity ωf and the second turning angular velocity ωb by a correction value CV greater than 1.

According to this configuration, the determination unit 102 corrects the sum of the first turning angular velocity ωf related to the feedforward control and the second turning angular velocity ωb related to the feedback control (i.e., the induced angular velocity ωd before correction). This makes it possible to improve the accuracy of the feedforward control and the feedback control during turning. This allows the autonomous mobile body 10 to improve the accuracy of the control results during turning.

[Another Example of Calculation Process of Correction Value CV]
In the above description, the calculation unit 101 calculates the ratio between the turning angular velocity ωm detected by the gyro sensor 33 and the calculated ideal turning angular velocity ωt as the correction value CV, but this is not limiting. The calculation unit 101 may calculate the difference between the turning angular velocity ωm detected by the gyro sensor 33 and the calculated ideal turning angular velocity ωt as the correction value CV. In more detail, the calculation unit 101 calculates the value obtained by subtracting the turning angular velocity ωm from the ideal turning angular velocity ωt as the correction value CV, as shown in the following formula (5).

CV = ωt - ωm ... (5)
CV: correction value ωt: ideal turning angular velocity ωm: turning angular velocity As shown in formula (5), in this embodiment, when the ideal turning angular velocity ωt and the turning angular velocity ωm are the same, the correction value CV is 0. Furthermore, when the turning angular velocity ωm is smaller than the ideal turning angular velocity ωt, the correction value CV is a value greater than 0, and when the turning angular velocity ωm is larger than the ideal turning angular velocity ωt, the correction value CV is a value less than 0.

In this case, instead of using equation (3), the determination unit 102 calculates the sum of the difference obtained by subtracting the correction value CV from the first turning angular velocity ωf and the second turning angular velocity ωb as the induced angular velocity ωd, as shown in equation (6).

ωd = ωf - CV + ωb ... (6)
ωd: induced angular velocity ωf: first turning angular velocity CV: correction value ωb: second turning angular velocity With this configuration, the determination unit 102 uses the difference between the actual turning angular velocity ωm detected by the gyro sensor 33 and the ideal turning angular velocity ωt that can be taken when traveling along the target route TR as the correction value CV. This allows the determination unit 102 to determine the induced angular velocity ωd so that there is no difference between the turning angular velocity ωm and the ideal turning angular velocity ωt.

The above-described embodiments may be modified as follows: The above-described embodiments and the following examples may be combined with each other as long as they are not technically inconsistent.
The steering angle δ is not limited to being detected by the front wheel potentiometer 31, and may be detected by another sensor such as an absolute encoder.

The speed detection unit is not limited to the front wheel encoder 32, and other sensors may be used. For example, the gyro sensor 33 may detect the speed by integrating the acceleration component parallel to the traveling direction.

In the embodiment, the autonomous moving body 10 is described as an unmanned towing vehicle, but this is not limited to this. The autonomous moving body 10 may be a reach-type unmanned forklift, a counterbalance-type unmanned forklift that does not have a reach function, etc.

In the embodiment, the autonomous moving body 10 is described as having two front wheels 14, but this is not limited to the above. The autonomous moving body 10 may also have one front wheel 14 and two rear wheels 15.

The autonomous moving body 10 may also have two front wheels 14 and one rear wheel 15.
Furthermore, the autonomous moving body 10 may have rear wheels 15 as steering wheels and drive wheels, or one of the front wheels 14 and the rear wheels 15 may be a steering wheel and the other may be a drive wheel.

10...autonomous moving body, 11...machine base, 14...front wheel, 15...rear wheel, 22...steering motor as drive unit, 23...travel motor as drive unit, 32...front wheel encoder as speed detector, 33...gyro sensor as turning angular velocity detector, 101...calculation unit, 102...determination unit, 103...drive control unit, AX1...front wheel axle, AX2...rear wheel axle, CV...correction value, CVR...right correction value, CVL...left correction value, L...wheelbase, TR...target route, v...travel speed, δ...steering angle, θd...induced steering angle, ωf...first turning angular velocity, ωb...second turning angular velocity, ωd...induced angular velocity, ωm...turning angular velocity, ωt...ideal turning angular velocity.

Claims (4)

A machine base having either one of the front wheels or the rear wheels steerable;
A drive unit that drives the steerable wheels;
a rotation angular velocity detection unit for detecting a rotation angular velocity of the machine base;
a calculation unit that calculates a correction value based on an ideal turning angular velocity when the machine travels along a target path and the turning angular velocity detected by the turning angular velocity detection unit;
a determination unit for determining an induced angular velocity of the steerable wheels based on the correction value;
a drive control unit that controls the drive unit based on the induced angular velocity determined by the determination unit ,
The calculation unit calculates a ratio between the turning angular velocity and the ideal turning angular velocity as the correction value,
the determination unit determines, as the induced angular velocity, a sum of a first rotation angular velocity related to a feedforward control of the machine base multiplied by the correction value and a second rotation angular velocity related to a feedback control of the machine base.
An autonomous moving body characterized by: A speed detection unit that detects a moving speed of the machine base is further provided,
the calculation unit further calculates, as the ideal turning angular velocity, a value obtained by dividing the moving speed of the machine base detected by the speed detection unit by a dimension of a wheelbase, which is a distance from a front wheel axle to a rear wheel axle, and multiplying the result by a tangent of a steering angle, and calculates the correction value based on the calculated ideal turning angular velocity.
The autonomous moving body according to claim 1 . The correction values include a left correction value used when turning the machine base left and a right correction value used when turning the machine base right,
the calculation unit calculates the left correction value based on the turning angular velocity detected by the turning angular velocity detection unit when the machine base is turning left, and calculates the right correction value based on the turning angular velocity detected by the turning angular velocity detection unit when the machine base is turning right,
the determination unit determines the induced angular velocity based on the left correction value when the machine base turns left while traveling along the target route, and determines the induced angular velocity based on the right correction value when the machine base turns right while traveling along the target route.
The autonomous moving body according to claim 1 or 2 . The drive control unit calculates an induced steering angle of the steerable wheels based on the induced angular velocity, and controls the drive unit so that the steering angle of the steerable wheels becomes the induced steering angle.
The autonomous moving body according to claim 1 .