Transport navigation robot and heading correction method thereof

Abstract

The application belongs to the technical field of automatic positioning and navigation, and provides a transport navigation robot and a heading correction method thereof, which realizes inertial navigation and heading correction of the robot trolley through an IMU inertial navigation module, a laser ranging correction module and a back-end processing unit fixed on the robot trolley. Compared with the AGV logistics transport robot using ground magnetic strips, the robot is not affected by the complex ground conditions and has relatively good adaptability in the indoor environment with more people and other mobile carriers. Compared with the traditional visual navigation relying on visual image data acquisition, the robot is less affected by the environmental light source. The robot does not need to use high-priced hardware or sensors such as laser radar and depth camera, so that the cost of the robot trolley is relatively low. The robot does not need to lay magnetic strips and paste protective magnetic strip tapes along the whole navigation path, and only needs to travel along the wall surface, so that the installation and maintenance costs can be reduced in a specific navigation environment.

Description

Technical Field

[0001] This invention belongs to the field of automated positioning and navigation technology, specifically relating to a method based on IMU A wall-mounted logistics transport robot using an inertial measurement unit (IMU) and a laser rangefinder sensor, and its heading correction method. Background Technology

[0002] With the development of automated positioning and navigation technology, indoor mobile robot navigation technology is becoming increasingly mature compared to outdoor (GPS) vehicle navigation technology, with a favorable market mechanism and increasingly broad application prospects. For example, automated production workshops in industrial environments, restaurant corridors in commercial environments, or logistics delivery channels in medical institutions are increasingly requiring intelligent logistics robots that can automatically travel back and forth along planned fixed routes to replace manual labor, save labor costs, and improve production or transportation efficiency. Therefore, it is essential to invent a logistics transportation robot suitable for indoor applications that is low-cost, simple to implement, and easy to implement.

[0003] In response to the above needs, there are currently many relevant solutions both domestically and internationally.

[0004] Currently, there are two main types of indoor logistics and transportation robots:

[0005] One is based on AGV Magnetic strip navigation robots offer advantages such as flexible path planning and relatively accurate navigation. However, traditional magnetic strip navigation robots require laying magnetic strips on the navigation surface beforehand and then attaching protective tape. Magnetic strips themselves have relatively poor wear resistance compared to the ground, making them suitable for installation in dry, clean environments. Therefore, they are well-suited for use in clean, automated industrial production workshops. When the application scenario involves a large flow of people or other mobile vehicles, and the environment is prone to ground wear, the magnetic strip navigation solution becomes less adaptable.

[0006] Another type is the vision-based line-following robot. Its navigation is also quite accurate. However, in indoor environments with complex or dim lighting, the quality of the visual images deteriorates, affecting navigation performance. Furthermore, it requires expensive LiDAR or depth cameras, resulting in higher costs. Summary of the Invention

[0007] To address the aforementioned problems, this invention proposes a relatively low-cost, less affected by ambient light, and environmentally adaptable system based on indoor floor wear. IMU A logistics transportation navigation robot equipped with a laser ranging sensor. To achieve the above objectives, the present invention adopts the following specific technical solution:

[0008] A transport navigation robot includes: a robot car fixed to a robot vehicle. IMUInertial navigation module, laser ranging correction module, and back-end processing unit;

[0009] IMU The inertial navigation module is used to acquire IMU Heading angle;

[0010] The laser ranging correction module is used to measure the distance between the robot and obstacles;

[0011] The back-end processing unit is used to implement inertial navigation and heading correction for the robot vehicle.

[0012] Preferably, the laser emitted by the laser ranging correction module is perpendicular to the side surface of the robot vehicle.

[0013] Preferably, the obstacle is a wall, fence, or partition that obstructs the movement of the robot vehicle.

[0014] Preferably, IMU The inertial navigation module hardware uses a six-axis gyroscope or a three-axis gyroscope.

[0015] Preferably, the laser ranging correction module includes four laser ranging sensors located at the front and rear ends of the left and right sides of the robot car, respectively, with all four sensors mounted at the same height; the laser ranging sensors are... TOF Laser rangefinder sensor.

[0016] Preferably, the back-end processing unit includes a main control module and a driver module; the main control module hardware adopts... The development board uses a hub servo motor driver as its drive module.

[0017] A method for correcting the course of a transport navigation robot includes the following steps:

[0018] S1. Compare the current heading angle Compared with the initial standard heading angle The magnitude relationship is used to control the angular velocity required to compensate for the angle difference based on the corrected travel time. This enables inertial navigation of the robot car;

[0019] S2. Establish a heading correction model so that the center point of the line connecting the centroids of the first laser rangefinder and the second laser rangefinder is... Distance from the wall d Equal to the distance between the first laser rangefinder and the obstacle Distance from the obstacle to the second laser rangefinder average This enables the robot car to correct its course.

[0020] Preferably, the method further includes the following steps before step S1:

[0021] Step S0: Establishing a gyroscope world coordinate system;

[0022] The gyroscope world coordinate system satisfies the right-hand rule.

[0023] Preferably, step S1 comprises the following steps:

[0024] S101, selecting the current relatively stable IMU heading angle as the initial standard heading;

[0025] S102, setting the linear velocity of the robot car as and the angular velocity as ,

[0026] When the current heading angle , the corrected travel time is obtained by using formula (1):

[0027] (1)

[0028] Where, is the angular velocity required to set the compensation angle difference;

[0029] When the current heading angle , the corrected travel time is obtained by using formula (2):

[0030] (2)

[0031] S103, the main control module sends the linear velocity and the angular velocity to the robot car driving module through the serial port, and controls the travel time of the angular velocity in real time.

[0032] Preferably, step S2 comprises the following steps:

[0033] S201, the transport navigation robot makes a first left turn or right turn in place, so that its side is parallel to the obstacle;

[0034] S202, the second left turn or right turn in place is fixed at an angle , and after a straight travel distance , it reaches the target position, and then makes a reverse direction turn in place at a fixed angle , so that its side is parallel to the obstacle.

[0035] Preferably, step S201 is divided into two cases:

[0036] When , the right turn in place makes​ The motion time for controlling right turn is calculated by the following formula:

[0037] (3)

[0038] wherein, is the data measured by the second laser ranging sensor;

[0039] is the measured data measured by the first laser ranging sensor;

[0040] is the set angular velocity of the robot car;

[0041] is the distance between the first laser ranging sensor and the second laser ranging sensor;

[0042] (4);

[0043] When , the left turn in place makes The motion time for controlling left turn is calculated by formula (3), and at this time,

[0044] (5).

[0045] Preferably, step S202 is divided into two cases:

[0046] When , the second time for right turn in place is obtained by formula (6):

[0047] (6)

[0048] wherein, is the set angular velocity of the second right turn in place and the left turn in place stage,

[0049] The running time of the straight driving stage is obtained by the following formula:

[0050] (7)

[0051] wherein, is the set linear velocity of the robot car in the straight driving process;

[0052] When , the second time for left turn in place is obtained by formula (6), and at this time, is the set angular velocity of the second left turn in place and the right turn in place stage;

[0053] The running time of the straight driving stage is obtained by formula (7).

[0054] Preferably, the method further comprises a step S5 of:

[0055] The main control module sends the linear velocity and angular velocity of the robot car to the drive module through a serial port, and sends the linear velocity and angular velocity to the drive module according to 、 、 Real-time control is performed to set the running time of the set linear velocity and angular velocity, so that the heading correction is realized.

[0056] The present application can achieve the following technical effects:

[0057] 1. The logistics transport robot is based on indoor obstacle navigation running, and compared with the logistics transport robot using ground magnetic strips, is not affected by complex ground conditions, and has relatively good adaptability in an indoor environment with more people and other mobile carriers. AGV

[0058] 2. The corrected heading navigation is obtained by laser ranging, and compared with the traditional visual navigation relying on visual image data, is relatively less affected by environmental light sources.

[0059] 3. The present application does not need to use high-priced hardware or sensors such as laser radar and depth camera, so that the cost of the robot car is relatively low.

[0060] 4. The present application does not need to lay magnetic strips and paste protective magnetic strip adhesive tape along the navigation path, and only needs to run along the obstacles, so that the installation and maintenance cost can be reduced in a specific navigation environment. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is a system framework diagram of a transport navigation robot according to an embodiment of the present application;

[0062] Figure 2 is an inertial navigation framework structure according to an embodiment of the present application; IMU

[0063] Figure 3 is a gyroscope world coordinate system according to an embodiment of the present application;

[0064] Figure 4 is a laser ranging framework structure of a robot car according to an embodiment of the present application;

[0065] Figure 5 is a wall-following heading correction model when laser ranging , according to an embodiment of the present application;

[0066] Figure 6 is a wall-following heading correction model when laser ranging , according to an embodiment of the present application;​​

[0067] Figure 7 laser ranging when the robot is moving along a wall , laser ranging when the robot is moving along a wall

[0068] Figure 8 laser ranging when the robot is moving along a wall , laser ranging when the robot is moving along a wall

[0069] Figure 9 laser ranging when the robot is moving along a wall

[0070] Reference signs:

[0071] robotic cart 1,

[0072] IMU inertial navigation module 2, six-axis gyroscope 21,

[0073] laser ranging correction module 3, first laser ranging sensor 31, second laser ranging sensor 32, third laser ranging sensor 33, fourth laser ranging sensor 34,

[0074] main control module 4, drive module 5. DETAILED DESCRIPTION

[0075] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not constitute a limitation on the present application.

[0076] The purpose of the present application is to provide a relatively low-cost, easy-to-implement and environmentally adaptable robot that is good at adapting to indoor ground that is easily worn, by IMU carrying out inertial navigation and using laser ranging sensors to measure the distance between the robot and obstacles to assist in correcting the heading, the transportation and navigation functions of the robotic cart in the indoor ground that is easily worn are realized. A transportation and navigation robot and a heading correction method thereof provided by the present application will be described in detail below through specific embodiments.

[0077] As shown in the system framework, it includes an Figure 1 inertial navigation module 2, a laser ranging correction module 3 and a back-end processing unit fixed on the robotic cart 1; IMU

[0078] IMU The inertial navigation module 2 is used to obtain IMU ​The heading angle and laser ranging correction module 3 are used to measure the distance between the robot car 1 and the obstacle on the side closest to the wall. The back-end processing unit is used to realize the inertial navigation and heading correction of the robot car 1.

[0079] The back-end processing unit includes a main control module 4 and a driver module 5. The hardware of the main control module 4 adopts... The development board uses a hub servo motor driver in drive module 5.

[0080] IMU The inertial navigation module 2 hardware employs a six-axis gyroscope 21 or a three-axis gyroscope. In a preferred embodiment of the present invention, such as... Figure 2 Shown IMU The inertial navigation frame uses a six-axis gyroscope 21, which is fixed at the center of gravity of the robot car 1.

[0081] In a preferred embodiment of the present invention, a wall is selected as an obstacle, but it can also be a fence, partition or other object that obstructs the movement of the robot car 1.

[0082] The laser ranging correction module 3 includes a first laser ranging sensor 31, a second laser ranging sensor 32, a third laser ranging sensor 33, and a fourth laser ranging sensor 34, located at the front and rear ends of the left and right sides of the robot car 1, respectively. Figure 4 As shown, the four laser rangefinders are installed at the same height, and the emitted lasers are all perpendicular to the side surface of the robot car 1. The four laser rangefinders are... TOF Laser rangefinder sensor.

[0083] Combination Figure 9 The flowchart of the heading correction method shown illustrates the two functions performed by the back-end processing unit of this invention: one is through... IMU The inertial navigation module 2 acquires the heading angle information to realize inertial navigation of the robot car 1; secondly, it uses real-time measured laser ranging data to realize the heading correction of the robot car 1.

[0084] exist Figure 2 On the basis of establishing such Figure 3 The world coordinate system of the gyroscope shown makes the six-axis gyroscope 21 z The axis is perpendicular to the horizontal ground and points downwards. y The axis is parallel to the horizontal ground and its direction is the forward direction of robot car 1. x The shafts are respectively with y shaft and z The axis is perpendicular and the positive direction is to the left of robot car 1. The gyroscope world coordinate system satisfies the right-hand rule. Additionally, in On a plane, IMU Heading angle byx The axis is positive when rotated clockwise and negative when rotated counterclockwise.

[0085] In a preferred embodiment of the present invention, the main control module 4 obtains the signal sent by the six-axis gyroscope 21 via serial communication. IMU Heading angle data, and the current relatively stable value of robot car 1 during its movement. IMU Heading angle As the initial standard heading.

[0086] During the movement of the robot car 1, errors inevitably occur within the system due to issues such as the accuracy of the driver control and the accuracy of the wheel shape and position, causing the robot car 1 to gradually veer off course.

[0087] Let the linear velocity of robot car 1 be... angular velocity ,like Figure 3 As shown, when Acquired IMU Heading angle When, let the angular velocity required to compensate for the angle difference be... Then, the angular velocity can be calculated using equation (1). When turning left, the travel time is adjusted accordingly.

[0088] (1)

[0089] when IMU Heading angle Then, use equation (2) to obtain the travel time for the right turn correction. :

[0090] (2)

[0091] at last linear velocity With angular velocity The data is sent to the drive module 5 of the robot car 1 via serial port, and according to... Real-time control of angular velocity The travel time is used to control the movement of the robot car 1, thereby achieving inertial navigation of the robot car 1.

[0092] In another embodiment of the present invention, the lasers emitted by the first laser ranging sensor 31 and the second laser ranging sensor 32 are not perpendicular to the obstacle surface. The actual distance between the robot car 1 and the obstacle can be calculated using trigonometric functions. Taking the case where the emitted laser is perpendicular to the obstacle surface as an example, the following is established: Figure 5 The heading correction model shown:

[0093] Let the distance data measured by the second laser rangefinder 32 be... The distance data measured by the first laser rangefinder 31 is The center point of the line connecting the centroids of the first laser rangefinder 31 and the second laser rangefinder 32 is... The distance is S Assume the distance between the six-axis gyroscope 21 and the wall is... m 1 to m The distance between 2 and the wall is the standard driving distance range. ).

[0094] As errors accumulate within the robot car 1's driving system, the robot car 1's position will deviate from the standard distance from the wall. Therefore, the purpose of heading correction is to align the center points of the first laser rangefinder 31 and the second laser rangefinder 32. The distance from the wall is located at and Between, that is ,when d Approaching or equal to and average This is to complete the course correction.

[0095] In a preferred embodiment of the present invention, the ranging accuracy of the laser ranging correction module 3 is less than 1 cm. The data is sent to the main control module 4 via serial port.

[0096] when At times, such as Figure 5 , Figure 7 As shown, the calculation is performed using formula (4). Distance of point from wall d :

[0097] (4)

[0098] Then, determine if Then adopt Figure 5 The modified model undergoes a two-step modification:

[0099] The first step is to set the robot car to linear speed 1. =0, angular velocity is Turn right in place That is, correct the heading of robot car 1 so that the side of robot car 1 is parallel to the wall. The movement time for controlling the right turn can be calculated by equation (3):

[0100] (3)

[0101] The second step is to perform a fixed right turn in place. Straight-line driving distance Then turn left at a fixed angle. This is to correct the robot car 1 The distance of the point from the wall. Let the angular velocity of the second in-place right turn be... The time for the second right turn can be calculated using the following formula (6).

[0102] (6)

[0103] Let the linear velocity during the straight-line travel in the second correction step be... From equation (7), the running time for the straight-line driving phase can be obtained:

[0104] (7)

[0105] Let the angular velocity during the left turn phase also be And the rotation angle is the same as that of a right turn. Therefore, the time for turning left in place is also... .

[0106] Similarly, the judgment if Then adopt Figure 7 The two-step correction model.

[0107] First, the course correction process is the same as step S201 above. Second, the correction process changes to first performing a fixed-angle left turn in place. Then travel in a straight line for a distance r Then turn right at a fixed angle. On the first robot car of the correction The distance of the point from the wall. The calculation methods for motion control time during turning and straight-line driving are the same as... Figure 5 The modified models are the same, namely (3), (6), and (7).

[0108] When laser ranging data At times, such as Figure 6 , Figure 7 As shown, the distance from the point to the wall is calculated using the following formula (5). d :

[0109] (5).

[0110] Similarly, judge when Then adopt Figure 6 The modified model is modified in two steps.

[0111] The first step is to set the robot car to linear speed 1. v =0, angular velocity is Turn left in place Correct the heading of robot car 1 so that its side is parallel to the wall. Similarly, the left turn time can be obtained from equation (4). The second step is...Figure 5 The second step is the same.

[0112] Judgment when Then adopt the following Figure 8 The modified model undergoes a two-step modification. The first step involves... Figure 6 The first step is the same, and the second step is the same. Figure 7 The second step is the same.

[0113] In another preferred embodiment of the invention, when calculating Distance from the point to the wall d satisfy At that time, the robot car 1 was made to move at a linear velocity v ( Angular velocity Simply drive in a straight line. Due to systematic errors, robot car 1 will reach a certain point after driving for a period of time. Figure 5 or Figure 6 or Figure 7 or Figure 8 Choose one of the four states shown, and then correct the course according to the corresponding model.

[0114] Finally, the main control module 4 sends the linear velocity and angular velocity of the robot car 1 to the drive module 5 via the serial port, and according to... , , The travel time is controlled in real time with a set linear velocity and a set angular velocity to achieve heading correction.

[0115] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0116] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0117] The above detailed description of the application is not intended to limit the scope of the application. Various other changes and modifications of the application will be apparent to those skilled in the art and such changes and modifications are intended to be included within the scope of the application as defined by the following claims.

Claims

1. A transport navigation robot, characterized by, Comprise: Fixed on the robot trolley IMU An inertial navigation module, a laser ranging correction module and a back-end processing unit the IMU The inertial navigation module is configured to obtain IMU heading angle; The laser ranging correction module is used to measure the distance between the robot car's wall-side side and the obstacle; the laser ranging correction module includes four laser ranging sensors located at the front and rear ends of the left and right side surfaces of the robot car, respectively, and the four laser ranging sensors are installed at the same height; the laser ranging sensors are... TOF A laser ranging sensor; the back-end processing unit is used to implement inertial navigation and heading correction for the robot vehicle; the heading correction process is as follows: establish a heading correction model, and make the center point of the line connecting the centroids of the first laser ranging sensor and the second laser ranging sensor... Distance from the wall d Equal to the distance between the first laser rangefinder and the obstacle Distance from the obstacle to the second laser rangefinder average This allows for course correction of the robotic vehicle; the transport navigation robot first turns left or right in place to align its side with the obstacle; then it turns left or right a second time at a fixed angle. Straight-line driving distance After reaching the target location, turn in the opposite direction at the fixed angle. So that its side is parallel to the obstacle.

2. The transport navigation robot of claim 1, wherein, The laser emitted by the laser ranging correction module is perpendicular to the side surface of the robot trolley.

3. The transport navigation robot of claim 1, wherein, The obstacle is a wall, fence or partition that hinders the travel of the robot trolley.

4. The transport navigation robot of claim 1, wherein, The IMU The inertial navigation module hardware employs a six-axis gyroscope or a three-axis gyroscope.

5. The transport navigation robot of claim 1, wherein, The back-end processing unit comprises a main control module and a driving module; the main control module is hardware The development board, the driving module adopts a hub servo motor driver.

6. A method for correcting the heading of a transport navigation robot according to any one of claims 1 to 5, characterized in that Comprise the following steps: S1, compare the current heading angle with the initial standard heading angle , and control the angular velocity required to compensate for the angle difference according to the modified travel time , to realize inertial navigation of the robot car S2, a heading correction model is established to make the center point of the line connecting the centroids of the first laser ranging sensor and the second laser ranging sensor the distance from the wall d equal to the average of the distance from the first laser ranging sensor to the obstacle the distance from the second laser ranging sensor to the obstacle , and the heading correction of the robot trolley is realized; step S2 comprises the following steps:​ S201, the transport navigation robot turns left or right for the first time, so that its side is parallel to the obstacle; S202、secondly, turn left or right in place by a fixed angle , straight driving distance After reaching the target position, turn in place by the fixed angle in the opposite direction So that the side is parallel to the obstacle.

7. The transport navigation robot course correction method of claim 6, wherein, Before step S1, it further comprises: Step S0: establishing a gyroscope world coordinate system; The gyroscope world coordinate system satisfies the right-hand rule.

8. The method of claim 6, wherein, Step S1 comprises the following steps: S101, Select the current more stable option. IMU heading angle As the initial standard course; S102、Set the linear velocity of the robot trolley as And the angular velocity is , When the current heading angle is obtained using equation (1) : （1） wherein ωc is the angular velocity needed to compensate for the angular difference; When the current heading angle is obtained using equation (2) : （2）； S103、the main control module sends the linear speed and the angular velocity to the robot car driving module through the serial port, and controls the angular velocity and the running time of the robot car in real time according to the linear speed .

9. The method of claim 6, wherein, Step S201 is divided into two cases: When a right turn in place is made the motion time for the right turn is calculated by the following equation: （3） wherein, data measured for the second laser ranging sensor; measured data measured for the first laser distance sensor; set an angular velocity for the robot cart; a distance between the first laser ranging sensor and the second laser ranging sensor; （4）； when At that time, turn left in place. The motion time for controlling the left turn is calculated using equation (3). At this time, （5）。 10. The method of claim 6, wherein, Step S202 is divided into two cases: When the second time to turn right in place is obtained by equation (6): （6） wherein is the set angular velocity for the second right turn in place and left turn in place phase, The running time of the straight-line driving stage is obtained by the following formula: （7） wherein, is the set linear velocity of the robot trolley during the straight-line driving process When the second time of the left turn in place is obtained by formula (6), at this time, is the set angular velocity of the second left turn in place and the right turn in place stage. The running time of the straight-line driving stage is obtained by formula (7).

11. The method of claim 6, wherein, Further comprising step S3: The main control module sends the linear velocity and angular velocity of the robot trolley to the driving module through a serial port, and controls the driving module to drive the robot trolley to move according to the linear velocity and angular velocity 、 、 The driving time of the linear velocity and the set angular velocity is set in real time to realize the course correction.

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