ES2401509B1 - GUIDING SYSTEM FOR AUTONOMOUS MOVEMENT OF VEHICLES IN STRUCTURED ENVIRONMENTS. - Google Patents

Abstract

The aim of the invention is a system for guiding autonomous vehicles through cameras and / or photodetectors to follow a path, which is determined by a set of laser emitters arranged in a structured environment, for example, in the different aisles of a greenhouse, and that determines the path to follow. # For the establishment of the path to follow, there are several laser emitters placed in the corridors of the greenhouse, which will be active depending on the aisles that the vehicle must travel to describe the expected path.

Description

GUIDANCE SYSTEM FOR AUTONOMOUS MOVEMENT OF VEHICLES IN STRUCTURED ENVIRONMENTS

Guidance system for autonomous movement of vehicles in structured environments.

Technical sector

1O The present invention is included within the sector of the auxiliary agriculture industry in general, and more specifically in the sector of the industry dedicated to the manufacture of machines and equipment for carrying out agricultural operations.

State of the art

15 The navigation systems currently used for autonomous vehicles in structured environments (for example a greenhouse) are complex and expensive. The most widely used are based on absolute location techniques with systems based on Global Positioning System (GPS) or through the use of

20 AGV (Automatic Guided Vehicle) beacons and guides, and relative location techniques based on odometry. The former have the disadvantage of low signal quality in closed environments and a margin of error that make them inefficient in these environments, as well as the need for a large economic investment in installation. Odometry-based systems present the problem of errors accumulated in

25 long journeys, which does not make them suitable for large structured environments, such as a greenhouse.

Patent E89304450 "Automatic vehicle control"; It presents a typical location system using beacons. The vehicle incorporates a system of lasers to recognize

30 marks or beacons in the environment. These beacons are represented by unique barcodes, which are used to estimate the relative position of the vehicle through triangulation (similar to the way GPS does with satellites). The proposed invention is an advance with respect to this system, since the laser is used to guide the vehicle along a defined path and not to position it.

35 In PCT / NL 1998/000450 "System and method for the control of vehicles", the authors present a reactive guidance system for a vehicle. The idea is basically to include in the work scenario of the vehicle to automate a set of markers - arranged at regular intervals on the surface or walls - to mark the route that

40 should follow the vehicle. As before, with respect to this patent, the system object of the invention differs, because it proposes a laser-based guidance system over a structured environment although, indeed, the trajectory can change depending on the active lasers. The main advantage of this mode of operation is that the laser emitters are always placed in an area "visible"; for the vehicle and so

45 There is no possibility of marker occlusions as could be the case with the cited patent. Note that this case is of special relevance in greenhouse environments where the vehicle is in areas not visible for markers, due to the presence of plants, most of the time.

In patent E98306075 quot; Method and system to describe, generate and verify

5 wireless paths for automatically guided carsquot; A semi-reactive guidance system is presented in which the vehicle reference path is initially specified (differential X, Y coordinate database). As the vehicle moves in the environment and obtains feedback from markers placed in said environment, it correctively corrects its trajectory. In the invention that

1 Or propose, a reference path a priori is not specified, and therefore the guidance system is fully reactive.

Description of the invention

The idea of the system proposed in the present invention is similar to the use of monorail guides or magnetic guides, with the difference of establishing the route by means of a laser emitter located in the longitudinal center of the path to be traveled (Figure 2). In this case, the vehicle should be equipped with a set of cameras and photodetectors that

20 allow the route marked by the network of laser emitters to be detected. These cameras will be placed on the front and on the sides of the vehicle. This technique offers acceptable accuracy in environments with a high number of obstacles, and the cost of implementation is not as high as in the case of monorail guides or the use of beacons.

25 The guidance system for carrying out greenhouse work proposed in the present invention, is a novelty in the field of the use of autonomous machines in the performance of operations in greenhouses, since it allows to automate any type of vehicle and at a cost reduced execution (acquisition of cameras

30 vision and laser emitters). The use of the guidance system means avoiding the presence of operators in the greenhouse to carry out dangerous operations (spraying tasks),

or help in collection and transport tasks.

The system that is intended to be patented is formed by a vision system consisting of three cameras: one front and two sides, a set of photodetectors on the front and side of the vehicle and a front sonar.

The front camera collects the images from a screen on which the laser pointer strikes. Using an artificial vision algorithm, the position of the laser point 40 with respect to the center of the screen will be determined. In this way, the orientation of the robot will be modified according to the estimated deviation from the center of the screen.

The two vision cameras located on both sides, in combination with photodetectors, determine the turns that the vehicle must experience to follow the appropriate path, by detecting a laser beam coming from the side aisle.

During the passage through the aisle, the side cameras remain inactive, with the front camera being responsible for directing the vehicle's trajectory. The images captured by the side cameras are used to detect the laser that indicates the change of trajectory to follow when the distance detected by the vehicle's front sonar is

5 less than a threshold indicating the end of the hall.

The artificial vision algorithm is based, first, on performing an image correction process (enhanced), then a segmentation process will be carried out to differentiate the parts that make up the image. In this way you can detect the point 1 O corresponding to the place where the laser beam has affected. Next, the deviation of said point (Euclidean distance) with respect to the central point of the image (center of the corridor) is calculated. Finally, using the camera's calibration parameters, this deviation will be passed from image units (pixels) to metric units, thus estimating the deviation from the center of the vehicle aisle. This measure is

15 will use low-level controllers that generate the appropriate control signals to move the wheels of the vehicle.

To be able to mark the route that the vehicle must follow inside the greenhouse, a mesh of laser emitters has been established between all the corridors of the greenhouse (see

20 Figure 1). Said transmitter mesh is connected to a fieldbus connected in turn remotely to a computer. The form of controller the status of the emitters is as follows.

First, the user establishes from the computer the path that the robot must follow.

25 Subsequently, the first lasers are turned on to mark the initial path of the robot. As the robot moves through the greenhouse it indicates to the remote computer the corridors through which it has moved, at this time the remote computer turns off the lasers of the past corridors and turns on the new lasers. In this progressive way, the reference route is established to continue minimizing the energy consumption by the emitters

30 lasers

Brief description of the figures

35 For a better understanding of what is described herein, some drawings are attached in which, by way of example only, figures 1 to 4 are included.

Figure 1: Shows the arrangement of the laser emitters in the greenhouse, and you can

40 observe an example of the described trajectory where they show which laser is active at each moment in order to define the path to follow.

Figure 2: Shows the process of laser detection by the vehicle and how it makes the turn to continue on the desired path.

45 Figure 3: Shows a perspective view of the head design designed for the use of both front and side cameras for the detection of laser signals

Claims (4)

5 1. Guidance system for autonomous movement of vehicles in structured environments comprising: a.-A system of laser emitters distributed by the work scenario and that determine the path to be followed by the vehicle. 1 O b.-A laser signal detection system formed by the use of cameras and photodetectors. c.-A support head for the signal detection system. 2. Camera and laser guidance system for autonomous movement of 15 vehicles in structured environments, according to claim 1 characterized in that the support head allows the housing of the front and side cameras, as well as the detection screen and the sonar. 3. Camera and laser guidance system for autonomous movement of 20 vehicles in structured environments, according to claims 1 and 2 characterized by having a configurable on / off system of the laser emitters that define the path to follow. 4. Camera and laser guidance system for autonomous movement of 25 vehicles in structured environments, according to claims 1 to 3, characterized in that the ignition system can be remotely controlled by radio, Wi-Fi or similar.