WO2017183001A1

WO2017183001A1 - Automated topographic mapping system"

Info

Publication number: WO2017183001A1
Application number: PCT/IB2017/052319
Authority: WO
Inventors: João SANTOS; Marco BARBOSA; João ANTUNES; Carlos Santos; Cláudio BRITO
Original assignee: Turflynx, Lda.
Priority date: 2016-04-22
Filing date: 2017-04-21
Publication date: 2017-10-26

Abstract

The present application comes from the need to automate the land surveying process. An automated topographic mapping system is disclosed here which integrates GNSS technology and movement sensors to precisely determine the location of limits, properties or simple interest landmarks, allowing its planimetric representation in a global coordinates system. To achieve this, a mechanical structure was developed specially adapted to integrate the different building blocks of the system, favouring, at the same time, its adaptation to several application scenarios, whether the system is coupled to a vehicle or is simply driven by a user.

Description

DESCRIPTION

"AUTOMATED TOPOGRAPHIC MAPPING SYSTEM"

Technical Field

The present application discloses an automated topographic mapping system.

Background

Currently, in order to make a precise survey of a terrain's limits, for example a golf course, with an error inferior to 10 centimetres, two distinct techniques are known:

I. Point survey resorting to GPS RTK equipment (Real Time Kinematic) ;

The survey with the traditional topography GPS RTK equipment consists in collecting several points that delimit the areas to be included in the map. A collection of each point is made by means of an operator who places a surveying pole on the ground and registers its location. This procedure, depending on the terrain extent, may have to be repeated thousands of times in order to get a precise outline of all the areas of interest. For example, on a golf course we would be interested in detecting the boundaries of fairways, greens, roughs, bunkers or lakes. I. Mapping through the collection and processing of georeferenced aerial images (photogrammetry) .

The use of georeferenced aerial images to draw a map of the several areas of a golf course implies the collection of photos through satellites, planes, helicopters or drones, where the means to be used depend on the desired degree of precision. Subsequently, it is necessary to process these photos with dedicated software, manually matching the points in the image with the points on the ground, thus creating the area delimitations to be shown on the map.

The document US 20090154793 Al describes an advanced photogrammetry system capable of merging images taken by a plane and by a satellite, together with other sensors, for automatic reconstruction of an extremely precise topographic map. This type of systems is useful to elaborate digital elevation maps of a terrain, however, they are not capable to automatically recognize, for example, the limits between two lawned areas with different cutting heights (in the order of millimetres) . This is only done, if the photographic resolution allows it, through manual matching. Furthermore, the use of aerial photos is also limited to areas where there are no visual obstructions between the camera and the terrain, for example trees.

Thus, it is observed that, in practice, the main problem of this kind of solutions, is the time required to collect and process all the points manually, whether by the need to reposition the surveying pole thousands of times, or by the need to identify thousands of points of interest in photos.

The fact that these techniques rely on a lot of manpower and use very dedicated equipment and computer programs greatly increases the cost of a topographic survey.

Currently, the manual surveying pole is equipped with a GPS RTK receiver ( ^rover' ) that acquires the desired point in a 3D coordinate system, and a level that is used by the operator to ensure vertical alignment.

To avoid the constant repositioning of the surveying pole it is possible to put the GPS aboard a motorized vehicle and collect points automatically. However, this solution by itself is valid only in flat terrains, where the vehicle and the GPS are not subject to slopes.

The document US 6425186 Bl, describes a mechanical system which allows coupling a surveying pole with a GPS module to a vehicle, and its integration with a laser sensor for point height measurement. In order to try to compensate for the rotation induced in the GPS antenna due to terrain slopes, this invention describes the use of a gyroscope on the surveying pole which forces it to always be vertically aligned. This automatically aligned mechanical system relies a lot on gyroscope's response time which, due to the force that it has to exert on the pole, may not be fast enough for certain vehicle travel speeds or very irregular terrains. Although indirectly using the same principles of a gyroscope (by means of an inertial sensor) , the now developed solution described below, instead of mechanically displacing the antenna, measures the displacement experienced in any of its rotation axes and compensates that rotation on the final position calculation estimated by software.

Also, it is only possible to collect points by a moving GPS receiver if the reception conditions are ideal and no signal obstruction exists between the GPS satellites and the receiving antenna. This is not the case on most golf courses due to, for example, the existence of trees and buildings near the areas of interest. This type of obstructions can increase the error of the GPS estimated position solution or make it completely impossible to calculate a solution.

Due to the problems and difficulties identified on the known systems in the above-mentioned state of the art, the developed technology comes to fill these limitations, allowing the collection of points during movement, with an automated process, always guaranteeing a precision better than 10cm, regardless of terrain relief and the existence of poor GPS signal reception areas.

Summary

The present application discloses an automated topographic mapping system characterized by comprising:

— a processing unit connecting

— a sensory block, which comprises at least an angular position sensor (4) and at least an inertial sensor (3) ,

— a receiver block, which comprises a GNSS antenna (2) and a radio antenna (14);

— and a battery module,

wherein the sensory block and the receiver block are integrated into a mechanical structure which comprises a metallic chassis (1), which integrates a free wheel (5) whose axis rests on a bearing support (6) and connects an angular position sensor (4) by means of a mechanical coupling (7); the mentioned chassis (1) comprising two free angular joints (10), an adjustable angular joint (9), where the GNSS antenna (2), the radio antenna (14) and the inertial sensor (3) are integrated; and also an adjustable linear joint (11) to adjust the fixing rod (8) height. In an embodiment of the system, the processing unit uses a microprocessor and comprises electronic signal acquisition mechanisms .

In an embodiment of the system, the sensory block additionally comprises a LIDAR sensor (12) .

In an embodiment of the system, the LIDAR sensor (12) is integrated on the adjustable angular joint (9) .

In an embodiment of the system, the fixing rod (8) is coupled to a vehicle through a mechanical fastening.

In an embodiment of the system, the free angular joints (10) are fixed and the fixing rod (8) is used as a handle.

In an embodiment of the system, the processing unit is configured to calculate a system's position through integration and processing of the data captured by the sensory block and the receiver block.

In an embodiment of the system, the GNSS antenna is adapted to acquire GPS signals, GLONASS and GALILEO, among other global navigation satellite constellations.

In an embodiment of the system, the radio antenna is configured to acquire data from a local GNSS station. General description

The present application discloses an automated topographic mapping system.

The system comprises a sensory block, which includes at least an angular position sensor and at least an inertial sensor (3), a receiver block, which comprises a GNSS antenna (2) and a radio antenna (14), a processing unit and a battery module. All sensors and antennas are connected by cable to the processing unit, where the signal acquisition and the data processing is made. The sensory block and the receiver block are integrated into a mechanical structure. This mechanical structure presents a metallic chassis (1) which integrates a free wheel (5) whose axis rests on a bearing support (6) and connects an angular position sensor (4) by means of a mechanical coupling (7) . Two free angular joints

(10) give the wheel the required degrees of freedom, vertical and horizontal, needed to its correct movement over the floor. An adjustable angular joint (9) allows adjusting and secure the upper support, which integrates a GNSS antenna

(2) , which is vertically aligned with an inertial sensor

(3) , a radio antenna (14) and a LIDAR sensor (12), with the desired vertical orientation. An adjustable linear joint

(11) allows adjusting the fixing rod height (8) which allows coupling the system to a motorized vehicle and, as such, allows it to be towed. Said adjustment can be made by tightening a screw or any other mechanical fastening method suitable for the purpose. The joint (11) is comprised of a sliding piece and a chute. These two pieces can be joined by a screw or any other mechanical fastening method suitable for the purpose. When the fastening element is tightened, the frictional force blocks the sliding piece. An alternative way of adjustment could be by using toothed sliding pieces and chute. In the main embodiment of the system, the chute is embedded in the fixing rod (8), therefore being the same piece .

The vehicle coupling is made through pipe clamps. Half of the clamp is "U" shaped, with the chassis dimensions of the vehicle to be coupled. The other clamp half is the fixing rod (8) itself, which has a flat face, which lies parallel to the side of the vehicle chassis. The tubular structure of the vehicle chassis lies between the two halves of the clamp, and the two halves of the clamp tighten against each other with two fastening elements, such as screws or rivets. These two halves are coated with rubber for a greater adhesion and a better fit to the tubular shape of the vehicle.

The present solution is versatile in the sense that half of the clamp is secured, the fixing rod (8), and the other can adapt to the dimensions of each vehicle.

Thus, to map a certain area, the operator only has to drive the vehicle along the area that it wishes to map.

In an embodiment of the system, the mentioned structure can be pushed by an operator along the terrain to be mapped. For this configuration, it is necessary to secure the free angular joints (10) and using the fixing rod (8) as a handle in a position that is comfortable to the operator.

The sensory block comprises at least an angular position sensor, which is coupled to the rotating axis of the free wheel, in order to determine its speed, and by extension, estimate the distance travelled by the system.

Furthermore, the sensory block comprises at least an inertial sensor, used to measure the angular accelerations that occur while it travels, thus allowing the rotation of the GNSS antenna to be estimated due to the irregularities and slopes of the terrain.

The GPS satellites signals, GLONASS or GALILEO are received by the GNSS antenna and processed in the processing unit which, using also the data of the local GNSS station received by radio and applying differential correction, calculates in real time (RTK) the precise position of the antenna. This position is then transformed according to the inertial sensor information originating the system's position estimate.

The processing unit includes a flash memory reader to store data and a Wi-Fi module to send data to the user. This unit comprises a microprocessor and signal acquisition electronics to interface with the sensory block. It is here that the data of all the sensors is processed, using a sensor fusion algorithm based on Kalman Filtering. The sensor fusion algorithm allows estimation of the system's real position through the integration in time of the measurements of the several sensors (GNSS, inertial sensor and angular position sensor of the wheel) that have some uncertainty associated. In the absence of GNSS signals due to obstructions, it is possible to estimate the system's position using only the angular position sensor measurements of the wheel. Thus, and taking into account the dynamics model, it is always possible to estimate the system's position even when the antenna is under rotation or when GNSS signals are weak or unavailable. The system's position estimation is saved in the processing unit at the frequency desired by the user (between 1 and 20Hz) to obtain the desired resolution. The final map is thus comprised of the set of points which represent the system's position along the course of time.

The battery module ensures the required power supply for the operation of all the electronic components that comprise the system.

In a particular embodiment of the system, the sensory block comprises additionally at least a LIDAR sensor. This allows to identify obstacles or reliefs of interest (trees, poles, bunkers, etc.) and map them relatively to the location of the mapping system itself. This sensor measures the distance and orientation of a set of points that represent the obstacle on the coordinate system of the mapping system (local coordinate system) . These points are subsequently transformed by the processing unit into the global coordinate map, taking into account the absolute position of the system. The final result is a file that represents the map according to that coordinate system. This can have different formats and be saved in a memory card or sent through wireless communication .

The main advantage of this technology lies in being able to produce a low-cost and, at the same time, precise and robust solution. This is the result of an arrangement of complex sensors and how they are integrated, both in terms of information (sensor fusion) and mechanical integration.

Brief figure description For easier understanding of this application, figures are attached in the annex that represent the preferred forms of implementation which nevertheless are not intended to limit the technique disclosed herein.

Figure 1 illustrates an isometric view of the system, wherein the reference numbers represent:

1 - Chassis;

2 - GNSS antenna;

3 - Inertial Sensor;

4 - Angular Position Sensor;

5 - Wheel;

6 - Wheel Axis Support (bearings);

7 - Coupling;

8 - Fixing Rod;

9 - Lockable Angular Joint (or adjustable) ;

10 - Angular Joint;

11 - Lockable Linear Joint (or adjustable) ;

12 - LIDAR Sensor;

13 - Processing Unit;

14 - Radio Antenna.

Figure 2 illustrates a side view of the system.

Figure 3 illustrates the system coupling to a golf cart.

Figure 4 illustrates an enlarged view of the fixing rod, and of the mechanical fastening used on the system coupling to a vehicle. Embodiment descriptions

Now, preferred embodiments of the present application will be described in detail with reference to the annexed drawings. However, they are not intended to limit the scope of this application.

In an embodiment, the system is used to perform the automatic topographic survey of a golf course. Therefore the system is adapted to be coupled to a golf cart or a buggy.

The present description is not, naturally, in any way restricted to the embodiments presented herein and someone of ordinary skill in the art can foresee many possibilities of modifying it without departing from the general idea, as defined in the claims. The embodiments described above are obviously combinable with each other. The following claims define additional preferred embodiments.

Claims

1. Topographical mapping automatic system characterized by comprising :

— a processing unit connecting

— and a battery module,

wherein the sensory block and the receiver block are integrated into a mechanical structure which comprises a metallic chassis (1), which integrates a free wheel (5) whose axis rests on a bearing support (6) and connects an angular position sensor (4) by means of a mechanical coupling (7); the mentioned chassis (1) comprising two free angular joints (10), an adjustable angular joint (9), where the GNSS antenna (2), the radio antenna (14) and the inertial sensor (3) are integrated; and also an adjustable linear joint (11) to adjust the fixing rod (8) height .

2. System according to claim 1, characterized by the processing unit being of the microprocessor type and comprising electronic signal acquisition mechanisms.

3. System according to claim 1, characterized by the sensory block additionally comprising a LIDAR sensor (12) .

4. System according to claim 3, characterized by the LIDAR sensor (12) being integrated on the adjustable angular joint (9) .

5. System according to claim 1, characterized by the fixing rod (8) being coupled to a vehicle through mechanical fastening .

6. System according to claim 1, characterized by the free angular joints (10) being fixed, the fixing rod (8) being used as a handle.

7. System according to claim 1, characterized by the processing unit being configured to calculate the system's position through integration and processing of the data captured by the sensory block and the receiver block .

8. System according to claim 7, characterized by the GNSS antenna being adapted to acquire GPS signals, GLONASS and GALILEU, among other global navigation satellite constellations .

9. System according to claim 7, characterized by the radio antenna being configured to acquire data from a local GNSS station.