GB2601365A - Location of objects over an area - Google Patents

Abstract

A system, method, and apparatus for placing or locating objects over a predetermined area, for instance for use as markers for a zone or surface mapping exercise. Such a map may then be used for robot orientation, for instance to allow an Autonomous Distributed Deposition Robot (ADDR) to guide itself to print on turf, e.g. for advertising purposes, or generally to self-navigate to places or locations of interest to perform a duty, such as to deposit a fertiliser, plant seeds, or other necessary payload at a particular geographic reference location, indoor or outdoor. The system has a scanner 10 directing a laser beam across an area such as a sports pitch. The laser operates autonomously, giving an audio signal to indicate to the operator where to place a number of reflectors 20 around the pitch. Once this is done, the scanner, again autonomously, starts a survey of the placed reflectors to ascertain their exact position and orientation, by measuring the distance to a series of points across the face of the reflector. These measurements are filtered and compared to data identifying the reflectors, so that the position of each reflector is accurately known. The set of reflectors 20, which have retro-reflector plates 26 also mounted on their tripods, can then be used for orientation for a robot, such as a robot printer for printing on the ground.

Description

Location of objects over an area The present invention relates to a system for placing or locating objects over a predetermined area, for instance for use as markers for a zone or surface mapping exercise. Such a map may then be used for robot orientation, for instance to allow an Autonomous Distributed Deposition Robot (ADDR) to guide itself to print on turf, e.g. for advertising purposes, or generally to self-navigate to places or locations of interest to perform a duty, such as to deposit a fertiliser, plant seeds, or other necessary payload at a particular geographic reference location. Such uses will usually be outdoors, but indoor applications are envisaged also, such as placement of objects autonomously.

Localisation in robotics often requires a map of fixed points of reference in a coordinate grid so at any point the robot device can locate itself using these points and calculate where it is on the grid.

Known processes of setting up these fixed points and obtaining their position are inherently complicated, require manual intervention, are time-consuming and require a trained technician skilled in surveying with specialist equipment, such as LiDAR.

It would be desirable to automate the identification, and setup, of fixed points for a localisation system to allow rapid installation, preferably across multiple sites, by a user without requiring great skill or training, enabling fast deployment of autonomous vehicles. Such an autonomous vehicle could be a ground printing system that requires fixed reference points with retroreflectors to navigate itself. These fixed points (reflectors) must have known X/Y coordinates and angles set around the print area.

According to one aspect of the invention there is provided a method of setting out or locating or identifying objects accurately over a given area, comprising: - providing a scanner and a set of objects to be placed or located or identified, the scanner having a laser that can be directed over the area and a means for measuring distance; - positioning the scanner at a point on the periphery of the given area, and activating the scanner so that it emits a beam in the direction of the first object; - moving the first object to a position where it intercepts the beam, if it does not already do so; - adjusting the distance of the first object from the scanner until the scanner indicates that the distance is correct, and placing the object; and -repeating the process for the other objects as required.

There could be an initial step of using a user interface to define a zone, surface, or area of shape for the placement of the objects (such as a rectangle, pentagon or race track) There can also be an initial step of determining a baseline, e.g. a zero angular orientation for the laser. This might be a touchline of a sports field, for instance, or a line parallel to such a line, or a line of sight to a significant further object such as a television camera.

There can also be a subsequent step, once the objects have been approximately positioned, of surveying them automatically and ascertaining their position and, preferably, orientation precisely, preferably to within 3mm or even lmm.

In a further aspect the invention is concerned with an apparatus for guiding the placement of objects at specified locations over a given area, comprising: - a scanner capable of emitting a visible beam at various angles in a horizontal plane, and including a means of measuring distance; -the scanner further including a means for emitting a visual and/or audio signal indicating to an operator whether the distance and/or angle of an object to be placed is as specified.

In particular for surveying applications, the scanner preferably further includes a processor, either integral or remote, for surveying the objects once they have all been placed, to establish their positions precisely and thus to define a map for use by a robot, for instance.

Preferably the means of measuring distance involves modulation of the laser beam itself, in much the same way as an "electronic tape measure". The audio signal, if used, can be a beep or series of beeps; in particular the time between beeps can decrease as the distance measured becomes closer to the specified distance, signalling to the operator when the object is correctly placed; this is similar to sensor systems used for car parking.

The apparatus will generally further include a set of passive reflectors to be placed by the operator and constituting the "objects".

The smart scanner system rules out the need for experienced surveyors by automating the process of setting up and scanning fixed points of reference such as the passive reflectors.

In a further aspect the invention concerns a method of determining the location of at least one object at planned positions around/over a given area, comprising the following steps: - providing a scanner in line of sight of the objects, the scanner being capable of directing a light beam at controllable angles over the area and of measuring the distance from the scanner to an object intercepting the beam, and having access to stored data concerning the size and shape of the objects; - the scanner moves/pans the beam over the objects and measures the distance to several points on each object, distinguishing these from neighbouring reflections; - the scanner compares the measured points with the stored data and thus ascertains the location and, preferably, orientation of the or each object.

The stored data will generally also include data concerning the approximate location of each object. This enables the scanner to direct the beam only, or mainly, within a tolerance of the locations where the objects are expected to be according to the stored location data, greatly shortening the survey time.

The beam will typically be a laser beam modulated to enable the scanner to measure the distance to an object.

In a survey process, the objects are usually flat panels mounted vertically, and the scanner identifies each panel by identifying straight lines of no greater width than the expected angular width of a panel at the measured distance, oriented to face the scanner; usually the panel is not exactly facing the scanner so the observed width is somewhat less and the distances of measured points recede from the scanner. Smoothing and filtering processes can be carried out to distinguish lines of points representing actual panels from spurious reflections.

The objects can be existing reflectors, e.g. fixed to walls, fences or other permanent structures, or they can be placed by an operator using methods as described above. Moreover once the positions of the reflectors are accurately ascertained by the survey, they can be used for a further subsequent step of guiding a robot by means of the objects.

A still further aspect of the invention envisages a scanner for use in determining the locations and orientations of objects at planned locations over/around an area or zone, comprising: - a means for generating and directing a beam over the area in various controllable directions; - a means for measuring distance to an object in these directions by reflection of the beam from the object; and; and - a processor for identifying a given set of reflections corresponding to a known object, and for calculating the location and, optionally, orientation of the object therefrom.

The means for generating and directing the beam is generally a laser device and it includes the distance-measuring means, e.g. by modulating the beam and measuring time of flight.

The scanner will usually further include, or have access to, a memory storing data about how near the object is and in roughly which direction, and to indicate accordingly to the processor whether the received signal is likely to correspond to the object sought. Reflections significantly nearer or further are classed as spurious, leaving a line of points representing e.g. a vertically mounted flat panel reflector. The measured distance of points in this line gives an orientation in the horizontal plane, which can then be sorted in a memory to build up a map of the set of objects. The processor and/or the memory are preferably located in the scanner but communication with an external computer/database is possible.

The invention is also directed to a set of objects placeable over an area for use in a navigation/trilateration/triangulation process, for instance for use in controlling the movement of a robot, comprising a scanner as described above and a set of reflectors consisting of reflecting areas fixed or mounted on mobile stands, the scanner optionally also including such a reflecting area.

In a refinement, the scanning process can use a method of dynamic scan resolution. Normally, laser technology loses range accuracy with increasing distance. To counter this, the system may use the measured distance to the target to change the scan resolution; for instance, if a step width of 0.25° is used for a target up to 10 metres away, a width of 0.125° may be used for a target further away, say up to 15 metres away or further. In between the known targets a much greater step width, e.g. 10-20°, can be used, since this area is known not to be of interest.

Preferably the equipment includes a user interface, in particular a hand-held device such as a tablet computer, containing a program interacting with the scanner to prompt for information and to give instructions for the next step, e.g. the placement of the objects/reflectors. The tablet is also preferably configured to display options such as the size and shape of the area of interest, and of the design to be printed for a printing application.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, embodiments will now be described with reference to the attached drawings, in which: Figure 1 illustrates the principle of the invention, showing objects to be placed in or around a given area; Figure 2 schematically shows a scanner in accordance with the invention; Figure 3 is an outline flow chart of the setup procedure; Figure 4 shows a plan view of an application similar to Figure 1 but for a rectangular area such as a sports pitch; Figure 5 is a view of an initial stage of an embodiment of the method; Figure 6 is a graphical representation showing the results of a typical survey stage of the method; and Figure 7 illustrates the geometry of the survey process; and Figure 3 is a flow chart of the process as it affects each component of the system.

DESCRIPTION OF EMBODIMENTS

Figure 1 shows an area 1 in or around which various objects, here tripods, 20 are to be placed using an intelligent scanner or survey device 10. Each object 20 has a reflector 22, or a part 22 that reflects, capable of giving a return signal to the scanner. It also has a retro-reflector 26 in the form of a vertical strip about 60 cm (30-100 cm) tall and 10 cm (5-25 cm) wide, for use in the subsequent navigation process, and the scanner also has one such reflector, in this embodiment.

The scanner or scanner unit 10, shown in Figure 2, is capable of being placed securely at a desired location, where it stands stably, e.g. likewise on a tripod 11. It includes a directional beam generator, usually a laser 12, which can be controlled and moved, or the entire scanner is turned, by an actuator 14 such as a stepper motor to point in any desired direction, possibly about a complete 360° turn, but preferably at least 180° and typically up to about 270-290°. It also contains a distance-measuring device or function, similar to that used in standard surveyor's measures, giving a distance reading of any object that the beam strikes. A separate measurer could however be used. The scan range is preferably at least 20m, often up to 50m, 100m or even more.

The scanner also contains a rechargeable battery, so it is self-contained, and should be able to carry out a number of surveys on a single charge; for instance, at least six and preferably ten such surveys might represent a day's work, allowing time for a recharge overnight.

The scanner further contains an interface so that it can be controlled remotely, in particular by an operator (not shown), using a tablet computer 100, for instance, connected by Wi-Fi if present, or Bluetooth, or any suitable means of communication. The smart scanner could create a Wi-Fi access point, for instance. The necessary calculations for the positioning are carried out by a processor on a circuit board 16 in the scanning unit, though this may also be done remotely, at least in part, for instance in the operator's tablet.

The scanner may repeatedly poll for progress via a network of APIs, or alternatively it may make use of MQTT socket technology to make the processing a direct communication process.

The scanner can scan objects in the observable arc, with a range typically of up to 100m, though with the use of a suitable sensor it could be more. Through filtering algorithms, it is then able to identify key features (reflector boards in the present case) to calculate the position, and in most cases also the angular orientation, of the objects; these can then be used as reference points.

Furthermore, to remove the need for a skilled surveyor, the scanner is designed to generate a number of audio and visual cues that guide the user to achieve the task of setting up the fixed points of reference (reflectors). The overall setup time for a fixed-point localisation system can be reduced from hours to minutes through this invention.

The smart scanner can analyse the use case and dynamically change the position that the fixed reference points should be placed. It is then able to guide the user to place these references (reflectors) dynamically on a case-by-case basis. This is done by means of a tablet computer 60 discussed below.

The set of objects 20 to be positioned is here a group of identical tripods 20 each having a passive reflecting board 22; a typical size of the reflectors would be cm width (say 20-100 cm in most cases) and 30 cm height (10-50 cm). These are to be placed around the periphery of the area 1 with the board approximately facing the centre of the area. The reflectors 20 will here be used as position references for a subsequent ground-printing process, carried out by a printer as described in co-pending GB application no. GB2016545.2, but many other applications are possible including ground marking or non-printing embodiments. The reflecting surfaces are made of highly reflecting material, most simply just a smooth white board, the requirements being that the operator can see where the laser hits the board and the scanner can detect a reflection at various angles (since the board will often not be facing the scanner). Selection of the board surface could be optimised by analysing the correlation between backscattering intensity of the laser (perhaps pulsed) and the spectral reflectance at the wavelength of the laser deployed.

The area is usually a planar or near-planar surface, and ideally flat and level -certainly if it is an indoor area or a sports field, though the system can cope with some deviation from level, for instance if the tripods are adjustable. Also, almost all professional sports pitches are formed to be slightly (c. 1%) convex, to aid runoff drainage. Adjustability when positioning in such instances is advantageous. The reflecting boards 22 and the scanner, or its laser, will in a typical example be at about head height, say about 1.5-2m, while the retroreflectors 26 will have their midpoint at the level of the ADDR, which might be about 0.8m.

A typical procedure for setting up the objects 20 in preparation for a subsequent print is as follows.

1. The Operator uses a tablet interface (100) to instruct the "smart" scanner 10 to start the survey process, by selecting or confirming inputs for the number of target objects to be placed, the scan distance for each of the target objects, and other important positional references.

2. The scanner signals the start of the process to the user through audio and/or visual cues.

3. The scanner homes the laser rotation (i.e. sets the orientation of the x axis), if necessary.

4. The scanner moves to the angle corresponding to the position of the first or next target object or reflector and begins measuring the distance to the expected line-of-sight surface; meanwhile the operator takes the reflector and moves it to intercept the laser beam.

5. The scanner waits until the operator crosses the laser beam; once such an interception is detected it starts to signal any necessary adjustment of the distance from the laser; to this end the scanner emits audio indicators from a buzzer that increase in frequency the closer the measured distance is to the target distance (a hot-cold methodology).

6. The scanner confirms a correct distance reading ten times and then allows the operator some time to set up the reflector, indicated by increasing frequency tones from the buzzer.

7. The scanner makes a final measurement to check that the distance is correct.

8. If the distance is correct, the scanner process continues to step 9; otherwise it loops back to step 5.

9. If there are still target objects or reflectors to be set, the scanner loops back to step 4.

10. Once all reflectors have been placed by the operator and turned to face toward the middle of the area of interest, being therefore within the required placement constraints, the scanner homes the laser rotation.

11. An audio signal informs the operator that the survey is about to begin.

12. Survey scanning then begins. The scanner directs itself towards each of the boards 22 in turn and measures the distance to a number of points across the surface of the reflector.

13. Survey time is reduced by only scanning the known arc area around the reflectors. One such hunting algorithm limits scanning to a 5-degree arc from the assumed centre point of the reflector, though other methods are possible depending on target object/reflector dimensional characteristics, such as inclusion of a camera within the scanner and deployment of image recognition to find the target, edge and feature detection, or object recognition for example, by comparing known images to images identified by the scanner's camera.

14. The scanner computes the survey at the end when it has collected all the measurements. In this way the position and orientation of each target object or reflector is accurately measured, and can be defined in dimensional terms (distance from scanner, length, angular orientation), and reference to a global coordinate system, for example.

15. The result, essentially a map of the layout of the target objects or reflectors, is automatically passed to the operator interface and transferred to the ADDR (e.g. printer), for instance via a router or the Cloud. The entire operation typically takes less than three minutes, in contrast to a manual process which might take hours and require specialist tools.

These steps are shown in outline in Figure 3, showing the states of the smart scanner as it proceeds through the prescribed steps, essentially autonomously apart from the fact that the physical approximate placement of the reflectors has to be done by the operator. Even this is not necessary if the survey takes place in a site with existing, fixed, target objects or reflectors and the survey indicates that they are (still) correctly positioned and aligned.

The ADDR can preferably create a Wi-Fi access point which the scanner can communicate directly through without any external networking infrastructure. The robot is used to host the operator interface server that communicates directly with the scanner webserver. It should therefore be present during the setup process, even though it is not needed for printing until after that process is finished. Alternatively the network can be hosted elsewhere in the system or even in a separate component.

The purpose of the wireless transfer is to automate transfer between the smart reflector and the robot. Eliminating the need for the operator to act removes the possibility for human error.

Typically the scanner itself has a reflector and is then itself used as a passive reflector for subsequent orientation, positioning or navigating operations. Normal triangulation or trilateration requires a minimum of three reflectors (including the "smart reflector"), but four or more can be used to suit the landscape. For instance, Figure 4 shows a total of six reflectors surrounding a long rectangular field.

In one mapping application for which the present setup system is useful, printing is required on the surface of a sports pitch. This print must therefore usually align with a feature of the pitch, such as a touchline. In this case, step 3 involves aligning the "home" or zero of the laser rotation to be parallel with the touchline.

This is also done by the operator placing a tripod 20 with its reflector 22 so that the laser is parallel, as shown in Figure 5. The operator is guided to place a reflector that will make up a line between the smart reflector and passive reflector allowing the operator to align it to another line (i.e. the pitch line or a landmark).

The process starts by placing the smart scanner roughly where print is required. After choosing which axis of the print (X or Y) to use for alignment in the operator interface the smart scanner starts to point to an initial position (position A). Once this is done, the operator is then required to move the scanner to the correct distance confirmed by the reflection from the passive reflector 22.

In fixed applications where the scanner is used to confirm location and orientation of already installed objects (or reflectors), as will often be the case indoors, for instance, a predefined known 0,0 reference will exist, and placement in that location will be assisted by manual markings and/or digital location assistive tools such as GPS, proximity sensors, or other range finder. The reflector-placing steps described below are then not needed.

Once the scanner 10 is at the correct distance, the laser remains active and the operator moves the passive reflector (i.e. from position 1 to position 2) to align the print with the pitch line until a point when they are satisfied. Now the smart reflector can carry out the rest of the guided setup and automated survey.

The "smart scanner" thus provides a set of processes that automate the complicated steps, taking responsibility away from the operator for otherwise complicated manual operations. For example, if the operator needs to set up an area of X by Y metres, he only needs to choose the location and orientation of the print, as the smart scanner guides the rest of the steps, completes the measurements and returns the computed results.

Once the operator has placed all the passive reflectors and the scanner has confirmed that they are all within the tolerance limits in terms of distance and orientation, the survey procedure starts (or this may be initiated by the operator). This procedure is illustrated in Figure 6, which shows a notional map held in the memory of the system. Here the scanner is at (0, 0) and the tripods 20 with their retroreflectors 26 are intended to be around the periphery of the area of interest. After the placement of the passive reflector tripods 20, the boards 22 are supposed to be at certain locations, assuming the operator has been following the guidance and the reflectors were not subsequently disturbed. A notional margin of error 220 is shown, which is a tolerance or range of angles (say 1-5°, typically about 2.5°) and distances (say 0.1, 0.2 or 0.5 m) within which the reflectors are expected to be found. The scanner scans these areas and detects reflections giving rise to lines corresponding to the boards 22. If all these lines are within the tolerances the survey is successful (Figure 6(a)).

If any of the lines are outside, the survey fails (Figure 6(b)) and at least one repositioning has to be carried out by the operator. This process is described in more detail below.

These results essentially form a map of the terrain, to be used, for instance, by an ADDR. The robot will require a precise location to lay the pixels on the ground.

Its only reference for navigation is the set of reflectors. Therefore, the setup inherently affects the print quality.

It is desirable to achieve an accuracy of distance measurement equivalent to the size of a blade of grass, say ±3 mm, and preferably ±1 mm. Such accuracy can be achieved by commercially available laser measuring sensors.

Furthermore, the data collection can be carried out during one sweep by using a "zone hunting" algorithm. By reserving slower scanning for use over small target zones (area 220 above), as opposed to continuous LIDAR measuring over the entire sweep, the operating time and measurement error can be reduced. Depending on hardware and gearing options, it is possible to achieve high angular accuracies, of ±0.25, ±0.10, ±0.05 or even ±0.01 degree, particularly if the scanner dynamically selects how many times the reflector is scanned by deploying machine learning or deep learning algorithms; for instance, scanning a reflector of a given width becomes increasingly challenging as the distance from the scanner increases and the arc of the reflector decreases.

The stepping motor rotating the laser should allow a single step that determines its arc to be as low as possible. In the present embodiment the minimum achievable arc step is 0.010, which at 50 m, say, represents a distance of about 10 mm, but clearly this can vary with different stepper motors.

An algorithm is used that determines the number of points the laser has to project onto a reflector to get enough data to compute its position.

In more detail, the survey proceeds as follows. The scanner contains in memory the ideal positions of the passive reflector boards 22. It scans within a suitable narrow range, say 2.5° or 5°, of each of these positions in turn, depending on distance and reflector dimensions. The angular scan interval can be preset, but preferably it is adjusted by an algorithm in dependence on the expected distance of each reflector. Assuming the board is approximately in the right position to start with, a set of measured points will result, most corresponding to genuine reflections but some spurious or inaccurate, due for instance to noise. Such inaccuracies can result from vibrations of the reflector, for example caused by wind disturbance, especially when the survey is conducted outdoors. A typical set of points is shown schematically as "m" in Figure 7.

A noise-cancelling algorithm automatically based on collated inputs of point distance, front-to-back distance of target object or reflector, and x, y distance between points, filters inaccuracies. In one embodiment, noise is reduced by smoothing out the data with a number, say ten, iterations of nearest-neighbour averaging, where the initially measured co-ordinates x, y of a point are replaced by p., py, where: Px = (pi.x + pi+i.x + pi --2.x)/3 Py = (pby + + pl-F2.y)/3 This gives rise to a new set of points in a cluster, representing the measured position of the reflector. For each point in the cluster the line length between adjacent points is then calculated, and the maximum length of the line calculated on the basis of the measured distance and the number of steps multiplied by the angle per step, using the cosine rule. Any points behind the known maximum line length (corresponding to the width of the reflector board 22 when seen face-on) can be discarded, as they will not represent a reflection from a part of the reflecting board. There may also be spurious points within the extent of the reflector but not lying on a line, i.e. not forming an angle of nearly 180° with their neighbours; these can also be discarded.

The reliable line of points thus determined then represents an accurate location in 2D space of the reflector. Distance measurements dl, d2 to the outer edges of the reflector give its orientation calculated by the cosine rule, as again apparent from Figure 7.

Once the line is determined, its normal is taken; the line of this normal should have been set up by the operator to point approximately in the direction of the centre of the area of interest, e.g. the image to be printed in a printing case, so that the robot has the best line of sight to the reflecting strip.

Once the location of one reflector has been accurately determined, the scanner moves on rapidly -for instance in angular steps of 1-100 -to the next reflector, until all have been surveyed; preferably the angular steps are determined autonomously from learned prior scans related to a reflector of a known size. The same is true if the reflectors are mounted on existing, fixed parts, such as parts of a stadium fence or the inside (or outside) of a warehouse. The set of data is then stored by the scanner 10 and also sent to the ADDR (not shown), and simultaneously copied to the cloud to create a permanent reference for future machine-learning applications (for example where an ADDR is required to operate in an identical environmental configuration).

In a refinement, during a survey the scanner or smart reflector takes account of the known distance of the passive reflector to adjust the angular resolution of its rotation, up to the limit of 0.010 in the present example. For instance, it can be ensured that the number of points measured across a reflector board is about the same regardless of distance, perhaps to within a factor of 2. This enables operation at maximum accuracy without slowing the process down for nearer reflectors, which would otherwise accumulate an excess number of points.

Algorithms and methods for target identification and validation could include:-1 Reflector Hunting, 2. Noise Filtering, 3. Clustering Methods, 4. Near-Neighbour point-cloud methods, 5. Near-neighbour angular-validation method, 6. Cluster Width method, 7. Geometry and heading identification 8. Dynamic reflector scanning Alternative algorithms for noise reduction and for identification of lines/edges/features related to fixed or mobile reflector targets, creating unique descriptors using image analysis methods, could include: For noise reduction: i. Kalman Savitzky-Golay iii. Gaussian For Reflector perpendicular plane recognition: i. Hough transforms ii. Radon Transforms Ransac iv. Brute-force v. Split and merge vi. Incremental vii. Linear regression viii. Expectation maximisation ix. Successive edge following x. Line tracking xi. Iterative end point following xii. Rided-2D xiii. Artificial intelligent / machine learning point-voting xiv. Piecewise approximation xv. Slope-intercept recognition The setup requires a minimum of three, preferably at least four, reflectors for a print, at least for a rectangular area, but, as noted with reference to Figure 4, more can be used.

Theoretically the smart reflector can guide the user to place as many fixed reference points as required and can scan a full 360 degrees to identify these references. In a typical case these references are a 50cm wide rectangular plate, for wider applications these reference points can take any 2D form conceivable that can be scanned from a single viewpoint (i.e. the smart scanner/reflector).

Figure 8 shows a flow chart detailing the steps in the setup process, and the part that each component plays. On the left is the operator, who initiates certain citations, such as to start the survey, and receives information on the tablet display 100, i.e. the operator interface. The tablet communicates via a data broker, i.e. the comms module in the ADDR (not shown), which is in turn in communication with the smart reflector 10, which signals its status back to the operator as each part of the placement/survey is completed.

While examples have been described with reference to sports fields or buildings, where the ground or floor would obviously be planar or flat, the system would work on ground that was not level, provided that it was continuous and not excessively steep, and provided that smart reflector scanner has line of sight with target objects or reflectors. Here the tripods could incorporate adjustment so that they could be made vertical and/or parallel in any location, using additional indicating means to determine parallelism or verticality between reflectors using sensors or levels.

The robot could operate as a single system, or it could operate within a distributed network which comprises one or many ADDR's (deposition robots) that may be working on a 'mission' together as a collective digitally joined 'fleet' (to cover the ground faster, or complete large area installations), or individually (but in different locations on different missions), yet still all centrally controlled, in each case requiring reference and navigation points provided by reflectors, hence the significant advantages arising from automating the placement of objects or reflectors.

Wider applications of this concept and technology could be as follows: * Any application that requires accurate placement of markers/emblems/ pixels in a location, possibly in or around a field for farming, or indoor applications such as a warehouse.

* Any application that requires accurate surveying of 2D feature profiles.

* Any application that has a need for points of reference to be placed out for the navigation system of a device.

* Navigation examples where GPS is not available or does not provide the localisation accuracy required for the application.

* The surveying algorithm on its own can be applied to applications that require surveying to be carried out in a focussed and efficient manner, especially by non-skilled operators, such as building-site surveys.

* Any application where markers must be placed relative to landmarks in the environment.

* Any application that requires a virtual co-ordinate grid be applied to an environment for use with navigation or localisation systems.

Claims (30)

1. Claims 1. A method of placing or locating objects at planned positions around/over a given area, comprising: - providing a scanner capable of directing a light beam at controllable angles over the area and of measuring the distance from the scanner to an object intercepting the beam; - having the scanner direct the beam in the direction where one of the objects is to be located, and placing this object in the path of the beam from the scanner at an initial distance; - providing a signal to an operator indicating whether the object should be placed nearer or further away from the scanner than the initial distance, while still in the path of the beam, and indicating when the object is at the planned distance; and - repeating the previous two steps for the remaining objects.
2. 2. A method according to claim 1, in which the signal is provided by the scanner, and includes an audible or a visible indication, or both.
3. 3. A method according to claim 2, in which an audible indication is given and consists of separate tones or pulses that increase in repetition frequency as the object moves nearer the planned distance, optionally turning continuous when the location point is reached.
4. 4. A method according to any preceding claim, in which the beam is a laser beam and is modulated to enable the scanner to measure the distance to an object.
5. 5. A method according to any preceding claim, and including the further step of surveying and accurately ascertaining the positions of the objects so placed.
6. 6. A method according to claim 5, in which the surveying step is carried out by directing the beam across the objects in turn and measuring the distance to each part of each of the objects in the horizontal plane so as to ascertain the location and orientation of each object.
7. 7. A method according to any preceding claim, including the further step of communicating the results of the survey to an external device.
8. 8. A method according to any preceding claim, in which the first object is placed in such a way that the line it forms with the scanner forms a base line for a co-ordinate system in the scanner and is aligned with a feature of the terrain.
9. 9. A method according to any preceding claim, including the further subsequent step of guiding a robot by means of the objects so placed.
10. 10. A method according to any preceding claim, in which the given area is a sports field, pitch or track.
11. 11. A scanner (10) for use in placing objects (20) at planned locations over/around an area of ground, comprising: - a memory for storing the planned locations of the objects; - a means (12) for generating and directing a beam over the area in various controllable directions corresponding to the planned locations; - a means for measuring distance in various directions; and - a signalling means for indicating to an operator whether an object in the path of the beam is at the relevant planned location.
12. 12. A scanner according to claim 10, in which the means for generating and directing the beam is a laser device (12) and it includes the distance-measuring means.
13. 13. A scanner according to claim 10 or 11, in which the signalling means emits a visual or an audible signal, or both.
14. 14. A scanner according to any of claims 10 to 12, further including a processor and a memory configured to calculate from each distance measurement how near the object is to its prescribed distance and to indicate accordingly to the signalling means the signal to be given to the operator.
15. 15. A scanner according to any of claims 10 to 13, in which the processor is configured, after the objects have been placed, to direct the beam and distance-measuring means to survey the objects and to generate precise measurements of their position and, optionally, orientation.
16. 16. A set of objects placeable over an area for use in a navigation/ trilateration/triangulation process, for instance for use in controlling the movement of a robot, comprising a scanner (10) according to any of claims 10 to 14 and a set of reflectors consisting of reflecting areas (26) mounted on stands (20), the scanner also including such a reflecting area.
17. 17. A method of determining the location of at least one target object in a given area, comprising the following steps: - providing a scanner in line of sight of the object, the scanner being capable of directing a light beam at controllable angles over the area and of measuring the distance from the scanner to an object intercepting the beam, and having access to stored data concerning the size and shape of the object; - the scanning the beam over the object and measuring the distance to several points on its surface; - comparing the measured points with the stored data and thus ascertaining the location and, preferably, orientation of the object.
18. 18. A method according to claim 17, in which the stored data also includes data concerning the approximate location of each object.
19. 19. A method according to claim 18, in which scanner directs the beam only, or mainly, within a tolerance of the locations where the object is expected to be according to the stored location data.
20. 20. A method according to any of claims 17 to 19, in which the beam is a laser beam and is modulated to enable the scanner to measure the distance to an object.
21. 21. A method according to any of claims 17 to 20, in which the object is a flat panel mounted vertically, and the scanner identifies the panel by identifying straight lines of no greater width than the expected angular width of a panel at the measured distance, oriented to face the scanner.
22. 22. A method according to any of claims 17 to 21, in which target identification and validation is carried out using algorithms such as Reflector Hunting, Noise Filtering, Clustering Methods, Near-Neighbour point-cloud methods, Near-neighbour angular-validation method, Cluster Width method, Geometry and heading identification, Dynamic reflector scanning.
23. 23. A method according to Claim 21 or 22, in which smoothing and filtering processes are carried out to distinguish actual panels from spurious reflections, such as I. Kalman ii. Savitzky-Golay and iii. Gaussian for Noise reduction, and i. Hough transforms ii. Radon Transforms iii. Ransac iv. Brute-force v. Split and merge vi. Incremental vii. Linear regression viii. Expectation maximisation ix. Successive edge following x. Line tracking xi. Iterative end point following xii. Rided-2D xiii. Artificial intelligent / machine learning point-voting xiv. Piecewise approximation xv. Slope-intercept recognition, for reflector perpendicular plane recognition.
24. 24. A method according to any of claims 17 to 23, in which the angular scan rate of the scanner over an object is finer in space and/or slower in time for objects at a greater measured or stored distance from the scanner than for nearer ones.
25. 25. A method according to any of claims 17 to 24, including the further subsequent step of guiding a robot or process by means of the objects whose locations and orientations have been ascertained.
26. 26. A scanner (10) for use in placing determining the locations and, preferably, orientations of one or more objects (20) at planned locations over/around an area of ground, comprising: optionally, a memory for storing expected locations of the objects; - a means (12) for generating and directing a beam over the area in various controllable directions; - a means for measuring distance to an object detected in such a direction; and - a processor for calculating whether a given set of reflections corresponds to a known or expected object.
27. 27. A scanner according to claim 26, in which the means for generating and directing the beam is a laser device (12) and it includes the distance-measuring means.
28. 28. A scanner according to claims 26 or 27, including the said memory or having access to a memory storing data about how near the object is, the data being usable to indicate accordingly to the processor whether the received signal is likely to correspond to the object sought.
29. 29. A scanner according to any of claims 26 to 28, wherein the processor and/or the memory is or are located in the scanner.
30. 30. A set of objects placeable over an area for use in a navigation/ trilateration/triangulation process, for instance for use in controlling the movement of a robot, comprising a scanner (10) according to any of claims 25 to 28 and a set of reflectors consisting of reflecting areas (26) fixed or mounted on mobile stands (20), the scanner optionally also including such a reflecting area.