HK40116702A - System and method for avoiding utility strikes by construction equipment - Google Patents

Description

A system and method for preventing construction equipment from colliding with public facilities.

Cross-references to related applications

This application claims priority to U.S. Provisional Patent Application No. 63/321,787, filed March 21, 2022, which is incorporated herein by reference.

Technical Field

The present invention relates generally to construction equipment, and particularly to a sensing system for construction equipment.

Background Technology

In the construction industry, utilities collisions (i.e., construction equipment collisions that often disrupt underground utility services) are frequent and result in significant direct and indirect costs. This is particularly common when excavating within or between built-up areas (which may contain gas mains, underground cables, and/or fiber optic cables, etc.). Collisions with gas mains and underground cables are hazardous to life and property. Repairs to fiber optic cables are extremely expensive and often result in communication loss for extended periods, which can have subsequent impacts on many types of services that depend on communication.

Unfortunately, none of the known methods for detecting underground public works are effective. Acoustic methods cannot detect public works. Magnetometers detect ferrous metal pipes, but this is unreliable and prone to misinterpretation. Active methods involving injected current and subsequent detection of electric and magnetic fields rely on conductivity continuity, which is not always guaranteed. Furthermore, these methods require operational experience and are generally considered unreliable.

Electric cables can be detected by their magnetic fields, but this is not the case for armored cables, because the armor shields the magnetic field.

Ground-penetrating radar (GPR) is the most common inspection method because it detects material discontinuities regardless of the material's properties. That is, it can detect all metals, all plastics, ceramics, and even voids. For cables, inspection is independent of whether they are energized. GPR can inspect fiber optic cables, and especially high-bandwidth fiber optic cables used in city-to-city communications, where breaks can lead to the most significant cost.

However, in routine use, GPR requires preliminary on-site surveys for locating public facilities and involves offline map preparation and coordination between the map and reference markers placed on-site. Because the coordination between radar maps and on-site references is often poor, and because the interpretation of GPR imagery requires a considerable amount of specialized knowledge, routine applications of GPR are impractical in many cases.

John Deere's GB2486375 describes an antenna to be placed on the teeth of an excavator's bucket such that the beam outlet is in a straight line with the bucket teeth. Such a beam orientation is ineffective for detecting public works during excavation.

Summary of the Invention

Therefore, according to a preferred embodiment of the present invention, a GPR (Ground Penetrating Radar) system is provided, comprising: an excavator having a bucket; a GPR unit mounted on the bucket; and a post-processing unit installed in a compartment of the excavator. The GPR unit includes: at least one GPR antenna mounted on and/or through a ground-penetrating base of the bucket; and a data processor installed within the upper part of the bucket. The data processor detects the presence of a hazard during the gradual removal of the soil layer. When the data processor detects a hazard during the gradual removal of the soil layer, the post-processing unit provides an alarm.

Furthermore, according to a preferred embodiment of the present invention, the data processor includes a radar controller for transmitting and receiving pulses in both SFCW (Striking Frequency Continuous Wave) and SFICW (Striking Frequency Interrupted Continuous Wave) modes.

Furthermore, according to a preferred embodiment of the invention, the data processor includes a tone calibrator for determining antenna defects. Since pulses are sequences of tones in the frequency domain, the data processor includes a pulse corrector for individually correcting tonal defects using the output of the tone calibrator.

Furthermore, according to a preferred embodiment of the invention, the tone calibrator corrects ringing in at least one GPR antenna.

Furthermore, according to a preferred embodiment of the invention, the data processor includes a sequence migration unit that receives corrected pulses from a pulse corrector to migrate the echo energy in the corrected pulses to the maximum likelihood point indicating the location of danger.

Furthermore, according to a preferred embodiment of the invention, at least one antenna is pointed towards the ground when the bucket is digging.

Furthermore, according to a preferred embodiment of the invention, at least one antenna is designed to withstand harsh excavation environments.

Furthermore, according to a preferred embodiment of the invention, at least one GPR antenna is installed within the volume of the bucket.

Furthermore, according to a preferred embodiment of the invention, the data processor includes an IMU (Inertial Measurement Unit) and a Kalman filter. The Kalman filter uses the constrained motion of the bucket to estimate the horizontal position of the bucket.

Furthermore, according to a preferred embodiment of the invention, the data processor includes a starting point determiner for establishing a reference, against which the horizontal and vertical coordinates of the public facility scatterer are measured.

Furthermore, according to a preferred embodiment of the invention, the alarm is a display alarm and/or an audible alarm.

Furthermore, according to a preferred embodiment of the invention, the post-processing unit includes a GPS unit for geolocating the excavator at the site. The post-processing unit includes location data from the GPS unit in a log of soil layer removal.

Furthermore, according to a preferred embodiment of the present invention, the system includes a communication unit for relaying the location of the danger and location data to an external agent.

Furthermore, according to a preferred embodiment of the present invention, the system includes at least one interface for receiving control information from the instrument for operator-assisted or autonomous operation.

Alternatively, according to an alternative preferred embodiment of the invention, the system further includes a transmitter and a plurality of receivers. The transmitter is mounted on the boom of the excavator and near the pivot between the boom and the bucket. The plurality of receivers are mounted in a compartment to receive signals from the transmitter. The data processor determines the horizontal position of the bucket based at least on time-of-flight measurements between the transmitter and the receivers.

Furthermore, according to a preferred embodiment of the invention, the transmitter and multiple receivers implement one of the following technologies: ultrasonics, UWB radar, millimeter-wave radar, and optics.

Furthermore, according to a preferred embodiment of the invention, the system includes: an inclinometer for measuring the inclination of the bucket relative to the horizontal plane. A data processor uses this inclination to determine the horizontal position.

According to a preferred embodiment of the present invention, a method for a GPR system is also provided. The method includes: using a GPR unit mounted on the bucket of an excavator to detect the presence of a hazard during the gradual removal of a soil layer, wherein the GPR unit includes: at least one GPR antenna mounted on and/or through a ground-mounted base of the bucket; and a data processor mounted within the upper portion of the bucket; and providing an alarm when the data processor detects a hazard during the gradual removal of the soil layer.

Furthermore, according to a preferred embodiment of the present invention, the detection includes transmitting and receiving pulses in both SFCW (Step Frequency Continuous Wave) and SFICW modes.

Furthermore, according to a preferred embodiment of the invention, the pulse is a sequence of tones in the frequency domain, and the detection includes: determining an antenna defect, and using the determined output to individually correct the defect in the tone. Determination includes correcting ringing in at least one GPR antenna.

Furthermore, according to a preferred embodiment of the invention, the detection includes: receiving a calibrated pulse and transferring the echo energy in the calibrated pulse to the maximum likelihood point indicating the location of the danger.

Furthermore, according to a preferred embodiment of the invention, the method includes: pointing at least one antenna toward the ground while the bucket is digging.

Furthermore, according to a preferred embodiment of the invention, the method includes: mounting at least one GPR antenna within the volume of the bucket.

Furthermore, according to a preferred embodiment of the invention, the detection includes: estimating the horizontal position of the bucket using a Kalman filter, the constrained motion of the bucket, and the output of the IMU (Inertial Measurement Unit).

Furthermore, according to a preferred embodiment of the invention, the detection includes: establishing a reference, based on which the horizontal and vertical coordinates of the public facility scattering body are measured.

Furthermore, according to a preferred embodiment of the invention, the method includes: geolocating the site of the excavator and including location data from the geolocation in a log of soil layer removal.

Furthermore, according to a preferred embodiment of the present invention, the method includes: relaying the location of the danger and location data to an external agent.

Furthermore, according to a preferred embodiment of the present invention, the method includes: receiving control information from the instrument for operator-assisted or autonomous operation.

Alternatively, according to an alternative preferred embodiment of the invention, the detection includes: determining the horizontal position of the bucket based at least on time-of-flight measurements between a transmitter and a plurality of receivers, wherein the transmitter is mounted on the boom of the excavator and near a pivot between the boom and the bucket, and the plurality of receivers are mounted in the cabin and receive signals from the transmitter.

Finally, according to a preferred embodiment of the invention, the method includes: measuring the inclination of the bucket relative to a horizontal plane, and detecting a method for determining a horizontal position using the inclination.

Attached Figure Description

The subject matter considered to be the present invention is specifically pointed out and clearly claimed in the concluding section of the specification. However, the organization and operation of the invention, as well as its objects, features, and advantages, can be best understood by referring to the following detailed description in conjunction with the accompanying drawings, in which:

Figures 1A, 1B, and 1C are schematic diagrams showing a GPR system that can be operated during excavation operations using an excavator.

Figures 2A, 2B, and 2C are schematic diagrams of the excavated trench through which the buried public facilities pass, the processing unit in the operator's cabin, and the display, respectively. They help to understand the GPR system in Figures 1A, 1B, and 1C.

Figure 3 is a block diagram illustrating a useful analog signal generator and preprocessor in the GPR system of Figure 1C;

Figure 4 is a block diagram illustration of a radar controller used for generating tones in the GPR system of Figure 1C.

Figures 5A and 5B show the conventional antenna response and the digitally corrected antenna response, respectively;

Figure 6 is a block diagram illustrating a useful GPR data interpreter in the GPR system of Figure 1C;

Figure 7 is a schematic diagram of an exemplary scattering pattern of pulses during the draw of the excavator;

Figure 8 is a block diagram illustrating a useful hazard identifier in the GPR system of Figure 1C;

Figures 9A and 9B are schematic diagrams of alternative GPR systems that can be operated during excavation operations using an excavator; and Figure 9C is a schematic diagram of triangulation operations performed by the system of Figure 9A.

It will be recognized that, for the sake of simplicity and clarity, the elements shown in the accompanying drawings are not necessarily drawn to scale. For example, for clarity, the dimensions of some elements may be exaggerated relative to others. Furthermore, where appropriate, reference numerals may be repeated between figures to indicate corresponding or similar elements.

Detailed Implementation

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, those skilled in the art will understand that the invention can be practiced without these specific details. In other instances, well-known methods, processes, and components have not been described in detail so as not to obscure the invention.

The applicant has recognized that a GPR system that integrates under-bucket detection with excavation operations can replace offline surveying and interpretation, and can enable the practical application of GPR as a protection against utility fractures. This can provide a safer excavation method.

Referring now to Figures 1A, 1B, and 1C, which together illustrate a GPR system 10 operable during excavation operations using excavator 11. GPR system 10 includes a GPR unit 12 attached to the excavating bucket 13 of the excavator or "excavator" 11, and a post-processing unit 14 housed in a compartment 19 in which the operator 17 can sit while operating the excavator 11. Excavator 11 can be any suitable excavating machinery, such as a backhoe excavator, loader, bulldozer, grader, or any other type of excavating construction vehicle.

GPR unit 12 may include transmitting antenna 30, receiving antenna 32, and GPR data processor 34, all of which are mounted within the volume of bucket 13. Antennas 30 and 32 may be mounted on, within, and/or through the grounding base 15 (FIG. 1B) of bucket 13. FIG. 1B shows exemplary antennas 30 and 32 mounted such that a portion extends through the base 15 and a portion lies on the inner surface of the base 15. GPR data processor 34 may be mounted on the upper portion 37 of bucket 13. GPR data processor 34 may be isolated from bucket 13 to prevent impacts and vibrations (e.g., by shock absorbers (not shown)) and may be powered from excavator 11.

The GPR data processor 34 may include an analog signal generator and preprocessor 21 (FIG. 1C), a motion sensor unit 23, a digital data processor 25, and a radio communication unit 22, such as a wireless device for cellular connectivity or a WiFi unit. The post-processing unit 14 may include a display 20 (e.g., a monitor or tablet computer) that radioly communicates with the radio communication unit 22, the GPS unit 24, and the speaker 26 for alerting the operator 17. The display 20 may include a menu system and touch sensing.

The transmitting antenna 30 and receiving antenna 32 can be any suitable GPR antenna pair capable of withstanding harsh excavation environments, such as the GPR antenna pair described in U.S. Patent 9,899,741 and U.S. Patent Application 17/259,170, filed July 18, 2019, by PCT and granted November 15, 2019, as U.S. Patent 11,502,416, all of which are assigned to the applicant of this invention and are incorporated herein by reference in their entirety. The GPR data processor 34 can control antennas 30 and 32, can process GPR data received from receiving antenna 32, and can examine the processed data to determine if a hazard (i.e., a utility) has been detected. If so, it can generate a visual alarm to be displayed on display 20 and/or an audio alarm for speaker 26 to instruct operator 17 to stop excavation and surveying.

In addition, the GPR data processor 34 can receive geolocation information of the excavator 11 from the GPS unit 24. The GPR data processor 34 can record excavation data, associate the excavation data with at least the geographical location of the excavator 11, and relay the excavation data to the display 22 via the radio communication unit 22. Furthermore, the GPR data processor 34 can relay the geographical location to a computerized archive (not shown) storing excavation evidence and/or to the central control unit for review by the construction team.

Figure 1A illustrates the basic process of excavating trench 40. Excavator 11 can be positioned 42, and operator 17 can use bucket 13 to excavate trench 40. Operator 17 can move bucket 13 horizontally to sequentially remove material layers from trench 40. According to a preferred embodiment of the invention, during the excavation of each layer, operator 17 can be manually or using computer-aided control to instruct to keep the base 15 of bucket 11 horizontal. This allows the radar beam 44 emitted from GPR unit 12 to remain vertical (i.e., detecting directly below and slightly in front of bucket 13). It will be appreciated that radar beam 44 can move horizontally with the horizontal movement of bucket 13, but can be viewed vertically to detect anything that may be below the current layer of trench 40.

The applicant has recognized that, because GPR unit 12 can vertically observe the ground below bucket 13, it can detect any public works facilities several layers below the layer currently being removed. Furthermore, the applicant has recognized that the initial detection may be unclear, assuming that public works facilities may be significantly lower than the current ground level, and assuming that soil type and the presence of moisture in the soil affect the quality of the detection. However, the detection can be significantly improved as each layer is removed. This allows for high-quality detection to occur well before bucket 13 can access any hidden public works facilities.

Furthermore, as discussed in U.S. Patent 11,085,170, assigned to the applicant and incorporated herein by reference in its entirety, the GPR data processor 34 can utilize the fact that the movement of the bucket 13 is horizontal when excavating the trench 40, and therefore, the rotation of the boom 50 and stick 52 of the excavator 11 can occur in only one plane. As discussed in U.S. Patent 11,085,170, this simplifies the calculation of the position of the receiving antenna 32 when the movement of the bucket 13, measured by the motion sensor unit 23, is used as input. Using these calculations, the GPR data processor 34 can determine the position of any detected utility relative to the starting point of the excavation. The GPR data processor 34 can then provide the position information to the display 20 and/or a computerized archive, or to a central control unit for inspection by the construction team.

Referring now briefly to Figures 2A, 2B, and 2C, which are schematic diagrams of the excavated trench 40 through which the buried utility 60 passes, the processing unit 17 in compartment 19, and the display 20 of the processing unit 14, respectively. Note that the display 20 displays an alarm on the screen in response to the detection of the buried utility 60, and also shows the location indicated as the distance from the starting point of the trench 40 and the depth of the buried utility 60.

The applicant has recognized that, for the automated detection of underground utilities in real time (i.e., during excavation), the data quality of the GPR system 10 must be significantly more accurate than that provided by the conventional GPR, which currently transmits and receives pulses. Therefore, the analog signal generator and preprocessor 21 can alternatively generate frequency sequences, which are the Fourier components of short pulses, for transmission by the transmitting antenna 30. The analog signal generator and preprocessor 21 can receive, amplify, and process the echo responses from the underground material. As described in more detail below, the analog signal generator and preprocessor 21 can construct short pulses based on the Fourier component echoes and can correct the Fourier component echoes for equipment defects in the signal chain before finally determining the short pulses.

Referring to FIG3, in an exemplary embodiment, the analog signal generator and preprocessor 21 may include a radar controller 70 and a GPR pulse corrector 72, and the digital data processor 25 may include a GPR data interpreter 74 and a hazard identifier 76.

The radar controller 70 can control the operation of antennas 30 and 32, and can activate antennas 30 and 32 respectively to sequentially transmit and receive sequences of tones at intervals of approximately 1/10 of a second. 100 to 400 tones can be transmitted and echo data can be stored; these tones are typically simple continuous wave carriers with stepped frequencies. In one embodiment, the principles described in U.S. Patent Application 16/163,799, filed October 18, 2018, and granted March 21, 2022, as U.S. Patent 11,280,881, assigned to the applicant and incorporated herein by reference in their entirety.

As discussed below, the GPR pulse corrector 72 can correct any aberrations in the pulses of the radar signal to generate pulses that are potentially more accurate than those of a conventional GPR system. The GPR data interpreter 74 can use the more accurate pulse data to detect buried utility 60 or other hazards and determine their location relative to the starting point of the trench 40. The hazard detector 76 can warn the excavation operator 17 of impending danger.

Referring now to Figure 4, it illustrates the operation of the radar controller 70 in generating a tone. The radar controller 70 can synthesize a tone to be transmitted according to the stepped frequency continuous wave (SFCW) technique. However, the SFCW method implies simultaneous transmission and reception, and its disadvantage is that weak received signals may be suppressed by transmitter leakage.

To avoid this situation, the radar controller 70 can additionally implement Interrupted Continuous Wave (ICW) technology, as discussed in U.S. Patent 6,664,914 (which is incorporated herein by reference). ICW technology can activate only one antenna 30 or 32 at a time, or can limit the duration for which both antennas are activated simultaneously. Switching between antennas can isolate the receiver antenna 32 while the transmitter antenna 30 is active, and vice versa. By integrating this technology into Stepped Frequency Interrupted Continuous Wave (SFICW) technology, even weak tones can be received. Furthermore, by alternating between SFCW and SFICW technologies, most targets can be detected.

Therefore, the radar controller 70 may include a GPRSFCW tone transmitter 80, a GPRSFCW tone receiver 82, and a switcher 84.

When performing SFICW technology, switch 84 can alternately activate transmitter 80 and receiver 82, or activate transmitter 80 and receiver 82 with minimal overlap. GPRSFCW tone transmitter 80 can produce tones that are typically, but not substantially, equidistant in frequency. Typically, when radar controller 70 detects interference, transmitter 80 can omit the tone, as described below. The ability to omit the tone allows GPR system 10 to tolerate interference and also allows it to avoid interfering with other radio-related systems. Transmitter 80 can provide the generated tones to transmitting antenna 30, which can then transmit these tones into trench 40. Receiver 82, when activated by switch 84, can receive reflected signals (e.g., radar echoes) and can provide the received signals to GPR pulse corrector 72. It will be appreciated that the timing of the switching can be designed so that radar controller 70 can suppress closer and stronger echoes, thereby enabling radar controller 70 to receive weaker tones that are typically farther away.

Before providing the tone to the GPR pulse corrector 72, the receiver 82 can check for interference. Specifically, the tone is assigned to a specific frequency in a specific time slot. Therefore, if the signal received in a specific time slot does not have the expected frequency for that time slot, the received signal is not a tone. Instead, the received signal contains interference, and therefore the receiver 82 may not pass that tone to the GPR pulse corrector 72.

The applicant has recognized that conventional GPR systems cannot approximate ideal pulses due to unsuppressible internal reflections. For example, reflections within the antenna structure produce ringing, which adversely affects resolution by extending pulse energy. The applicant also recognizes that these detrimental effects can be significantly suppressed by correcting the tone and thereby generating a synthesized tone.

To locate defects in the device, the radar controller 70 may additionally include a tone calibrator 86, which may be a high-fidelity bypass link (e.g., a calibration path) connecting the end of the transmit path to the beginning of the receive path, such that the calibration signal is never transmitted into the air, but only within the hardware. The resulting "radar" signal will only be subjected to the actual distortion imposed by the transmitting and receiving hardware. The tone calibrator 86 may occasionally activate the calibration path and may store the resulting calibration signal.

The GPR pulse corrector 72 can perform digital correction on each received tone using a method similar to that employed by a vector network analyzer (a common laboratory instrument). Since the correlation correction is performed in the frequency domain, and since the corrected tones form a Fourier series, the GPR pulse corrector 72 can perform an inverse Fourier transform (a standard signal processing operation) on the corrected tones to convert them into corrected pulses. Therefore, the GPR pulse corrector 72 can restore the fidelity of the received tone through independent digital correction of the tone. This is illustrated in Figures 5A and 5B, which are now briefly referenced. Figures 5A and 5B show the conventional antenna response and the digitally corrected antenna response, for example, the antenna response that can be generated by the GPR pulse corrector 72. It can be seen that the conventional antenna response of Figure 5A has antenna ringing, while the corrected response of Figure 5B is close to the theoretical ideal, with very little antenna ringing. It will be appreciated that the GPR pulse corrector 72 can be implemented in a conventional signal processing unit.

Referring now to Figure 6, which shows the elements of a GPR data interpreter 74, this interpreter can process pulse sequences received during the radar's approach and retreat as it passes the buried utility 60. It will be appreciated that, before processing the pulses, the horizontal position of the GPR unit 12 at each emission point can be determined such that the arrival time of the pulse indicating the depth of the buried utility 60 can be correlated with its horizontal position. A motion sensor system 23 can be used to determine the horizontal position and can trigger new tone emission sequences based on the horizontal movement of the bucket 13. For example, the motion sensor system 23 can trigger tone emission for every 1 cm of horizontal movement.

The GPR data interpreter 74 may include a horizontal position determiner 90 and a sequence migration unit 92. The horizontal position determiner 90 may receive horizontal position information from at least one of a variety of sensor systems, and the sequence migration unit 92 may examine a pulse sequence to determine the depth of a hazard (e.g., buried utility 60). The GPR data interpreter 74 may also include a start position determiner 94 to indicate when the operator 17 begins excavating the next layer of trench 40 and to store the horizontal position coordinates of the bucket position at the start of excavation.

The starting position determiner 94 can receive the bearing of the excavator 11's axis of rotation from the Hall effect compass on the GPS 24 on the excavator 11. Additionally, the operator 17 can initiate "pulling" at a known extension of the bucket 13. Using this information, the starting position determiner 94 can determine the starting position for pulling.

A motion sensor system 23 may include a 6-DOF IMU 96 and a constrained Kalman filter 98, as mentioned above, which can utilize the constrained motion of the mechanical linkages of the cantilever 50 and the rod 52 to reduce the inherent drift of the accelerometer of the IMU 96. This is described in U.S. Patent 11,085,170, owned by the applicant and incorporated herein by reference. The IMU typically has a gyroscope, which in this embodiment can also provide offset orientation for scanning of the bucket 13.

The IMU 96 can measure the movement of the bucket 13 and its output can be provided to a constrained Kalman filter 98, which in turn can generate the position of the bucket 13 at each time point. Note that, as mentioned above, the operator 17 can ensure that the bucket 13 moves horizontally as it excavates each layer of the trench 40.

When operator 17 brings bucket 13 to a rest point before starting to excavate the next level (referred to as "pulling"), starting position determiner 94 can register that rest point as the starting position, and then level position determiner 90 can be activated to begin operation. Level position determiner 90 can determine the horizontal position relative to that zero point or starting point.

Sequence transfer unit 92 can process the pulse sequence received during the pull and can transfer the echo energy in the pulse to the maximum likelihood point, thereby indicating the location of the scattering object (i.e., the buried utility 60). Sequence transfer is known and discussed in Exploplation Seismology (Sheriff and Geldart, Cambridge University Press, ISBN 0-521-48626-4 (Lib. of Congress), after page 237).

Referring now briefly to Figure 7, an exemplary scattering pattern of the pulse is shown as the bucket 13 passes over the buried utility 60 during the pulling process. The points indicate the depth reported as the bucket 13 moves horizontally within the trench 40 (as indicated by the horizontal line 110). It can be seen that the first point (point 112) is far from the horizontal line 110. As the bucket 13 moves horizontally along the trench 40, the points approach the horizontal line 110 and then move away from it. The point at the peak, marked 114, is closest to the horizontal line 110 and indicates the true depth of the buried utility 60.

The migration unit 92 can process pulse data continuously and automatically. The migration unit 92 can utilize pattern recognition technology to determine the x-z coordinates of one or more targets, where x is the horizontal distance from the start of bucket movement and z is the depth from the horizontal plane. It will be appreciated that by using the pattern recognition process, the obtained position and depth information can be more accurate, ideally eliminating the need for human intervention to check whether the buried utility 60 is in the position determined by the migration unit 92. It should also be appreciated that this accuracy can facilitate autonomous or semi-autonomous operation of the excavator 11. For this purpose, the GPR system 10 may include at least one interface to receive control information from the instrument for operator-assisted or autonomous operation.

Referring now briefly to Figure 8, as shown, the hazard detector 76 can receive horizontal position and hazard depth information generated by the GPR data interpreter 74, and when this information indicates a hazard, it can provide position and depth information to the display 20 and activate an alarm. Furthermore, the hazard detector 76 can instruct the post-processor 14 (Figure 1C) to activate a series of audible tones using the speaker 26. The machine operator 17 can assess whether the indicated hazard will be encountered during the next digging of the bucket and can react accordingly.

Returning to Figure 6, alternative methods exist that measure GPR motion (indicated as "Other Sensors" 120 in Figure 6) and determine the horizontal position based on it. The horizontal position determiner 90 can combine its output with the outputs of the IMU 96 and the constrained Kalman filter 98, or they can be used independently. While the IMU can be self-contained within the GPR unit 12, other methods may require more complex installations, involving mounting sensors on or outside the structure of the excavator 11.

The applicant has recognized that inertial measurement requires calibration, which necessitates a pause during the digging operation. Furthermore, an IMU with the necessary mass is expensive. In an alternative embodiment, system 10 can utilize the "time-of-flight" distance between a designated fixed-point digging rod 52 (FIG. 1A) and a known reference position on compartment 19. This is illustrated in Figures 9A and 9B, referring now to Figures 9A and 9B.

Figure 9A shows an excavator 11 with a transmitter 130 mounted on the digging bar 52 and multiple receiver units 133 (shown in Figure 9B) mounted in the compartment 19. For example, the transmitter 130 may be positioned relatively close to the bucket pivot 135 to provide relatively accurate position determination, and there may be three or more receivers 133, wherein two receivers 133A and 133B may be formed as receiver unit 132A mounted above the operator 17's head (e.g., on a crossbar extending across the top of the compartment 19), one mounted on the right side of the compartment 19 and one mounted on the left side of the compartment 19, and a receiver 133C may be formed as receiver unit 132B near the operator 17's feet on the centerline of the compartment.

As can be seen from Figure 9B, receiver 133 can form triangle 134, which can be an equilateral triangle, wherein receivers 133A and 133B form the base of triangle 134 with receiver unit 132A, and receiver 133C forms the vertex of triangle 134 with receiver unit 132B.

In this embodiment, transmitter 130 may transmit signals continuously, for example, at times _t1 , _t2 , and _t3 , as shown in FIG9A. Receiver 133 may receive these signals and may provide its output to horizontal position determiner 90. Determiner 90 may use time-of-flight calculations to determine the distance _di of transmitter 130 as seen by each receiver 133 in a coordinate system defined by a fixed position on cabin 19.

Determiner 90 can perform conventional triangulation calculations based on the distance d_{_i} measured by each receiver 133 to locate the position of transmitter 130 on excavator 52, represented in a coordinate system centered on the compartment. Referring now to Figure 9C, Figure 9C illustrates the triangulation operation for finding the coordinates (x, y, z) of transmitter 130. Figure 9C shows the distances d₁, d₂, and d _₃ of receivers 133A, 133B, and 133C, and their coordinates (x_₁ _, y_₁, z_₁ ), (x _₂, y_₂, z_₂), and (x _₃ , y _₃ , z_₃ ), respectively. Determiner 90 can form three equations for the three unknowns (the coordinates x, y, and z of transmitter 130), as follows:

(d _i ) ² = (x - x _i ) ² +(y - y _i ) ² +(z - z _i ) ² , where i = 1, 2, 3 (1)

Using Equation 1, the determiner 90 can thus determine the coordinates of the transmitter 130 on the digging rod 52. It will be appreciated that the vertical distance D between the bucket pivot 135 and the antenna 12 can be fixed because the operator 17 can keep the bottom plate of the bucket 13 level, allowing the determiner 90 to combine the coordinates of the transmitter 130 with the fixed vertical distance D to determine the position of the antenna 12. This is also true even when there is an angle between the bucket 13 and the digging rod 52, so that the influence of the known angle can be included when estimating the antenna's position. The known angle can be measured by any suitable angle sensor (e.g., an inclinometer 136 mounted within the data processor 34 in the bucket 13). The inclinometer 136 can measure the deviation of the bucket 13 from the horizontal plane and infer the deviation of the bottom surface of the bucket 13 from the horizontal plane.

It will be recognized that time-of-flight calculation and triangulation calculation are simple and well-known, and therefore, the determiner 90 can quickly determine the horizontal position of the bucket 13.

It will be appreciated that the transmitter 130 and receiver 133 of this embodiment are relatively low-cost technologies. Furthermore, since no calibration is required during operation and therefore no pause is needed, the operation is simpler than using an IMU 96.

The transmitter 130 and receiver 133 can employ any suitable technology, such as ultrasonic, UWB radar, millimeter-wave radar, and optics. In all cases, the transmitter is located at a designated point on rod 52, and the receiver is positioned at a reference location coordinate.

The determiner 90 can perform a one-time calibration by measuring the positional error of the transmitter 130 at a known location. Due to the short propagation distance involved, a high signal-to-noise ratio at the receiving point is practically feasible. Signal resolution is given by dividing the propagation speed by the signal bandwidth, and accuracy is proportional to the resolution divided by the square root of the signal-to-noise ratio. In all cases, accuracy approaching one centimeter is possible. The marginal advantage of ultrasonics is that the low propagation speed of sound compared to electromagnetic waves reduces the bandwidth requirements, thus impacting design and cost.

It will be recognized that the GPR system 10 can integrate detection into the excavation action and into standard trench excavation operations, thereby gradually approaching potential utility hazards during soil layer removal. It will also be recognized that this gradual removal of soil reduces the requirements for penetration and detection depth, thus making the application applicable to a wider range of soil conditions.

Furthermore, the GPR system 10 can achieve excellent measurement quality by applying pulse synthesis techniques to enhance waveform fidelity, thereby correcting for defects in the synthesized components at the level of the individual frequency components transmitted in the Fourier spectrum of the pulse. This can result in improved resolution properties. Specifically, the correction technique can compensate for antenna defects, which are a major source of defects in conventional GPR systems. These improved aggregations can be supplemented by algorithmic methods for hazard detection, which can reduce or eliminate the need for human interpretation, enabling the successful application of GPR detection to avoid damage to public facilities. In this embodiment, the operator 17 can be replaced by an automated excavation control system to ensure that the bucket 13 moves horizontally at an optimal speed during each layer of excavation of the trench 40.

GPR system 10 can eliminate the need for registration between surveying and on-site operations, as well as the need for human expertise in interpreting GPR data. Furthermore, GPR system 10 can reduce the amount of operator training required and does not require additional skills beyond those necessary for operating the excavator 11.

It will also be recognized that, since the GPR unit 12 can be installed within the volume of the excavating bucket, it can provide an installation with minimal compromise to the bucket's digging efficiency. Furthermore, as discussed above, antennas 30 and 32 are pointed towards the ground when the bucket is digging; therefore, the GPR system 10 can be oriented to detect buried obstacles. Additionally, the GPR system 10 can geolocate the excavation site using the detected objects and can index the information to broadcast it to an external agent via WiFi.

It will also be recognized that the GPR system 10 can provide real-time (i.e., during excavation) alerts for hazards below the surface.

Unless otherwise specifically indicated, it will be appreciated as is apparent from the foregoing discussion that throughout this specification, the use of terms such as “processing,” “computing,” “operation,” “determining,” etc., refers to the actions and/or processes of any type of computing device, such as a general-purpose or special-purpose computer, for example, a client/server system, mobile computing device, tablet device, smart appliance, cloud computing unit, signal processing unit, or similar electronic computing device, which manipulates and/or converts data in the registers and/or memory of a computing system into other data in the memory, registers, or other such information storage, transmission, or display devices of the computing system.

Embodiments of the present invention may include means for performing the operations described herein. Such means may be specifically configured for the desired purpose, or may comprise a computing device or system typically having at least one processor and at least one memory, selectively activated or reconfigured by a computer program stored in a computer. The resulting means, when instructed by software, can transform a general-purpose computer into the inventive elements discussed herein. Instructions may define the inventive means operating with a desired computer platform. Such a computer program may be stored in a computer-readable storage medium, such as, but not limited to, any type of disk, including optical disks, magneto-optical disks, read-only memory (ROM), volatile and non-volatile memory, random access memory (RAM), electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic or optical cards, flash memory, disk-on-key, or any other type of medium suitable for storing electronic instructions and capable of being coupled to a computer system bus. The computer-readable storage medium may also be implemented as a cloud storage device.

Some general-purpose computers may include at least one communication element for enabling communication with data networks and/or mobile communication networks.

The processes and displays presented herein are not inherently related to any particular computer or other device. Various general-purpose systems may be used with the programs taught herein, or it may prove convenient to construct more specialized devices to perform the desired methods. The desired architectures of various such systems will emerge from the description below. Furthermore, embodiments of the invention are not described with reference to any particular programming language. It will be appreciated that the teachings of the invention as described herein can be implemented using various programming languages.

While the features of the invention have been shown and described herein, many modifications, substitutions, alterations, and equivalents will now occur to those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and alterations falling within the true spirit of the invention.

Claims (33)

1. A GPR (Ground Penetrating Radar) system, comprising: Excavating machines, which have buckets; A GPR unit, mounted on the bucket, includes: at least one GPR antenna mounted on and/or through the grounding base of the bucket; and a data processor mounted within the upper part of the bucket for detecting the presence of hazard during the gradual removal of the soil layer; and A post-processing unit, installed in the compartment of the excavator, is used to provide an alarm when the data processor detects the danger during the gradual removal of the soil layer. 2. The GPR system according to claim 1, wherein the data processor comprises: a radar controller, which is configured to transmit and receive pulses in both SFCW (Step Frequency Continuous Wave) and SFICW (Step Frequency Interrupted Continuous Wave) modes. 3. The GPR system of claim 2, wherein the pulse is a sequence of tones in the frequency domain, wherein the data processor includes: a tone calibrator for determining antenna defects, and wherein the data processor includes: a pulse corrector for individually correcting defects in the tones using the output of the tone calibrator. 4. The GPR system of claim 3, wherein the data processor comprises: a sequence migration unit that receives a corrected pulse from the pulse corrector to migrate the echo energy in the corrected pulse to a maximum likelihood point indicating the location of the danger. 5. The GPR system according to claim 3, wherein the at least one GPR antenna is pointed to the ground when the bucket is digging. 6. The GPR system of claim 1, wherein the at least one GPR antenna is designed to withstand harsh excavation environments. 7. The GPR system according to claim 1, wherein the at least one GPR antenna is mounted within the volume of the bucket. 8. The GPR system according to claim 3, wherein the tone calibrator is used to correct ringing in the at least one GPR antenna. 9. The GPR system of claim 1, wherein the data processor includes an IMU (Inertial Measurement Unit) and a Kalman filter, the Kalman filter being used to estimate the horizontal position of the bucket using the constrained motion of the bucket. 10. The GPR system of claim 9, wherein the data processor comprises: a starting point determiner for establishing a reference, wherein the horizontal and vertical coordinates of the utility scatterer are measured based on the reference. 11. The GPR system of claim 1, wherein the alarm is at least one of a display alarm and an audible alarm. 12. The GPR system of claim 9, wherein the post-processing unit comprises: a GPS unit for geolocating the site of the excavator, and wherein the post-processing unit includes location data from the GPS unit in a log of the removal of the soil layer. 13. The GPR system of claim 12, further comprising: a communication unit for relaying the location of the hazard and the location data to an external agent. 14. The GPR system of claim 1, further comprising: at least one interface for receiving control information from the instrument for operator-assisted or autonomous operation. 15. The GPR system of claim 1, further comprising: The launcher is mounted on the boom of the excavator and near the pivot between the boom and the bucket; and Multiple receivers are installed inside the cabin to receive signals from the transmitter; The data processor is used to determine the horizontal position of the bucket based at least on the time-of-flight measurement between the transmitter and the receiver. 16. The GPR system of claim 15, wherein the transmitter and the plurality of receivers implement one of the following technologies: ultrasonic, UWB radar, millimeter-wave radar, and optics. 17. The GPR system of claim 15, further comprising: an inclinometer for measuring the inclination of the bucket relative to a horizontal plane, the data processor for using the inclination to determine the horizontal position. 18. A method for a GPR (Ground Penetrating Radar) system, the method comprising: A GPR unit mounted on the bucket of an excavator is used to detect the presence of hazards during the gradual removal of soil layers. The GPR unit includes: at least one GPR antenna mounted on and/or through the ground mount of the bucket; and a data processor mounted within the upper part of the bucket; and When the data processor detects the danger during the gradual removal of the soil layer, an alarm is provided by the post-processing unit installed in the compartment of the excavator. 19. The method of claim 18, wherein the detection comprises: transmitting and receiving pulses in both SFCW (Step Frequency Continuous Wave) and SFICW (Step Frequency Interrupted Continuous Wave) modes. 20. The method of claim 19, wherein the pulse is a sequence of tones in the frequency domain, wherein the detection comprises: determining an antenna defect, and using the determined output to individually correct the defect in the tones. 21. The method of claim 20, wherein the detection comprises: receiving a calibrated pulse and shifting the echo energy in the calibrated pulse to a maximum likelihood point indicating the location of the danger. 22. The method of claim 20, further comprising: pointing the at least one GPR antenna toward the ground while the bucket is digging. 23. The method of claim 18, further comprising: mounting the at least one GPR antenna within the volume of the bucket. 24. The method of claim 20, wherein the determination comprises: correcting ringing in the at least one GPR antenna. 25. The method of claim 18, wherein the detection comprises: estimating the horizontal position of the bucket using a Kalman filter, employing the constrained motion of the bucket and the output of an IMU (Inertial Measurement Unit). 26. The method of claim 25, wherein the detection comprises: establishing a reference, wherein the horizontal and vertical coordinates of the public facility scattering body are measured based on the reference. 27. The method of claim 18, wherein the alarm is at least one of a display alarm and an audible alarm. 28. The method of claim 25, further comprising: geolocating the site of the excavator and including the location data from the geolocation in a log of the removal of the soil layer. 29. The method of claim 28, further comprising: relaying the location of the danger and the location data to an external agent. 30. The method of claim 18, further comprising: receiving control information from the instrument for operator-assisted or autonomous operation. 31. The method of claim 18, wherein the detection comprises: The horizontal position of the bucket is determined at least based on time-of-flight measurements between the transmitter and multiple receivers, wherein the transmitter is mounted on the boom of the excavator and near a pivot between the boom and the bucket, and the multiple receivers are mounted in the cabin and receive signals from the transmitter. 32. The method of claim 31, wherein the transmitter and the plurality of receivers implement one of the following technologies: ultrasonic, UWB radar, millimeter-wave radar, and optics. 33. The method of claim 31, further comprising: measuring the inclination of the bucket relative to a horizontal plane, the detection being used to determine the horizontal position using the inclination.