Non-contact drilling system and method

Abstract

Disclosed are systems and methods for autonomously or substantially autonomously drilling or tunneling various geological formations, including one or more non-contact drilling elements that direct energy to the drilling face to remove material from the drilling face by fracturing, crushing, and removing the material. The system can automatically execute methods for controlling a set of drilling parameters that affect the flow of energy directed to the drilling face. The system can also automatically execute methods for monitoring, directing, maintaining, and / or adjusting a set of drilling controls, such as, for example, the standoff distance between the system and the drilling face, the temperature of exhaust gases directed to the drilling face, the rate of material removal from the drilling face, and / or the thermal or topological characteristics of the drilling face during the drilling operation.

Description

Cross-Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 059,927, filed Jul. 31, 2020, entitled "Excavation Method by Plasma," which is hereby incorporated by reference in its entirety. This application claims the benefit of U.S. Provisional Application No. 63 / 151,036, filed Feb. 18, 2021, entitled "System for Excavating Geology by Jet Collision," which is hereby incorporated by reference in its entirety.

Technical Field

[0002] The present invention generally relates to the field of underground excavation, and more particularly, to a novel and useful underground excavation method using a novel and useful non-contact excavation system in the field of underground excavation.

Brief Description of the Drawings

[0003] [Figure 1] FIG. 1 is a flowchart of an example of excavation using a non-contact excavation element. [Figure 2] FIG. 2 is a schematic diagram of an example of a system for excavating with a non-contact excavation element. [Figure 3] FIG. 3 is a flowchart of an example of a method of excavating with a plasma torch. [Figure 4A] FIG. 4A is a schematic diagram of an example of a system for excavating with a plasma torch. [Figure 4B] FIG. 4B is a schematic diagram of an example of a system for excavating with a plasma torch. [Figure 5] FIG. 5 is a flowchart of an example of a method of excavating with a cutter head including a jet engine. [Figure 6] FIG. 6 is a schematic diagram of an example of a system for excavating with a cutter head including a jet engine.

Best Mode for Carrying Out the Invention

[0004] The following description of embodiments of the present invention is not intended to limit the invention to these embodiments, but rather to enable those skilled in the art to create and use the invention. The variations, configurations, implementations, implementation examples, and examples described herein are optional and not limited to those variations, configurations, implementations, implementation examples, and examples described herein. The invention described herein may include any and all permutations of these variations, configurations, implementations, implementation examples, and examples. 1. Method

[0005] As shown in Figure 1, the drilling method S100 may include, at a first time point, driving a non-contact drilling element facing the drilling surface from the drilling surface to a target standoff distance in block S110, and, once the non-contact drilling element has been activated in block S120 to remove material from the drilling surface, detecting a first profile of the drilling surface in block S130, and adjusting the target standoff distance to a second target standoff distance in block S140. As shown in Figure 1, the method S100 may also include, in response to the first profile showing a first gradient less than the target gradient range, decreasing the target standoff distance to a second target standoff distance in block S150, or in response to the first profile showing a first gradient greater than the target gradient range, increasing the target standoff distance to a second target standoff distance in block S160. Method S100 may also include, at a second point in time, repositioning the non-contact drilling element toward the drilling surface in block S170 according to a second target standoff distance.

[0006] As shown in Figure 3, the second plasma drilling method S200 may include, at a first time point, driving a plasma torch facing the drilling surface from the drilling surface to a target standoff distance in block S210, operating the plasma torch to remove material from the drilling surface in block S220, detecting a first profile of the drilling surface in block S230, and adjusting the target standoff distance to a second target standoff distance in block S240. As shown in Figure 3, method S200 may also include, in block S250, decreasing the target standoff distance to a second target standoff distance in response to the first profile showing a first gradient less than the target gradient range, or in block S260, increasing the target standoff distance to a second target standoff distance in response to the first profile showing a first gradient greater than the target gradient range. Method S200 may also include, in block S270, repositioning the plasma torch toward the drilling surface at a second time point according to a second target standoff distance.

[0007] As shown in Figure 5, the third method S300, which drills with a cutter head including a jet engine, may include, at a first time point, in block S310, driving the cutter head facing the drilling surface from the drilling surface to a target standoff distance; in block S320, operating the cutter head to direct exhaust gas at a target exhaust gas temperature from the nozzle to the drilling surface and remove material from the drilling surface; in block S330, detecting a first temperature of the exhaust gas directed to the drilling surface; and in block S340, adjusting the first temperature of the exhaust gas directed to the drilling surface. As shown in Figure 5, method S300 may also include, in block S350, instructing the fuel metering unit to adjust the rate of fuel entering the combustor so as to maintain the temperature of the exhaust gas leaving the nozzle at or near the target exhaust gas temperature; and in block S360, instructing the air metering unit to adjust the mass of air entering the combustor so as to maintain the temperature of the exhaust gas present in the nozzle at or near the target exhaust gas temperature.

[0008] Variations of methods S100, S200, and S300 include, first, driving a non-contact drilling element facing the drilling surface to a target standoff distance from the drilling surface, operating the non-contact drilling element to remove material from the drilling surface, detecting a first standoff distance from the non-contact drilling element to the drilling surface, calculating a first removal rate from the drilling surface based on a first difference between the target standoff distance and the first standoff distance at a first time point, increasing the target standoff distance in response to the first removal rate falling below the target removal rate, and at a second time point following the first time point, driving the non-contact drilling element to a target standoff distance, operating the non-contact drilling element to remove material from the drilling surface, detecting a second standoff distance from the non-contact drilling element to the drilling surface, and calculating a second removal rate from the drilling surface based on a second difference between the target standoff distance and the second standoff distance at a second time point. In response to the second removal rate falling below the first removal rate, the target standoff distance may be reduced. 2. System

[0009] As shown in Figure 2, the system 100 for non-contact drilling may include a chassis 110, a propulsion system 120 positioned with the chassis 110 to advance the chassis 110 in a first direction toward the drilling surface 200 and to retract the chassis 110 in a second direction toward the drilling surface, a non-contact drilling element 130 connected to the chassis 110 and configured to operate in response to a set of drilling parameters, and a depth sensor 190 configured to measure the standoff distance between the chassis 110 and the drilling surface 200. The system 100 may also include a controller 180 connected to the propulsion system 120, the non-contact drilling element 130, and the depth sensor 190 and configured to control the propulsion system 120, the non-contact drilling element 130, and the depth sensor 190 in response to the depth sensor 190 measuring the standoff distance between the chassis 110 and the drilling surface 200.

[0010] In one variation of system 100 shown in Figures 4A and 4B, system 100 may include a chassis 110, a propulsion system 120 positioned with the chassis 110 to advance the chassis 110 in a first direction toward the drilling surface 200 and to move the chassis 110 backward in a second direction away from the drilling surface 200, a plasma torch 132 connected to a power source 134 and a gas supply source 136, and a plasma torch ram 170 connecting the plasma torch 132 to the chassis 110. As shown in Figures 4A and 4B, the plasma torch ram 170 can be configured to position the plasma torch 132 on the chassis 110, to move the plasma torch 132 forward and backward along the chassis 110 along a longitudinal axis (X-axis) substantially parallel to a first and second direction, to tilt the plasma torch 132 along a pitch angle and a yaw angle relative to the longitudinal axis, to lift the plasma torch 132 vertically along a vertical axis (Z-axis) substantially perpendicular to the longitudinal axis, and to move the plasma torch 132 laterally along the longitudinal axis and a transverse axis substantially perpendicular to the longitudinal axis. As shown in Figures 2, 4A, and 4B, the system 100 may also include a depth sensor 190 configured to measure the standoff distance between the chassis 110 and the excavation surface 200, and a waste discharger configured to draw waste from a first position to a second position between the chassis 110 and the excavation surface 200. In this variant of the exemplary embodiment, system 100 may also include a controller 180 connected to the propulsion system 120, plasma torch 132, plasma torch ram 170, and depth sensor 190, and configured to drive the propulsion system 120, plasma torch 132, plasma torch ram 170, and depth sensor 190 in response to the depth sensor 190, which measures the standoff distance between the chassis 110 and the excavation surface 200.

[0011] In another variation of system 100 shown in Figure 6, system 100 may include a chassis 110 and a cutter head 140, the cutter head 140 including a compressor 142 configured to compress air coming in from a ground fresh air supply source, a combustor 144 configured to mix the compressed air coming out of the compressor 142 with fuel flowing in from a ground fuel supply source to ignite the fuel, a turbine 154 configured to extract energy from the combustion fuel and compressed air coming out of the combustor 144 to rotate the compressor 142, and a nozzle 160 configured to direct exhaust gases 220 coming out of the turbine 154 to induce a jet impact area at the drilling surface 200. As shown in Figure 6, system 100 may also include a cutter head ram 170 connected to the cutter head 130 and configured to position the cutter head 130 relative to the drilling surface 200, a temperature sensor 156, and a controller 180 connected to the cutter head 130, the temperature sensor 156, and the cutter head ram 170. In this variation of the system 100 of the embodiment, the controller 180 can be configured to track the temperature of the exhaust gas 220 exiting the nozzle 160 based on a signal output by the temperature sensor 156, and to adjust the rate of fuel entering the combustor 144 to maintain the temperature of the exhaust gas 220 exiting the nozzle 160 below the melting temperature of the geological material present in the drilling site and above the fracturing temperature. As shown in Figures 2 and 6, the system 100 may also include a propulsion system 120 connected to the controller 180 and positioned with the chassis 110 to advance the chassis in a first direction toward the drilling surface 200 and to retract the chassis 110 in a second direction. 3. Applications

[0012] In general, one or more variations of system 100 can perform blocks of methods S100, S200, and S300 to autonomously or substantially autonomously excavate or tunnel through various geological formations while increasing the efficiency of drilling speed and power (fuel, electricity, flammable gas) consumption. In general, system 100 may include one or more non-contact drilling elements that direct energy (e.g., by high temperature, high pressure, electromagnetic radiation, etc.) toward the drilling surface and remove material from the drilling surface by fracturing, crushing, and removing the material. To operate autonomously or substantially autonomously, system 100 can automatically perform blocks of methods S100, S200, and S300 to control a set of drilling parameters (power, gas flow, air flow, fuel flow, etc.) that affect the flow of energy directed toward the drilling surface. Furthermore, the system 100 can automatically execute blocks of methods S100, S200, and S300 to monitor, direct, maintain, and / or adjust a series of drilling controls, including, for example, the standoff distance between the system 100 and the drilling surface, the temperature of the exhaust gas directed towards the drilling surface, the rate of material removal from the drilling surface, and / or the thermal or topological characteristics of the drilling surface during drilling. An example of an application of an embodiment of the non-contact drilling system 100 is described below with reference to the drawings. 3-1. Applications: Modifications of plasma drilling

[0013] Generally, methods S100 and S200 are performed by the plasma drilling system 100 (hereinafter referred to as "system 100") during plasma drilling operation, and the plasma torch power, gas flow rate, orientation, forward speed, and standoff distance can be adjusted as a function of the drilling shape (or "profile") and the rate of material removal from the drilling surface in order to maintain the drilling shape and efficient drilling. More specifically, system 100 can perform blocks of methods S100 and S200 to track the actual standoff distance from the plasma torch to the drilling surface, implement closed-loop control to maintain the actual standoff distance at the target standoff distance, characterize the drilling effect based on the difference between the actual standoff distance and the predicted standoff distance as a function of power and gas flow input to the plasma torch, derive a drilling surface profile based on the standoff distance at various positions across the drilling surface, change the target standoff distance and the orientation of the plasma torch to increase drilling efficiency and maintain the target drilling surface profile across the drilling surface, and adjust the power and gas flow to the plasma torch to maintain high drilling efficiency by considering the target standoff distance and the orientation of the plasma torch over time during drilling.

[0014] For example, System 100 may monitor the drilling surface profile (or "shape") based on the standoff distance measured by System 100 across the drilling surface, and then increase the target standoff distance if the drilling profile shows a high slope (e.g., steep slope, very concave), or decrease the target standoff distance if the drilling profile shows a low slope (e.g., shallow, minimal concave, localized convexity). System 100 may also increase the gas flow rate and power to the plasma torch and / or slow down the plasma torch's forward (or "supply") speed in response to detecting a narrow drilling cross-section to widen the drilling, or decrease the gas flow rate and power to the plasma torch and / or slow down the plasma torch's forward speed in response to detecting a wide drilling cross-section to maintain a desired drilling width or reduce the size of the drilling cross-section. Furthermore, the system 100 can direct (or "tilt") the plasma torch towards the area of ​​the drilling surface closest to the front end of the system 100—which may result in a lower removal rate with the system 100's current operating parameters due to geological variations—and the power and / or gas flow rate to the torch can be adjusted to preferentially remove material from this area of ​​the drilling surface.

[0015] Therefore, by monitoring a single standoff distance between the torch and the drilling surface, system 100 can track the rate of material removal from the drilling surface, adjust the target standoff distance based on this removal rate, and maintain a high removal rate from the drilling surface by adjusting the power and gas flow rate to the plasma torch to compensate for this target standoff distance. Furthermore, by monitoring multiple standoff distances between system 100 and the region spanning the drilling surface, system 100 can characterize the profile of the drilling surface, adjust the target standoff, power and gas flow rate to maintain the target shape of the drilling, detect low-yield (or high-elasticity) regions across the drilling surface, and adjust the orientation of the plasma torch, target standoff, power and gas flow rate to prioritize the removal of material from such low-yield regions.

[0016] Methods S100 and S200 are described herein as being performed by system 100 during horizontal excavation work. However, system 100 may additionally or alternatively perform blocks of methods S100 and S200 during vertical and inclined excavation work.

[0017] Generally, system 100 uses plasma to excavate subsurface geology while executing blocks of methods S100, S200, avoiding rock melting (e.g., lava formation) and instead maintaining decay in the form of gas (e.g., gaseous carbonate) accompanied by fragments (e.g., rock fragments). This allows the spoil ejector within system 100 to limit spoil trapping between system 100 and the drilling surface and limit spoil collection along the spoil ejector (e.g., by condensation of molten rock or "slag" at lower temperatures on the surface within the spoil ejector) so that the spoil—that which has been removed from the drilling surface—can be pulled backward from the drilling. Additionally or alternatively, system 100 adjusts power, gas flow rate, and / or standoff distance according to blocks of methods S100, S200 to achieve a target rate of lava formation (e.g., target lava volume formation rate) in preparation for applying lava to the surface of the hole to form a lava tube of a target thickness and profile.

[0018] In particular, various geological formations, such as sandstone, granite, and basalt, can contain a large proportion of crystals (such as SiO2). For example, basalt typically contains 30-40% SiO2 by volume, and can sometimes contain as much as 80% SiO2 by volume. SiO2 has a relatively low melting temperature. However, the crystalline structure of SiO2 can decompose below its melting temperature. Therefore, by implementing blocks of methods S100 and S200, system 100 can control the temperature of the material at the drilling surface to be near the crystalline decomposition temperature of SiO2 and below its melting temperature, thereby decomposing the crystalline structure of the material across the drilling surface, and consequently crushing (or decomposing) the material without melting it (or by controlling the volume of molten material per unit distance drilled by system 100).

[0019] More specifically, system 100 executes the blocks of methods S100, S200 to crush and collapse rock (and soil, etc.) at the excavation face before these materials melt. By crushing the material at the hole face rather than melting it, system 100 can remove less complex debris (e.g., only gas and solid rock fragments rather than gas, debris, and lava) with less heat. This extends the operating life of the components of system 100, reduces the energy consumption per unit distance (or volume) of excavation, improves the efficiency and life of system 100, and thereby reduces the overall cost associated with the excavation operation.

[0020] Furthermore, the effectiveness of the fragmented material at the excavation face (e.g., due to thermal shock) may be a function of pressure and heat. To increase the pressure at the excavation face, system 100 can reduce the distance from the plasma torch to the excavation face (hereinafter "stand-off distance") and / or increase the gas flow rate through the plasma torch. System 100 can also increase the plasma torch power to compensate for the increased gas flow rate. Similarly, to increase the temperature of the excavation face, system 100 can reduce the excavation speed, increase the dwell time, reduce the stand-off distance, and / or increase the torch output and gas flow rate.

[0021] Methods S100, S200 are described herein as being executed by system 100 to drill through siliceous geology that contains a high proportion of crystals such as SiO2. However, system 100 can additionally or alternatively execute the blocks of methods S100, S200 to drill through other igneous, metamorphic, and sedimentary geology such as intermediate, mafic, and ultramafic geology, such as sand, soil, silty sand, clay, boulders, loam, etc.

[0022] Furthermore, methods S100, S200 are described herein as being performed by system 100 to remove material from the excavation face by crushing and gasification (or vaporization) while minimizing or eliminating melting of the material at the excavation face. However, system 100 can execute the blocks of method S100 additionally or alternatively to control the melting rate or volume of the material at the excavation face, such as to achieve a target thickness of a vitrified layer of rock that lines the walls of the excavation. 3.2 Applications: Jet thrust drilling variations

[0023] Generally, the jet thrust type variations of system 100 include a chassis, a propulsion subsystem (e.g., a set of drive wheels or tracks) configured to advance the chassis through underground excavation, and a fully enclosed cutter head attached to the chassis that includes a Brayton-cycle turbojet engine (hereinafter, "engine"). The cutter head is configured to compress fresh air from a surface air supply source in a compressor, mix this compressed air with fuel from a surface fuel source, combust this mixture, extract energy from these combustion products to drive the compressor, and discharge these high-temperature, high-mass flow exhaust gases toward the surface of the underground excavation. These high-temperature, high-mass flow exhaust gases reach the excavation face within the jet impact region, imparting a thermal shock to the geology of the excavation face and thus leading to fragmentation of the geology and removal of rock fragments from the excavation face.

[0024] Furthermore, vitrification at the drilling face can reduce or suppress thermal fracturing at the drilling face, and therefore may result in a reduction in rock removal per unit time and per unit energy consumed by the system 100 compared to rock removal by fracturing. Accordingly, the system 100 further includes a temperature sensor configured to output a signal representing the temperature of these exhaust gases, and a controller configured to maintain the temperature of these exhaust gases below the minimum melting temperature of all geological formations present at the face (e.g., below 1400°C) or below the melting temperature of a specific geological formation detected at the drilling face by changing the fuel flow rate to the engine (e.g., "throttle position") and / or other drilling parameters in the engine, thereby preventing vitrification of the surface of the drilling face, maintaining fracturing of the entire drilling face, and maintaining a large amount of rock removal per unit time and per unit energy consumed by the system 100.

[0025] In particular, system 100 can penetrate rock by thermal fracturing by executing blocks of method S100, S300, directing a high-energy (e.g., high temperature and / or high mass flow rate) stream of exhaust gases towards the drilling surface. These high-energy exhaust gases rapidly transfer thermal energy to the surface of the drilling surface, resulting in rapid thermal expansion of a thin layer of rock at the surface of the drilling surface. The expansion and local stress occur along the natural discontinuities and heterogeneities present in the microstructure of the rock matrix, causing differences in the expansion of the minerals that make up the rock matrix, resulting in stress and strain along and between the mineral particles. Because the geology is generally brittle, the rapid thermal expansion of the rock at the surface of the drilling surface causes this thin, hot surface layer of rock to fracture away from the cooler rock behind the drilling surface. Thus, this thin, hot surface layer of rock may break into rock fragments (or spalls) and separate from the surface of the drilling surface during this fracturing process. The mechanisms of fracture or induction of microstresses on the surface of the excavation face may differ across lithologies, based on the mineralogical, material, chemical, and physical properties of the surface exposed to these exhaust gases.

[0026] However, if the temperature of the exhaust gases reaching the drilling face exceeds the melting temperature of the geological material at the surface of the drilling face, the surface of the drilling face may melt and flow down the drilling face rather than fracturing and detaching from it. Lava absorbs more energy per unit mass than fragments, and instead of breaking and detaching from the surface of the drilling face like fragments, it may flow down the drilling face slowly and thermally shield the non-molten material on the drilling face (e.g., material immediately behind or surrounding the area of ​​molten material) from the energy carried by the exhaust gases output by the engine. Therefore, compared to fracturing, molten rock at the drilling face can result in an immediate decrease in the volume or mass of rock removed from the drilling face per unit time and per unit energy consumed by the engine. This is because the energy consumed by the engine is directed towards the phase change of the rock at the drilling face rather than the continuous fracturing of thin layers of rock from the drilling face.

[0027] Therefore, System 100 includes a Brayton-cycle turbojet engine with an outlet nozzle facing the drilling surface to generate high-temperature exhaust gases and direct these exhaust gases at high volumetric flow rates, in order to achieve rapid fracturing and material removal from the drilling surface by maintaining high pressure and high total heat flux at the drilling surface. System 100 can also implement closed-loop control to maintain the temperature of these exhaust gases below the melting temperature of all geological formations (e.g., 825°C to compensate for melting temperatures between 900°C and 1400°C for most geological formations), or below the melting temperature of specific geological formations detected at the drilling surface. Thus, the geological formations at the drilling surface may be less likely to melt in the presence of these exhaust gases from the engine. System 100 can also maintain high mass flow rates to compensate for sub-melting temperature exhaust temperatures to generate a high heat flux at the drilling surface, thereby increasing the mining rate of rock at the drilling surface, while keeping the risk of melting at the drilling surface low for a wide range of geological formations.

[0028] Furthermore, the engine can approach converting nearly 100 percent of the energy contained in the supplied fuel (e.g., liquid diesel) into the thermal and kinetic energy of the exhaust gases, which the system 100 uses to fracture the rock towards the drilling face. In one example of implementation, the engine includes a combustor for burning fuel, a turbine for converting the pressure and thermal energy of the gases leaving the combustor into the mechanical rotation of a drive shaft, and an integrated axial compressor driven by the turbine via the drive shaft to draw air into the engine, compress this air, and send this air to the combustor.

[0029] Therefore, the engine is completely enclosed and may require no external (i.e., above-ground) support systems at all, or only minimally, to excavate underground tunnels through various geological formations. In particular, system 100 may only be connected to an air supply source that provides fresh, unconditioned above-ground air at any temperature and humidity to the compressor, a fuel supply source that provides fuel from an above-ground source (e.g., a fuel tank) to a fuel metering unit in the engine, and / or a ground monitoring system or remote control via low-power sensors and data lines.

[0030] Therefore, virtually all energy consumed during drilling is consumed by the engine at the drilling surface, converting the chemical energy of the fuel into heat at the drilling surface, the kinetic energy of the exhaust gases that generate pressure at the drilling surface, the kinetic energy of the exhaust gases that move debris away from the drilling surface and pull it towards the rear of the engine, and the kinetic energy that rotates the turbine and compressor. In particular, since the compressor and combustor are fully integrated into the engine and the engine is configured to operate on only an (unregulated) supply of air and fuel, system 100 may require that energy be consumed by fans, pumps, cooling systems, etc., to power and cool above-ground subsystems or to supply air to the engine, or to consume energy by such systems, or to have it consumed to a minimum.

[0031] Therefore, system 100 can minimize the setup time and complexity required to excavate underground tunnels. For example, an operator can excavate a shallow trench at the starting point of the tunnel, position system 100 in the trench, connect a fuel supply line extending backward from system 100 to a fuel reservoir on the surface (e.g., a mobile fuel supply rig), position the end of an air supply line extending backward from system 100 in an unobstructed location on the surface, and start the engine with, for example, a small electric starter motor incorporated into system 100.

[0032] Next, the engine draws air into the compressor via an air supply line, burns the pressurized air and fuel in the combustor, extracts energy from the exhaust gases generated by the turbine to power the compressor, and releases the hot gases at a high mass flow rate toward the drilling face, thereby crushing and removing the material from the drilling face. Simultaneously, the propulsion subsystem can move the engine forward at a rate proportional to the removal of material from the drilling face in order to maintain the standoff distance between the nozzle and the drilling face. Additionally or alternatively, the propulsion subsystem can advance the engine based on the removal of material from the drilling face, the temperature and velocity of the exhaust gases discharged from the nozzle, the raster rate of the nozzle across the drilling face, and / or the standoff distance, in order to maintain a consistent heat flux across the drilling face.

[0033] Thus, by performing the blocks of methods S100 and S300, system 100 can remove material from the excavation surface without substantial above-ground air and power support systems, thereby simplifying the setup and deployment of system 100 for excavating underground tunnels. 4. Initialization of excavation

[0034] To begin drilling, system 100 is positioned at the drilling entrance. For example, in horizontal drilling, a ground opening (or "launch shaft") is dug (e.g., manually) at the drilling start depth to a width and length sufficient to accommodate system 100 horizontally. When system 100 is positioned at the drilling entrance and the torch is adjacent to the drilling surface, the controller can implement the methods and techniques described later to measure the standoff distance from the torch to the drilling surface, implement closed-loop control to drive the torch to the nominal standoff distance (e.g., 6 inches), and activate the torch by ramping it to the baseline power setting and baseline gas flow rate. 5. Closed-loop control

[0035] As described later, during the drilling phase, the controller 180 can receive data, monitor sensors, measure parameters, determine the state of the system 100, calculate corrections, adapt to changes in the geology of the drilling surface 200, and send commands and instructions to one or more components, subsystems, actuators, or sensors of the system 100 to autonomously or substantially improve or optimize the performance of the system 100 (e.g., drilling rate) at the drilling surface 200.

[0036] The closed-loop control described herein can generally be applied to any type of non-contact drilling element 130. In embodiments, the system 100 may include a non-contact drilling element 130 configured to move material from the drilling surface 200 by temperature, pressure, airflow, or a combination thereof. In certain embodiments, the non-contact drilling element 130 includes a plasma torch, a cutter head including a Brayton jet engine, or a flame jet. However, the system 100 may optionally or additionally include any other thermal and / or pressure-induced non-contact drilling element 130. 5.1 Standoff distance

[0037] In one embodiment shown in Figure 2, the system 100 includes a single depth sensor 190 positioned near the front of the system 100, close to the non-contact drilling element 130. The depth sensor 190 includes a contact probe 192, a linear actuator 194 configured to extend the contact probe 192 toward the drilling surface 200 and to retract the contact probe 192 into a thermal shielding housing or the like, and an encoder or other sensor configured to track the length of the contact probe 192 extending from the front of the system 100.

[0038] In this implementation, the controller 180 can intermittently trigger the depth sensor 190 to perform a standoff measurement cycle, such as once per minute. During the standoff measurement cycle, the controller 180 can instruct the linear actuator 194 to extend the contact probe 192 out of the housing, and when the actuator's resistance (or current draw from the actuator) reaches a threshold resistance (or threshold stall current), it can read a length measurement from the sensor, have this length measurement returned to the controller 180, and trigger the linear actuator 194 to pull the contact probe 192 back into the housing.

[0039] Furthermore, when the contact probe 192 is extended outside the housing of the depth sensor 190 during the standoff measurement cycle, the controller 180 can adjust the drilling parameters of the non-contact probe of the non-contact drilling element 130 (e.g., airflow, fuel flow, gas flow, power) to lower the surface temperature at the drilling surface 200, thereby reducing thermal shock and / or thermal-induced strain on the contact probe 192. When the linear actuator 194 returns the contact probe 192 to the housing, the controller 180 can then readjust or modify the drilling parameters of the non-contact drilling element 130 to raise the surface temperature of the drilling surface 200 and restart drilling.

[0040] Upon receiving a length measurement from the depth sensor 190, the controller 180 can store this length measurement as the current standoff distance. The controller 180 calculates the ram reset distance based on the current longitudinal position of the non-contact drilling element ram 170, resets the non-contact drilling element ram 170 to its home position over the reset distance, and activates the propulsion system 120 to move the system 100 forward by the sum of the ram reset distances plus the difference between the current standoff distance and the current target standoff distance, thereby positioning the non-contact drilling element 130 at the target standoff distance.

[0041] In another implementation, the contact probe 192 can be spring-loaded on a linear actuator 194, and / or the depth sensor housing can be spring-loaded on a chassis 110. During a standoff measurement cycle, the controller 180 triggers the depth sensor 190 to extend the contact probe 192 to the current target standoff distance. If the contact probe does not fit the resistance at this target standoff distance, the controller 180 retracts the non-contact drilling element ram 170 to its home position and advances the propulsion system 120 until the contact probe 192 fits the resistance (i.e., makes contact with the drilling surface 200), thereby setting the non-contact drilling element 130 to the target standoff distance, and records the drilling distance since the last standoff measurement cycle based on the distance the non-contact drilling element ram 170 and propulsion system 120 have traveled in the drilling, and then the contact probe 192

[0042] In this implementation, after recording the standoff distance and resetting the non-contact drilling element 130 to the target standoff distance during the standoff measurement cycle, the controller 180 can implement a dead reckoning technique to estimate the current standoff distance as a function of the last measured standoff distance and drilling parameters related to the non-contact drilling element 130, and implement closed-loop control to adjust the position of the non-contact drilling element ram 170 and / or advance the propulsion system 120 to maintain the estimated current standoff distance at the target standoff distance. The controller 180 can then trigger the next standoff measurement cycle when the estimated drilling distance completed by the system 100 exceeds a threshold distance (e.g., 1 inch) or after a threshold duration.

[0043] For example, after recording the standoff distance during a standoff measurement cycle, the controller 180 can calculate the total drilling distance over the drilling interval between the current and previous standoff measurement cycles by summing the changes in the positions of the non-contact drilling element ram 170 and the propulsion system 120 since the previous standoff measurement cycle with this standoff length measurement. In this example, the controller 180 can also record drilling parameters during this drilling interval and calculate or refine a standoff distance model that links a linear drilling distance as a function of time to the drilling parameters and the standoff distance based on the data collected over this drilling interval (and the previous drilling interval). The controller 180 can then implement a dead reckoning technique to estimate a linear drilling distance over the next drilling interval based on the standoff distance model, the drilling parameters during the drilling interval, and the last estimated standoff distance, and re-estimate the standoff distance based on this linear drilling distance, and advance the non-contact drilling element ram 170 and / or propulsion system 120 during this drilling interval to maintain the actual standoff distance between the non-contact drilling element 130 and the drilling surface 200 at the target standoff distance.

[0044] As shown in Figures 4A and 4B, in one modification of the embodiment, the non-contact drilling element 130 is a plasma torch 132. In this modification, the contact probe 192 can be electrically shielded, and the system 100 can periodically or continuously read the standoff distance from the depth sensor 190. For example, the contact probe 192 may include a stainless steel or low-alloy steel shaft and be driven to a reference voltage such as the same voltage as the cathode in the plasma torch 132, or the average voltage of the cathode and anode in the plasma torch 132, thereby generating an electric field around the contact probe 192 that repels charged plasma, gas, and debris flowing between the plasma torch 132 and the drilling surface 200.

[0045] Therefore, in this implementation, the controller 180 can drive the contact probe 192 forward to maintain continuous or substantially continuous contact with the drilling surface 200, and the controller 180 can drive the plasma torch ram 170 and / or propulsion system 120 forward to maintain a target standoff distance between the plasma torch 132 and the drilling surface 200 based on a standard distance read and output by the depth sensor 190.

[0046] Alternatively, the depth sensor 190 can cause the contact probe 192 to vibrate periodically or continuously back and forth (for example, along the X-axis shown in Figure 4B) during operation, for example, by partially retracting the contact probe 192 to allow fracture. For example, the contact probe 192 can be partially retracted to allow rock fracturing and crushing at the drilling surface 200 in front of the contact probe 192, or the contact probe 192 can be fully retracted into a thermally shielded housing within the chassis 110 to allow cooling of the contact probe 192, and then advanced to make contact with the drilling surface 200. Once the contact probe 192 is in contact with the drilling surface 200, the controller 180 can determine or calculate the current standoff distance as described above.

[0047] The controller 180 can also periodically drive the plasma torch ram 170 and / or the propulsion system 120 forward to maintain the target standoff distance between the plasma torch 130 and the drilling surface 200, based on the length of the contact probe 192 measured at the last contact between the plasma torch 130 and the drilling surface 200. Furthermore, the controller 180 can employ dead reckoning techniques to estimate the current standoff distance, adjust the position of the plasma torch ram 170, and / or advance the propulsion system 120 to maintain this estimated current standoff distance at the target standoff distance, and adjust drilling parameters such as power and gas flow rate to the plasma torch 132 at time intervals between successive standoff distance measurements by the contact probe 192.

[0048] In another variation of the embodiment, system 100 includes a plurality of contact depth sensors 190, each extending from the front of system 100 and configured to measure the distance from its position on the front of system 100 to a corresponding position on the excavation surface.

[0049] In one implementation, system 100 includes a set of contact depth sensors 190 arranged in a pattern around the front of system 100. The set of contact depth sensors 190 may include two or more depth sensors 190 arranged to cooperate in determining a range of depths up to the drilling surface 200, from which the controller 180 can estimate or interpolate the topography of the drilling surface 200. For example, sets of three, four, five, or six contact depth sensors 190 can be arranged symmetrically or asymmetrically around the front of system 100 to provide three, four, five, or six depth measurement points, from which the controller 180 can determine a generalized topography of the drilling surface 200, and based on this, the controller 180 can perform closed-loop control to manage and optimize system performance.

[0050] In this variation of the embodiment, the system 100 implements the methods and techniques described above to periodically or intermittently measure the distance from each contact depth sensor 190 to the drilling surface 200. The shortest distance to the drilling surface 200. Next, the controller 180 identifies a specific contact probe 192 that indicates the shortest distance to the drilling surface 200, which can generally represent the location of a low-yield (or most resilient) region in the drilling surface 200, and advances the plasma torch ram 170 and / or propulsion system 120 toward the drilling surface 200 to set the standoff distance between the specific contact probe 192 and the corresponding low-yield region of the drilling surface 200 as a target standoff distance.

[0051] As shown in Figure 4B, the controller 180 can also tilt the plasma torch ram 170 toward the depth sensors 190 by an angular distance proportional to the difference between the shortest standoff distance 300 and the longest standoff distance 302 measured by the set of depth sensors 190 (e.g., pitch, yaw). When the axis of the plasma torch 132 is oriented toward a direction closer to the low-yield region of the drilling surface, the system 100 can preferentially heat and fracture this low-yield region of the drilling surface 200. The controller 180 can also perform dead reckoning to predict the removal of material from the drilling surface 200, and when the controller 180 predicts the removal of material from the low-yield region of the drilling surface 200 and the flattening or smoothing of the drilling surface 200, it can return the plasma torch 132 to its central position coaxial with the drilling.

[0052] In a similar implementation, after measuring the standoff distance at each depth sensor 190, the controller 180 can interpolate the depth profile around the drilling based on these standoff measurements and the known positions of these depth sensors 190 on the front of the system 100. Generally, the shallowest section of the depth profile represents the low yield region at the drilling surface 200, and, taking into account the current position of the system 100 relative to the drilling surface 200, the deepest section of the depth profile represents the maximum yield region at the drilling surface 200. Therefore, taking into account the current operating parameters of the plasma torch 132, the controller 180 can tilt the plasma torch 132 toward the shallowest section of the depth profile to an angular distance proportional to, for example, the distance between the shallowest and deepest sections of the depth profile or the distance between the shallowest section of the depth profile and the plane of the nominal drilling surface, and continue or restart the operation of the plasma torch 132 with its axis pointed toward the low-yield region of the drilling surface 200 in order to preferentially heat and fracture this low-yield region of the drilling surface 200. To concentrate material removal in this low-yield region, the controller 180 can maintain (or increase) the gas flow rate and / or power to the plasma torch 132 in order to reduce the target standoff distance and increase the pressure in this low-yield region of the drilling surface 200 while preventing the material from melting in this low-yield region. As described above, the controller 180 can implement dead reckoning to predict the removal of material from the drilling surface and / or directly measure changes in the drilling profile. When the controller 180 predicts or measures the removal of material from this low-yield region toward the nominal drilling surface shape, the controller 180 may repeat the above process to level the drilling surface 200 toward the nominal drilling surface shape before tilting the plasma torch 132 toward the next shallowest section of the depth profile and recentering the plasma torch 132 to zero degrees in pitch and yaw positions before resuming longitudinal drilling parallel to the drilling axis.

[0053] Therefore, in this modification, the system 100 can scan the torch to different angular positions with respect to the longitudinal axis of drilling, and selectively increase material removal from the low-yield region of the drilling surface 200 based on the standoff distance from the front end of the system 100 to the periphery of the drilling surface 200.

[0054] In a similar modification, system 100 further includes a central contact depth sensor 190 inserted from an outer set of contact depth sensors 190, such as being positioned near the axial center on the front of system 100. Thus, the controller 180 can interpolate the drilling profile over the drilling surface 200 by fusing standoff measurements from the central depth sensor 190 with simultaneous standoff measurements from the set of peripheral depth sensors 190.

[0055] For example, if the drilling profile represents the gradient from the periphery of the drilling surface 200 to the center of the drilling surface 200, and this is less than the target depth range (i.e., the drilling surface is excessively flat), the controller 180 can predict that the drilling is too deep. Therefore, the controller 180 can reduce the target standoff distance from the center depth sensor 190 to the center of the drilling surface 200 to reduce thermal material removal around the drilling, and reduce the power to the plasma torch 132 to prevent melting near the center of the drilling surface 200, taking this shortened target standoff distance into account. In this example, the controller 180 may additionally or alternatively increase the forward speed of the propulsion system 120 and / or the plasma torch ram 170 in response to calculating a high removal rate simultaneously with a shallow gradient across the drilling surface.

[0056] Conversely, if the gradient from the periphery of the drilling surface 200 to the center of the drilling surface 200 is greater than the target depth range (i.e., the drilling surface 200 is excessively conical), the controller 180 can predict that the drilling is too small and too narrow for the system 100 to advance. Therefore, the controller 180 can increase the target offset distance, power, and gas flow rate to achieve greater pressure and energy around the drilling. In this example, the controller 180 can additionally or alternatively reduce the advance speed of the propulsion system 120 and / or plasma torch ram 170 in response to calculating a steep gradient across the drilling surface 200 and a low removal rate (as described later).

[0057] Therefore, in this variation, the system 100 can scan or raster the plasma torch 132 to different positions across the drilling surface 200 (e.g., pitch, yaw, elevation along the Z axis, translation along the Y axis) to selectively increase material removal from low-yield regions of the drilling surface 200 based on the profile of the drilling surface 200 derived from the standoff distances between multiple positions across the drilling surface 200 from the front end of the system 100.

[0058] In another variation of the embodiment shown in Figure 2, the system 100 includes one or more single-point non-contact depth sensors 190.

[0059] In one implementation configuration, system 100 includes a thermally shielded sensor housing, a thermally shielded shutter positioned across an opening in the shutter housing, and a point depth sensor positioned in the housing behind the shutter, such as a 190 radar-based depth sensor (e.g., millimeter-wave radar sensor), an infrared sensor, an ultrasonic sensor, or a laser (LIDAR, time of flight, etc.) sensor.

[0060] During operation, the controller 180 can open the shutter, sample the depth sensor 190 to capture a depth measurement at a point on the drilling surface 200, and then close the shutter to protect the depth sensor 190 from excessive heat. For example, the controller 180 can intermittently trigger the depth sensor 190 to perform a standoff measurement cycle, such as once per minute, as described above.

[0061] Alternatively, system 100 may include a temperature sensor within the sensor housing. During operation, the controller 180 can periodically sample from this temperature sensor, open the shutter to read a standoff measurement from the depth sensor 190 when the temperature inside the housing falls below the operating temperature range, and close the shutter to stop the standoff measurement when the temperature inside the housing exceeds the operating temperature range.

[0062] In this modification, the system 100 can perform the methods and techniques described above to verify the standoff distance from the non-contact drilling element 130 to the drilling surface 200 based on the output of the depth sensor 190, and reposition the non-contact drilling element ram 170 and / or propulsion system 120 to maintain the target standoff distance.

[0063] In this variation, system 100 also includes a plurality of single-point non-contact depth sensors 190, which implement the above methods and techniques for calculating a drilling perimeter or drilling surface profile, and then the orientation of the non-contact drilling element 130 and associated drilling parameters can be adjusted according to this drilling perimeter or drilling surface profile by implementing the methods and techniques described herein.

[0064] In another variation of the embodiment, system 100 includes a thermally shielded sensor housing, a thermally shielded shutter positioned across an opening in the shutter housing, and a multipoint depth sensor 190, such as a radar-based depth sensor 190, including a multipoint millimeter-wave radar sensor, a 2D depth camera, or a 3D LiDAR camera, positioned in the housing behind the shutter. In this implementation, the controller 180 can open the shutter to sample the depth sensor 190 during the standoff measurement cycle, derive a drilling surface profile from the output of the depth sensor 190 during the standoff measurement cycle, and adjust the operation of system 100 accordingly as described above.

[0065] For example, the controller 180 directly interpolates a 3D profile of the drilling surface 200 from the output of the depth sensor 190, which includes multiple depth measurements, to multiple points on the drilling surface 200, tilting the non-contact drilling element 130 to an orientation corresponding to the shallowest region represented by the drilling surface profile, thereby bringing the non-contact drilling element 130 closer to the corresponding low-yield region of the drilling surface 200, and adjusting the drilling parameters of the non-contact drilling element 130 by decreasing the target standoff distance in this low-yield region of the drilling surface in proportion to the slope from this low-yield region to the center of the drilling, thereby preventing material melting in this low-yield region of the drilling surface 200.

[0066] In this variation of the embodiment, the controller 180 can intermittently or continuously sample the depth sensor 190 while removing material from this low-yield region of the drilling surface 200, recalculating the profile of the drilling surface accordingly, and reorienting the non-contact drilling element 130 to align with the lowest-yield region detected in each subsequent drilling surface profile thus calculated by the controller 180. In particular, as the gradient across the drilling surface profile decreases, the controller 180 can recenter the longitudinal axis of the non-contact drilling element 130 with the longitudinal axis of the drilling, increase the standoff distance, and adjust the drilling parameters of the non-contact drilling element to contact the drilling element 130 and achieve more uniform fracturing, gasification, crushing, and general removal of material across the entire drilling surface 200.

[0067] In other variations of the embodiment, system 100 may include a set of depth sensors 190, which may include a combination of a contact sensor and a non-contact sensor. Furthermore, in yet another variation of the embodiment, the system may include a non-contact depth sensor 190, which may include subcomponents or functions (e.g., an optical camera paired with a LiDAR rangefinder), that can provide optical or phase data relating to a temperature profile or a phase profile of the drilling surface 200, which will be described in more detail below. 5.2 Closed-loop control: Temperature control

[0068] As shown in Figure 6, in one modification of the embodiment, the non-contact drilling element 130 includes a cutter head 140 containing a Brayton turbojet engine. In this variation of the embodiment, the controller 180 can use closed-loop control to maintain a target temperature of the exhaust gas 220 directed toward the drilling surface 200. Alternatively, the closed-loop temperature control described herein can be applied to other types of non-contact drilling elements 130 containing one or more plasma torches 132 and / or flame jets.

[0069] As shown in Figure 6, this variation of system 100 may include a controller 180, a temperature sensor 156 (e.g., a thermocouple) positioned near the exit of the nozzle 160 (e.g., near the exit of the nozzle 160, or between the nozzle 160 and the drilling surface 200), and a fuel metering unit 146 configured to adjust the rate at which fuel is injected into the flame tube. Generally, during operation, the controller 180 tracks the temperature of the exhaust gas 220 exiting the nozzle 140 based on the signal output by the temperature sensor 156 and adjusts the rate at which fuel enters the combustor 144 via the fuel metering unit 146, thereby maintaining the temperature of the exhaust gas 220 exiting the nozzle 140 below the melting temperature of all geological formations, or below the melting temperature of a specific geological formation predicted or detected at the drilling surface 200.

[0070] In particular, the controller 180 sets a target exhaust gas temperature as described below, samples the temperature sensor 156 to track the temperature of the exhaust gas 220 exiting the nozzle 140, and then, if the temperature of these exhaust gases 220 is lower than the target temperature, performs closed-loop control to adjust the fuel metering unit 156 to increase the proportion of fuel injected into the combustor 144. However, if the temperature of the exhaust gases 220 is higher than the target temperature, the fuel metering unit 146 can be adjusted to decrease the proportion of fuel injected into the combustor 144. For example, the controller 180 can read the temperature of the exhaust gases 220 at a frequency of 10 Hz, then calculate the average of these temperatures, and update the fuel flow rate at a frequency of 1 Hz based on this average temperature.

[0071] In one modified embodiment, the system 100 further includes an air metering unit 148 configured to change the dilution ratio of a first portion of compressed air entering the primary zone of the combustor 144 to a second portion of compressed air entering the dilution zone of the combustor 144.

[0072] In one implementation, the air metering unit 148 includes a sleeve 150 configured to slide over a range of positions along the combustor 144, including a 1:0 dilution ratio position where the sleeve 150 completely exposes a first set of perforations in the combustor 144 and completely surrounds a second set of perforations; a 2:1 dilution ratio position where the sleeve 150 largely exposes the first set of perforations in the combustor 144 and largely surrounds a second set of perforations; a 1:1 dilution ratio position where the sleeve 150 similarly exposes the first and second sets of perforations in the combustor 144; and a 1:2 dilution ratio position where the sleeve 150 largely surrounds the first set of perforations in the combustor 144 and largely exposes a second set of perforations.

[0073] In this variation of the embodiment, the air metering unit 148 may also include an actuator 152 configured to move the sleeve 150 along this range of positions. Thus, during operation, the controller 180 can set a target exhaust gas temperature as described below, detect the temperature of the exhaust gas 220 exiting the nozzle 140, and perform closed-loop control to adjust the air metering unit 148 to increase the dilution ratio and fuel flow rate to maintain the target air-fuel ratio if the temperature of the exhaust gas 220 is lower than the target temperature, and adjust the air metering unit 148 to decrease the dilution ratio and fuel flow rate to maintain the target air-fuel ratio if the temperature of the exhaust gas 220 is higher than the target temperature.

[0074] Generally, the controller 180 can set a target exhaust gas temperature based on nominal drilling geological conditions or real-time drilling characteristics, and then perform closed-loop control to adjust the fuel flow rate and / or dilution ratio in the combustor 144 based on the difference between the measured temperature of the exhaust gas 220 exiting the nozzle 140 and the target temperature.

[0075] For example, in the aforementioned implementation, the controller can set and implement a fixed target exhaust gas temperature of 825°C, which is lower than the minimum melting temperature of most geological formations.

[0076] The controller 180 can also periodically perform a temperature test loop, which includes increasing the target exhaust gas temperature, adjusting the fuel flow rate and / or dilution ratio to achieve this exhaust gas temperature, measuring the standoff distance as described above, calculating the current drilling speed, and repeating this temperature test loop. If the current drilling speed is greater than the previous drilling speed at a lower target temperature (for example, if the material on the drilling face is fracturing and being discharged from the drilling face at a greater speed than before), the controller 180 can further increase the target exhaust gas temperature and repeat the process. However, if the current drilling speed is less than the previous drilling speed at a lower target temperature (for example, if the material on the drilling face is melting rather than fracturing), the controller 180 can decrease the target exhaust gas temperature and repeat this temperature test loop. Therefore, in this example, the controller 180 can adjust the target exhaust gas temperature in real time based on the drilling speed, including raising the target exhaust gas temperature to maintain high thermal shock and fracture of hard geological formations, and lowering the target exhaust gas temperature to prevent melting of softer geological formations, thereby maximizing the amount of material removed from the drilling face 200 by keeping the exhaust temperature higher than the average fracture temperature on the surface and lower than the minimum melting temperature at any point on the surface. 5.3 Closed-loop control: Removal rate

[0077] The system 100 can additionally or alternatively calculate the removal rate and adjust power, gas flow rate, and / or target standoff distance, etc., based on the difference between this removal rate and the target removal rate (or target removal rate range). In particular, the controller 180 can, as described above, implement closed-loop control to adjust the standoff distance, the orientation of the non-contact drilling element, and drilling parameters to maintain uniform fracturing and crushing of the rock at the drilling surface 200 without melting, while maintaining the minimum removal rate (or minimum advance) from drilling.

[0078] For example, in the configuration of the plasma torch 132, increasing the power to the plasma torch 132 increases the gas flow rate through the plasma torch 132, which in turn increases the pressure at the drilling surface 200 and increases the removal rate. However, as the power and gas flow rate through the plasma torch 132 increase, the operating life of the plasma torch 132 components shortens non-linearly, reducing the total amount of material removed from drilling using these plasma torch 132 components, requiring the system 100 to be withdrawn from the drilling site more frequently for maintenance, requiring a greater power and gas supply, and reducing the overall operating efficiency of the system 100.

[0079] Similarly, in the jet engine cutter head configuration 140, increasing the airflow, fuel flow, and afterburner usage increases the temperature and pressure at the drilling surface 200, resulting in a temporarily higher removal rate. However, a scenario of complete combustion of the cutter head 140 also results in a temperature spike at the drilling surface 200, leading to material melting and generating large debris that hinders the further advance of the system 100 through the drilling. This can induce increased wear and replacement rates of the components of the cutter head 140, significantly increasing the operating cost of the system 100 while reducing its overall operating efficiency. Therefore, the controller 180 can implement closed-loop control to adjust the system's operating parameters to maintain both a minimum removal rate from the drilling and high overall operating efficiency.

[0080] In a variation of the system 100 including a single-point depth sensor 190, the controller 180 performs the methods and techniques described above to calculate the forward velocity of the drilling surface 200 by summing the changes in standoff measurements, the advance of the non-contact drilling element ram 170, and the advance of the chassis 110 over a certain time interval (e.g., between two standoff measurement cycles), and dividing this sum by the length of this time interval. The controller 180 can then calculate the removal rate (e.g., volume of material) from the drilling surface 200 by multiplying the forward velocity by the nominal or target cross-sectional area of ​​the drilling surface.

[0081] Alternatively, in a variation of the system 100 including multiple single-point depth sensors 190 and / or multi-point depth sensors 190, the controller 180 may perform the methods and techniques described above to calculate the drilling surface profile during a continuous standoff measurement cycle, calculate the offset distance between two consecutive drilling surface profiles based on the sum of the changes in standoff measurements, the advance of the non-contact drilling element ram 170, and the advance of the chassis 110 over the time interval between these standoff measurement cycles, calculate the volume between these drilling surface profiles based on this offset distance, and then calculate the removal rate during this time interval by dividing this deposit by the length of this time interval.

[0082] In this variation, the controller 180 can access a single target removal rate for drilling and then perform closed-loop control to adjust drilling parameters, including power, gas flow rate, fuel flow rate, air flow rate, exhaust gas temperature, and / or target standoff distance, based on the target removal rate.

[0083] Alternatively, the operator can collect core samples at intervals along the target drilling depth and the planned drilling path, process these core samples to derive the geology along the planned path, and generate a target removal rate schedule based on this geology. For example, the operator could specify a high target removal rate along the portion of the planned path characterized by loose soil, a moderate to high target removal rate along the portion of the planned path characterized by sandstone, a moderate target removal rate along the portion of the planned path characterized by limestone, and a low target removal rate along the portion of the planned path characterized by granite in the target removal rate schedule.

[0084] Therefore, during operation, the controller 180 can track its position along the planned path of the excavation, query the target removal rate schedule for the target removal rate in the excavation area currently occupied by the system 100, and then load this target removal rate.

[0085] During operation, the controller 180 can compare the current removal rate with the target removal rate and adjust the drilling parameters based on this difference.

[0086] In particular, a reduction in the removal rate below the target removal rate may result from fracturing of the drilling surface 200 and, rather than, the melting of rock at the drilling surface 200, or from a change in the geology at the drilling surface (e.g., to a material with less SiO2). In the former case, the controller 180 can adjust the drilling parameters to reduce melting at the drilling surface, for example by reducing the power and gas flow rate in the plasma torch 132 configuration and / or increasing the standoff distance. In the latter case, the controller 180 can adjust the drilling parameters to increase the pressure at the drilling surface 200, and consequently increase fracturing, for example by increasing the power and gas flow rate and / or decreasing the standoff distance in the plasma torch 132 configuration. In the cutter head 140 configuration, the controller 180 can similarly adjust drilling parameters such as fuel flow rate, air flow rate, exhaust temperature, and / or standoff distance to reduce or increase the pressure and / or temperature at the drilling surface 200 and adapt to changes in the geology.

[0087] In one embodiment, if the current removal rate is less than the target removal rate, the controller 180 can first increase the target standoff distance (e.g., by a step width of 0.500 inches) and retract the drilling element ram 170 while maintaining other drilling parameters over a first time interval. The controller 180 can then perform a standoff measurement cycle and recalculate the removal rate from the drilling surface 200. If this removal rate has increased, the controller 180 can further increase the target standoff distance and retract the non-contact drilling element ram 170 accordingly (e.g., by an additional step width of 0.500 inches) to retest the current removal rate. The controller 180 can repeat this process until the removal rate decreases or decreases to below a threshold change in the removal rate, at which point the controller 180 can decrease the target standoff distance, advance the non-contact drilling element ram 170, and perform similar methods and techniques to test the effect of the adjusted drilling parameters on the removal rate.

[0088] Therefore, in this implementation, the controller 180 can first increase the target standoff distance to anticipate the decrease in removal rate due to melting of the drilling surface 200w. If increasing the standoff distance between the non-contact drilling element 130 and the drilling surface 200 increases the removal rate, the controller 180 can confirm that the decrease in removal rate is due to the melting of the material at the drilling surface 200 and can further increase the removal rate and further decrease the melting at the drilling surface 200 before increasing the drilling parameters that result in further material melting by repeatedly increasing the standoff distance.

[0089] However, if increasing the standoff distance reduces or has no effect on the removal rate, the controller 180 can predict that the decrease in removal rate is due to a change in geology at the drilling face 200. Therefore, the controller 200 can adjust the drilling parameters as needed to decrease the target standoff distance and increase the pressure at the drilling face 200. For example, the controller can repeatedly decrease the standoff distance, run a standoff measurement cycle, recalculate the removal rate, and verify the increase in removal rate corresponding to the decrease in standoff distance. After verifying the increase in removal rate corresponding to the decrease in standoff distance, the controller can repeatedly adjust the drilling parameters to increase the pressure at the drilling face 200, recalculate the removal rate, and then readjust or maintain the drilling parameters if the pressure at the drilling face 200 increases further and the removal rate decreases.

[0090] Therefore, in this implementation, the controller 180 first increases the target standoff distance in response to a decrease in the removal rate and verifies that this increase in the target standoff distance improves the removal rate. Then, if it verifies that the removal rate does not improve even after increasing the target standoff distance, it only decreases the target standoff distance, thereby anticipating further melting of the excavation surface 200 and the generation of slag in the excavation and along the discharge system.

[0091] Additionally or alternatively, the controller 180 may, by employing similar methods and techniques, first adjust the drilling parameters to reduce the pressure at the drilling surface 200 in accordance with the decrease in the removal rate, verify that the adjusted drilling parameters improve the removal rate, and then, if it verifies that the removal rate could not be improved due to the previous decrease in pressure at the drilling surface 200, readjust or maintain the drilling parameters to increase the pressure at the drilling surface 200, thereby preempting further melting of the drilling surface 200 and the generation of slag in the drilling and along the discharge system. 5.4 Closed-loop control: Characterization of the excavation surface

[0092] In another modification of the embodiment shown in Figure 6, the system 100 includes an optical sensor 164 directed towards the drilling surface 200 and configured to output an image of the jet impact area (e.g., a color image, an infrared image). In this example, the controller 180 accesses the image of the drilling surface 200 captured by the optical sensor 164 and scans the image for “bright” (i.e., high intensity, high color value) pixels that indicate molten material at the drilling surface 200. If the controller 180 detects “bright” areas in the image and therefore indicates molten material at the drilling surface 200, the controller 180 can lower the target exhaust gas temperature. Conversely, if the controller 180 does not detect “bright” areas in the image and therefore indicates that there is no molten material at the drilling surface 200, the controller 180 can raise the target exhaust gas temperature. The controller 180 can then adjust the fuel flow rate and / or dilution ratio in the combustor 144 to achieve this updated target exhaust gas temperature. The controller 180 can repeat this process periodically at a frequency such as 1 Hz.

[0093] In the example described above, the controller 180 can use similar methods and techniques to detect hotter—but not yet melted—regions (e.g., "hot spots") on the excavation surface 200 based on images captured by the optical sensor, and update the target exhaust gas temperature accordingly.

[0094] Generally, the optical sensor 164 is configured to detect the frequency and amplitude of photons emitted on or near the drilling surface 200 during non-contact drilling and to convert the detected frequency and amplitude into an image of the drilling surface 200. In one embodiment, the optical sensor 164 can scan the drilling surface 200 at or near the non-contact thermal impact point from a nominal standoff distance. Alternatively, the optical sensor 164 can perform a full-surface static scan of the drilling surface 200 to detect photons emitted after impact by the non-contact drilling element 130. In another alternative embodiment, the optical sensor 164 can follow the raster pattern of the non-contact drilling element subassembly by, for example, being mounted on or moving in cooperation with the non-contact drilling element ram 170. In a modified example of the embodiment, the optical sensor 164 can be paired with a light source (not shown) for illuminating the drilling surface 200 during optical scanning of the drilling surface 200.

[0095] In one implementation, the optical sensor 164 can detect and interpret photons emitted and / or reflected from the drilling surface using a red-green-blue (RGB) camera detector. Using the RGB camera detector, the optical sensor 164 can generate and store a two-dimensional image representing the photon emission and / or reflection at the drilling surface 200 in an RGB view. In another implementation, the optical sensor 164 can detect and interpret photons emitted and / or reflected from the drilling surface using a cyan-magenta-yellow-black (CMYK) camera detector. Using the CMYK camera detector, the optical sensor 164 can generate and store a two-dimensional image representing the photon emission and / or reflection at the drilling surface 200 in a CMYK view. In yet another implementation, the optical sensor 164 can detect and interpret photons emitted and / or reflected from the drilling surface using an infrared (near-infrared or far-infrared) camera detector. Using an infrared camera system, the optical sensor 164 can generate and store a two-dimensional image of the drilling surface 150 in an infrared view.

[0096] In another variation, the optical sensor 164 includes a combination of RGB, CMYK, infrared, multispectral, and hyperspectral detectors, used in parallel or sequentially during the drilling process. For example, the system can use an RGB camera detector in combination with or sequentially with a hyperspectral imaging device to obtain visible and invisible light depictions of the drilling surface 200. The controller 180 can then merge or integrate each image into a more complete spectral view of the drilling surface 200, showing the current or near-current temperature profile of the drilling surface 200.

[0097] Additionally or alternatively, system 100 can implement object tracking techniques to detect and track material moving away from the drilling surface based on features detected in a series of images captured by the optical sensor 164, and estimate the temperature or phase of this material based on the color, brightness, and / or intensity of pixels identified as fragments in these images. The controller 180 can then increase the target exhaust gas temperature if no molten material moving away from the drilling surface 200 is detected, or conversely, decrease the target exhaust gas temperature if molten material moving away from the drilling surface 200 is detected. The controller 180 can adjust the target exhaust gas temperature based on any other real-time or near-real-time drilling characteristics detected or tracked by sensors or detectors communicating with the controller 180. 6. Example Configuration

[0098] In general, the techniques and methods described herein may be applied to non-contact drilling of any type or modality, including but not limited to plasma torches, jet engine thrust, flame jets, acoustic energy, electromagnetic radiation (e.g., lasers, millimeter-wave directional energy), or combinations or subcombinations thereof. Therefore, the following embodiments should be understood as not limiting the applicability of other types or modalities of non-contact drilling elements. 6.1 Example: Plasma Torch System

[0099] In one variation of system 100 shown in Figures 4A and 4B, system 100 may include a chassis 110, a propulsion system 120 positioned with the chassis 110 to advance the chassis in a first direction toward the drilling surface 200 and to retract the chassis 110 in a second direction toward away from the drilling surface 200, a plasma torch 132 connected to a power source 134 and a gas supply source 136, and a plasma torch ram 170 that positions the plasma torch 132 on the chassis 110. As shown in Figures 4A and 4B, the plasma torch ram 170 can be configured to position the plasma torch 132 along at least five degrees of freedom. The plasma torch ram 170 can be configured to position a plasma torch 132 on a chassis 110, to move the plasma torch 132 forward and backward along the chassis 110 along a longitudinal axis (X-axis) substantially parallel to a first and second direction, to tilt the plasma torch 132 along a pitch angle and a yaw angle with respect to the longitudinal axis, to lift or push the plasma torch 132 vertically along a vertical axis (Z-axis) substantially perpendicular to the longitudinal axis, and to move or pull the plasma torch 132 laterally along a horizontal axis (Y-axis) substantially perpendicular to the longitudinal axis and the vertical axis.

[0100] As shown in Figures 2, 4A, and 4B, system 100 may also include a depth sensor 190 configured to measure the standoff distance between the chassis 110 and the excavation surface 200, and a spoil discharger configured to pull the waste from a first position to a second position between the chassis 110 and the excavation surface 200. In this variant of the exemplary embodiment, system 100 may also include a controller 180 connected to a propulsion system 120, a plasma torch 132, a plasma torch ram 170, and a depth sensor 190, configured to drive the propulsion system 120, the plasma torch 132, the plasma torch ram 170, and the depth sensor 190 in response to the depth sensor 190 measuring the standoff distance between the chassis 110 and the excavation surface 200. Generally, the controller 180 can autonomously or semi-autonomously manage and direct system 100 to achieve efficient removal of material from the excavation surface 200 by implementing closed-loop control of the types described above (e.g., standoff distance, temperature control, removal rate, excavation surface characterization).

[0101] In one variation of the embodiment of the plasma torch 132, the system 100 includes a plurality of plasma torches 132 arranged in an array at the front end of the system 100. For example, the system 100 may include a primary central plasma torch 132 and a set of secondary plasma torches 132, such as three, five, or seven torches, arranged in a symmetrical or asymmetrical pattern around the primary central torch.

[0102] In this modified version, the controller 180 can perform the methods and techniques described above to monitor the standoff distance to the drilling surface 200, the periphery profile of the drilling surface 200, and / or the surface profile of the drilling surface 200 based on the output of one or more single-point or multi-point depth sensors 190 located at the front end of the system 100. Furthermore, the controller 180 can perform the additional methods and techniques described above to characterize and interpret the temperature profile of the drilling surface 200 and operate and direct one or more sets of plasma torches to maintain a desired temperature at the drilling surface 200 (e.g., sufficient to generate debris but insufficient to generate molten material). Furthermore, the controller 180 can perform the additional methods and techniques described above to maintain a target removal rate, autonomously adjust to fluctuations in the calculated removal rate, and autonomously drive or steer the system 100 along a drilling path that matches the target removal rate.

[0103] In this variation, the controller 180 can also implement a block of method S100 to adjust the power and gas flow rate to individual torches in the set based on standoff distance, removal rate, temperature profile, and profile metrics of the drilling surface 200. For example, instead of tilting a single torch toward a low-yield region detected on the drilling surface 200 as described above to increase heat and material removal in this region, the controller 180 can instead increase the power and gas flow flux to a specific torch (or subset of torches) closest to this low-yield region to break up this low-yield region on the drilling surface 200.

[0104] In this variation, each plasma torch 132 can also be attached to an independently operating plasma torch ram 170. Thus, the controller 180 can derive the surface or periphery profile of the drilling surface as described above, and independently operate the plasma torch ram 170 to set each plasma torch 132 to a standoff distance assigned based on the last (or estimated) surface or periphery profile of the drilling surface 200, and independently adjust the target standoff distance of these plasma torches 132 based on the material removal rate or detected temperature from the corresponding area of ​​the drilling surface 200. 6.2 Example: Variations of Jet Engine Cutter Heads

[0105] In another variation of system 100 shown in Figure 6, system 100 may include a chassis 110 and a cutter head 140, the cutter head 140 including a compressor 142 configured to compress air flowing in from a ground fresh air supply source, a combustor 144 configured to mix the compressed air leaving the compressor 142 with fuel flowing in from a ground fuel supply source and ignite the fuel, a turbine 154 configured to extract energy from the combustion fuel and the compressed air leaving the combustor 144 to rotate the compressor 142, and a nozzle 160 configured to direct exhaust gases 220 leaving the turbine 154 to induce a jet impact region at the drilling surface 200. As shown in Figure 6, system 100 may also include a cutter head ram 170 connected to the cutter head 130 and configured to position the cutter head 130 relative to the drilling surface 200, a temperature sensor 156, and a controller 180 connected to the cutter head 130, the temperature sensor 156, and the cutter head ram 170. In this variation of the system 100 of the embodiment, the controller 180 can be configured to track the temperature of the exhaust gas 220 exiting the nozzle 160 based on a signal output by the temperature sensor 156 and to adjust the rate of fuel entering the combustor 144 to maintain the temperature of the exhaust gas 220 exiting the nozzle 160 below the melting temperature of the geological material present in the drilling site and above the fracturing temperature. As shown in Figures 2 and 6, the system 100 may also include a propulsion system 120 connected to the controller 180 and positioned with the chassis 110 to advance the chassis in a first direction toward the drilling surface 200 and to retract the chassis 110 in a second direction away from the drilling surface 200.

[0106] System 100 includes or is connected to a fuel supply line. In one embodiment, the fuel supply line includes a thermally shielded, flexible fuel line that connects to a ground fuel reservoir (e.g., a mobile diesel fuel tank), passes through a tunnel, and connects to the cutter head 140 to supply fuel to the cutter head 140 during operation.

[0107] System 100 may also include a fuel pump (not shown) integrated into the cutter head 140 and configured to draw fuel from a ground fuel reservoir through a fuel supply line to maintain a minimum fuel pressure within the cutter head 140. For example, System 100 may include a mechanical fuel pump driven by power taken from the turbine 154. Alternatively, System 100 may include an electric fuel pump and a generator (or an electric starter motor operating in generator mode) driven by power taken from the turbine 154 to power the electric fuel pump and draw fuel from the ground fuel reservoir.

[0108] Additionally or alternatively, the ground fuel reservoir may include a fuel pump configured to push fuel toward the engine through the fuel supply line. Furthermore, system 100 may include a series of inline fuel pumps positioned along the fuel supply line, such as for the length of the extended tunnel excavation (tens, hundreds of feet, etc.), and configured to increase fuel pressure and maintain fuel flow along the fuel supply line.

[0109] Furthermore, as the fuel supply line extends from the above-ground fuel reservoir along the tunnel to the cutter head 140, the fuel supply line may be heated by exhaust gases that move away from the excavation face 200, around the cutter head 140, and backward through the tunnel towards the tunnel opening behind the cutter head 140. Thus, the fuel flowing through the fuel supply line is heated by these exhaust gases on its way to the cutter head 140, recovering some thermal energy from these exhaust gases and returning this thermal energy to the cutter head 140. The cutter head 140 then returns this reused heat, along with any additional heat from the combustion of this fuel, to the excavation face 200.

[0110] System 100 also includes an outside air supply line (or “hose”) that includes a ground inlet, runs through a tunnel behind the cutter head 140, connects to the inlet of the cutter head 140, and supplies fresh air to the compressor 142 during operation. Specifically, the air supply line supplies fresh air from the ground to the cutter head 140, which compresses this fresh air in the compressor 142, mixes this compressed fresh air with fuel received via the fuel supply line, ignites this air-fuel mixture in the combustor 144, extracts some energy from the exhaust gases that burn and expand via the turbine 154 to rotate the compressor 142, and then releases these hot, high-mass-flow exhaust gases 220 toward the excavation face 200 to break and remove material from the excavation face 200.

[0111] For example, the air supply line may include a flexible duct hose and a thermal shield configured to cover a first portion of the flexible duct hose that follows immediately after the cutter head 140 (e.g., a 10-foot portion of the air line just behind the engine), shielding the flexible duct hose from the hot exhaust gases 220 and debris moving around the cutter head 140 away from the drilling surface. In this example, the air supply line may also omit the thermal shield for the rest of the flexible duct hose. Thus, this second portion of the flexible duct hose may be heated by the exhaust gases 220 moving around the flexible duct hose behind the engine. The fresh air traveling through the duct hose is therefore heated by these exhaust gases 220 on its way to the cutter head 140, and some thermal energy can be recovered from these exhaust gases 220 and returned to the cutter head 140, where the cutter head 140 returns this recycled heat along with additional heat from the combustion of fuel to the drilling surface 220. Therefore, in this implementation, the air supply line can function as a heat exchanger to recycle the heat moving from the excavation surface 220 and return this heat to the cutter head 140.

[0112] As shown in Figure 6, the compressor 142 is configured to compress air flowing in from a fresh air supply on the ground. Generally, the compressor 142 is described herein as defining a radial compressor that is coupled to and driven by the turbine 154 and located on the same drive line as the turbine 154. For example, the compressor 142 may include a single or multi-stage axial-flow compressor comprising a set of compressor stator vanes fixed to the engine, a compressor rotor rotating within the engine, and a set of compressor rotor vanes attached to the compressor rotor. However, the compressor 142 may instead include a centrifugal compressor. The compressor 142 may also be driven by the turbine 154 via a gearbox, belt drive, or other power transmission subsystem.

[0113] As shown in Figure 6, the combustor 144 is configured to mix compressed air exiting the compressor with fuel flowing in from a fuel supply source and to ignite this fuel mixture. In one embodiment, the combustor 144 includes one or more flame tubes arranged parallel to the compressor 142 and the turbine 154, each flame tube defining a primary zone with a first set of perforations and a dilution zone with a second set of perforations. In this embodiment, the combustor 144 may also include a fuel injector attached to a fuel metering unit 146 that sprays fuel into the flame tube before it reaches the primary zone. During operation, a first portion of the compressed air exiting the compressor 142 moves through the first set of perforations into the primary zone of the flame tube, where it mixes with the fuel to form an air-fuel mixture at or near a target ratio (e.g., leaner than the stoichiometric ratio). This air-fuel mixture then burns (almost completely) at (almost) constant pressure within the primary zone of the flame tube and flows into the dilution zone on its way to the turbine 154. Simultaneously, a second portion of the air exiting the compressor 142 moves around and outside the primary zone of the flame tube, passing through the second set of perforations in the flame tube and mixing with the high-temperature combustion products moving from the primary zone to the dilution zone of the flame tube. This second portion of compressed air may be much cooler than these high-temperature combustion products and can therefore lower the average temperature of the combustion products exiting the combustor, and thus lower the average temperature of the exhaust gas that subsequently exits the nozzle 160 and is directed toward the excavation surface.

[0114] As described above, system 100 can also control the exhaust gas temperature by controlling the “dilution ratio” of the first portion of compressed air and the second portion of compressed air that enters the flame tube and is diverted around it, thereby adjusting the fuel flow rate to the combustor and maintaining the target air-fuel mixture within the primary zone of the flame tube.

[0115] As shown in Figure 6, the turbine 154 is configured to extract energy from the combustion products leaving the combustor 144 and rotate the compressor 142. In particular, the turbine 154 may include a set of turbine stator blades attached to the engine, a turbine rotor that rotates within the engine and is coupled to the compressor rotor (e.g., via a drive shaft and / or gearbox), and a set of turbine rotor blades attached to the turbine rotor. The combustion products leaving the combustor 144 expand isentropically as they travel through the turbine stator and rotor blades of the turbine 154, thus reducing the temperature and pressure of these combustion products and converting this energy into rotation for the compressor 142.

[0116] As shown in Figure 6, the nozzle 160 is coupled to the output of the turbine and is configured to direct the exhaust gas 220 from the turbine towards the jet impact area of ​​the drilling surface 200.

[0117] In one embodiment, the system 100 includes a fixed-area nozzle 160 that directs exhaust gas toward the drilling surface 200, forming a jet impact area of ​​a target size (e.g., target diameter) on the drilling surface 200 at a target standoff distance (or within a narrow range of the target standoff distance) as determined by the controller 180 between the nozzle 160 and the drilling surface 200. For example, the fixed-area nozzle 160 can be configured with a nozzle shape that produces an impact area approximately 10 times the width of the nozzle 160, thereby achieving a flow of exhaust gas 220 including a high-temperature central region shielded by a thick boundary layer, efficient convection within the central region, a high heat transfer rate from the central flow to the drilling surface 200, and a high fracturing rate within the jet impact area.

[0118] As described herein, the controller 180 controls the standoff distance and angular position of the nozzle 160 on the chassis 110 via the cutter head ram 170—and thus relative to the drilling surface 200—to induce a controlled jet impact on the surface of the drilling surface 200, and thus evenly drill one distinct cross section of the drilling surface 200 before advancing the chassis 110 forward.

[0119] In one modified embodiment, the system 100 includes a variable area nozzle 160 with a variable aperture 162 through which exhaust gas 220 can flow. In this modification, by adjusting the area of ​​the nozzle, the controller 180 can adjust the jet impact area at the drilling surface 200, and thus control the power density (i.e., heat flux per unit area) within the jet impact area at the drilling surface 200.

[0120] Generally, the speed of the compressor 142 may correlate with the mass flow rate of air passing through the cutter head 140, and therefore with the pressure in the jet impact region at the drilling surface 200. Similarly, the fuel flow rate may correlate with the exhaust gas temperature, turbine, and compressor speeds. Therefore, during operation, the controller 180 may also implement closed-loop control by increasing the fuel flow rate and increasing the nozzle area to raise the exhaust gas temperature to a (fixed or variable) target temperature, thereby compensating for the increase in compressor speed resulting from the increase in fuel flow rate and maintaining a controlled (e.g., constant) pressure throughout the jet impact region. Similarly, the controller 180 may further implement closed-loop control by decreasing the fuel flow rate to lower the exhaust gas temperature to a (fixed or variable) target temperature, and decreasing the nozzle area, thereby compensating for the decrease in compressor speed resulting from the decrease in fuel flow rate and maintaining a controlled (e.g., constant) pressure throughout the jet impact region.

[0121] In a similar example, the controller 180 can reduce the velocity of the exhaust gas exiting the nozzle by implementing additional closed-loop control that increases the nozzle area at higher compressor speeds, thereby maintaining the exhaust gas flow at subsonic speeds.

[0122] Conversely, the controller 180 can adjust the nozzle area to maintain a supersonic exhaust gas flow and place a first shock diamond (i.e., a localized rapid change in density and pressure) in the exhaust gas flow at the drilling surface 200. The complex flow of exhaust gas 220 in and around this shock diamond placed at the drilling surface by the system 100 can result in high rates of heat transfer, thermal shock, and pressure shock across the jet impact region, leading to a high fracture rate and material removal rate from the jet impact region. Therefore, in this implementation, the controller can monitor the standoff distance from the engine to the drilling surface 200 by any of the methods or techniques described herein and adjust the nozzle area based on the current exhaust gas temperature and the current airflow rate (or compressor speed, turbine speed) through the cutter head 140 and the current standoff distance to place a shock diamond (e.g., a first shock diamond) in the exhaust gas flow at the current standoff distance, generating thermal and pressure shock at the drilling surface 200 to increase the material removal rate.

[0123] In another example of closed-loop control of the variable-area nozzle 160, the controller 180 detects when hard geological formations (e.g., igneous and metamorphic rocks) are present on the drilling surface 200. By maintaining an exhaust gas temperature lower than the lower melting temperature of softer geological formations, melting at the excavation face 200 can be prevented under mixed geological excavation face conditions or during the transition from hard to softer geological formations along the tunnel, while increasing the energy density within the jet impact zone and maintaining a high level within the jet impact zone despite these harder geological formations. Similarly, in this example, if soft geological formations (e.g., sedimentary rocks) are present at the excavation face, the controller 180 can increase the size of the jet impact zone by increasing the nozzle area, thereby maintaining a high fracturing rate over a wider excavation area with more uniform rock removal across the entire width and height of the excavation.

[0124] As shown in Figure 6, the system 100 also includes a temperature sensor 156 (e.g., a thermocouple) positioned near the exit of the nozzle 160 (e.g., between the nozzle 160 and the drilling surface 200) and a fuel metering unit 146 configured to adjust the rate at which fuel is injected into the combustor 144. Generally, during operation, the controller 180 tracks the temperature of the exhaust gas 220 exiting the nozzle 160 based on the signal output by the temperature sensor 156 and adjusts the rate at which fuel enters the combustor 144 via the fuel metering unit 146 so that the temperature of the exhaust gas 220 exiting the nozzle 160 can be kept below the melting temperature of all geological formations, or below the melting temperature of specific geological formations predicted or detected at the drilling surface 200.

[0125] As described herein, the controller 180 sets a target exhaust gas temperature as described above, samples the temperature sensor 156 to track the temperature of the exhaust gas 220 exiting the nozzle 160, and then performs closed-loop control by adjusting the fuel metering unit 146 to increase the proportion of fuel injected into the flame tube if the temperature of these exhaust gases 220 is lower than the target temperature, and adjusts the fuel metering unit 146 to decrease the proportion of fuel injected into the combustor 144 if the temperature of the exhaust gases 220 is higher than the target temperature.

[0126] As shown in Figure 6, the system 100 includes an air metering unit 148 configured to change the dilution ratio between a first portion of compressed air entering the primary zone of the combustor 144 and a second portion of compressed air entering the dilution zone of the combustor 144.

[0127] In one implementation, the air metering unit 148 includes a sleeve 150 configured to slide over a range of positions along the combustor 144, including a 1:0 dilution ratio position where the sleeve 150 completely exposes a first set of perforations in the combustor 144 and completely surrounds a second set of perforations; a 2:1 dilution ratio position where the sleeve 150 largely exposes the first set of perforations in the combustor 144 and largely surrounds the second set of perforations; a 1:1 dilution ratio position where the sleeve 150 similarly exposes the first and second sets of perforations in the combustor 144; and a 1:2 dilution ratio position where the sleeve 150 largely surrounds the first set of perforations in the combustor 144 and largely exposes the second set of perforations.

[0128] In this variation of the embodiment, the air metering unit 148 may also include an actuator 152 configured to move the sleeve 150 along this range of positions. Thus, during operation, the controller 180 can perform closed-loop control by setting a target exhaust gas temperature as described below, detecting the temperature of the exhaust gas 220 exiting the nozzle 140, and if the temperature of the exhaust gas 220 is lower than the target temperature, adjusting the air metering unit 148 to increase the dilution ratio and accordingly increase the fuel flow rate to maintain the target air-fuel ratio, and if the temperature of the exhaust gas 220 is higher than the target temperature, adjusting the air metering unit 148 to decrease the dilution ratio and accordingly decrease the fuel flow rate to maintain the target air-fuel ratio. The air metering unit 148 is adjusted to increase the dilution ratio, and the fuel flow rate is increased accordingly to maintain the target air-fuel ratio. If the temperature of the exhaust gas 220 is higher than the target temperature, the air metering unit 148 is adjusted to decrease the dilution ratio, and the fuel flow rate is decreased accordingly to maintain the target air-fuel ratio. Closed-loop control can be implemented to perform the following: If the temperature of the exhaust gas 220 is lower than the target temperature, the fuel flow rate is increased accordingly to maintain the dilution ratio and the target air-fuel ratio. If the temperature of the exhaust gas 220 is higher than the target temperature, the air metering unit 148 is adjusted to decrease the dilution ratio and the fuel flow rate is decreased accordingly to maintain the target air-fuel ratio.

[0129] Generally, the controller 180 can set a target exhaust gas temperature based on nominal drilling geological conditions or real-time drilling characteristics. Next, closed-loop control is performed to adjust the fuel flow rate and / or dilution ratio in the combustor 144 based on the difference between the measured temperature of the exhaust gas 220 exiting the nozzle 140 and the target temperature. Generally, the controller 180 can set a target exhaust gas temperature based on nominal drilling geological conditions or real-time drilling characteristics, and then perform closed-loop control to adjust the fuel flow rate and / or dilution ratio in the combustor 144 based on the difference between the measured temperature of the exhaust gas 220 exiting the nozzle 140 and the target temperature.

[0130] Furthermore, as shown in Figure 6, the system 100 may also include an afterburner 158 configured to inject fuel into the exhaust gas 220 exiting the turbine 154 in order to rapidly increase the temperature and pressure of the exhaust gas reaching the drilling face 200. The controller 180 may be configured to selectively activate the afterburner 158 (through control of ignition and fuel flow) in order to rapidly increase the temperature of the exhaust gas 220 and the pressure of the exhaust gas 220 impacting the drilling face 200. The afterburner 158 may define a recirculation zone close to its end to fix the afterburner flame. The afterburner 150 may further include a spark plug, a glow plug, or other electrical or electromagnetic starter for igniting the afterburner flame and initiating vaporization of the injected fuel. In another variation of the embodiment, when adjusting the temperature and / or pressure of the exhaust gas 220 on the excavation surface 200, the controller 180 may be configured to first adjust the start and / or fuel flow rate to the afterburner 158, and then adjust the fuel flow rate or dilution ratio as necessary by the methods and techniques described above.

[0131] In one variant of the embodiment, the afterburner 158 can be supplied with fuel, such as liquid diesel fuel, from the main fuel supply line. Alternatively, the afterburner 158 can be supplied with a different type of fuel (e.g., a mixture of kerosene and gasoline, biodiesel, etc.) through a separate fuel line. Furthermore, the controller 180 can selectively increase or decrease the nozzle area of ​​the variable area nozzle 160 in coordination with the operation of the afterburner 158 in order to maintain a constant pressure in the nozzle 160.

[0132] In another variation of the embodiment, system 100 further includes a compressor tap (not shown) positioned between the compressor 142 and the combustor 144, and a cryogenic jet coupled to the compressor tap and positioned near the drilling surface 200, configured to blow away debris removed from the drilling surface 200 by the hot exhaust gas output from the nozzle 160, away from the drilling surface 200 and behind the cutter head 140.

[0133] For example, a cryogenic jet can be positioned below the nozzle 140 and directed downward and / or toward the bottom corner of the drilling surface 200 so that the compressed air released by the cryogenic jet moves backward the debris that falls from the drilling surface and accumulates in this bottom corner of the drilling surface, thereby exposing it to fracturing by the exhaust gas 220 released from the bottom nozzle 160 of the drilling surface 200. Therefore, the system 100 can extract a third portion of compressed air from the output of the compressor 142 via a compressor tap and supply this compressed air to a cryogenic jet, blowing this third portion of compressed air toward the bottom region of the excavation surface 200, thereby drawing back any debris and larger rock fragments that might otherwise accumulate along the bottom of the excavation surface 200, thus exposing the bottom corners of the excavation surface 200 to the nozzle 160 for further crushing.

[0134] Additionally or alternatively, in this modification, the system 100 may include a set of cryogenic jets positioned around the outer casing of the cutter head 140 near the nozzle 140, facing the rear of the cutter head (i.e., opposite the drilling surface) and connected to a compressor tap. In this implementation, the set of cryogenic jets guides cryogenic air along the outer casing of the cutter head 140 to form a cryogenic boundary layer along the chassis 110, thermally shielding the chassis 110 from hot exhaust gases and debris flowing around the cutter head 140 away from the drilling surface 200 during operation.

[0135] In another variation, system 100 is Arranged in a row in front of the compressor 142, coupled to the air supply line, and driven by a turbine 154 (e.g., in a high-bypass fan configuration), the system is configured to output a second flow of cryogenic compressed air separate from the compressor 142, combustor 144, and nozzle 160. In this variation, system 100 may also include a backflow subsystem configured to direct this second flow of cryogenic compressed air backward away from the excavation face 200, pulling debris moving away from the excavation face 200 away from the excavation face, through the cutter head 140, and out of the tunnel. For example, the backflow subsystem can direct the second flow of cryogenic compressed air backward (i.e., away from the excavation face 200 and in the opposite direction to the air flowing from the air supply source to the cutter head 140), thereby increasing the flow velocity of the exhaust gas 220 and the fracturing around and through the cutter head, and cooling the chassis 110 of system 100 by creating a low-pressure region between the rear of the cutter head 140 and the excavation face 200.

[0136] As shown in Figures 2 and 6, the cutter head 140 can be mounted on the chassis 110, and the propulsion subsystem 120 can advance the chassis 110 and the cutter head 140 toward the newly exposed surface of the excavation face 200 as the system 100 excavates the tunnel.

[0137] For example, the chassis 110 and propulsion subsystem 120 can form a wheeled or tracked cart driven by an electric, hydraulic, or pneumatic motor powered via a generator, pump, or compressed air tap connected to the cutter head 140. The chassis 110 may also include a cutter head ram 170 configured to move the cutter head 140 with at least five degrees of freedom. The cutter head ram 170 can be configured to position the cutter head 140 on the chassis 110, move the cutter head 140 forward and backward along the chassis 110 in a longitudinal direction (e.g., along the X-axis) to maintain a standoff distance between the nozzle 160 and the drilling surface 200, pitch and yaw the cutter head 140 on the chassis 110 (e.g., up to ±10° in pitch and yaw) to scan (or "raster") the jet impact area across the drilling surface 200, and / or lift or push the cutter head 140 vertically along the Z-axis and move or pull the cutter head 140 laterally along the Y-axis on the chassis 110 to scan the jet impact area across the drilling surface 200.

[0138] In this embodiment, the controller 180 can perform one or more closed-loop controls to fully retract the cutter head ram 170, advance the propulsion subsystem 120 to position the nozzle 160 at (approximately) a target standoff distance from the drilling surface 200, raster the nozzle 160 across the drilling surface 200 to break up and remove rock on the drilling surface area larger than the cross-section of the system 100 and selectively pause (or "stay") the nozzle 160 to position the jet impact area in a low drilling rate area of ​​the drilling surface 200, and advance the cutter head ram 170 according to the removal rate calculated during this raster cycle.

[0139] The controller 180 can repeat the closed-loop process over multiple raster cycles until the cutter head ram 170 reaches the peak of its forward movement, at which point the controller 180 can fully retract the cutter head ram 170 and advance the propulsion subsystem 120 forward, positioning the nozzle 160 at (approximately) the target standoff distance from the drilling surface 200 before repeating this process. Furthermore, in this example, the controller 180, By maintaining a constant fuel flow rate through the combustor 144 and / or afterburner 158, thereby maintaining a constant temperature and pressure of the exhaust gas 220 exiting the nozzle, and by adjusting the scanning speed at which the system 100 rasterizes the nozzle 160 across the drilling surface 200, a target drilling profile (e.g., D-shape) exceeding the target drilling size (e.g., width and height) and drilling length can be achieved. 7. Conclusion

[0140] The systems and methods described herein can be at least partially embodied and / or implemented as machines configured to receive computer-readable media containing computer-readable instructions. Instructions can be executed by computer-executable components integrated into hardware / firmware / software elements of applications, applets, hosts, servers, networks, websites, communication services, communication interfaces, users' computers or mobile devices, wristbands, smartphones, or any suitable combination thereof. Other systems and methods of the embodiments can be at least partially embodied and / or implemented as machines configured to receive computer-readable media containing computer-readable instructions. Instructions can be executed by computer-executable components integrated into computer-executable components integrated with the types of devices and networks described above. The computer-readable media can be any suitable computer-readable media such as RAM, ROM, flash memory, EEPROM, optical devices (CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component may be a processor, but any suitable dedicated hardware device can (alternatively or additionally) execute the instructions.

[0141] Those skilled in the art will recognize from the above detailed description, as well as from the drawings and claims, that modifications and changes can be made to embodiments of the present invention without departing from the scope of the present invention as defined in the following claims.

Claims

1. First, the plasma torch facing the drilling surface is driven from the drilling surface to the target standoff distance. Activate the plasma torch to remove the material from the drilling surface. The first profile of the excavation surface is detected, The target standoff distance is adjusted to the second target standoff distance by either decreasing the target standoff distance to the second target standoff distance in response to a first profile showing a first gradient less than the target gradient range, or increasing the target standoff distance to the second target standoff distance in response to a first profile showing a first gradient greater than the target gradient range. Next, the plasma torch is repositioned toward the drilling surface according to the second target standoff distance. A method of drilling using plasma.

2. The controller extends the contact probe of the linear actuator to an extended position close to the drilling surface. The controller moves the linear actuator to retract the contact probe to a recessed position within the heat shield housing distal to the drilling surface. The controller determines the current standoff distance to the drilling surface by calculating the difference in the length of the contact probe at the extended and retracted positions. The method according to claim 1, wherein a first profile of the excavation surface is detected by means of the method.

3. The controller reduces the power output and gas flow rate to the plasma torch to lower the surface temperature of the drilling surface when the contact probe is not in the retracted position. The controller increases the power output and gas flow rate to the plasma torch while the contact probe is in the retracted position, thereby resuming drilling on the drilling surface. The method according to claim 2.

4. The controller saves the current standoff distance. The controller calculates the reset distance of the plasma torch ram based on the current longitudinal position of the plasma torch ram, which moves the plasma torch along its longitudinal direction. The controller moves the plasma torch ram by the plasma torch ram reset distance and resets it to the home position. The controller activates the propulsion system to move the drilling rig by the sum of the plasma torch ram reset distance and the difference between the current standoff distance and the current target standoff distance. The method according to claim 2, for adjusting the target standoff distance.

5. The controller detects that the contact probe is not in contact with the excavation surface. The controller moves the torch ram back to its home position. The controller activates the propulsion system to move the drilling rig until the contact probe encounters resistance. The controller determines that the contact probe is in contact with the excavation surface. The controller sets the plasma torch to the target standoff distance. The controller instructs the linear actuator to retract the contact probe. The method according to claim 1, for detecting a first profile of the excavation surface.

6. The reference voltage of the contact probe is driven to an electrical shielding voltage, thereby generating an electric field around the contact probe that repels the plasma plume generated by the plasma torch. The controller instructs the linear actuator to drive the contact probe forward to maintain continuous contact with the excavation surface. The controller drives the plasma torch ram forward to maintain the target standoff distance between the plasma torch and the drilling surface. The method according to claim 1, for detecting a first profile of the excavation surface.

7. The controller opens the shutter to expose the non-contact depth sensor. The controller samples the depth signal received by the depth sensor. The controller determines the depth measurement to the drilling surface based on the depth signal. The controller closes the shutter to shield the depth sensor from excessive heat on the drilling surface. The method according to claim 1, for detecting a first profile of the excavation surface.

8. The controller interpolates the 3D drilling surface profile based on the depth signal. The controller directs the plasma torch towards the region represented by the three-dimensional drilling surface profile. The controller adjusts the target standoff distance to the excavation surface area in proportion to the slope between the excavation surface area and the excavation center. The controller adjusts the power output and gas flow to the plasma torch to prevent material melting in the drilling surface area. The method according to claim 7.

9. Furthermore, the controller will, between the first time and the second time, Estimated standoff distance, Adjust the position of the torch ram to maintain the current standoff distance at the estimated standoff distance. Based on the estimated standoff distance, adjust the power output and gas flow rate of the plasma torch. The method according to claim 1.

10. moreover, The controller calculates the offset distance between the first and second excavation surface profiles based on the sum of the changes over time intervals in the first and second standoff distances, the cumulative torch ram advance between the first and second standoff distances, and the cumulative chassis advance between the first and second standoff distances. The controller calculates the volume of material to be removed between the first excavation surface profile and the second excavation surface profile continuous with the first excavation surface, based on the offset distance. The controller calculates the removal rate during the time interval by dividing the volume by the duration of this time interval. The method according to claim 1.

11. moreover, The controller compares the removal rate to the target removal rate. The controller adjusts the target standoff distance to the adjusted target standoff distance based on the deviation between the removal rate and the target removal rate. The controller verifies that the adjusted target standoff distance improves the removal speed. The method according to claim 10.

12. moreover, The controller compares the removal rate to the target removal rate. The controller adjusts the power output and gas flow rate of the plasma torch to adjusted power output and adjusted gas flow rate based on the deviation between the removal rate and the target removal rate. The controller verifies that the regulated power output and regulated gas flow rate improve the removal rate. The method according to claim 10.

13. In the first time, a non-contact drilling element facing the drilling surface is driven from the drilling surface to a target standoff distance, By activating the non-contact drilling element, material is removed from the drilling surface. The first profile of the excavation surface is detected, The target standoff distance is adjusted to the second target standoff distance by decreasing the target standoff distance to the second target standoff distance in response to a first profile indicating that the first gradient is less than the target gradient range, and increasing the target standoff distance to the second target standoff distance in response to a first profile indicating that the first gradient is greater than the target gradient range. In the second time, the non-contact drilling element is repositioned toward the drilling surface according to the second target standoff distance. Methods of excavation.

14. The controller causes the linear actuator to extend the contact probe to an extended position near the drilling surface, The controller causes the linear actuator to retract the contact probe to a retracted position within a thermally shielded housing distal to the drilling surface. The controller determines the current standoff distance to the drilling surface by calculating the difference in the length of the contact probe at the extended and retracted positions. By doing so, the first profile of the excavation surface is detected. The method according to claim 13.

15. The controller adjusts the drilling parameters of the non-contact drilling element when the contact probe is not in the retracted position to reduce the surface temperature of the drilling surface. The controller adjusts the drilling parameters of the non-contact drilling element and resumes boring at the drilling surface when the contact probe is in the retracted position. The method according to claim 14.

16. The controller determines that the contact probe is not in contact with the excavation surface, The controller positions the non-contact drilling element to its home position. The controller activates the propulsion system to move the drilling rig until the contact probe encounters resistance. The controller determines that the contact probe is in contact with the excavation surface. The controller sets the non-contact drilling element to the target standoff position. The controller instructs the linear actuator to retract the contact probe. The method according to claim 13.

17. The non-contact drilling element comprises a plasma torch, The reference voltage of the contact probe is driven to an electrical shielding voltage, thereby generating an electric field around the contact probe that repels the plasma plume generated by the plasma torch. The controller instructs the linear actuator to drive the contact probe forward to maintain continuous contact with the excavation surface. The controller drives the plasma torch ram forward to maintain the target standoff distance between the plasma torch and the drilling surface. The method according to claim 13, for detecting a first profile of the excavation surface.

18. The controller opens the shutter to expose the non-contact depth sensor, The controller samples the depth signal received by the depth sensor. The controller determines the depth measurement to the drilling surface based on the depth signal. The controller closes the shutter to shield the depth sensor from excessive heat on the drilling surface. The method according to claim 13, for detecting a first profile of the excavation surface.

19. The controller interpolates the three-dimensional drilling surface profile based on the depth signal, The controller directs the plasma torch towards the region represented by the three-dimensional drilling surface profile. The controller adjusts the target standoff distance to the excavation surface area in proportion to the slope between the excavation surface area and the excavation center. The controller adjusts the drilling parameters of the non-contact drilling element to prevent material melting in the drilling surface area. The method according to claim 18.

20. Between the first time and the second time, by the controller, Estimate the standoff distance, Adjust the position of the non-contact drilling element to maintain the current standoff distance at the estimated standoff distance. Based on the estimated standoff distance, adjust the drilling parameters of the non-contact drilling element. The method according to claim 13.

21. The controller calculates an offset distance between a first excavation surface profile and a second excavation surface profile continuous with the first excavation surface, based on the sum of the changes over time intervals in the first standoff distance, the second standoff distance, the cumulative torch ram advance between the first standoff distance and the second standoff distance, and the cumulative chassis advance between the first standoff distance and the second standoff distance. The controller calculates the volume of material to be removed between the first and second excavation profile based on the offset distance. The controller calculates the removal rate during the time interval by dividing the volume by the duration of this time interval. The method according to claim 13.

22. Furthermore, The controller compares the removal rate to the target removal rate. The controller adjusts the target standoff distance to the adjusted target standoff distance based on the deviation between the removal rate and the target removal rate. The controller verifies that the adjusted target standoff distance improves the removal speed. The method according to claim 21.

23. Furthermore, The controller compares the removal rate to the target removal rate. The controller adjusts the drilling parameters of the non-contact drilling element to the adjusted drilling parameters based on the deviation between the removal rate and the target removal rate. The controller verifies that the regulated power output and regulated gas flow rate improve the removal rate. The method according to claim 22.

24. The non-contact drilling element comprises a plasma torch, Drilling parameters include the power output and gas flow rate of the plasma torch. Adjusted drilling parameters include adjusted power output and adjusted gas flow rate. The method according to claim 23.

25. A non-contact drilling element comprises a compressor configured to compress air entering from a fresh air supply source on the ground, a combustor configured to mix the compressed air exiting the compressor with fuel entering from a fuel supply source on the ground and ignite the fuel, a turbine configured to extract energy from the combustion fuel and compressed air exiting the combustor to rotate the compressor, and a cutter head equipped with a nozzle configured to direct the exhaust gas exiting the turbine to induce a jet impact area on the drilling surface. The drilling parameters include the velocity of the fuel entering the combustor and the mass of the air entering the combustor. The adjusted drilling parameters include the rate of fuel entering the adjusted combustor and the mass of air entering the adjusted combustor. The method according to claim 23.

26. The non-contact drilling element further comprises an afterburner connected to a controller and configured to inject fuel into the exhaust gases exiting the turbine to increase the temperature of the exhaust gases exiting the nozzle, The drilling parameters further include the afterburner status. The adjusted drilling parameters include the second state of the afterburner. The method according to claim 25.

27. ​​The non-contact drilling element comprises a cutter head, and further, The controller sets the target exhaust gas temperature for the exhaust vent directed towards the excavation surface by the cutter head. The controller receives images of the excavation surface captured by the optical sensor. The controller scans the image of the excavation surface to find a series of pixels that indicate molten material. The controller reduces the target exhaust gas temperature in response to detecting a series of pixels indicating molten material. The method according to claim 13.

28. Furthermore, The controller receives a set of images of the drilling surface captured by the optical sensor. The controller scans a set of images of the drilling surface to find a set of pixels that indicate the ejected material is moving away from the drilling surface. The controller characterizes the ejected material based on the optical properties of the set of pixels associated with the ejected material. The controller reduces the target exhaust gas temperature in accordance with characterizing the ejected material as a molten material. The method according to claim 27.

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