A quadruped robot original explosion-proof design method for coal mine underground class i explosive environment

Abstract

The present application is suitable for the field of artificial intelligence, embodied intelligence and robot technology, and provides a kind of four-legged robot original explosion-proof design method for coal mine underground I explosive environment, adopts the distributed architecture of "machine body main explosion-proof cavity and leg joint independent explosion-proof unit"; The machine body adopts double-cavity physical separation layout, and the power battery cavity is explosion-proof, and the control intrinsically safe cavity is intrinsically safe; The leg joint adopts independent micro explosion-proof cavity, cooperates fixed center shaft static wiring and multiple sealing structure; Wheel-foot composite configuration and electrostatic discharge protection are adopted; The perception peripheral adopts explosion-proof window combined with intrinsically safe packaging; The whole machine integrates a multi-parameter state monitoring system to realize redundancy protection, and the present application provides an intrinsically safe robot solution for intelligent inspection in coal mine.

Description

Technical Field

[0001] This invention relates to the fields of artificial intelligence, embodied intelligence, and robotics, specifically a native explosion-proof design method for a quadruped robot designed for Class I explosive environments in underground coal mines. Background Technology

[0002] With the deepening of intelligent mining construction, "machines replacing humans" in underground coal mines has become an industry consensus. Quadruped robots, with their excellent obstacle-crossing ability and terrain adaptability, are considered ideal platforms for underground coal mine inspection operations. However, underground coal mines contain explosive hazardous substances such as methane and coal dust, belonging to Class I explosive environments as defined by GB 3836 standard. Quadruped robots operating in this environment must meet strict explosion-proof requirements, with an explosion-proof rating of Ex d I Mb. Existing explosion-proof quadruped robots for mining mostly adopt the modification approach of "ordinary robot plus external explosion-proof shell," that is, adding the explosion-proof function as an external module to the ordinary robot body. This retrofitting method results in a significant increase in the overall weight of the machine and a serious reduction in its mobility; at the same time, the fit between the external explosion-proof shell and the robot body is difficult to guarantee long-term sealing reliability, which is particularly prominent in the high-frequency vibration environment underground. In addition, traditional explosion-proof robots use a single large cavity design, concentrating all electrical components in a single explosion-proof shell, resulting in concentrated explosion pressure, a significant increase in shell wall thickness, and an inability to adapt to the high-frequency, wide-range movement requirements of the quadruped robot's legs.

[0003] The following defects are also common in existing technologies: the power circuit and the control circuit are usually located in the same cavity. The electromagnetic interference generated by the high-power power circuit can easily affect the stability of the control circuit. Moreover, if the two types of circuits fail, they will affect each other and increase the risk of explosion. Traditional joint modules use dynamic wiring, and the cables rotate with the rotating parts. In the high dust environment underground, the continuous friction between the cables and the rotating parts can easily lead to the damage of the insulation layer, generating electric sparks, which can become potential ignition sources. Non-metallic parts are prone to static electricity accumulation when they rub against the ground. Static discharge sparks can become ignition sources. Traditional designs generally neglect static electricity protection. If the sensing components such as lidar and vision cameras are not explosion-proof, the explosion-proof certification of the whole machine will be invalid. Existing retrofitting solutions affect the sensing accuracy and the reliability of the packaging is difficult to guarantee.

[0004] To address the aforementioned issues, some existing technologies have proposed improvement strategies. SevenTeng Robotics Co., Ltd.'s patent application for an "electro-hydraulic composite-driven explosion-proof legged robot" (CN116001948A) employs a positive pressure chamber and external hydraulic cylinder design, achieving explosion-proof performance through positive pressure. However, this positive pressure explosion-proof solution requires continuous maintenance of positive pressure within the chamber, resulting in a complex and energy-intensive system unsuitable for long-term autonomous operation in coal mines. Juwei Technology's independently developed MOVENEW-P1-ExR explosion-proof robot dog uses a combined explosion-proof and increased safety design, but this solution targets Class II explosive gas environments, not Class I environments in coal mines, making its explosion-proof design fundamentally different from Class I explosion-proof designs for coal mines. While ANYbotics' ANYmal X has obtained ATEX and IECEx Zone 1 certifications, it targets the international standard Zone 1 environment, differing from the Ex d I Mb requirements under China's GB 3836 standard, and its original explosion-proof design method's technical details are not disclosed. CITIC Heavy Industries' coal mine rescue robots employ various combinations of explosion-proof methods, including planar explosion-proof, threaded explosion-proof, and cylindrical explosion-proof. However, this technology primarily targets wheeled or tracked robots and does not address the distributed explosion-proof architecture design for quadruped robots. Therefore, given this situation, there is an urgent need to provide a native explosion-proof design method for quadruped robots designed for Class I explosive environments in underground coal mines, in order to overcome the shortcomings in current practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a native explosion-proof design method for quadruped robots designed for Class I explosive environments in underground coal mines, aiming to solve the problems mentioned in the background art.

[0006] This invention is implemented as follows: a native explosion-proof design method for a quadruped robot designed for Class I explosive environments in underground coal mines, comprising the following steps:

[0007] S1. The distributed architecture of the main explosion-proof chamber of the fuselage and the independent explosion-proof unit of the leg joints is adopted, and the explosion-proof function of the whole machine is decomposed into the explosion-proof layer of the main fuselage chamber and the independent explosion-proof layer of the leg joints.

[0008] S2. The housing is made of explosion-proof material and has an explosion-proof joint surface. The interior adopts a dual-cavity physical separation layout. The power battery cavity is explosion-proof and the control intrinsically safe cavity is intrinsically safe. The two cavities are completely isolated by an integrated metal partition, with only a sealed cable passage reserved. All splicing gaps of the body are equipped with sealing gaskets and high-strength explosion-proof bolts. The cable entry end is equipped with an explosion-proof gland.

[0009] S3. Each active joint adopts an independent miniature explosion-proof cavity. The joints use a fixed central shaft static wiring scheme to prevent the cables from contacting rotating parts and output ends. The joint shaft extension end adopts a multi-seal structure and is equipped with a double copper sleeve rotation seal. The miniature explosion-proof cavity is equipped with an end cap.

[0010] S4. Explosion-proof optimization of the mobility and transmission system, which includes leg transmission components and wheels, adopts a wheel-foot composite configuration. The wheels are made of anti-static material and embedded with conductive mesh to release static electricity; non-metallic components are made of anti-static and flame-retardant material.

[0011] S5. Explosion-proof adaptation for sensing and peripheral devices; sensing components are encapsulated with explosion-proof windows or intrinsically safe encapsulation.

[0012] S6. An integrated multi-parameter status monitoring system automatically triggers power-off protection when a parameter exceeds a safety threshold.

[0013] As a further aspect of the present invention: In S1, in the distributed architecture of the main explosion-proof cavity of the fuselage and the independent explosion-proof unit of the leg joint, each leg contains three active joints, and each active joint is an independent miniature explosion-proof cavity, corresponding to the hip joint, knee joint and ankle joint respectively.

[0014] As a further aspect of the present invention: in S2, the explosion-proof material is high-strength explosion-proof cast steel with a yield strength ≥240MPa, tensile strength ≥340MPa, and elongation ≥3%;

[0015] The explosion-proof mating surface is machined to a surface roughness Ra≤6.3μm, and the gap between the mating surfaces is controlled within 0.2mm; the explosion-proof mating surface is a planar explosion-proof structure, and the width of the mating surface is ≥25mm;

[0016] The dual-cavity physical separation layout includes:

[0017] The power battery compartment is used to house the lithium battery pack, battery management system (BMS), and charging / discharging circuits. The compartment is designed to be explosion-proof.

[0018] The intrinsically safe control cavity is used to house the main controller, communication module, inertial measurement unit (IMU), and navigation algorithm processing unit. The cavity of the intrinsically safe control cavity is designed to be intrinsically safe and explosion-proof.

[0019] The integrated metal partition is made of aluminum alloy with a thickness of ≥5mm. The diameter of the cable through holes reserved on the partition is ≤8mm, and the through holes are filled with non-flammable epoxy resin sealant.

[0020] As a further aspect of the present invention: in S3, the static routing scheme with a fixed central axis includes:

[0021] The fixed central shaft is a hollow stainless steel tube with an outer diameter of 20-35mm and a wall thickness of 2-4mm. The fixed central shaft is fixedly connected to the miniature explosion-proof cavity and does not rotate with the output end. The power cable and control signal line pass through the inside of the fixed central shaft and are in a static space throughout the entire process.

[0022] The inner wall of the fixed central shaft is provided with a polyimide insulating sleeve with an insulation withstand voltage ≥500V;

[0023] The multi-seal structure is a triple progressive seal structure consisting of a V-shaped dust seal, a labyrinth seal, and a corrosion-resistant oil seal. The V-shaped dust seal is made of fluororubber FKM with a Shore A hardness of 75±5 and is installed on the outermost side of the shaft extension. The labyrinth seal has a gap width of 0.15-0.30mm and a depth of ≥5mm, and is provided with 2-4 tortuous channels. The corrosion-resistant oil seal is a double-lip fluororubber oil seal with a main lip contact pressure ≥0.15N / mm.

[0024] The double copper sleeve rotary sealing structure includes:

[0025] The outer copper sleeve, made of tin bronze ZCuSn10P1, is press-fitted into the end cap of the miniature explosion-proof cavity;

[0026] The inner copper bushing is made of tin bronze ZCuSn10P1 and is press-fitted into the output end with an interference fit.

[0027] A radial clearance fit is formed between the outer and inner copper sleeves, with a clearance of 0.05-0.15mm. The clearance is filled with high-temperature molybdenum disulfide grease to form a non-contact dynamic seal.

[0028] As a further aspect of the present invention: in S4, the walking wheel is made of antistatic rubber material with a volume resistivity of 10. 6 -10 8 Ω·cm, the metal conductive mesh embedded inside the walking wheel is a copper wire woven mesh with a mesh density ≥20 mesh and a copper wire diameter ≥0.1mm.

[0029] As a further aspect of the present invention: in S4, the leg transmission component is made of 20CrMnTi carburized and quenched alloy steel, with a carburized layer depth of 0.8-1.2mm, a surface hardness of HRC58-62, and a core hardness of HRC30-35.

[0030] The non-metallic components are made of antistatic and flame-retardant material with a surface resistance of 10. 6 -10 9 Ω.

[0031] As a further aspect of the present invention: in S5, the explosion-proof window encapsulation includes:

[0032] High-strength tempered borosilicate glass window, thickness ≥8mm, light transmittance ≥90%, stainless steel metal pressure ring is used to press the window and the shell together, and fluororubber sealing gaskets are set between the pressure ring and the shell and between the pressure ring and the window.

[0033] The intrinsically safe packaged gas sensor and temperature probe limit the energy to intrinsically safe parameters of Ui≤28V, Ii≤93mA, and Pi≤0.65W through a series current-limiting resistor and a parallel Zener diode.

[0034] As a further aspect of the present invention: in S6, the multi-parameter state monitoring system includes:

[0035] The voltage monitoring module monitors the power battery voltage and the voltage of each power supply line in real time.

[0036] The current monitoring module monitors the motor drive current and intrinsically safe circuit current in real time.

[0037] The temperature monitoring module monitors the surface temperature of the housing, the temperature of the motor windings, and the battery temperature in real time.

[0038] The deformation monitoring module uses strain gauge sensors to monitor the micro-deformation of the explosion-proof joint surface;

[0039] When any parameter exceeds the preset safety threshold, the system cuts off the main power supply via a solid-state relay, triggering a safety shutdown.

[0040] As a further aspect of the present invention, the quadruped robot formed by the design method possesses the following performance indicators:

[0041] Explosion-proof rating ExdIMb, protection rating IP66 / IP67, total weight ≤150kg, endurance ≥2h, movement speed ≥0.5m / s, obstacle crossing height ≥200mm, slope gradient ≥20°, explosion-proof joint gap ≤0.2mm, static pressure test pressure ≥1.5 times the reference pressure, grounding resistance ≤4Ω.

[0042] The present invention also provides a quadruped robot manufactured using the above method for use in Class I explosive environments in underground coal mines.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] This invention employs a distributed explosion-proof architecture consisting of a main explosion-proof chamber in the fuselage and independent explosion-proof units for the leg joints, achieving native explosion-proof design from the bottom layer of the entire machine. Compared to a single large-cavity design, this distributed architecture can reduce the shell wall thickness by 30%-40%, reduce the overall weight by 25%-35%, and improve leg movement flexibility.

[0045] This invention employs a dual-cavity physical isolation design, designing the power battery cavity and the intrinsically safe control cavity as explosion-proof and intrinsically safe respectively, thus completely separating the power circuit and control circuit and cutting off the cross-cavity propagation path of the ignition source. Compared to a hybrid design within the same cavity, this solution can reduce electromagnetic interference by more than 60dB and increase the fault isolation rate to 99.9%.

[0046] This invention employs a static cable routing scheme with a fixed central axis, ensuring that the cable does not contact rotating components during joint movement. After 20,000 hours of continuous operation testing, the cable insulation layer maintained 100% integrity, with no wear or failure observed.

[0047] This invention employs a triple-layered sealing system consisting of a V-shaped dustproof ring, a labyrinth seal, and a corrosion-resistant oil seal, combined with a double copper sleeve rotary seal, forming a multi-layered protection system. It has passed IP67 immersion tests (1m water depth, 30min) and dust tests (talc powder, 2kg / m³). 3 (8h), with no water or dust entering the cavity.

[0048] This invention utilizes an antistatic and flame-retardant material (surface resistance 10 ohms) 6 -10 9 The system consists of a four-level electrostatic protection system, which includes an anti-static rubber wheel, a metal conductive mesh, and a grounding terminal (grounding resistance ≤ 4Ω). This system can control the electrostatic potential of the entire machine surface to within 100V, which is lower than the electrostatic potential threshold corresponding to the minimum ignition energy of methane.

[0049] This invention employs a differentiated explosion-proof strategy that combines explosion-proof window packaging with intrinsically safe packaging, adapting to different sensing components such as lidar, vision cameras, gas sensors, and temperature probes. This ensures sensing accuracy while meeting explosion-proof requirements, and avoids the failure of overall certification due to non-explosion-proof components.

[0050] The multi-parameter status monitoring system of the present invention can monitor voltage, current, temperature and deformation in real time, and automatically cut off power protection when the parameters exceed the safety threshold. The response time is ≤10ms, which improves the fault response speed by two orders of magnitude and further enhances the intrinsic safety redundancy.

[0051] The design method proposed in this invention covers six dimensions: overall architecture, body cavity, leg joints, transmission system, sensing peripherals, and redundancy protection. It can guide the explosion-proof design of various quadruped robots in Class I explosive environments in coal mines. Attached Figure Description

[0052] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0053] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0054] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] The present invention will be further explained below with reference to specific embodiments.

[0056] Example 1:

[0057] Please see Figure 1 The present invention provides a native explosion-proof design method for a quadruped robot designed for Class I explosive environments in underground coal mines, comprising the following steps:

[0058] S1: Top-level design of the explosion-proof architecture for the entire machine

[0059] The aircraft adopts a distributed architecture consisting of a main explosion-proof fuselage chamber and independent explosion-proof units for the leg joints. The main explosion-proof fuselage chamber is a rectangular cast steel shell with external dimensions of 600mm × 400mm × 250mm, a wall thickness of 8mm, and an internal net volume of approximately 40L. The four legs are symmetrically distributed at the four corners of the fuselage. Each leg contains three active joints: the hip joint, the knee joint, and the ankle joint. Each joint is an independent cylindrical miniature explosion-proof chamber with an outer diameter of 80mm, a length of 120mm, a wall thickness of 6mm, and an internal net volume of approximately 0.4L.

[0060] The main explosion-proof chamber of the fuselage houses the power battery pack (7-cell lithium batteries, 25.2V, 20Ah), main controller, 5G communication module, and power management unit. Each leg contains three active joints, each of which is an independent miniature explosion-proof chamber. The main explosion-proof chamber of the fuselage is connected to the leg joints via explosion-proof flexible tubing. The flexible tubing is made of stainless steel braided mesh with a rubber lining, with an explosion-proof rating of Ex d I Mb and a bending radius ≥ 5 times the tubing diameter.

[0061] S2: Explosion-proof structure design for the main fuselage cavity

[0062] The shell is made of high-strength explosion-proof cast steel with a yield strength ≥240MPa, tensile strength ≥340MPa, and elongation ≥3%. The shell is manufactured using low-pressure casting and undergoes T6 heat treatment. The outer surface of the shell is coated with epoxy zinc-rich primer and polyurethane topcoat, achieving a corrosion resistance rating of C4. All explosion-proof mating surfaces (including front and rear end covers, top cover, and cable interfaces) are machined to a surface roughness Ra≤6.3μm, with a width of 28mm and a gap of 0.15mm for planar explosion-proof mating surfaces. After manufacturing, the shell undergoes a static pressure test at 1.5 times the reference pressure (1.5MPa), maintaining the pressure for 10 seconds without leakage or permanent deformation.

[0063] The internal design employs a dual-cavity physical separation layout: the left side houses the power battery cavity (explosion-proof type, Ex d), which contains a 7-cell lithium battery pack (25.2V, 20Ah), the BMS battery management system, and charging / discharging circuitry; the right side houses the intrinsically safe control cavity (intrinsically safe type, Exi), which contains the main controller, 5G communication module, IMU inertial measurement unit, and SLAM navigation algorithm processing unit. The two cavities are completely isolated by an integrated aluminum alloy partition (6mm thick), with three pre-drilled cable through-holes (6mm in diameter) filled with non-flammable epoxy resin sealant to cut off the cross-cavity propagation path of the ignition source, ensuring that the two types of circuits do not interfere with each other.

[0064] All seams in the casing are fitted with fluororubber gaskets (2mm thick, Shore A 70), and are evenly tightened with 24 M8 stainless steel explosion-proof bolts at a torque of 8 N·m to ensure uniform pressure distribution throughout the circumference. The cable entry end is equipped with an M20×1.5 explosion-proof gland (nickel-plated brass) and adopts a double compression sealing structure: the first layer is an NBR rubber sealing ring (compression 20%), and the second layer is a PTFE stuffing box (compression force 6 N·m) to prevent dust and water from entering the cavity along the cable seams.

[0065] S3: Leg-protected joint adaptation design

[0066] Each leg's hip, knee, and ankle joints feature an independent miniature explosion-proof cavity design. The cavity integrates a frameless torque motor (rated torque 8 N·m, peak torque 24 N·m), a 17-bit magnetic encoder, and a harmonic reducer (reduction ratio 100:1, backlash ≤1 arcmin). The cavity is made of cast steel, with an outer diameter of 80 mm, a length of 120 mm, a wall thickness of 6 mm, and a volume of approximately 0.4 L, meeting the volume limitations requirements for miniature explosion-proof enclosures in GB3836.2-2021.

[0067] The joints employ a static cabling scheme with a fixed central shaft: the central shaft is a hollow 304 stainless steel tube with an outer diameter of 25mm, a wall thickness of 3mm, and an internal hollow diameter of 19mm. One end of the central shaft is fixedly connected (welded) to the rear end cover of the joint housing, while the other end supports the output flange via a deep groove ball bearing but does not rotate with it. Power cable (3×1.0mm)2 The copper core multi-strand flexible cable (with an oil-resistant neoprene rubber sheath) and the encoder control signal line (shielded twisted pair, core diameter 0.15mm, 24AWG) pass through the inside of the central shaft, remaining in a static space throughout and not contacting any rotating parts. The inner wall of the central shaft is fitted with a polyimide insulating sheath (wall thickness 0.2mm, withstand voltage 500V).

[0068] The joint shaft extension end adopts a triple progressive sealing structure: the outermost is a V-shaped dustproof ring (fluororubber FKM, Shore A 75, wire diameter 3.5mm, inner diameter 30mm), used to block large dust particles and water spray; the middle is a labyrinth seal (gap 0.2mm, depth 8mm, 3 tortuous channels), used to block fine dust and water vapor; the innermost is a corrosion-resistant oil seal (double-lip fluororubber oil seal, TC type, 30×42×7mm, main lip contact pressure 0.18N / mm), used to seal lubricating oil and prevent external media from entering.

[0069] The rotating parts employ a double copper sleeve rotary seal: the outer copper sleeve (tin bronze ZCuSn10P1, outer diameter 42mm, inner diameter 35mm, length 15mm) is press-fitted into the joint housing end cap; the inner copper sleeve (tin bronze ZCuSn10P1, outer diameter 34.9mm, inner diameter 30mm, length 15mm) is press-fitted into the rotating output shaft. The radial clearance between the two copper sleeves is 0.08mm, filled with molybdenum disulfide high-temperature grease, forming a non-contact dynamic seal.

[0070] The internal control circuit of the joint strictly adheres to intrinsically safe energy limit requirements: the control voltage is 12V (converted from 24V power voltage through a DC-DC step-down module), and the maximum current is limited to within 100mA through a series current-limiting resistor (120Ω, 1W), ensuring that the electric spark energy is less than 0.1mJ under normal operation and any single fault condition, which is lower than the minimum ignition energy of methane of 0.28mJ.

[0071] S4: Explosion-proof optimization for mobile and transmission systems

[0072] The leg drive gear (module 1mm, number of teeth 20 / 60) is made of 20CrMnTi carburized and quenched alloy steel, with a carburized layer depth of 1.0mm, surface hardness HRC60, and core hardness HRC32. The gear is ground to a precision grade of 6 (GB / T 10095.1), with a tooth surface roughness Ra≤0.8μm.

[0073] The outer casing is made of flame-retardant nylon PA66 with added conductive carbon black, containing 15% carbon black and having a surface resistivity of 10. 7 Ω, flame retardant rating UL94 V-0. The cable sheath is made of conductive neoprene rubber with a volume resistivity of 10. 7 Ω·cm. The surface resistivity of all non-metallic parts is controlled within 10 Ω·cm.6 -10 9 Within the Ω range.

[0074] The design adopts a wheel-foot composite configuration: each leg is equipped with a walking wheel at its end, with a wheel diameter of 120mm, a wheel width of 40mm, and a tread made of antistatic rubber (volume resistivity 10). 7 (Ω·cm, Shore A hardness 65) to prevent static sparks from generated by friction between the wheel surface and the ground. The wheel body is internally fitted with a copper wire mesh as a conductive metal mesh (25 mesh size, 0.15mm diameter copper wire), and the copper mesh is connected to a conductive copper strip (4mm² cross-sectional area). 2 Connect to the fuselage grounding terminal.

[0075] The machine is equipped with 4 dedicated grounding terminals (nickel-plated brass, M8 thread, 16mm² cross-sectional area). 2 The grounding terminals are located at the four corners of the fuselage. The grounding terminals are connected via a 16mm... 2 The yellow-green bicolor grounding wire is connected to the underground grounding grid, and the actual measured grounding resistance is 2.8Ω (requirement ≤4Ω).

[0076] S5: Sensing and Explosion-proof Adaptation for Peripherals

[0077] All external sensing components must meet Class I explosion-proof requirements to avoid invalidating the explosion-proof certification of the entire device due to non-explosion-proof components in certain areas.

[0078] The lidar system employs an explosion-proof window enclosure: the window is made of high-strength tempered borosilicate glass, 100mm in diameter, 10mm thick, and has a light transmittance of 92%. The window is secured to the housing using a 304 stainless steel pressure ring (120mm outer diameter, 5mm thickness), which is uniformly tightened by eight M5 stainless steel screws with a torque of 4 N·m. Fluororubber O-ring gaskets (2.5mm wire diameter, 95mm inner diameter) are installed between the pressure ring and the housing, and between the pressure ring and the window.

[0079] The visual camera uses the same explosion-proof window packaging solution, with a window diameter of 60mm and a thickness of 8mm.

[0080] The gas sensor (catalytic combustion methane sensor) adopts an intrinsically safe package: the sensor probe is connected to the intrinsically safe circuit through a series current-limiting resistor (100Ω, 0.5W) and a parallel Zener diode (24V), which strictly limits the energy on the probe side within the intrinsically safe threshold. The measured parameters are Ui=12V, Ii=50mA, Pi=0.3W, which are lower than the intrinsically safe threshold (Ui≤28V, Ii≤93mA, Pi≤0.65W).

[0081] The temperature probe (PT100 platinum resistance thermometer) also uses an intrinsically safe package, is powered by a constant current source (1mA), and has a power consumption of less than 0.01W.

[0082] The 5G communication antenna adopts an intrinsically safe explosion-proof antenna, and the antenna shell is made of conductive PC / ABS alloy with a surface resistivity of 10. 7 Ω, antenna gain 5dBi, operating frequency band 3.5GHz.

[0083] S6: Redundancy Design

[0084] An integrated multi-parameter condition monitoring system includes:

[0085] (1) Voltage monitoring module: The INA219 current / voltage sensor is used to monitor the power battery voltage (accuracy ±0.1%, normal operating range 20-29.4V) and the power supply voltage of each circuit (12V intrinsically safe circuit, 5V control circuit, 24V motor drive circuit).

[0086] (2) Current monitoring module: The ACS712 Hall current sensor is used to monitor the motor drive current (range ±30A, accuracy ±1.5%, single leg peak ≤20A) and intrinsically safe circuit current (≤100mA).

[0087] (3) Temperature monitoring module: The DS18B20 digital temperature sensor is used to monitor the surface temperature of the housing (accuracy ±0.5°C, ≤80°C), the motor winding temperature (≤120°C) and the battery temperature (≤45°C).

[0088] (4) Deformation monitoring module: A BF350-3AA strain gauge sensor (sensitivity coefficient 2.0, grid length 3mm) is attached near the explosion-proof joint surface to monitor micro-deformation with a detection accuracy of ±1μm.

[0089] Safety threshold settings: Undervoltage or overvoltage protection is triggered when the power battery voltage is less than 18V or greater than 30V; overcurrent protection is triggered when the motor drive current is greater than 25A; overheat protection is triggered when the casing surface temperature is greater than 80°C; and structural abnormality protection is triggered when the deformation of the explosion-proof joint surface is greater than 50μm. When any parameter exceeds the threshold, the system cuts off the main power supply within 8ms via a solid-state relay and simultaneously uploads a fault code to the ground monitoring center via the 5G module, triggering a safe shutdown.

[0090] The performance indicators of the quadruped robot manufactured using the design method of this embodiment are as follows, based on testing:

[0091] Explosion-proof rating: Ex d I Mb;

[0092] Protection rating: IP67;

[0093] Total weight: 92kg;

[0094] Battery life: 3.5 hours (inspection mode);

[0095] Movement speed: 1.2 m / s (flat ground);

[0096] Obstacle clearance height: 250mm;

[0097] Gradient: 25°;

[0098] Explosion-proof mating surface gap: 0.15mm;

[0099] Length of explosion-proof mating surface: 28mm;

[0100] Static pressure test: 1.5MPa, holding pressure for 10s is qualified;

[0101] Grounding resistance: 2.8Ω;

[0102] Dynamic seal life: ≥20,000 hours;

[0103] Intrinsically safe circuit parameters: Ui=12V, Ii=50mA, Pi=0.3W.

[0104] Example 2:

[0105] The difference between this embodiment and Embodiment 1 is that:

[0106] (1) The shell material is selected from AISi10Mg(Fe) high-strength cast steel alloy with yield strength ≥260MPa, tensile strength ≥360MPa, elongation ≥5% after T6 heat treatment, and further weight reduction of 15%;

[0107] (2) The central shaft is made of hollow carbon fiber composite tube (T700 carbon fiber / epoxy resin), with an outer diameter of 30mm and a wall thickness of 4mm. Compared with stainless steel 304 tube, it reduces weight by 60% while maintaining sufficient torsional stiffness.

[0108] (3) The rotating parts are sealed with a three-copper sleeve structure (with an additional intermediate floating copper sleeve). The intermediate copper sleeve is pre-tightened by a spring to automatically compensate for wear gaps, and the sealing life is increased to ≥30,000 hours.

[0109] (4) The walking wheels adopt a magnetic quick-release structure. The wheel body and the legs are connected by magnetic coupling. Replacement can be completed within 30 seconds without tools, adapting to the rapid maintenance needs of complex underground terrain;

[0110] (5) The multi-parameter status monitoring system adds an AI edge computing module (NVIDIA Jetson Nano) to train an LSTM neural network model based on historical data to achieve fault prediction (accuracy rate ≥85% for early warning 30 minutes in advance).

[0111] Table 1 shows a comparison between the present invention and existing major technologies:

[0112] Table 1. Comparison of the present invention with existing major technologies

[0113]

[0114] In summary, the original explosion-proof design method proposed in this invention is superior to existing technologies in terms of explosion-proof safety, structural reliability, mobility, lightweighting, and electrostatic protection, and is especially suitable for Class I explosive environments in underground coal mines.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A native explosion-proof design method for a quadruped robot designed for Class I explosive environments in underground coal mines, characterized in that, Includes the following steps: S1. The distributed architecture of the main explosion-proof chamber of the fuselage and the independent explosion-proof unit of the leg joints is adopted, which decomposes the explosion-proof function of the whole machine into the explosion-proof layer of the main fuselage chamber and the independent explosion-proof layer of the leg joints. S2. The housing is made of explosion-proof material and has an explosion-proof joint surface. The interior adopts a dual-cavity physical separation layout. The power battery cavity is explosion-proof and the control intrinsically safe cavity is intrinsically safe. The two cavities are completely isolated by an integrated metal partition, with only a sealed cable passage reserved. All splicing gaps of the body are fitted with sealing gaskets and high-strength explosion-proof bolts. The cable entry end is equipped with an explosion-proof gland; S3. Each active joint adopts an independent miniature explosion-proof cavity. The joints use a fixed central shaft static wiring scheme to prevent the cables from contacting rotating parts and output ends. The joint shaft extension end adopts a multi-seal structure and is equipped with a double copper sleeve rotation seal. The miniature explosion-proof cavity is equipped with an end cap. S4. Explosion-proof optimization of the mobility and transmission system, which includes leg transmission components and wheels, adopts a wheel-foot composite configuration. The wheels are made of anti-static material and embedded with conductive mesh to release static electricity; non-metallic components are made of anti-static and flame-retardant material. S5. Explosion-proof adaptation for sensing and peripheral devices; sensing components are encapsulated with explosion-proof windows or intrinsically safe encapsulation. S6. An integrated multi-parameter status monitoring system automatically triggers power-off protection when a parameter exceeds a safety threshold.

2. The design method according to claim 1, characterized in that, In S1, in the distributed architecture of the main explosion-proof cavity of the fuselage and the independent explosion-proof unit of the leg joint, each leg contains three active joints, and each active joint is an independent miniature explosion-proof cavity, corresponding to the hip joint, knee joint and ankle joint respectively.

3. The design method according to claim 1, characterized in that, In S2, the explosion-proof material is high-strength explosion-proof cast steel with a yield strength ≥240MPa, tensile strength ≥340MPa, and elongation ≥3%. The explosion-proof mating surface is machined to a surface roughness Ra≤6.3μm, and the gap between the mating surfaces is controlled within 0.2mm; the explosion-proof mating surface is a planar explosion-proof structure, and the width of the mating surface is ≥25mm; The dual-cavity physical separation layout includes: The power battery compartment is used to house the lithium battery pack, battery management system (BMS), and charging / discharging circuits. The compartment is designed to be explosion-proof. The intrinsically safe control cavity is used to house the main controller, communication module, inertial measurement unit (IMU), and navigation algorithm processing unit. The cavity of the intrinsically safe control cavity is designed to be intrinsically safe and explosion-proof. The integrated metal partition is made of aluminum alloy with a thickness of ≥5mm. The diameter of the cable through holes reserved on the partition is ≤8mm, and the through holes are filled with non-flammable epoxy resin sealant.

4. The design method according to claim 1, characterized in that, In S3, the fixed central axis static routing scheme includes: The fixed central shaft is a hollow stainless steel tube with an outer diameter of 20-35mm and a wall thickness of 2-4mm. The fixed central shaft is fixedly connected to the miniature explosion-proof cavity and does not rotate with the output end. The power cable and control signal line pass through the inside of the fixed central shaft and are in a static space throughout the entire process. The inner wall of the fixed central shaft is provided with a polyimide insulating sleeve with an insulation withstand voltage ≥500V; The multi-seal structure is a triple progressive seal structure consisting of a V-shaped dust seal, a labyrinth seal, and a corrosion-resistant oil seal. The V-shaped dust seal is made of fluororubber FKM with a Shore A hardness of 75±5 and is installed on the outermost side of the shaft extension. The labyrinth seal has a gap width of 0.15-0.30mm and a depth of ≥5mm, and is provided with 2-4 tortuous channels. The corrosion-resistant oil seal is a double-lip fluororubber oil seal with a main lip contact pressure ≥0.15N / mm. The double copper sleeve rotary sealing structure includes: The outer copper sleeve, made of tin bronze ZCuSn10P1, is press-fitted into the end cap of the miniature explosion-proof cavity; The inner copper bushing is made of tin bronze ZCuSn10P1 and is press-fitted into the output end with an interference fit. A radial clearance fit is formed between the outer and inner copper sleeves, with a clearance of 0.05-0.15mm. The clearance is filled with high-temperature molybdenum disulfide grease to form a non-contact dynamic seal.

5. The design method according to claim 1, characterized in that, In S4, the walking wheels are made of antistatic rubber with a volume resistivity of 10. 6 -10 8 Ω·cm, the metal conductive mesh embedded inside the walking wheel is a copper wire woven mesh with a mesh density ≥20 mesh and a copper wire diameter ≥0.1mm.

6. The design method according to claim 1, characterized in that, In S4, the leg transmission component is made of 20CrMnTi carburized and quenched alloy steel, with a carburized layer depth of 0.8-1.2mm, a surface hardness of HRC58-62, and a core hardness of HRC30-35. The non-metallic components are made of antistatic and flame-retardant material with a surface resistance of 10. 6 -10 9 Ω.

7. The design method according to claim 1, characterized in that, In S5, the explosion-proof window encapsulation includes: High-strength tempered borosilicate glass window, thickness ≥8mm, light transmittance ≥90%, stainless steel metal pressure ring is used to press the window and the shell together, and fluororubber sealing gaskets are set between the pressure ring and the shell and between the pressure ring and the window. The intrinsically safe packaged gas sensor and temperature probe limit the energy to intrinsically safe parameters of Ui≤28V, Ii≤93mA, and Pi≤0.65W through a series current-limiting resistor and a parallel Zener diode.

8. The design method according to claim 1, characterized in that, In S6, the multi-parameter state monitoring system includes: The voltage monitoring module monitors the power battery voltage and the voltage of each power supply line in real time. The current monitoring module monitors the motor drive current and intrinsically safe circuit current in real time. The temperature monitoring module monitors the surface temperature of the housing, the temperature of the motor windings, and the battery temperature in real time. The deformation monitoring module uses strain gauge sensors to monitor the micro-deformation of the explosion-proof joint surface; When any parameter exceeds the preset safety threshold, the system cuts off the main power supply via a solid-state relay, triggering a safety shutdown.

9. The design method according to claim 1, characterized in that, The quadruped robot formed by the described design method has the following performance indicators: Explosion-proof rating ExdIMb, protection rating IP66 / IP67, total weight ≤150kg, endurance ≥2h, movement speed ≥0.5m / s, obstacle crossing height ≥200mm, slope gradient ≥20°, explosion-proof joint gap ≤0.2mm, static pressure test pressure ≥1.5 times the reference pressure, grounding resistance ≤4Ω.

10. A quadruped robot designed for Class I explosive environments in underground coal mines, manufactured using the method described in any one of claims 1 to 9.

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