Trolley control system integrating functions of tracking, fire searching and extinguishing and obstacle avoidance

Abstract

The invention discloses a trolley control system integrating functions of tracking, fire searching and extinguishing and obstacle avoidance. Belongs to the technical field of vehicle control systems and comprises a chip module, four tracking modules, four obstacle avoidance modules, five flame sensing modules, a power circuit, an L298N driving module, a steering engine module, an L9110 driving module, a motor 1 and a motor 2 which are connected with one another. The invention discloses a tracking trolley control system with a single-chip microcomputer as a core. The system is a control system for realizing the capability of self-handling various emergencies in a specified range of the intelligent trolley. The system has the characteristics of high flexibility, labor cost saving, safety, reliability, energy conservation, environmental protection, strong expandability, easy maintenance, high precision and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle control systems and relates to a vehicle control system that integrates tracking, fire-finding and obstacle avoidance functions; specifically, it relates to a control system for an intelligent vehicle that can track in a specified area while meeting the requirements of obstacle avoidance, fire-finding and fire-fighting, and can be used in dangerous areas such as small fires. Background Art

[0002] At present, as a highly anticipated research focus of intelligent vehicles, the core function of the tracking car is to achieve autonomous navigation according to the preset path, which is indispensable for building an intelligent transportation system. At the same time, it also occupies a key research position in the field of industrial robots; the application of tracking cars can improve work efficiency, reduce labor costs, and realize automated, intelligent and efficient transportation and management. In addition, the intelligent car has the ability to autonomously track according to the preset path, which is suitable for a variety of complex situations, such as emergency rescue missions after disasters such as earthquakes and floods, as well as detection and cleanup operations in high-risk environments such as nuclear radiation or chemical pollution.

[0003] However, most of the current control systems for tracking vehicles are single-function. Some tracking vehicles only have the tracking function, while others have the tracking and obstacle avoidance functions. However, in some special occasions, in addition to tracking, fire finding and extinguishing functions are also required. Therefore, it is necessary to design a vehicle control system that integrates tracking, fire finding and extinguishing, and obstacle avoidance. The obstacle avoidance function is introduced on the basis of tracking, and at the same time, the function of detecting fire sources and extinguishing fires is carried out during the tracking process. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to propose a trolley control system integrating tracking, fire finding and extinguishing, and obstacle avoidance.

[0005] The technical solution of the present invention is: the vehicle control system integrating tracking, fire-finding and obstacle avoidance functions of the present invention comprises an interconnected chip module, a four-way tracking module, four obstacle avoidance modules, a five-way flame sensor module, a power supply circuit, an L298N drive module, a steering gear module, an L9110 drive module, a motor 1 and a motor 2;

[0006] Wherein, the power supply circuit includes a 5V DC power supply and a 12V DC power supply;

[0007] The four-way tracking modules, four obstacle avoidance modules, five-way flame sensor modules and one end of the 5V DC power supply are respectively connected to the input end of the chip module through wireless signals, and the output end of the chip module is respectively connected to the input end of the L298N drive module, the servo module and the L9110 drive module through wireless signals.

[0008] Furthermore, the input end of the 12V DC power supply is connected to the L298N driving module via a wireless signal, and the output end of the L298N driving module is connected to the motor 1 via a wireless signal;

[0009] The output end of the L9110 driving module is connected to the motor 2 via a wireless signal.

[0010] Furthermore, the chip module adopts a single-chip microcomputer of the STC89C52RC model, which is a single-chip microcomputer chip based on the 8051 architecture and is composed of an interconnected CPU core, memory, clock and timer, serial port and interrupt system.

[0011] Furthermore, the four-way tracking module includes four-way infrared tracking sensor circuits, which are composed of LM339 chips, transmitters, receivers and other basic circuits; it adopts a dual-in-line 14-pin plastic package structure, and has four independent voltage comparators installed inside, and shares a set of power supplies;

[0012] The four obstacle avoidance modules use TCRT5000 reflective photoelectric switch sensors, which consist of an infrared transmitter and a phototransistor with a 3.5mm pin package;

[0013] The five-way flame sensing module includes a five-way flame sensor, which contains an infrared receiving tube. The infrared receiving tube has a PN junction with infrared light sensitive characteristics, which is a photosensitive diode and can detect short-wave near-infrared rays emitted by flames in the range of 700-1100nm.

[0014] Further, the five-way flame sensor has two working modes, the first of which can output digital signals, namely: high and low levels;

[0015] The second type can output analog signals, that is, voltage signals.

[0016] Furthermore, the power supply circuit adopts a three-stage linear voltage regulator circuit of the power conversion chip LM1117MP.

[0017] Furthermore, the servo module adopts an SG90 servo, and includes a DC motor, a reduction device and a position feedback system inside the servo module;

[0018] The L9110 drive module is a fire extinguishing drive circuit, which is a dual-channel DC motor drive chip used to control the rotation direction and speed of the DC motor;

[0019] The L298N driver module is a full-bridge driver L298N module. This component adopts the internal analog quantity conversion standard and is a driver module that converts digital signals into analog signal outputs.

[0020] Furthermore, the system is also equipped with a 78M05 voltage regulator chip, which is a linear voltage regulator; it is used to adjust the input voltage to an output voltage of 5V and maintain stability when the input voltage changes or the load changes.

[0021] Furthermore, the system is also connected to an alarm system, which includes a buzzer, a 1K resistor and a PNP transistor.

[0022] Furthermore, the operation method of the trolley control system integrating tracking, fire finding and extinguishing, and obstacle avoidance functions is characterized in that the operation steps are as follows:

[0023] Step (1): After each module and MCU of the system are powered, the MCU and the connected sensors will be initialized;

[0024] Step (2): After the initialization process is completed, the steering engine module and the four-way tracking module begin to detect the black line on the road surface;

[0025] Step (3): When the navigation mark is detected, the system activates the tracking subroutine and the car moves along the predetermined path;

[0026] Step (4): As the car moves, if the four obstacle avoidance modules detect an obstacle, the system will switch to the obstacle avoidance subroutine. At this time, the tracking subroutine is paused to ensure that the car can identify the obstacle.

[0027] Step (5): If the five-way flame sensor module detects a fire during the tracking mission, the fire extinguishing subroutine will be activated and the tracking operation of the vehicle will be interrupted to focus on the fire extinguishing operation.

[0028] The beneficial effects of the present invention are: 1. High flexibility: the intelligent tracking car can work in various environments and has strong adaptability; 2. Save labor costs: the intelligent tracking car can replace manual firefighting work, improve work efficiency and reduce labor costs; 3. Safe and reliable: the intelligent tracking car has safety protection functions, such as obstacle avoidance, emergency stop, etc., to ensure that no harm is caused to personnel and equipment when performing related tasks; 4. Energy saving and environmental protection: the intelligent tracking car is usually battery-powered, has no exhaust emissions, and is environmentally friendly; 5. Strong scalability: the intelligent tracking car can be equipped with different equipment as needed, such as cameras, robotic arms, etc., to achieve multiple functions; 6. Easy maintenance: the intelligent tracking car has a simple structure and easy maintenance, which reduces maintenance costs; 7. High precision: through advanced sensors and control systems, the intelligent tracking car can accurately travel along the predetermined path to reduce errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1It is the overall system block diagram of the intelligent car of the present invention;

[0030] Figure 2 It is the plan layout diagram of the STC89C52RC chip in the present invention;

[0031] Figure 3 is a plan view of the power module of the present invention;

[0032] Figure 4 It is a planar layout diagram of the driving power supply in the present invention;

[0033] Figure 5 It is the main flow chart of the present invention. DETAILED DESCRIPTION

[0034] The specific technical solutions of the present invention are further described in detail below in conjunction with specific examples.

[0035] As shown in the figure, the present invention discloses a tracking car control system with a single chip microcomputer as the core. The purpose of the system is to realize a control system that enables the intelligent car to self-process various emergencies within a specified range;

[0036] Specifically, the vehicle control system integrating tracking, fire-finding and obstacle avoidance functions includes interconnected chip modules, four tracking modules, four obstacle avoidance modules, five flame sensor modules, power supply circuit, L298N drive module, steering gear module, L9110 drive module, motor 1 and motor 2;

[0037] Wherein, the power supply circuit includes a 5V DC power supply and a 12V DC power supply;

[0038] The four-way tracking module, the four obstacle avoidance modules, the five-way flame sensor module and one end of the 5V DC power supply are respectively connected to the input end of the chip module through wireless signals, and the output end of the chip module is respectively connected to the input end of the L298N drive module, the steering gear module and the L9110 drive module through wireless signals;

[0039] The input end of the 12V DC power supply is connected to the L298N driving module via a wireless signal, and the output end of the L298N driving module is connected to the motor 1 via a wireless signal;

[0040] The output end of the L9110 driving module is connected to the motor 2 via a wireless signal.

[0041] Furthermore, the STC89C52RC single-chip microcomputer is used as the core of the car control system to complete the careful construction of the hardware circuit and the detailed planning of the software system; the L298N chip effectively drives the dual-channel DC motor to realize the forward and reverse control of the motor; the four-channel infrared reflection sensor is used as the vehicle's tracking system to track the path by identifying the black guide line on the white road surface; the infrared double-tube obstacle avoidance sensor module ensures the system's obstacle avoidance response capability; and the integration of five-channel flame detection sensor, L9110 motor driver and SG90 servo is specially designed for performing precise fire source positioning and fire extinguishing tasks; the software architecture covers the main program and the subroutine design of each specific function; its circuit structure is concise and clear, and has the characteristics of easy implementation.

[0042] Furthermore, the design of the intelligent car includes chip design (chip module), power module design (5V DC power supply and 12V DC power supply), four-way infrared tracking sensor design (four-way tracking module), infrared obstacle avoidance module design (four obstacle avoidance modules), five-way flame sensor design (five-way flame sensor module), SG90 steering gear design (steering gear module), L298N drive module design (L298N drive module), L9110 fire extinguishing device design (L9110 drive module) and alarm system design, such as Figure 1 As shown;

[0043] Further, the chip design (chip module): This system is a multifunctional tracking car control system design based on a single-chip microcomputer. When the car completes various functions in a specified environment, various sensors and single-chip microcomputers need to cooperate with each other; the single-chip microcomputer model STC89C52RC is used, such as Figure 2 As shown in the figure, STC89C52RC is a single-chip microcomputer chip based on 8051 architecture. It is mainly composed of CPU core, memory, clock and timer, serial port, interrupt system, etc. It has the advantages of low power consumption, fast response speed, high performance, and high reliability of peripheral interface. It is widely used in temperature control, electronic products, smart home and other fields.

[0044] Further, the power module design (5V DC power supply and 12V DC power supply): In order to build a complete embedded system, a power supply circuit is designed to ensure continuous and stable power supply of the system; the power supply circuit of this system uses the power conversion chip LM1117MP three-stage linear voltage regulator circuit to provide the working voltage for the microcontroller, such as Figure 3 shown.

[0045] Further, the L298N driver module design (L298N driver module): In order for the L298N chip to work properly, a stable voltage is required; the car drive circuit power supply module, such as Figure 4 shown.

[0046] Furthermore, this system uses the 78M05 voltage regulator chip, which is a linear voltage regulator; it is often used to adjust the input voltage to an output voltage of 5V, and it can remain stable when the input voltage changes or the load changes; using 78M05 can simplify circuit design. The chip has functions such as overheat protection and short circuit protection, which can protect the circuit from damage, and has a low cost, which meets the needs.

[0047] Further, the four-way infrared tracking sensor design (four-way tracking module): the four-way infrared tracking sensor circuit in this system is composed of an LM339 chip, a transmitter, a receiver and other basic circuits; the LM339 chip integrated circuit adopts a dual-in-line 14-pin plastic package structure, and is equipped with four independent voltage comparators, sharing a set of power supplies, and LM339 has excellent performance, flexible use, wide application, low interference, easy assembly, easy use, high precision, strong stability and other characteristics;

[0048] This system uses a four-channel infrared tracking sensor circuit. A two-channel tracking circuit can only complete simple tracking on straight lines and curves. Compared with a two-channel tracking circuit, a four-channel infrared tracking sensor has more advantages. The four-channel tracking can realize the car's driving on right angles, acute angles, curves and other routes with high accuracy. It can achieve more complete detection during tracking and better meet the needs in real life.

[0049] Furthermore, the infrared obstacle avoidance module design (four obstacle avoidance modules): the most commonly used sensors currently include TCRT5000 reflective photoelectric switch sensor, laser obstacle avoidance sensor, infrared array sensor and other sensors; this system uses TCRT5000 reflective photoelectric switch sensor, which consists of an infrared emitter and a 3.5mm pin packaged phototransistor; at this level, this system uses infrared pairs of tubes instead of phototransistors.

[0050] Furthermore, the five-way flame sensor design (five-way flame sensor module): the flame sensor is mainly based on the sensitivity of infrared rays to flames, and contains an infrared receiving tube inside. The infrared receiving tube has a PN junction with infrared light sensitive characteristics inside, which belongs to a photosensitive diode and can detect short-wave near-infrared rays (SW-NIR) with a wavelength range of 700-1100nm emitted by flames; through comparison of multiple schemes, the five-way flame sensor adopted in this system has two working modes; the first one can output digital signals (high and low levels); the second one can output analog signals (voltage signals), which can measure signals more accurately and is suitable for high-precision occasions; the flame sensor has high detection accuracy and reliability, can monitor multiple directions or multiple fire sources at the same time, and improve the accuracy and timeliness of fire warning; and the flame sensor can also reduce false alarms by comparing data from different channels, thereby improving the stability of the system.

[0051] Further, the SG90 servo design (servo module): This system uses the SG90 servo; the servo can accurately control the angle; the servo contains a DC motor, a set of reduction gear and a position feedback system; this feedback system enables the servo to accurately know its current position and rotate to the desired position according to the control signal;

[0052] The SG90 servo has the following advantages: small size, light weight, large torque, low noise, and low power consumption; it has a set of precision reduction gearbox device inside, which rotates very smoothly and has low noise when working; the motor is energy-saving and can greatly save electricity consumption when working.

[0053] Furthermore, the car driving circuit design (L298N driving module design (L298N driving module): The movement of the car in this system adopts the full-bridge driver L298N module; this component adopts the internal analog quantity conversion standard, and is a driving module that converts digital signals into analog signal output; this module has the characteristics of strong ability, low heat generation, and strong anti-interference ability; making the driving module more stable during operation.

[0054] Furthermore, the fire extinguishing drive circuit design (L9110 drive module): In order to realize the fire extinguishing function in this system, it is necessary to drive the DC motor and other devices to realize the fire extinguishing; currently there are mainly motor drive modules such as L293D, TB6612FNG, DRV8825, etc.; this system adopts L9110H bridge drive module (L9110 drive module); it is a dual-channel DC motor drive chip, which is used to control the rotation direction and speed of the DC motor, but it cannot perform PWM adjustment by itself, and can perform speed regulation function through the input of other microprocessor signals; it has internal over-current protection and over-temperature protection functions, which can effectively protect the chip from damage caused by excessive motor load or excessive working environment temperature.

[0055] Furthermore, the alarm system; this system uses a buzzer, a 1K resistor, and a PNP transistor to form a basic buzzer alarm circuit; the resistor is used to limit the base current of the transistor to ensure that it is within the appropriate working range. At this time, the transistor acts as a switch in the circuit. When the microcontroller outputs a low level, the transistor is turned on, allowing current to flow through the buzzer, and the buzzer vibrates and makes a sound to realize the alarm function.

[0056] Further, software design:

[0057] Keil5 (KeilμVision 5) is an embedded software development tool; it provides an integrated development environment (IDE) including components such as compilers, debuggers, and emulators, which can be used to develop various embedded systems based on the ARM architecture.

[0058] This platform is a feature-rich, easy-to-use embedded system development tool suitable for the development and debugging of various ARM microcontroller application programs. This design uses this software platform for program development.

[0059] The main flow chart is designed as follows Figure 5 As shown: The main control system is the control processing center of the entire system information and the controlled equipment. It exchanges information with the main control equipment through the collection of controlled equipment information to realize related functions; the main program flow chart is as follows Figure 5 shown.

[0060] exist Figure 5 In the process, after each module and microcontroller of the system are powered, the microcontroller and the connected sensors will be initialized; after the initialization process is completed, the servo returns to its position and the tracking sensor begins to detect the black line on the road; once these navigation marks are detected, the system activates the tracking subroutine and the car will travel along the predetermined path; as the car moves, if the obstacle avoidance sensor system detects an obstacle, the system will immediately switch to the obstacle avoidance subroutine. At this time, the tracking subroutine will be paused to ensure that the car can quickly identify the obstacle; in addition, if the flame detection module detects a fire during the tracking task, the fire extinguishing subroutine will be immediately activated, and the tracking operation of the car will be interrupted to focus on the fire extinguishing action; the above process ensures that the system responds quickly and intelligently, giving priority to emergency situations, ensuring the safety of the car and the effective execution of the task.

[0061] In the system design process, in order to meet the needs of actual applications, the following key aspects need to be paid attention to:

[0062] (1): Strive to reduce the cost of the system; when designing this system, multiple solutions are compared to select devices with better performance and lower cost;

[0063] (2): This system adopts a modular design approach; modular design makes development, maintenance and upgrades more convenient, while ensuring the stable operation of the system;

[0064] (3): On-site wiring. When the system is designed, wiring and placement of various obstacles are carried out, and the intelligent tracking car is debugged.

[0065] Embodiment 1:

[0066] First, test the four-way tracking module. The sensor mainly consists of two parts: the main control board circuit and the infrared tube board. One end of the main control board is connected to the I / O port of the microcontroller STC89C52RC and the extended VCC and GND, and the other end is connected to the infrared tube board. Fix the position of the board to ensure that all the wires are correctly connected without short circuit or poor contact. Power on the microcontroller and the sensor module, adjust the detection distance of one of the probes clockwise to the maximum, and the indicator light will be on. Put the probe on a piece of white paper with a black line, and face the probe to the black line. The indicator light is still on. Adjust the potentiometer counterclockwise until the indicator light goes out, indicating that the probe is successfully adjusted. Other probes are debugged in the same way. After the debugging of the four-way sensor is completed, power on the L298 driver module and the tracking sensor, set the specified runway, and test the tracking function by straight lines and right-angle turns.

[0067] Embodiment 2:

[0068] Infrared obstacle avoidance module test, when installing and debugging the sensor, first ensure that the infrared sensor is installed in the predetermined position; after confirming that the circuit connection is correct and there are no potential problems such as short circuit, power on the sensor, at this time, the sensor's power indicator light will light up; select one of the sensors for debugging and analysis, and the debugging method of the other three sensors is the same; within the effective distance, first rotate the potentiometer counterclockwise to the minimum value, and the sensor's sensitivity is at the lowest state; gradually adjust the potentiometer clockwise to increase the sensitivity of the sensor until the sensor can detect obstacles; in this process, once the sensor detects an obstacle, its status indicator light will light up, and the buzzer will sound, indicating that the sensor has successfully detected the obstacle. When the obstacle is eliminated, the car continues to perform related work; four obstacle avoidance sensors are used, the main purpose of which is to increase the safety of the car and improve the accuracy of obstacle detection; the obstacle avoidance function of the present invention is realized by completing the obstacle avoidance operation on the basis of tracking.

[0069] Embodiment three:

[0070] Fire-finding and fire-extinguishing test, the fire-finding and fire-extinguishing system is mainly composed of five-way flame sensors, L9110 drive device and SG90 servo device; connect the I / O port, VCC, and GND of the five-way flame sensors, L9110 drive device and SG90 servo device to the I / O port of the microcontroller and the external VCC and GND respectively; fix the position of each module to ensure that there is no short circuit in each module; power on each module and the power indicator light is normally on; control the detection distance by adjusting the potentiometer of the flame sensor. When D1 of the flame sensor detects a flame, the servo rotates 45 degrees counterclockwise and turns on the L9110 drive device to extinguish the fire; when one of D2, D3, and D4 of the flame sensor detects a flame, the servo does not move and turns on the L9110 drive device to extinguish the fire; when D5 of the flame sensor detects a flame, it rotates 45 degrees clockwise and turns on the L9110 drive device to extinguish the fire.

Claims

1. A trolley control system integrating tracking, fire finding and extinguishing, and obstacle avoidance functions, characterized in that: It includes interconnected chip modules, four-way tracking modules, four obstacle avoidance modules, five-way flame sensor modules, power supply circuit, L298N driver module, steering gear module, L9110 driver module, motor 1 and motor 2; Wherein, the power supply circuit includes a 5V DC power supply and a 12V DC power supply; The four-way tracking modules, four obstacle avoidance modules, five-way flame sensor modules and one end of the 5V DC power supply are respectively connected to the input end of the chip module through wireless signals, and the output end of the chip module is respectively connected to the input end of the L298N drive module, the servo module and the L9110 drive module through wireless signals.

2. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The input end of the 12V DC power supply is connected to the L298N driving module via a wireless signal, and the output end of the L298N driving module is connected to the motor 1 via a wireless signal; The output end of the L9110 driving module is connected to the motor 2 via a wireless signal.

3. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The chip module adopts a single-chip microcomputer of the STC89C52RC model, which is a single-chip microcomputer chip based on the 8051 architecture and is composed of an interconnected CPU core, memory, clock and timer, serial port and interrupt system.

4. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The four-way tracking module includes four-way infrared tracking sensor circuits, which are composed of LM339 chips, transmitters, receivers and other basic circuits; it adopts a dual-in-line 14-pin plastic package structure, and has four independent voltage comparators installed inside, and shares a set of power supplies; The four obstacle avoidance modules use TCRT5000 reflective photoelectric switch sensors, which consist of an infrared transmitter and a phototransistor with a 3.5mm pin package; The five-way flame sensing module includes a five-way flame sensor, which contains an infrared receiving tube. The infrared receiving tube has a PN junction with infrared light sensitive characteristics, which is a photosensitive diode and can detect short-wave near-infrared rays emitted by flames in the range of 700-1100nm.

5. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 4 is characterized in that: The five-way flame sensor has two working modes. The first mode can output digital signals, namely: high and low levels; The second type can output analog signals, that is, voltage signals.

6. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The power supply circuit adopts a power conversion chip LM1117MP three-stage linear voltage stabilization circuit.

7. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The servo module adopts an SG90 servo, which contains a DC motor, a reduction device and a position feedback system; The L9110 driver module is a fire extinguishing driver circuit, which is a dual-channel DC motor driver chip used to control the rotation direction and speed of the DC motor; The L298N driver module is a full-bridge driver L298N module. This component adopts the internal analog quantity conversion standard and is a driver module that converts digital signals into analog signal outputs.

8. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The system is also equipped with a 78M05 voltage regulator chip, which is a linear voltage regulator; it is used to adjust the input voltage to an output voltage of 5V and keep it stable when the input voltage changes or the load changes.

9. The vehicle control system integrating tracking, fire finding and extinguishing and obstacle avoidance functions according to claim 1 is characterized in that: The system is also connected to an alarm system, which includes a buzzer, a 1K resistor and a PNP transistor.

10. The method for operating a trolley control system integrating tracking, fire finding and extinguishing, and obstacle avoidance functions as described in any one of claims 1 to 9, characterized in that: The operation steps are as follows: Step (1): After each module and MCU of the system are powered, the MCU and the connected sensors will be initialized; Step (2): After the initialization process is completed, the steering engine module and the four-way tracking module begin to detect the black line on the road surface; Step (3): When the navigation mark is detected, the system activates the tracking subroutine and the car moves along the predetermined path; Step (4): As the car moves, if the four obstacle avoidance modules detect an obstacle, the system will switch to the obstacle avoidance subroutine. At this time, the tracking subroutine is paused to ensure that the car can identify the obstacle. Step (5): If the five-way flame sensor module detects a fire during the tracking mission, the fire extinguishing subroutine will be activated and the tracking operation of the vehicle will be interrupted to focus on the fire extinguishing operation.

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