Abstract: To ensure the safe operation of crawler cranes, a safety monitoring system is an important safety protection device. This paper introduces a safety monitoring system based on the C8051F040 microcontroller, which has functions of protection, alarm, real-time recording, and display of multiple operating parameters. It can improve the automation level, control precision, and operational safety of cranes.
Keywords : crawler crane, safety monitoring, microcontroller
The Research of Crawler Crane Safety Monitoring and Control System
Jia yunfang Bi youming Yang tiemei
(Taiyuan University of Science and Technology, Taiyuan, Shanxi)
Abstract: For making crawler crane to work safely, safety monitoring and control system
is an important safety protection device.The paper introduces a kind of safety monitoring and control system based on single chip microcomputer C8051F040.The system has the function
of protection,alarm,record and display work parameters.Using it can enhance automatic degree,control precision and operation safety of crane.
Key words: crawler crane, safety monitoring and control system, single-chip microcomputer
Due to the complex structure and diverse boom configurations of crawler cranes, accidents involving them can result in significant losses. Therefore, safety monitoring devices are an indispensable and crucial component for ensuring the safe operation of large crawler cranes. Crawler crane safety monitoring systems not only improve the safety performance of crawler cranes but also enhance their operational efficiency. This paper introduces a crawler crane safety monitoring system based on the C8051F040 microcontroller. This system implements conventional functions such as status detection, control, and overload alarms for crawler cranes, and features dot-matrix LCD Chinese and graphic display, as well as overload recording capabilities. Utilizing this system can improve the automation level, control precision, and operational safety of the crane.
1. System Composition and Main Functions
This force system mainly consists of a tension sensor, an angle sensor, and a measurement, data transmission, and processing system. Safety monitoring devices are often installed on the hoisting rope in front of the hook of a crawler crane to take force. However, installing the sensor in front of the hook not only affects the normal operation of the crane but also makes the crane susceptible to damage. This paper proposes taking force from the luffing rope of the crawler crane, which eliminates the influence of the above-mentioned factors and also solves the problem of the influence of the boom weight and angle on force taking when taking force from the luffing rope.
Based on the measured boom angle and current operating conditions, the working radius is calculated, and the current rated load is calculated using an interpolation algorithm. Simultaneously, the actual load is calculated by measuring the luffing force. When the actual load is less than the rated value for the corresponding operating condition, the LED alarm display shows white, indicating normal lifting operation. When the actual load exceeds 90% of the rated value for the corresponding operating condition, the system issues an alarm signal, and the alarm display shows yellow. When the actual load exceeds the rated value for the corresponding operating condition but is less than 110% of the rated value, the system issues an alarm signal, and the alarm display shows red. Simultaneously, the power supply for the lifting and increasing radius directions should be cut off, but the mechanism can still move in the lowering and decreasing radius directions. When the actual load exceeds 110% of the rated value for the corresponding operating condition, the system immediately cuts off the operating power. The LED display shows the working radius and load information. A real-time data recording chip records load values and overload information under abnormal conditions.
Figure 1 Hardware Composition
2 Hardware Circuit
The system hardware composition is shown in Figure 1, including sensors, C8051F040 microcontroller, keyboard input, reset circuit, clock circuit, data storage, alarm and braking circuit, LCD display, etc.
2.1 Data Acquisition Channel
The data acquisition channel uses tension and angle sensors. The tension sensor is the BROSA-0111, used in lifting equipment, cranes (mounted on ropes), conveyors, and general mechanical engineering; it is easy to install. The angle sensors are all BROSA-0802, absolute angle sensors used in hydraulic lifting platforms, excavators, loaders, and mobile cranes; they are also easy to install. The tension and angle sensors respectively acquire the luffing rope tension and boom elevation angle signals. Since both sensors output standard 4~20mA current signals, they can be converted into 0~2.5V voltage signals suitable for microcontrollers via an I/V conversion circuit. Finally, the voltage signals are sent to an A/D converter for conversion.
The C8051f040 microcontroller integrates an 8-channel 12-bit AD conversion module, which features fast conversion speed, high accuracy, and convenient reading. The signals from the tension sensor and angle sensor are fed into IN1 and IN2 respectively. After passing through the I/V conversion circuit, they are sent to AIN0.0 and AIN0.1 of the AD converter to convert the analog signals into corresponding digital signals for data processing.
The interface circuit between the tension sensor and the microcontroller in the system is a current-to-voltage conversion circuit. The designed current-to-voltage conversion circuit diagram is shown in Figure 2.
Let the resistance of W1 in the diagram be X, the input current be IN1, and the output voltage be AIN0.0, then:
Require:
Input current range: 4～20mA
Output voltage range: 0～2.5V
Substituting the values into the formula above as required, we can obtain the following expression:
The conversion circuit with IN2 as input and AIN0.1 as output is the same as the circuit described above. Here, we will only introduce one example.
2.2 Data Storage
In microcontroller applications, it is often necessary to save data so that it is not lost even after a power outage. This instrument needs to save the crane's operating parameters, sensor calibration coefficients, and recorded data when the crane is overloaded. Two data storage methods are used here.
2.2.1 FLASH Data Storage
The K9F5608U0A, a high-capacity, high-reliability non-volatile flash memory manufactured by SAM SUNG using CMOS floating gate technology and a non-memory architecture, was selected for this application. Its main features include the ability to modify stored data online and retain the modified data even when power is off. The on-chip controller, status register, and dedicated command set provided by this device allow for flexible application in various memory system circuits. Its 8-bit I/O ports facilitate the multiplexing of address, data, and commands, significantly reducing the pin count and allowing for future expansion of storage capacity without altering the system board design.
2.2.2 USB flash drive storage
Data is stored using a plug-and-play USB flash drive, which can be moved at any time, and the data can be read and modified via a PC. The microcontroller can read the crane load characteristic curve stored on the USB flash drive, and can also save overload data stored in FLASH memory to the USB flash drive. Furthermore, other functions can be expanded to include storing crane fault signals.
This system uses the CH375 dedicated USB controller chip from Nanjing Qinheng Company. The CH375 is a general-purpose USB bus interface chip that supports both USB-HOST and USB-SLAVE modes. In USB host mode, the CH375 supports various commonly used full-speed USB devices, allowing external microcontrollers to communicate with USB devices via the CH375 according to the corresponding USB protocols. The CH375 also includes built-in firmware with a dedicated communication protocol for handling mass storage devices, enabling external microcontrollers to directly read and write common USB storage devices (including USB hard drives, USB flash drives, and USB flash drives) in sector-based units.
Figure 2 Current/Voltage Conversion Circuit Diagram
2.3 Circuit Design of Real-Time Clock Module
This instrument has an overload data recording function for future crane fault analysis or maintenance. In addition to parameters related to crane operation, the overload data must also include the time of recording; therefore, this instrument should be able to provide time information such as year, month, day, hour, and minute.
The S-3530A serial real-time clock chip is a serial CMOS real-time clock chip that supports the I2C bus interface. It features accurate timing, extremely low power consumption, and simple connection with peripheral circuits. The integrated RAM inside the chip can store a certain amount of data and can be used to save the constants required by the system. It is easy to use and has high reliability.
2.4 Alarm and Display Circuit
When an overload occurs, the alarm circuit will promptly issue an alarm. The system's display section is required to display real-time graphical data of operating parameters such as boom length, boom elevation angle, working radius, actual lifting capacity, rated lifting capacity, and torque-to-mass percentage during normal operation. This means the display device must be able to display characters, Chinese characters, and graphics. The LCD monitor used is the Beijing Diwen Technology Co., Ltd. M600 LCD monitor, which features a large 640 × 480 dot matrix screen, supports mixed display of graphics and characters, and facilitates the design of a user-friendly interface.
3 Software Design
Software design is a crucial aspect of security monitoring and protection devices. Modular software design was implemented using the C programming language. The software functional modules are shown in Figure 3.
During program execution, the safety monitor first performs a self-test and initialization, then converts the analog signal to an analog signal (A/D converter) and displays the collected data on the LCD in real time. If the measured lifting torque is overloaded, the software will output an audible alarm, a visual alarm, or a forced shutdown signal based on the collected information. The software has the function of recording overload data. Overload data can be displayed by inputting it via the keyboard.
4. Conclusion
This safety monitoring device has undergone rigorous laboratory simulation testing and has demonstrated excellent performance, meeting design requirements. It can accurately reflect the lifting torque characteristics of the tracked crane and accurately control the lifting capacity and luffing range of the tracked crane. It plays a good protective role in the safe operation of the tracked crane, improves work efficiency, and effectively prevents accidents.
Figure 3 Software Functional Modules
References
[1] Pan Zhuojin. C8051F040/1/2/3/4/5/6/7 High-speed Mixed-Signal ISP FLASH Microcontroller Datasheet [Z]. Xinhualong Electronics Co., Ltd.
[2] CH375 Chinese Manual (Part 1) [Z]. Nanjing Qinheng Electronics Co., Ltd.
[3] Ling Liuyi. Serial Real-Time Clock Chip S-3530A and Its Application in 51 Microcontroller System [J]. Peripheral Electronic Components. 2004(10). 45-47
[4] Hu Wenshan, Zhou Hong, Wu Bangchun. Amplitude torque limiter for crawler cranes [J]. Lifting and Transport Machinery. 2004(12). 19-21
[5] Lü Zhongke, Zhang Yuanliang. Application of USB flash drive in crane safety monitoring device [J]. Lifting and Transport Machinery. 2008(12). 24-28
[6] Gao Jiyong. Development of safety alarm and protection device for truck crane using MCS-51 microcontroller [J]. Journal of Hebei Institute of Technology, 1995(1), 1-5
[7] Li Hua. Practical Interface Technology of MCS-51 Series Microcontrollers. Beijing University of Aeronautics and Astronautics Press, 1993.
About the author:
Jia Yunfang, female, born in November 1984, is a graduate student majoring in Control Theory and Control Engineering at Taiyuan University of Science and Technology.
Mobile phone: 13453142153
Email: [email protected]
Contact Information: P.O. Box 633, Taiyuan University of Science and Technology, No. 66 Wuliu Road, Wanbailin District, Taiyuan City. Contact Person: Jia Yunfang
Postal code: 030024
