CAN bus and DSP-based multi-function crane safety monitoring system

Abstract: A digital signal processor based on fieldbus technology ADSP2105 and multifunctional crane safety monitoring system. The system consists of minimum system nodes, such as intelligent nodes and master node module. Communication between modules using Controller Area Wind (CAN) to complete. The system has the friendly interface and protection function, high reliability, and have some self-diagnostic function.

Construction crane is one of the necessary equipment, a wide application in construction. However, potential risk factors crane more prone to fatal accidents. Bureau of Technical Supervision has specialized to develop and publish a "crane design" (GB3811-83), "Lifting the safety overload protection device technical specifications" (GB12602-90), "Crane Safety Regulations" (GB6067-85) and other standards, required to be equipped with various types of lifting machinery safety devices. Therefore, development of new multi-function crane safety monitoring and protection system is necessary. Based on this, at home and abroad in recent years has developed a number of crane safety devices, such as load limiters, torque limiter, lifting height meter, anti-collision devices, such as wind speed alarm. But they are single function, if you need a variety of protection, must be installed on multiple machines, so not only expensive, but also to the maintenance and use of inconvenienced. Crane urgent need for a multi-user functionality in one versatile security monitoring system, and that crane control functions with a strong ability to master self-diagnosis in order to reduce operation and maintenance of the labor intensity and to ensure the safety of cranes.

Crane users concerned about safety aspects relating to the working parameters are: the main hook and the hook of the crane load and vice lifting height, the main boom and jib (tower arm) and lift the lifting torque angle, work rate, wire rope condition, wind speed (force) the size of the process of lifting the vibration condition and under load array of various information (such as the luffing cylinder pressure, hydraulic system pressure, temperature, engine speed parameter, oil temperature) and so on. How do working conditions on these parameters tour collection, algorithm processing, and real-time output control, and tips are the key to this system.

CAN bus and DSP-based multi-function crane safety monitoring system

In recent years, field bus technology, digital signal processing technology continues to evolve and mature as well as a variety of new emergence of large-scale integrated devices, laid-based system to achieve the technical and material basis.

Fieldbus (Field Bus) standard and its technology is the focus of attention in the field of international control for industrial control, with the greatest advantage of fieldbus can save a lot of wiring. Maintenance and installation costs, the same time, field bus capable of delivering multiple process variables. Controller Area Network (Controller Area Network) field bus belonging to the scope, it is an effective support of distributed control (Distributed Controller) or real-time control (Real-time Controller) serial communication network, a German Bosch company in early 1980 to solve many modern vehicle control and test equipment for data exchange between the developed a serial data communication protocol is a communication rate up to 1Mbps of multi-master bus (Multiple Master Multiple Slave, the M3S). CAN bus communication interface with integrated physical layer CAN protocol and data link layer features to complete the framing of the communication data processing. It does this by encoding blocks of communications data to ensure that the number of network nodes within the dynamic, and to a different node to simultaneously receive the same data. Data length of up to 8 bytes, ensures real-time communication; and to provide appropriate testing protocol using CRC error handling feature, ensure reliability of data communication. The system uses CAN bus for more than features to address many modules (nodes) between the communications.

The emergence of digital signal processor digital signal processing made a revolutionary change. It uses a Harvard bus architecture, data bus and the bus separation procedures, which can be read and the data operation instruction, instruction is basically a machine cycle in the implementation of on-chip hardware multiplier loaded with the multiplier and accumulator to connect the bus line, to continuous high-speed multiplication and accumulation operations. Its computing power so strong, suitable for a large number of high-speed signal processing, since inception, in a short period of time less than 20 years, then the rapid development, has been very widely used. To Texas Instruments Inc. TMS series, for example, has grown to the current fifth generation.

A system architecture diagram

Basic components of the system shown in Figure 1. System consists of a master node (central processing unit), an intelligent node and eight minimum system nodes. Minimum System includes tension sensor node node 1 (Vice hook), the angle sensor node 2 (jib), tension sensor node 3 (main hook), the angle sensor node 4 (main arm), the wind sensor nodes 5, 6 anti-collision sensor nodes a high degree of sensor node 7 (main hook), a high degree of sensor node 8 (Vice hook), etc., all nodes are responsible for collecting different pastor signal, and for A / D conversion (individual node is not carried out A / D conversion, such as high node incremental optical encoder disk can be directly obtained digital signal), then by field bus communication with the master node. The modules, the maximum bus length not more than 130 meters, the bit rate set at 500kbps, bus timing is: BTR0, 01H; BTR1, 1CH.

1.1 the master node (central processing unit)

System master node structure diagram shown in Figure 2. CPU manufactured by Analog Devices of ADSP2105. It is a high cost performance, performance DSP devices mature in a 100ns cycle, complete the following: take two operands, modified point operand address unit to multiply the two operands and the results accumulate to a 40-bit and the. As the program within the hardware loop, so every time 100ns to implement the operation of these advanced directives. WSI's PSD311 programmable peripheral device effectively programmable logic, I / O ports and memory integrated on a single chip, can achieve peripheral functions of the system. ADSP2105 in contact with the PSD311 and other peripheral devices provide great flexibility in timing. It can be four separate memory space allocated for each individual the number of wait states to accommodate the wide differences in the timing. We ADSP2105 the "waiting register" for the EPROM, RAM and external memory strobe pulse arrange a wait state, that is, 200ns cycle time, to meet the PSD311 120ns the device's timing requirements. As the bus access in ADSP2105 cloth inside, PSD311 data lines connected with the D15 ~ D8. ADSP2105's "D22" line offers PSD311 the "A14" address line, / BMS (Boot Memory Select) as EPROM's chip select, and with the PSD311's "A19" input connected.
Chosen as the CAN controller SJA1000, CAN controller interface driver chip using PCA82C250. EEPROM for data RAM, set the input used to save critical data in case when power is lost.

1.2 Intelligent Node

Schematic of Intelligent Systems node in Figure 3. Philips's high-performance 80C592 chip 8-bit microcontrollers, is available and the CAN controller 80C522 PCA82C200 combination of features, and has 8 analog input channels of 10-bit A / D converter and two of 15 priority interrupt sources. PSD311 for the external ROM, RAM and decoding chips. 80C52 ADC will use onboard sensors collected off various analog / digital signal into a digital signal (analog signal only), sent to the system components via CAN master node; and receive the master node to the output signal, control and get off various relays and a variety of solenoid valves.

1.3 Minimum System node

Minimum system nodes using the standard connection method ISO/DIS11898 shown in Figure 4. P82C150 is the bit rate with automatic detection and correction, including CAN protocol controller chip 16-bit I / O devices. It's 16 I / O port line direction, digital and analogue programming options available. Comes with 6 analog input channels include 10-bit A / D converter with 0.1% accuracy, complete accuracy can meet the system requirements.

CAN bus and DSP-based multi-function crane safety monitoring system

2 System functions and features

System in real time on the sensor signals from various quarters sampling tour, after the corresponding calculated the actual condition of the crane operation parameters and parameter comparison with the standard of work, when the limit value of 90% to reach pre-alarm, alarm when more than 100% and mandatory stop control. At this time the direction of crane movement can not continue to risk, such as lying on pole, outriggers, from upgrades. System also provides a friendly interface, users can easily accomplish a specific parameter setting and commissioning work, calibration and other auxiliary functions, display screen and voice prompts according to real-time understanding of the relevant operation parameters in order to make appropriate and timely action.

System is characterized by the largest machine can get up to dynamically add or delete specific nodes (CAN control module). High-performance DSP and peripheral devices PSD to ensure the system flexibility, robustness and scalability.

Integrated crane safety crane safety monitoring system is the future trend monitoring system, which will gradually replace the single-function security devices, such as load limiters, torque limiter, lifting height meter, anti-collision devices, speed alarm, etc. as mainstream products.