CN102564106A - Wood drying remote monitoring system based on DSP (digital signal processor) - Google Patents

Abstract

The invention discloses a wood drying remote monitoring system based on a DSP (digital signal processor), which relates to a wood drying remote monitoring system and solves problems of low drying efficiency and complication in operation of an existing wood drying remote monitoring system. The wood drying remote monitoring system comprises a remote server, a monitoring host and a field controller. The monitoring host and the field controller are in data transmission by a serial bus, the monitoring host and the remote server are in data transmission via an Internet according to the TCP (transmission control protocol), and the field controller can run independently, can also receive various commands from the remote server and the monitoring host via a network bus and the serial bus and feeds data back to the monitoring host after the commands are executed. The wood drying remote monitoring system is applicable to automatic wood drying places with middle and large-size drying kilns.

Description

DSP-based Wood Drying Remote Monitoring System

technical field

The invention relates to a remote monitoring system for wood drying based on DSP, which belongs to the field of monitoring.

Background technique

At present, the wood drying process has gradually developed and matured. Computers have been widely used in my country's wood drying industry. Wood drying has been developed from manual control by operators to computer-based automatic control. However, there is still a certain gap between the automation degree of domestic wood drying equipment and foreign countries. It is mainly manifested in:

1. Relying heavily on the experience and professional knowledge of operators: although some wood drying enterprises have realized semi-automatic and fully automatic control, however, operators, especially technicians, are required to have certain basic knowledge of wood drying and instrument maintenance ; Otherwise, if the abnormal phenomenon in the drying process cannot be dealt with in time, the instrument will be interrupted, which will affect the drying process and directly affect the drying quality.

2. Lack of good human-computer interaction methods: Compared with foreign control systems, the existing domestic fully automatic drying control system still stays at the stage of membrane switch plus liquid crystal display, which makes it difficult for operators to carry out human-computer interaction very conveniently. The reliable operation of the system indirectly increases the work intensity of the operator.

3. The wood drying monitoring equipment is outdated and the control accuracy is not high: although some transmitters and data collectors with microprocessors have been introduced abroad, with high measurement accuracy and strong anti-interference ability, but due to their high cost and high price, In order to reduce the cost of equipment, many wood drying factories often still use manual operation, the control instruments and detection devices are incomplete, the reliability of equipment work is poor, and the level of automation is low. However, some domestic wood drying equipment manufacturers have introduced fully automatic control systems. There is still a certain gap in the detection and control of drying parameters, and some advanced control concepts and control methods are still in theoretical research and simulation.

4. Serious waste of wood drying energy: At present, due to the defects of the wood drying automatic monitoring system, the exhaust and air intake methods cannot be well controlled to control the temperature and humidity in the drying kiln, so that a large amount of energy is discharged into the air, resulting in The waste of energy and different degrees of air pollution lead to low efficiency of energy utilization.

Contents of the invention

The object of the present invention is to provide a remote monitoring system for wood drying based on DSP in order to solve the problems of complex operation, obsolete equipment and waste of energy in the existing wood drying monitoring system.

The DSP-based wood drying remote monitoring system of the present invention includes a remote server, a monitoring host and a field controller, and the field controller includes a microprocessor 1, a temperature and humidity sensor 2, a balance moisture content sensor 3, and a detection module 5 , an early warning module 6, a control module 7, a multi-way switch 9, a drive module 8, and n wood moisture content sensors 4, where n is a natural number,

The temperature and humidity sensor 2 collects the temperature and humidity signal of the drying kiln, and the temperature and humidity signal output end of the temperature and humidity sensor 2 is connected with the temperature and humidity signal input end of the detection module 5;

The balanced moisture content sensor 3 collects the balanced moisture content signal of the drying kiln, and the balanced moisture content signal output terminal of the balanced moisture content sensor 3 is connected with the balanced moisture content signal input terminal of the detection module 5;

Each wood moisture content sensor 4 collects the moisture content signal of a piece of wood, and the moisture content signal output end of each wood moisture content sensor 4 is connected with a moisture content signal input end of the detection module 5;

The sensor signal output end of detection module 5 is connected with the sensor signal input end of microprocessor 1, and the first output end of microprocessor 1 is connected with the input end of warning module 6;

The second output terminal of the microprocessor 1 is connected to the input terminal of the control module 7, and the output terminal of the control module 7 is connected to the input terminal of the multi-way switch 9, and the multi-way switch 9 outputs the control signal of the flue valve and the control signal of the dehumidification valve and steam injection valve control signal;

The third output terminal of the microprocessor 1 is connected with the input terminal of the driving module 8, and the driving module 8 outputs the control signal of the heating furnace and the control signal of the fan.

The advantages of the present invention: the realization scheme of the remote monitoring system for wood drying based on DSP in the present invention is simple, the cost is low, the wood drying cycle is short, the efficiency is high, the energy consumption is low, and the wood is heated evenly, and it is not easy to crack and warp. Phenomenon, to ensure the drying quality.

Description of drawings

Fig. 1 is a structural schematic diagram of the remote monitoring system for wood drying based on DSP according to the present invention.

Detailed ways

Specific embodiment one: the present embodiment is described below in conjunction with Fig. 1, the wood drying remote monitoring system based on DSP described in the present embodiment, it comprises remote server, monitoring main frame and field controller, and described field controller comprises microprocessor 1 , temperature and humidity sensor 2, balance moisture content sensor 3, detection module 5, early warning module 6, control module 7, multi-way switch 9, drive module 8, and n wood moisture content sensors 4, n is a natural number,

The temperature and humidity sensor 2 collects the temperature and humidity signal of the drying kiln, and the temperature and humidity signal output end of the temperature and humidity sensor 2 is connected with the temperature and humidity signal input end of the detection module 5;

The balanced moisture content sensor 3 collects the balanced moisture content signal of the drying kiln, and the balanced moisture content signal output terminal of the balanced moisture content sensor 3 is connected with the balanced moisture content signal input terminal of the detection module 5;

Each wood moisture content sensor 4 collects the moisture content signal of a piece of wood, and the moisture content signal output end of each wood moisture content sensor 4 is connected with a moisture content signal input end of the detection module 5;

The sensor signal output end of detection module 5 is connected with the sensor signal input end of microprocessor 1, and the first output end of microprocessor 1 is connected with the input end of warning module 6;

The second output terminal of the microprocessor 1 is connected to the input terminal of the control module 7, and the output terminal of the control module 7 is connected to the input terminal of the multi-way switch 9, and the multi-way switch 9 outputs the control signal of the flue valve and the control signal of the dehumidification valve and steam injection valve control signal;

The third output terminal of the microprocessor 1 is connected with the input terminal of the driving module 8, and the driving module 8 outputs the control signal of the heating furnace and the control signal of the fan.

Specific embodiment two: the difference between this specific embodiment and the wood drying remote monitoring system based on DSP described in specific embodiment one is that the field controller can further include a liquid crystal touch screen 10, which can communicate with the microprocessor 1 through the liquid crystal touch screen 10 For data interaction.

In this embodiment: the current state of the drying kiln can be displayed through the liquid crystal touch screen 10, and some drying parameters can also be set.

In terms of hardware design: the field controller adopts the DSP2812 core board LT8504 embedded development board for development and design, mainly completes the design of external storage circuit, touch screen interface circuit, signal input and output drive circuits, and connects with the serial port of the monitoring host to achieve reliable communication .

Software design: The monitoring host uses the object-oriented visual programming language Delphi7 to complete the design of the human-computer interaction interface under the Windows operating system, and uses the serial communication function of Delphi7 to realize the communication with the field controller. Delphi is known as the fourth-generation programming language, which has the characteristics of simplicity, high efficiency and powerful functions. Compared with VC, Delphi is simpler and easier to master, but it is not inferior in function; compared with VB, Delphi is more powerful and more practical. It can be said that Delphi has the characteristics of powerful VC and easy learning of VB at the same time. Utilizing the powerful functions of Delphi can effectively and greatly improve the programming efficiency. The on-site controller uses embedded C language programming to design various functional subroutines and main programs under the Linux operating system, and designs the communication subroutine of the on-site controller to realize communication with the monitoring host.

The design of the overall system scheme mainly includes four parts: system control scheme, remote server scheme design, monitoring host scheme design and field controller scheme design. The following is a brief introduction to the technical routes of these four schemes:

1. System control scheme

According to the basic principles of wood drying, determine the control parameters and the range of parameter values in the drying process, design the detection and control methods of the parameters, and formulate a detailed drying process.

1) System function

On the one hand, the monitoring system needs to complete the real-time collection of the temperature, humidity, and wet bulb temperature of the wood drying kiln, and calculate the equilibrium moisture content of the wood based on the collected values, and display the specific values of the above analog quantities in real time. Numerical and setting calculations, so as to control the corresponding execution components to perform corresponding actions, so as to realize precise control of system parameters. At the same time, it is necessary to store the data collected in real time during the process, so that users can analyze and summarize the test after the test process is over. On the other hand, real-time monitoring and control of the operating status of the drying system, real-time monitoring of switching signals such as total stop, manual, automatic, and limit switches of the intake and exhaust valves, to determine the operating status of the drying system and to control it according to the operating status of the drying system The corresponding AC contactors and relays in the system perform relevant actions, and automatically execute according to the set drying process.

2) Drying process

Comprehensively comparing the advantages and disadvantages of various drying methods, the present invention adopts the automatic control of steam drying, and the drying process is divided into four stages.

① Heating and preheating stage: Continue to raise the temperature to make the temperature in the drying room reach the set value, while keeping the equilibrium moisture content in the drying room unchanged from the set value. The purpose of this stage is to bring the temperature of the sawn timber in the core of the pile to the drying temperature, while the equilibrium moisture content remains unchanged, thereby avoiding hardening of the timber surface.

②Drying stage: After the preheating stage is over, it enters the drying stage. In this stage, the heating temperature becomes the drying temperature, and the equilibrium moisture content at this time changes with the moisture content of the wood and the set drying potential. During this process, the sawn timber A moisture content gradient is generated inside and outside, and the moisture inside the wood gradually moves to the surface and evaporates, and the wood gradually dries.

③ Humidity conditioning stage: When the sawn timber is dried to the required moisture content, final humidity conditioning treatment is required. The purpose is to dry the undried wood, moisten the over-dried wood, and distribute the final moisture content along the wood section. Uniform, reducing the internal stress of the dried sawn timber.

④ Cooling stage: After the humidity control stage is over, it enters the cooling stage. At this time, the heating must be stopped, the humidity should be maintained, the fan should be rotated, and the intake and exhaust channels should be opened. When the indoor temperature is only 10°C higher than the outdoor temperature, the fan should be turned off to end the drying.

2. Remote server solution design

In the wood drying remote monitoring system, the communication between the monitoring host and the remote service is realized through the Internet. When encountering an urgent problem that cannot be solved by the expert system in the monitoring host, it can get in touch with the drying expert on the remote server in real time so that Problems can be resolved in a timely manner. At this time, it is necessary to complete data transmission and remote control through the Internet.

In order to ensure the reliability and stability of the communication between the monitoring host and the server, the communication between the monitoring host and the server in the present invention mainly adopts the TCP network protocol, and the programming mode adopts the B/S mode.

3. Monitoring host solution design

The design of the monitoring host program includes the selection of monitoring host program development tools and the design of detailed functions of the monitoring host.

1) Selection of monitoring host program development tools

Delphi is known as the fourth-generation programming language, which has the characteristics of simplicity, high efficiency and powerful functions. Compared with VC, Delphi is simpler and easier to master, but it is not inferior in function; compared with VB, Delphi is more powerful and more practical. It can be said that Delphi has the characteristics of powerful VC and easy learning of VB at the same time. Delphi uses many advanced features and design ideas of the Microsoft Windows graphical user interface, supports features such as classes, encapsulation, inheritance, and polymorphism, and allows users to customize controls. Utilizing the powerful functions of Delphi can effectively improve the programming efficiency. Therefore, we use the Delphi object-oriented programming language for the program development of the monitoring host computer of the present invention.

2) Functional design

The monitoring host can select the appropriate drying benchmark for each drying kiln through the connection with each field controller, understand the drying process and equipment status in real time, and can directly control the equipment in the kiln if necessary. As the information center and management center, the monitoring host can be turned on when necessary, establish contact with each field controller, and comprehensively display the information of each drying kiln; it can also be turned off to allow the field controller to continue to work. Its main functions are as follows:

①Operation Instructions: Mainly introduce the operation and usage of the system.

②Selection and revision of drying benchmarks: the system has established various drying benchmark databases, allowing users to confirm the physical characteristics of the wood to be dried, including tree species, geometric dimensions and initial moisture content, etc., to determine and display the moisture content and duration of the wood Kiln temperature and drying gradient process curve for independent variables. The benchmark database can also be revised according to the actual drying conditions, such as additions and deletions.

③Control function: Interrupt receiving data uploaded by the field controller, and transmit initialization setting parameters and control commands through the communication serial port to control the action of the field controller.

④ Display function: real-time monitoring and display of the drying parameter values and equipment status in the kiln. According to all the listed abnormal conditions in the production process, such as the value exceeding the limit, abnormal state, etc., it will immediately alarm, and at the same time analyze and display the possible fault reasons.

⑤Communication function: When encountering an urgent problem that cannot be solved by the expert system, it can get in touch with the drying experts at the remote server in real time and obtain a solution to troubleshoot in time and reduce losses.

⑥ System management function: do detailed log management for user login, logout, operation, etc., among which the operation record can be used as one of the references for evaluating the performance of the drying system.

⑦Print function: the drying process of each kiln can be printed out in detail, so as to check the deficiencies and sum up experience.

4. On-site controller scheme design

The scheme design of the field controller includes the selection of the microprocessor of the field controller and the detailed function design of the field controller.

1) Selection of field controller microcontroller

After analyzing the functional requirements of the system in detail, the DSP2812 core board LT8504 embedded development board is selected as the core of the field controller to form the control system. The core processor of DSP2812 core board LT8504 embedded development board is TMS320F2812 processor. The processor is a 32-bit high-performance processor with high main frequency and low power consumption; the chip integrates 128K*16-bit program FLASH, 18K*16-bit data SRAM; 128-bit program security lock; three 32-bit timers; 4 16-bit timers; multi-channel digital input and output; 16-channel PWM output; 8 CAP input channels, 2*8 12-bit AD; 2 serial communication interfaces; 1 ECAN bus interface.

2) Functional design

The on-site controller is located at the front end of the kiln measurement and control, and performs the measurement and control functions of the kiln environmental parameters, wood status and equipment status. The on-site controller can run alone (stand-alone mode), and can also accept various commands from remote servers and monitoring hosts through network buses and serial buses, and feed back data to the monitoring host after executing commands (controlled mode). On-site control The liquid crystal touch screen configured by the controller can display the collected parameter values and the set process parameter values, and can also be used to set the drying reference. The functional block diagram of the on-site controller is shown in Figure 1.

Claims (4)

1. The remote monitoring system for wood drying based on DSP is characterized in that it includes a remote server, a monitoring host and a field controller, and the field controller includes a microprocessor 1, a temperature and humidity sensor 2, a balance moisture sensor 3, a detection Module 5, control module 7, multi-way switch 9, drive module 8, and n wood moisture content sensors 4, n is a natural number, The temperature and humidity sensor 2 collects the temperature and humidity signal of the drying kiln, and the temperature and humidity signal output end of the temperature and humidity sensor 2 is connected with the temperature and humidity signal input end of the detection module 5; The balanced moisture content sensor 3 collects the balanced moisture content signal of the drying kiln, and the balanced moisture content signal output terminal of the balanced moisture content sensor 3 is connected with the balanced moisture content signal input terminal of the detection module 5; Each wood moisture content sensor 4 collects the moisture content signal of a piece of wood, and the moisture content signal output end of each wood moisture content sensor 4 is connected with a moisture content signal input end of the detection module 5; The second output terminal of the microprocessor 1 is connected to the input terminal of the control module 7, and the output terminal of the control module 7 is connected to the input terminal of the multi-way switch 9, and the multi-way switch 9 outputs the control signal of the flue valve and the control signal of the dehumidification valve and steam injection valve control signal; The third output terminal of the microprocessor 1 is connected with the input terminal of the driving module 8, and the driving module 8 outputs the control signal of the heating furnace and the control signal of the fan. 2. The DSP-based wood drying remote monitoring system according to claim 1, characterized in that it also includes an early warning module 6, which is used for system abnormality alarms. 3. The DSP-based wood drying remote monitoring system according to claim 1 or 2, is characterized in that it also includes a liquid crystal touch screen 10, and the liquid crystal touch screen 10 is used to display the parameter values collected and the process parameter values that have been set Can also be used to set dry benchmarks. 4. The remote monitoring system for wood drying based on DSP according to claim 3, wherein the on-site controller is realized by using the DSP2812 core board LT8504 embedded development board.

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