Intelligent Instrument Development Trend Analysis

The emergence of smart instruments has greatly expanded the scope of application of traditional instruments. Intelligent devices have been widely used in household appliances, scientific research institutions and industrial enterprises due to their advantages of small size, strong functions, and low power consumption.

1. The working principle of intelligent instrument The sensor picks up the information of the measured parameter and converts it into an electric signal. After filtering to remove the interference, it sends it into multiple analog switches. The single-chip microcomputer commutates the analog switch one by one and sends the signals of each input channel to the program control one by one. Gain amplifier, the amplified signal is converted into the corresponding pulse signal by a/d converter and then sent to the single-chip microcomputer; the single-chip microcomputer performs corresponding data operation and processing (such as nonlinear correction, etc.) according to the initial value set by the instrument; The result is converted into the corresponding data for display and printing; at the same time, the MCU compares the calculation results with the set parameters stored in the on-chip flash ROM or e2prom (Electrically Erasable Memory). After that, according to the calculation results and control requirements, corresponding control signals (such as alarm device triggers, relay contacts, etc.) are output. In addition, the intelligent instrument can also be composed of a distributed measurement and control system with a PC. A single-chip computer is used as a slave to collect various measurement signals and data. The serial communication is used to transmit information to a host computer, a PC, and is managed globally by a PC.

2. Features of smart instruments With the continuous development of microelectronics technology, integrated CPUs, memories, timers/counters, parallel and serial interfaces, watchdogs, preamps, and even a/d, d/a converters The VLSI chip (ie, SCM) appears on a chip as a circuit. Take the one-chip computer as the main body, combine computer technology and measurement and control technology together, and form the so-called "intelligent measurement and control system", namely intelligence instrument.

Compared with traditional instruments, smart instruments have the following features:

1 Operational automation. The entire measurement process of the instrument, such as keyboard scanning, range selection, switch start closure, data acquisition, transmission and processing, and display printing, is controlled by a single-chip microcomputer or a microcontroller to achieve full automation of the measurement process.

2 has a self-test function, including auto-zero, automatic fault and status inspection, automatic calibration, self-diagnosis and automatic range conversion. Smart meters can automatically detect the location of the fault or even the cause of the fault. This self-test can be run when the instrument is started, and it can also be run during instrument operation, which greatly facilitates instrument maintenance.

3 has data processing capabilities, which is one of the main advantages of smart instruments. The use of a microcontroller or microcontroller in smart instruments has made many problems that were previously difficult or impossible to solve with hardware logic, and can now be solved with great flexibility using software. For example, a conventional digital multimeter can only measure resistance, AC/DC voltage, and current, while an intelligent digital multimeter can not only perform the above measurements, but also perform measurements such as zero shift, averaging, extreme value, and statistics. Analysis and other complex data processing functions not only free the user from heavy data processing, but also effectively improve the measurement accuracy of the instrument.

4 has a friendly human-machine dialogue ability. The intelligent instrument uses the keyboard instead of the switch in the conventional instrument, and the operator can realize some measurement function simply by inputting a command through the keyboard. At the same time, the intelligent instrument also informs the operator through the display screen of the instrument's operating conditions, working conditions, and the results of measurement data processing, making the operation of the instrument more convenient and intuitive.

5 has programmable control capabilities. General smart instruments are equipped with standard communication interfaces such as gpib, rs232c, rs485, etc. It is very convenient to form an automatic measurement system with various functions required by the user together with the pc and other instruments to complete more complicated test tasks.

3. Overview of the Development of Intelligent Instruments In the 1980s, microprocessors were used in instruments. The instrument front panel began to develop in the direction of the keyboard, and the measurement system was often connected through the ieee-488 bus. Different from the traditional independent instrument mode, personal instruments have been developed.

In the 1990s, the intelligentization of instrumentation was highlighted in the following aspects: The advancement of microelectronics technology has influenced the design of instrumentation more profoundly; the advent of dsp chips has greatly enhanced the digital signal processing capabilities of instrumentation; the development of microcomputers, Make the instrument and instrument have stronger data processing ability; The increase of the image processing function is very common; The vxi bus has been widely used.

In recent years, the development of intelligent measurement and control instruments has been particularly rapid. A variety of intelligent measurement and control instruments have appeared in the domestic market. For example, intelligent throttle flowmeters capable of automatic differential pressure compensation, intelligent multi-stage temperature controllers capable of temperature control, and digital PIDs Smart regulators for complex control laws, and intelligent chromatographs that can analyze and process various spectra.

There are many kinds of intelligent measuring instruments in the world. For example, the dstj-3000 series of smart transmitters produced by Honeywell's new edition of “China Instrument Manufacturers List” can be used to carry out composite measurement of differential pressure status and can be used for transmission. The device body temperature, static pressure and other automatic compensation, its accuracy can reach ± ​​0.1% fs; the United States racat-dana 9303 ultra-high-level watch, the use of microprocessors to eliminate current flowing through the resistance of the thermal noise, Measurement level can be as low as -77db; Fluke Corporation's super multi-function calibrator 5520a, the internal use of three microprocessors, the short-term stability of 1ppm, linearity can reach 0.5ppm; digital production of the United States foxboro Corporation Self-tuning regulators, using expert system technology, can quickly adjust the regulator based on field parameters, just like experienced control engineers. This regulator is particularly suitable for control systems where the object changes frequently or non-linearly. Because this regulator can automatically adjust the adjustment parameters, the entire system can always maintain the best quality in the production process.

4, the development trend of smart instruments 4.1 miniaturization of micro-intelligent instruments refers to microelectronics technology, micro-mechanical technology, information technology and other integrated application in the production of the instrument, so that the instrument becomes a small, full-featured intelligent instruments. It can complete signal acquisition, linearization, digital signal processing, control signal output, amplification, interface with other instruments, and human interaction. With the continuous development of micro-electro-mechanical technology, micro-intelligent instruments, their technologies continue to mature, prices continue to decline, so their application areas will continue to expand. It not only has the functions of traditional instruments, but also can play a unique role in the fields of automation technology, aerospace, military, biotechnology, and medical care. For example, it is currently necessary to measure several different parameters of a patient at the same time and perform control of certain parameters. Usually the patient's body is inserted into several tubes, which increases the chance of patient infection. Micro-intelligent instruments can measure multiple parameters at the same time. And it is small and implantable in the human body, making these problems solved.

4.2 Multifunctional Multifunction is a feature of smart instrumentation.

For example, in order to design faster and more complex digital systems, instrument manufacturers have created function generators with functions such as pulse generators, frequency synthesizers, and arbitrary waveform generators. This multi-functional integrated product instrumentation product catalog “National Project Proposal Under Construction” has higher performance (eg, accuracy) than dedicated pulse generators and frequency synthesizers, and provides a variety of test functions. Better solution.

4.3 Artificial intelligence Artificial intelligence is a new field of computer applications. It uses computers to simulate human intelligence for use in robots, medical diagnostics, expert systems, and proof of reasoning. The further development of intelligent devices will contain certain artificial intelligence, that is, replacing part of the human brain work, and thus in the visual (graphics and color identification), hearing (speech recognition and language understanding), thinking (reasoning, judgment, learning and association) Other aspects have a certain ability.

In this way, smart devices can autonomously perform detection or control functions without human intervention. Obviously, the application of artificial intelligence in modern instrumentation allows us not only to solve a class of problems that are difficult to solve with traditional methods, but also to solve the problems that cannot be solved by traditional methods.

4.4 Integrate isp and emit technologies to implement internet access for instrumentation systems (networking)

With the rapid development of network technology, internet technology is gradually infiltrating into the field of industrial control and intelligent instrumentation system design. The intelligent instrumentation system is based on internet-based communication capabilities and remotely upgraded and functionally-redesigned intelligent instrumentation systems. And system maintenance.

In-system programming (isp technology) is a state-of-the-art technology that modifies, configures, or reorganizes software. It is a kind of first proposed by lattice semiconductor company that allows us to carry out every link in the product design and manufacturing process, and even after the product is sold to end users, it has the logic and function of its devices, circuit boards or the entire electronic system at any time. The latest technology for configuration or reorganization capabilities. The isp technology eliminates some of the limitations of traditional technologies and connection flaws, and is conducive to board design, manufacturing, and programming. Isp hardware is flexible and easy to modify software to facilitate design and development. Since isp devices can be handled on a printed circuit board (pcb) like any other device, programming isp devices do not require specialized programmers and more complex processes, as long as they are performed via a PC, an embedded system processor, or even an internet remote network. Programming.

The embedded micro-internet Internet connection technology was proposed by Emware Corporation when it created the eti (extend the internet) expansion of the internet alliance. It is a technology for accessing embedded devices such as SCMs to the internet. Using this technology, it is possible to connect 8-bit and 16-bit microcomputer systems to the internet to implement remote-based data acquisition, intelligent control, and upload/download of data files.

At present, connectone, emware, tapeking, and domestic p&s companies all provide internet-based device-networking software, firmware, and hardware products.

4.5 Virtual Instrument is the New Stage for the Development of Intelligent Instrument The main functions of the measuring instrument are composed of three parts: data acquisition, data analysis and data display.

In the virtual reality system, data analysis and display are completely completed by the PC software. Therefore, as long as the additional data acquisition hardware is provided, the measurement instrument can be composed with a PC. This kind of PC-based measuring instrument is called a virtual instrument. In the virtual instrument, using the same hardware system, as long as the application of different software programming, you can get completely different measuring instruments. Visible, the software system is the core of the virtual instrument, "software is the instrument."

Traditional intelligent instruments use some sort of computer technology in instrument technology, while virtual instruments emphasize the absorption of instrument technology in general computer technology. The software system at the core of the virtual instrument is versatile, popular, visual, extensible, and scalable, and it can bring great benefits to users. Therefore, it has the application prospect and market that traditional intelligent instruments cannot match. .

5. Conclusion The intelligent instrument is a combination of computer science, electronics, digital signal processing, artificial intelligence, vlsi and other emerging technologies and traditional instrumentation technologies. With the development of related technologies such as application-specific integrated circuits and personal instruments, smart instruments will be more widely used. The single-chip computer technology, which is the core component of smart devices, is the driving force for the development of smart devices in the direction of miniaturization, multi-functionality, and more flexibility. It can be expected that smart instruments of various functions will be widely used in various fields of society in the near future.