The Research Of Portable Torque Wrench Test Instrument Based On Linux

At present domestic torque wrench calibrator is mostly mechanical, which not only had long development cycle, bulky, heavy quality and not easy to carry. But also with slow verification speed, small storage capacity, complex human-computer interaction, and large restricted by use of the environment. According to the above situation,this paper developed a portable torque wrench calibrator based on Linux, This paper developed a portable torque wrench calibrator based on Linux. The detection instrument can be applied to various large and medium-sized enterprises, has a good human-computer interaction interface, can quickly check and store large amounts of data.The paper by studying the physical properties of metal strain gauge, establishes physical model of the torque sensor. Analyzes the influence of the bending moment and axial force on torque measurement accuracy, and know that the torque value and the output voltage of the torque sensor is direct proportion relationship. On the hardware platform, the article carries on the detailed design for data acquisition unit, which contained a power management circuit, analog-to-digital conversion circuit, MSP430acquisition circuit and serial communication circuit between MSP430and ARM. To meet the requirements of easy to carry, the power management circuit uses7.4V lithium batteries. But because each circuit module will require different power supply voltage, at the same time design a7.4V to5V and5V to3.3V power supply switching circuit. Due to the design requirements of high precision, low power consumption, analog-to-digital conversion circuit selects CS5530that is a24-bit ABC with Ultra low noise Amplifier, after the conversion, sends the data into the Acquisition system through its serial interface. Requirements in the design of test instrument can quickly handle large amounts of data, so the data collection is designed by ultra-low power MSP430, the data processing is performed by ARM embedded platform, the communication between MSP430and ARM through the RS232serial port. Software unit is composed of embedded Linux, Qt and database application software platform and main design the visual application system. Main software function includes:recording, storing or displaying maximum torque values; querying the torque verification result and history; modifying, storing or printing date; printing calibration certificate; for system maintenance and user management, etc.The experimental results show that the development of a portable torque wrench calibrator based on Linux, its various technical indicators and functions meet the design requirements. This paper for torque wrench production departments and industry provides an easy to operate, visual and able to do a lot of good quick verification of data storage and portable torque wrench calibrator.