High-precision Strain Signal Measurement And Simulation Module Design

Since ancient times,weights and measures have been closely related to people’s lives and socio-economics.Now weighing apparatus has been widely used in people’s daily life,trade calculations,automatic weighing systems and automatic packaging.Electronic scales usually use strain sensors to convert mass(pressure)signals into weak electrical signals for measurement.High-precision weighing indicator can be calibrated with manual weighing simulator which output weak ratio signal.Manual weighing simulator is expensive,bulky,and inefficient,and cannot achieve program-controlled calibration.This problem has become an urgent technical key to be solved in the field of weighing instruments,which is not conducive to the industrial production of weighing instruments.This paper proposes a high-precision strain signal measurement and generation design method.It uses lower resolution DACs to achieve high resolution signal output.It adopts dual 16 bit current output DACs,one used for coarse adjustment and the other used for fine adjustment.The two outputs are different weights sum and differential attenuation output.It uses the ADC to monitor the output signal to modify the DAC settings,for achieving a high accuracy,high resolution,and low temperature drift simulation output of the strain signal.Strain bridge excitation is adopted active driving method which can effectively reduce signal noise and external interference for achieving high-precision measurement of the strain signal.The excitation voltage of the strain signal can be programmed for fitting different kinds of sensors.This optimization of the analog hardware circuit is fully utilized with the knowledge of error theory.All resistor networks for signal amplification and attenuation make up by the series and parallel combination of low-cost,normal low-temperature drift chip resistors for achieving low temperature drift in the signal proportional conversion process,this method not only maintains the temperature stability of signal measurement and occurrence,but also greatly reduces the hardware cost of the module.This paper realizes complete design of the instrument functions.The hardware circuit has no mechanical switch or relay switch,and can support RS485,USB,LAN,touch screen,etc.It realizes full program-controlled calibration and strain signal measurement and strain signal simulation.The module has the advantages of high-precision,convenient power supply,low hardware cost,and small size.After three rounds of updating,this design has achieved the expected features of hardware circuit and software.