Design And Research Of Smart Wrench

To ensure the reliability of bolt connection,torque wrench as a well-known tightening tool,widely used in transportation,machinery,electric power and other industries.Threaded connections at critical locations require the torque-angle method,so the torque wrench have to measure the angle.Most domestic torque wrenches didn’t have the angle detection function,while the import ones are expensive.Therefore,it is particularly important to design an angle measuring smart wrench with high accuracy and low cost.This paper introduces the research status of smart wrenches at home and abroad and its advantages and disadvantages on the market.The principles of measuring torque and angle by different sensors was also analyzed.According to actual needs,a smart torque wrench which can measure both torque and angle was designed,with the characteristics of high measurement precision,convenient calibration,low power consumption,overload sound and light alarm,large amount of data storage,etc.The hardware and software design of the smart torque wrench was completed.The hardware design mainly includes MCU minimum system by low power STM32 series MCU,torque measuring by strain gauge,angle detection by MEMS gyroscope sensor,power supply and charging circuit,and the module of sound and light alarm,storage and wireless communication.The software design includes all codes to realize various practical functions.In order to improve the accuracy of angle measurement,the noise source of the gyroscope was analyzed,and digital filtering,threshold judgment and dynamic zero methods were used to filter the noise.The prototype test proves that each module of the smart wrench meets the design requirements and has stable performance.Accuracy tests were carried out on similar products of two foreign brands with this design.It was confirmed that the accuracy of this design in measuring torque and angle is at a high level,which can meet the requirements of use and meet the original design intention.