| In the linear scenarios of industrial automation,linear motors have significant advantages over the combination of rotary motors and transmission devices.Linear position detection is an important part of linear motor servo control,directly affecting the operational performance and position accuracy of linear motors.Traditional linear position detection devices have drawbacks such as large size,high cost,and short measurement stroke.To address these issues,this paper proposes two linear motor position detection systems based on magnetoresistive sensor arrays,which have the advantages of small size,low cost,long measurement stroke,and non-contact.The main research content of this paper is as follows:(1)The magnetoresistive effect,anisotropic magnetoresistive effect,and anisotropic magnetoresistive effect sensor were analyzed,and neodymium-iron-boron was selected as the position detection permanent magnet.The spatial magnetic field of the permanent magnet was analyzed using equivalent magnetic charge model theory calculation and Maxwell finite element simulation,and the spatial position relationship between the permanent magnet and the sensor was determined.(2)The characteristics of the HMC1501 magnetoresistive sensor were introduced,and a linear motor position detection scheme based on the HMC1501 sensor array was designed.The linearly output voltage signal of the HMC1501 sensor is converted into the position information of the mover within a small range.The external interrupt function of STM32 is used in conjunction with a hysteresis comparator to switch the detection interval,and the position information is transmitted to a PC host computer for visualization display via serial communication.The feasibility of the scheme was verified by building an experimental platform.After calibration,the static error and dynamic error of the detection system were tested.The experimental results show that the static error of the linear motor position detection system based on the HMC1501 sensor array is about ±10μm,and the dynamic error is ±150μm.(3)The characteristics of the HMC1512 magnetoresistive sensor were introduced,and a linear motor position detection scheme based on an HMC1512 sensor array was designed.The angle relationship between the mover and the sensor in the horizontal direction is obtained by performing inverse tangent operation on the sin output and cos output of the HMC1512 sensor.The position information of the mover within a small range is obtained through conversion calculation.The sensor array is synchronously collected by multiple channels of AD7606 driven by FPGA,and the detection interval is judged according to the sine output of each sensor.The position information is transmitted to a PC host computer for visualization display through serial communication.The problem of non-orthogonality between sin and cos signals was analyzed,and a normalization method was proposed.The feasibility of the scheme was verified by building an experimental platform.After calibration,the static and dynamic errors of the detection system were tested.The experimental results show that the static error of the linear motor position detection system based on the HMC1512 sensor array is about ±1μm,and the dynamic error is about ±60μm.The two linear motor position detection systems designed in this study achieve accurate measurement of the mover position of linear motors.By changing the number of sensors,they can be applied to non-contact detection of linear positions of any length and have broad practical industrial application value. |
