Sensor experiment device and control method thereof

Abstract

The invention discloses a sensor test device and a control method thereof, the sensor test device comprises a test mainboard, the test mainboard is provided with a unified sensor interface, the sensor interface is connected with a customized acquisition board, and the customized acquisition board is used for connecting a corresponding sensor to obtain data of the sensor; and the test mainboard is connected with the customized acquisition board through a unified communication protocol to obtain sensor data. The test mainboard is connected with the customized acquisition board through a unified sensor interface and a communication protocol to obtain sensor data, and an experiment device capable of flexibly expanding the sensor is provided, so that the sensor experiment teaching quality can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of teaching equipment, and in particular to a sensor experimental device and a control method thereof. Background Art

[0002] Sensor experiments are the main course experiments for majors such as instrumentation, automation, electronic information, mechanical electronics, and artificial intelligence. The conventional experimental content is to test sensors with different detection principles such as resistance, capacitance, inductance, piezoelectric, and photoelectric. On the one hand, the theoretical part of sensor teaching experiments often involves complex physical, chemical, or biological effects, as well as signal processing and electronic circuit knowledge. These contents are highly theoretical and cover a wide range of knowledge, which makes students feel obscure and difficult to understand, and their interest in learning is not high. On the other hand, the experimental content is mostly based on verification experiments, the experimental projects are out of touch with practice, and there is a lack of independent innovation experiments, which is not conducive to cultivating students' comprehensive abilities.

[0003] For majors such as artificial intelligence and mechanical and electronic engineering, the main training goal is to apply sensors to different industries. In recent years, various new sensors have emerged. Creating some sensor experimental projects based on application scenarios is more in line with production reality and can easily improve students' hands-on ability and creativity.

[0004] Conventional sensor experimental devices reserve multiple types of interfaces such as A / D, I / O, IIC, UART, SPI, etc., and several interfaces of each type are reserved. When doing experiments, according to the interface type of the sensor, it can be directly connected to the interface of the host. It is more intuitive and students can understand and become familiar with different interface types and communication protocols.

[0005] With the development trend of digitalization and intelligence of sensors, there are many types of sensors, new sensors are constantly emerging, and the interface forms are becoming more and more diversified, such as voice recognition modules, image recognition modules, positioning and navigation modules, chip-type attitude sensors, etc. The use of traditional sensor experimental hosts will cause a rapid increase in the number and types of hardware interfaces, and each interface is not universal. It is also difficult to reasonably determine the number of each type of interface. At the same time, once a sensor with a new interface type is encountered, the experiment cannot be carried out. In summary, the development of an experimental device that combines actual application scenarios and can flexibly expand sensors is helpful to improve the quality of sensor experimental teaching.

[0006] Application number 202221954802.2, announcement number CN 218525215 U, utility model name: Programmable main controller for programming education, records the following content: the number of connection arrangements between the sensor interface and the main control board is eight, the sensor interface is arranged on the side of the shell and exposed, and the sensors matched by the sensor interface are color sensors, color LEDs, ultrasonic sensors, touch sensors, tracking sensors, and sensor adapter boards. In this document, the sensor interfaces of the main control board connected to the color sensor, color LED, ultrasonic sensor, touch sensor, tracking sensor, and sensor adapter board are different, and no unified communication protocol is set, and the sensor interface cannot be replaced at will. Summary of the invention

[0007] In view of at least one defect of the prior art, the purpose of the present invention is to provide a sensor experiment device, in which the experiment main board connects to the customized acquisition board through a unified sensor interface and communication protocol to obtain sensor data, and to provide a sensor experiment device that can flexibly expand sensors, which helps to improve the quality of sensor experiment teaching.

[0008] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a sensor experimental device, including an experimental mainboard, the experimental mainboard is provided with a unified sensor interface, the sensor interface is connected to a customized acquisition board, and the customized acquisition board is used to connect to the corresponding sensor to obtain its data; the experimental mainboard is connected to the customized acquisition board via a unified communication protocol to obtain sensor data.

[0009] The experimental mainboard is connected to the experimental computer to form the host. The sensor interface uniformly adopts the XH2.54-4P interface, and the communication protocol uniformly adopts the MODBUS-RTU communication protocol.

[0010] The experimental mainboard is connected to a customized control board, which is used to connect the control device, and the experimental mainboard and the customized control board are connected using a unified control interface and a communication protocol, and the communication protocol uses the MODBUS-RTU communication protocol.

[0011] The sensor experimental device is a synchronous comparison experimental device for multiple temperature sensors. There are at least two sensor interfaces, each of which is connected to a temperature sensor of a corresponding type through a corresponding customized acquisition board. The temperature sensor is fixedly installed in a cold and hot shock experimental box. The cold and hot shock experimental box is provided with a box body, and a vent / pressure relief structure is provided on the box wall of the box body; a dry ice box / refrigeration device is provided at the upper part of the inner cavity of the box body; a heating device is provided at the lower part of the inner cavity of the box body; an air flow circulation device is fixedly provided in the box body, wherein the refrigeration device, the heating device, and the air flow circulation device are control devices;

[0012] The experimental mainboard adjusts the temperature of the hot and cold shock test box through a dry ice box / refrigeration device and a heating device, achieving box temperature adjustment from dozens of degrees below zero to hundreds of degrees above zero, reading the measurement results of different temperature sensors, and visually displaying the temperature synchronization comparison experimental characteristics of various types of temperature sensors by measuring the values ​​of each temperature sensor from low temperature to high temperature, and conducting normal temperature measurement experiments and destructive experiments on the temperature sensors.

[0013] There are 5 sensor interfaces, which are connected to thermal resistors, thermocouples, thermistors, infrared temperature sensors, and digital temperature sensors through corresponding customized acquisition boards; the temperature synchronization comparison experiment characteristics include synchronization data change curve, measurement error, over-range state, and over-temperature fault state; the temperature reference used by the experimental main board for box temperature adjustment is: when it is lower than -25 degrees, the measured temperature of the thermal resistor is used as the reference temperature, when it is between -25 and 120 degrees, the digital temperature sensor is used as the reference temperature, and when it is higher than 120 degrees, the infrared temperature sensor is used as the reference temperature.

[0014] The sensor experimental device is a synchronous comparison experimental device for multiple weighing sensors, and the synchronous comparison experimental device includes a fixed object, at least one tension weighing sensor is connected in series at the bottom of the fixed object through a suspension rope, a tray is arranged below the tension weighing sensor, the bottom tension weighing sensor is connected to the edge of the tray by at least two suspension ropes to suspend the tray, at least one pressure weighing sensor is stacked on the upper surface of the tray, and the tension weighing sensor and the pressure weighing sensor are both provided with their own customized acquisition boards, which are connected to the experimental main board through a unified sensor interface;

[0015] Use the sling and pallet to measure the same object;

[0016] (1) Zero calibration: without placing any weights, perform zero calibration on all tension load cells and pressure load cells; (2) Range calibration: place full-scale weights and perform range calibration on all tension load cells and pressure load cells; (3) Hysteresis characteristics: the weight of the weights gradually increases from small to large, collect the measured values ​​of each tension load cell and pressure load cell, then the weight of the weights gradually decreases from large to small, collect the measured values ​​of each tension load cell and pressure load cell, and the host draws the hysteresis characteristic curves of different types of load cells, and intuitively compares the hysteresis characteristics of load cells with different structures and materials; (4) Creep characteristics: place full-scale weights, periodically read Take the measurement value of each tension load cell and pressure load cell, and draw a curve of the measurement value change over time. As time goes by, the measurement results of some tension load cells or pressure load cells will gradually show errors, and the errors will gradually increase. The creep characteristics of load cells with different structures and materials can be intuitively compared. After the experiment, zero point calibration and range calibration need to be re-performed. (5) Overload characteristics: This experiment is a destructive experiment. The weight of the weight gradually increases from small to large until it exceeds the maximum bearing weight of several tension load cells or pressure load cells, causing serious deviations in the measurement value. The error change characteristics of the tension load cell or pressure load cell under overload conditions are collected.

[0017] The sensor experimental device is an intelligent access control experimental device, which includes an image acquisition component, a fingerprint recognition related component, and a voice recognition component; the image acquisition component includes a face recognition sensor, which is connected to the experimental main board via a corresponding customized acquisition board; the fingerprint recognition related component includes a fingerprint recognition sensor, which is connected to the experimental main board via a corresponding customized acquisition board; the voice recognition component includes a voice recognition sensor, which is connected to the experimental main board via a corresponding customized acquisition board;

[0018] The intelligent access control experimental device provides a voice password access control method. A string of numbers and letters is set as the password. When the voice recognition component recognizes the corresponding string and there are no other numbers and letters in a period of time before and after, the password is considered correct and a signal is sent to the experimental mainboard. The experimental mainboard controls the electromagnet to be energized, and the electromagnet is energized to control the access control to open; if the password is incorrect, the electromagnet is powered off and the access control is not opened; the electromagnet is a control device.

[0019] A control method including the sensor experimental device, the key of which is: the experimental mainboard is provided with a polling sensor process: the main program of the experimental mainboard reads the data of each sensor in turn, and determines whether it is connected at the same time, and reading the data of each sensor includes the following steps:

[0020] Step A1, sending a query instruction to the i-th sensor;

[0021] Step A2: Set the waiting time to T di , start the timer and wait for the sensor to return data; (Because the response time of each sensor is different, the host sets a different waiting time for each sensor. If the sensor does not return data within the set time, it is considered that the sensor is not connected.)

[0022] Step A3: If the set time T di If the data returned by the sensor is received, go to step A4, otherwise go to step A5;

[0023] Step A4: Adjust T according to the setting method di The sensor connection is normal, the sensor data is processed, and the process goes to step A6;

[0024] Step A5, set the sensor connection failure flag, set the sensor data to invalid, and go to step A6;

[0025] Step A6: The sensor query ends.

[0026] The key to the control method of the sensor experimental device is: in step 4, T di The setting and adjustment methods include: When the experimental mainboard is powered on for the first time, first set T di The initial value is the same for each sensor, T di =T dinit , T dinit Able to meet the response time of any sensor;

[0027] Each time the sensor is polled, if di Receive sensor data within the time, record the sensor response time T ri If the response time exceeds the longest response time T of the sensor in the previous polling rimax The value of T is updated rimax The value of T rimax The value is equal to T ri , that is, T rimax =T ri ;The purpose is to record the longest response time of the sensor.

[0028] If T di >f s T rimax , where f s is the insurance factor, then reduce T di The value of each decrease is ΔT di , T di =T di -ΔT di , ΔT diIt is a reduction.

[0029] Significant effect: The present invention provides a sensor experiment device and a control method thereof. The experiment main board connects to a customized acquisition board through a unified sensor interface and communication protocol to obtain sensor data, and provides a sensor experiment device that can flexibly expand sensors, which helps to improve the quality of sensor experiment teaching. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a detailed module structure diagram of the present invention; Figure 2 The program flow chart for polling sensors on the experimental mainboard;

[0031] Figure 3 A flowchart to guide the process of voice interactive experiment; Figure 4 A flow chart to supervise the experimental process;

[0032] Figure 5 It is the structural diagram of the hot and cold shock test box; Figure 6 It is the connection diagram of various temperature sensor components and the experimental main board; Figure 7 It is a schematic diagram of the combined experimental structure of various weighing sensors; Figure 8 This is a schematic diagram of the circuit module for the synchronous comparison experiment of multiple weighing sensors; Fig. 9 This is the flow chart of the synchronous comparison experiment of various weighing sensors; Fig.10 Block diagram for connecting components for the smart light control experiment; Fig.11 The module diagram of the connection components for the smart access control experiment; Fig.12 It is a flow chart of the voice password determination process;

[0033] Fig.13 This is a schematic diagram of the connection of intelligent voice experiment components; Fig.14 This is a connection diagram of the smart watering experiment components;

[0034] Fig.15 This is a connection diagram of the intelligent material and water adding experiment components; Fig.16 This is a schematic diagram of the connection of the urban meteorological monitoring experiment components; Fig.17 This is a schematic diagram of the connections for the air pollution monitoring experiment components;

[0035] Fig.18 This is a schematic diagram of the connection of the field environment monitoring experiment components; Fig.19 This is a schematic diagram of the connection of the experimental components for the part posture control; Fig. 20 This is a schematic diagram of the connection of the movement statistics experiment components;

[0036] Fig.21 This is the circuit diagram of the experimental main board; Fig. 22 Custom control panel circuit diagrams for heating, fans, lights, and speakers; Fig.23The circuit diagram of the custom acquisition board for thermocouples; Fig.24 The circuit diagram of the custom acquisition board for the thermal resistor; Fig.25 The circuit diagram of the custom acquisition board for thermistor; Fig.26 Circuit diagram of custom acquisition board for speech recognition; Fig. 27 This is a schematic diagram of the installation of the magnetic levitation device. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1-Figure 27 As shown, the present invention relates to a sensor experimental device and a control method thereof, and the specific measures taken are as follows:

[0039] 1. Unify the interface between the host and the sensor: The experimental mainboard uses a unified hardware interface and communication protocol to connect to the sensor, and the experimental mainboard only retains several identical sensor interfaces. For example, the XH2.54-4P interface and MODBUS-RTU communication protocol are used. In order to achieve a unified sensor interface, it is necessary to design a corresponding customized acquisition board for each sensor. The customized acquisition board is used to read the sensor data and send it to the experimental mainboard according to the unified communication protocol. The experimental mainboard is connected to the experimental computer to transmit the sensor data to the experimental computer; the experimental mainboard is also connected to a touch screen.

[0040] Advantages: Only one sensor interface needs to be designed on the experimental mainboard, and a large number of interfaces can be arranged without considering the number of different types of interfaces. The interfaces on the experimental mainboard are universal, avoiding plugging the wrong interface. The experimental mainboard and the customized acquisition board only need one connection line, which greatly simplifies the wiring during the experiment, and different types of sensors can be connected at will. (Similar to the computer USB interface, it can connect a variety of different types of devices such as mouse, keyboard, printer, mobile hard disk, camera, etc.).

[0041] The overall composition of the experimental teaching aids is as follows Figure 1 As shown, with the experimental mainboard as the core, the sensor information is collected and uploaded to the experimental computer. The role of the customized acquisition board is to convert the information of various sensors into standard data and send it to the experimental mainboard according to the standard communication interface. The industrial standard Modbus-RTU protocol is used between the experimental mainboard and the customized acquisition board. Each customized acquisition board has a unique number (ID), that is, each sensor has a unique number. Several standard interfaces are designed on the experimental mainboard, and each standard interface can be connected to any sensor supported by this experimental device.

[0042] The experimental main board communicates with the customized control board to control lights, alarms and other equipment. The industrial standard Modbus-RTU protocol is also used between the experimental main board and the customized control board. Each customized control board has a unique number (ID), that is, each control device has a unique number. Several standard interfaces are designed on the experimental main board. Each standard interface is universal and can be connected to any device supported by this experimental device.

[0043] like Figure 1 As shown, the customized acquisition board includes a thermal resistor acquisition board, a thermocouple acquisition board, a photosensitive acquisition board, a fingerprint acquisition board, etc.; the thermal resistor acquisition board is used to connect thermal resistors; the thermocouple acquisition board is used to connect thermocouples; the photosensitive acquisition board is used to connect photoresistors; the fingerprint acquisition board is used to connect fingerprint modules, among which the sensor interfaces J1, J2, J3, etc. uniformly use the XH2.54-4P interface. The control interfaces P1, P2, P3, etc. have the same structure. The customized control board includes a lighting control board, an alarm control board, a motor control board, etc. The lighting control board is used to control lighting; the alarm control board is used to control the alarm; and the motor control board is used to control the motor.

[0044] 2. Sensor plug and play: The communication protocol is customized according to the type of sensor. The experimental mainboard automatically identifies the connected sensors and the unplugged sensors, supports hot plugging, and realizes plug and play.

[0045] Advantages: The current conventional sensor experimental device requires the host and the sensor to be correctly connected before the experiment can begin. Because the interface type of each sensor is different, the host is required to initialize each sensor interface when powered on, identify the connected sensor connection is normal, and then enter the experimental program. The sensor interface of the present invention adopts a unified interface. Therefore, the experimental mainboard uniformly initializes all sensor interfaces when powered on, and there is no need to initialize the sensor immediately. The host automatically identifies the connection and disconnection of the sensor through a customized two-way communication protocol and reads the data of the connected sensor.

[0046] In terms of hardware, an indicator light is set next to each sensor interface on the experimental mainboard to indicate the status of the sensor interface. For example, if the light is off, it means that there is no sensor connected, if the light is on, it means that the sensor is connected, and if the light flashes, it means that data is being transmitted.

[0047] The process of mainboard polling sensor: Figure 2 As shown, the main program reads the data of each sensor in turn and determines whether it is connected. Reading the data of each sensor generally includes the following steps:

[0048] (1) Send a query command to the i-th sensor, where i is the sensor number.

[0049] (2) Set the waiting time to T di, start the timer and wait for the sensor to return data. (Because the response time of each sensor is different, the host sets a different waiting time for each sensor. If the sensor does not return data within the set time, it is considered that the sensor is not connected.)

[0050] (3) If at the set time T di If the data returned by the sensor is received, go to step (4); otherwise, go to step (5).

[0051] (4) Adjust T according to a certain method di size (see below), set the sensor connection normal flag, process the sensor data, and go to step (6).

[0052] (5) Set the sensor connection failure flag, set the sensor data to invalid, and go to step (6).

[0053] (6) This sensor query ends.

[0054] T di How to set up and adjust:

[0055] In the conventional method of polling sensors by the mainboard, the query waiting time of each sensor is the same. For example, the response time of MODBUS devices for industrial use is often set to a fixed value. If the number of sensors is large, the polling cycle will be long. In order to reduce the polling time, the present invention automatically adjusts the waiting time when the host polls according to the response time of each sensor, thereby shortening the polling time.

[0056] When the experimental mainboard is powered on for the first time, it does not know the response time of each sensor. First, set T di The initial value is the same for each sensor, T di =T dinit , T dinit Able to meet the response time of any sensor, such as 500ms.

[0057] Each time the sensor is polled, if di Receive sensor data within the time and record the sensor response time T ri If the response time exceeds the longest response time T of the sensor in the previous polling rimax , then update T rimax , that is, T rimax =T ri , the purpose is to record the longest response time of the sensor.

[0058] If T di >f s T rimax , where f sis the insurance factor (for example, 2), then reduce T di , T di =T di -ΔT di , ΔT di is the reduction amount (for example, 1ms each time). Gradually approaching f s T rimax ; When equal to or less than f s T rimax When di .

[0059] 3. Voice interactive experiment guidance: One of the customized acquisition boards is a voice recognition module, which is connected to a microphone; one of the customized control boards is a voice generation module, which is connected to a speaker; it can realize automatic voice guidance prompts for the experiment process. During the experiment, the host sends voice prompts according to the current experimental steps, listens to the students' answers, and prompts the experimental operation steps based on the answers.

[0060] like Figure 3 As shown, it mainly includes the following links:

[0061] (1) During the experiment preparation: After the experimental device is turned on, it will issue a voice prompt to prompt the student to select an experimental project, wait for the student to answer, automatically recognize the student's voice, and enter the corresponding experimental project program.

[0062] (2) At the beginning of the experiment: Voice prompts students to connect the sensors, and constantly reminds students of sensors that have not been connected, sensors that are connected incorrectly, etc.

[0063] (3) During the experiment: Voice prompts the students about the current operation precautions and the next operation content. During the experiment, if the mainboard detects common faults or operation errors, voice prompts the students about the troubleshooting and correction methods.

[0064] (4) When the experiment is completed: voice prompts for basic evaluation of the experimental results, disconnection of the power supply, organization and storage of experimental materials, etc. Advantages: Voice interaction can guide students' operations in real time, improve experimental efficiency, solve common problems in the experimental operation process, and reduce the workload of teachers' guidance.

[0065] 4. Image sensor experiment and student identification

[0066] This experimental device is equipped with a camera, one of which is a custom acquisition board for the image acquisition board. The image acquisition board is connected to the camera, which is used to identify students and supervise the experimental process. The camera is set in a fixed position, facing the experimenter, so that the experimenter's face can be photographed. The camera has two uses. One is to conduct image acquisition and recognition experiments, such as face recognition access control, clocking in at work, etc. The other is to automatically identify the identity of students to ensure that students complete the experiment independently and prevent other students from operating on their behalf during the experiment.

[0067] Here is an explanation of student identification: In order to save space, the laboratory tables are usually placed closely together, and there is no distance between adjacent students. There are laboratory racks on the laboratory tables, and laboratory instruments are placed on the laboratory racks. The laboratory racks and laboratory instruments usually block most students' operation processes, so during the experiment, it is difficult for teachers to supervise each student to complete the experimental operation independently. Figure 4 As shown, in order to supervise students to complete experiments independently (especially during experimental exams), the experimental device uses a camera. During the experiment, when a major operation link is detected, a photo is automatically taken. During the entire experiment, several photos will be taken. When the facial features in the photos taken are detected to be inconsistent, a voice prompt will be issued, such as: the experimenter is detected to be inconsistent, which greatly reduces the difficulty of supervision.

[0068] 5.Synchronous comparison experiment of multiple similar sensors

[0069] Conventional sensor experiments usually only conduct separate experiments on one type of sensor in each experiment. For example, in a thermistor experiment, the resistance of the thermistor is measured as the temperature changes, and the corresponding relationship between the resistance and temperature and the measurement accuracy are recorded and analyzed. However, for practical applications, there are many types of temperature sensors, such as thermistors, thermocouples, thermistors, infrared temperature sensors, digital temperature sensors, etc. It is necessary to select the appropriate type of temperature sensor according to the specific application scenario. This experimental device provides a simultaneous comparison experiment of multiple sensors, which intuitively displays the characteristics of different types of sensors, including temperature sensors and weighing sensors. 5.1 Simultaneous comparison experiment of multiple temperature sensors

[0070] like Figure 5 , Figure 6 , Figure 21-Figure 25As shown, the structure is: a temperature-adjustable experimental box (a simple small hot and cold shock experimental box), equipped with various temperature sensors such as thermal resistors, thermocouples, thermistors, infrared temperature sensors, digital temperature sensors, etc. The experimental mainboard adjusts the temperature of the experimental box through a heating device to achieve a temperature range of dozens of degrees below zero (the temperature of dry ice is -78.5 degrees) to hundreds of degrees above zero (achieved by heating, such as the temperature of the fin heating rod is about 450 degrees), and reads the measurement results of different temperature sensors. Because different types of sensors have their own ranges and temperature resistance ranges, exceeding the range will cause the measurement error to become larger, and exceeding the temperature resistance range will cause sensor failure. By measuring the values ​​of each sensor from low temperature to high temperature, the synchronous data change curve, measurement error, over-range state, over-temperature fault state, etc. of each sensor are intuitively displayed. It is a normal temperature measurement experiment + destructive experiment.

[0071] Structural description: (1) The vent / pressure relief structure is designed to balance the air pressure inside and outside the box to prevent explosion hazards. (2) The dry ice box / refrigeration device is installed near the upper part of the box cavity, taking advantage of the fact that cold air has a high density and naturally flows downward. (3) The heating device is installed near the lower part of the box cavity, taking advantage of the fact that hot air has a low density and naturally flows upward. (4) The air circulation device is a fan, which is used to increase the air flow speed in the box to make the temperature more uniform. (5) The object to be measured is placed directly opposite the infrared sensor probe to reduce the distance between the infrared sensor probe and the object to be measured, thereby improving measurement accuracy.

[0072] Temperature adjustment instructions:

[0073] (1) Experimental preparation: Place sufficient dry ice in the experimental box so that the temperature inside the box drops and stabilizes at a temperature close to that of dry ice.

[0074] (2) Temperature reference: In the process of changing from low temperature to high temperature, select appropriate temperature sensor data as the reference. For example, when the temperature is below -25 degrees, the measured temperature of the thermistor is used as the reference temperature; when the temperature is between -25 and 120 degrees, the digital temperature sensor is used as the reference temperature; when the temperature is above 120 degrees, the infrared sensor is used as the reference temperature.

[0075] (3) Temperature regulation: The experimental mainboard collects the temperature of each sensor and adjusts the power of the heating device to achieve temperature closed-loop regulation. The greater the heating power, the higher the temperature.

[0076] Fig.21 The circuit diagram of the experimental mainboard; MCU is the main control chip of the experimental mainboard, U4 and U5 are serial port to RS485 interface chips, which convert RS485 sensor data into serial port data and send it to the main control chip, or send the main control chip instructions to the custom control board, CN1-CN6 are the unified sensor interface of U4, and CN7-CN10 are the unified control interface of U5; Fig. 22The circuit diagram of the custom control board for heating, fan, light and speaker. Since the circuits are the same, only one circuit diagram is drawn. The single-chip microcomputer U11 of the custom control board obtains the experimental mainboard data through the unified control interface CN7, and drives the heating, fan, light and speaker to work through the driver chip U9. The U9 model is LF05P15W-ADJ, and U6 is a serial port to RS485 chip; Fig.23 The circuit diagram of the custom acquisition board for thermocouples; P1 is connected to the thermocouple, the conversion chip U8 converts the thermocouple data into digital signals and sends them to the single-chip microcomputer U21, the single-chip microcomputer U21 converts the thermocouple data into serial port data, and U6 converts the serial port data into RS485 data and transmits it to the experimental main board via CN1; Fig.24 This is the circuit diagram of the custom acquisition board for the thermal resistor. The single-chip microcomputer U31 obtains the signal of the thermal resistor PT100 and sends it to the experimental main board through the sensor interface CN2; Fig.25 This is the circuit diagram of the custom acquisition board for thermistor. The single-chip microcomputer U41 collects the signal of the thermistor and sends it to the experimental main board through the sensor interface CN3; Fig.26 This is the circuit diagram of the custom acquisition board for speech recognition. The single-chip microcomputer U51 collects the microphone MIC signal through the conversion chip U10 (model SU-03T) and sends it to the experimental main board through CN4; the detailed working principles of these circuits are not repeated here.

[0077] 5.2 Synchronous comparison experiment of multiple weighing sensors

[0078] Conventional weighing sensor experiments only target one type of weighing sensor, and the main contents include zero point calibration, range calibration, zero point drift, hysteresis characteristics, etc.

[0079] Since there are many types of structural forms and elastic materials of weighing sensors, and the working characteristics of different weighing sensors vary greatly, it is necessary to select a suitable weighing sensor according to the actual application scenario.

[0080] The present invention proposes a combination structure of multiple weighing sensors, realizes a synchronous comparison experiment of the multiple weighing sensors, and intuitively displays and compares the working characteristics of different weighing sensors.

[0081] like Figure 7-Figure 9 As shown, it includes 4 weighing sensors, 2 of which are tension type and 2 are pressure type. It uses a hanging rope and a pallet to measure the same object.

[0082] (1) Zero point calibration: Without placing any weights, perform zero point calibration on all weighing sensors.

[0083] (2) Range calibration: Place full-scale weights and calibrate the range of all weighing sensors.

[0084] (3) Hysteresis characteristics: The weight of the weight is gradually increased from small to large, and the measurement values ​​of each weighing sensor are collected. Then the weight of the weight is gradually reduced from large to small, and the measurement values ​​of each weighing sensor are collected. The host draws the hysteresis characteristic curves of different types of weighing sensors to intuitively compare the hysteresis characteristics of weighing sensors with different structures and materials.

[0085] (4) Creep characteristics: Place full-scale weights, read the measurement values ​​of each weighing sensor periodically (for example, 1 minute), and draw a curve of the measurement value changes over time. As time goes by, the measurement results of some weighing sensors will gradually show errors, and the errors will gradually increase. The creep characteristics of weighing sensors with different structures and materials can be intuitively compared. Zero point calibration and range calibration need to be re-performed after the experiment.

[0086] (5) Overload characteristics: This experiment is a destructive experiment. The weight of the weight increases gradually from small to large until it exceeds the maximum bearing weight of several weighing sensors, causing serious deviations in the measured values. The error change characteristics of the sensor under overload conditions are collected. For example: the maximum bearing weights of the four weighing sensors are 10kg, 10kg, 20kg, and 20kg respectively. During the overload experiment, when the weight exceeds 10kg, errors begin to appear in the measurement values ​​of weighing sensors No. 1 and No. 2. At this time, the measurement values ​​of weighing sensors No. 3 and No. 4 are still accurate. Therefore, the errors of weighing sensors No. 1 and No. 2 can be calculated. The weight of the weight is gradually increased until it approaches 20kg, but does not exceed 20kg. The experiment is stopped and the host draws the error change curves under different overload weights. Fig. 27 As shown, a corresponding magnetic suspension device is fixedly arranged above the No. 2 weighing sensor and the No. 3 weighing sensor, and a corresponding electromagnetic coil is arranged in the magnetic suspension device. The No. 2 weighing sensor and the No. 3 weighing sensor are provided with a shell made of silicon steel material. The electromagnetic coil is connected to the experimental mainboard as a control device. The electromagnetic coil current is adjusted by the experimental mainboard, so that the magnetic suspension device has a suction force on the No. 2 weighing sensor and the No. 3 weighing sensor that is equal to their respective weights, so that the No. 2 weighing sensor and the No. 3 weighing sensor are in a suspended state, and the self-weight of the No. 2 weighing sensor and the No. 3 weighing sensor is prevented from affecting the measurement accuracy. Preferably, the experimental mainboard is also connected to the electromagnetic coil via a frequency converter. When the experimental mainboard outputs direct current to the electromagnetic coil, the weighing sensor is in a suspended state. When the experimental mainboard outputs alternating current to the electromagnetic coil through the frequency converter, the weighing sensor is in an alternating creep state, and the anti-creep performance of the weighing sensor is detected.

[0087] 6. Sensor application scenario experiment: Conventional sensor experiments are experiments on the principles and characteristics of a single sensor, and there are few experiments on sensor application scenarios. In addition to realizing experiments on a single sensor, this experimental device also proposes to use multiple sensors and control devices to realize some application scenarios, which is helpful to improve students' interest, hands-on ability, and innovation ability.

[0088] 6.1 Smart Home Scenario Experiment: Fig.10 As shown in the figure, (1) Intelligent lighting control experiment. Infrared human body sensing sensors and ultrasonic human body sensing sensors are used. When a person is detected, the experimental mainboard controls the light to turn on. When no one is present, the experimental mainboard controls the light to turn off. The experimental interface (touch screen or experimental computer) displays the time when the person is detected and the time when the person leaves. The image is used to identify the student's identity, and the voice is used to guide the experimental process. The connection components required for the experiment are as follows: Fig.10 As shown, for simplicity, components are used to represent a customized acquisition board and sensors or a customized control board and a controlled object, and the computer and human-computer interface are omitted.

[0089] (2) Intelligent access control experiment. Figure 11-Figure 12 As shown in the figure, there are three unlocking methods, including face recognition, fingerprint recognition, and voice password recognition. Among them, face recognition and fingerprint recognition are the same as conventional access control, so they will not be repeated.

[0090] This experimental device provides a voice password access control method. A string of numbers and letters is set as the password. When the voice recognition component recognizes the corresponding string and there are no other numbers and letters within a period of time before and after, the password is considered correct. The electromagnet controls the access control switch.

[0091] (3) Intelligent voice experiment. Fig.13 As shown, it includes light control and fan (motor) control. The light control experiment is to control the light switch, brightness adjustment, and color temperature adjustment through voice. The fan control experiment is to control the fan switch and speed adjustment through voice.

[0092] 6.2 Smart Agriculture Scenario Experiment

[0093] (1) Intelligent watering experiment. Fig.14 As shown, the automatic watering scenario of soil drying is simulated, the soil moisture content is collected, and the motor-driven water pump is started when it is lower than a certain value, and the water pump is stopped when it is higher than a certain value. The image acquisition component is used to collect soil images.

[0094] (2) Intelligent material and water addition experiment. Fig.15 As shown, the scene of automatically adding feed and water in a farm is simulated, where water level sensor 1 is used to detect whether the water tank is short of water, water level sensor 2 is used to detect whether the water tank is full of water, material sensor 1 is used to detect whether the feed box is short of material, material sensor 2 is used to detect whether the feed box is full of material, the material sensor can use a capacitive proximity switch, the solenoid valve control component is used to control the water supply pipeline switch, and the motor control component is used to control the feed motor switch. The image acquisition component is used to collect farm images, the voice recognition component is used to recognize voice commands, and the voice control component is used to issue voice prompts.

[0095] 6.3 Intelligent Environment Monitoring Scenario Experiment

[0096] (1) Urban meteorological monitoring experiment. Fig.16 As shown, the sensors include wind speed and direction sensors, air temperature and humidity sensors, PM2.5 / PM10 sensors, noise sensors, etc., and sensors that meet the interface standards can be added. The control equipment includes voice control components and lighting control components. Set the alarm range of the PM2.5 / PM10 sensor, and when it exceeds the alarm range, sound and light alarms are issued. The wind speed and direction sensor and the customized acquisition board form a wind speed / wind direction component; the air temperature and humidity sensor and the customized acquisition board form an air temperature and humidity component, and the remaining sensors and the customized acquisition board also form corresponding components, the same below.

[0097] (2) Air pollution monitoring experiment. Fig.17 As shown, the sensors include oxygen concentration sensor, carbon dioxide concentration sensor, VOC concentration sensor, formaldehyde concentration sensor, ammonia concentration sensor, methane concentration sensor, etc. Sensors that meet the interface standards can be added. Set the alarm range of each sensor concentration, and when it exceeds the alarm range, sound and light alarms are issued.

[0098] (3) Field environmental monitoring experiments. Fig.18 As shown, the sensors include soil temperature / PH value / conductivity / water content sensor, air temperature and humidity sensor, wind speed and direction sensor, light sensor, precipitation sensor, etc. Sensors that meet the interface standards can be added. Set the alarm range of each sensor concentration, and when it exceeds the alarm range, sound and light alarm will be issued.

[0099] 6.4 Intelligent manufacturing scenario experiment: (1) Part posture control experiment. Fig.19 As shown, the sensor includes a posture sensor (a 3-axis acceleration sensor, a 6-axis posture sensor, etc. may be used), and the control device includes a motor control component. The posture sensor is used to detect the tilt angle of the part, and the motor is used to adjust the tilt angle of the part. The experimental process is to input the target tilt angle change curve of the part, and the experimental mainboard reads the posture sensor and adjusts the motor rotation at the same time, so that the part tilt angle tracks the target tilt angle.

[0100] 6.5 Intelligent positioning and navigation experiment: (1) Movement statistics experiment. Fig. 20 As shown, the sensor includes a satellite positioning module (such as model LC761C), and the experimental mainboard displays longitude, latitude, altitude, speed, moving distance, cumulative climb altitude, etc. in real time.

[0101] The advantages of the present invention are as follows: the hardware connection is simplified, and the integration and expansion are easy. Only one type of interface is designed on the mainboard, and there are many interfaces. It is not necessary to consider the number of different types of interfaces, and it is avoided to plug the wrong interface. Only one type of connecting wire is needed, which greatly simplifies the wiring in the experimental process, and different types of sensors can be connected at will. The sensor is plug-and-play. The host automatically identifies the connection and disconnection of the sensor through a customized two-way communication protocol, reads the data of the connected sensor, and automatically prompts the sensor that needs to be connected and disconnected.

[0102] End of instruction manual.

Claims

1. A sensor testing device, characterized in that: It includes a test mainboard, which is provided with a unified sensor interface, the sensor interface is connected to a customized acquisition board, and the customized acquisition board is used to connect to corresponding sensors to obtain data; The experimental main board is connected to the customized acquisition board via a unified communication protocol to obtain sensor data.

2. A sensor testing device according to claim 1, characterized in that: The test mainboard is connected to a test computer to form a host.

3. A sensor testing device according to claim 2, characterized in that: The experimental main board is connected to a customized control board, and the customized control board is used to connect to the control device. The experimental main board and the customized control board use a unified control interface connection and communication protocol communication.

4. A sensor testing device according to claim 3, characterized in that: The sensor test device is a synchronous comparison experimental device for multiple temperature sensors. There are at least two sensor interfaces. Each sensor interface is connected to a temperature sensor of a corresponding type through a corresponding customized acquisition board. The temperature sensor is fixedly installed in a cold and hot shock test box. The cold and hot shock test box is provided with a box body. A vent / pressure relief structure is provided on the box wall of the box body; a dry ice box / refrigeration device is provided at the upper part of the inner cavity of the box body; a heating device is provided at the lower part of the inner cavity of the box body; an air flow circulation device is fixedly provided in the box body, wherein the refrigeration device, the heating device, and the air flow circulation device are control devices; The temperature of the hot and cold shock test box is adjusted by the dry ice box / refrigeration device and the heating device, and the measurement results of different types of temperature sensors are read. By measuring the values ​​of each temperature sensor from low temperature to high temperature, the temperature synchronization comparison experimental characteristics of various types of temperature sensors are intuitively displayed, and normal temperature measurement experiments and destructive experiments are carried out on the temperature sensors.

5. A sensor testing device according to claim 4, characterized in that: There are 5 sensor interfaces, which are connected to thermal resistors, thermocouples, thermistors, infrared temperature sensors, and digital temperature sensors through corresponding customized acquisition boards; The characteristics of temperature synchronization comparison experiment include synchronization data change curve, measurement error, over-range state, over-temperature fault state; The temperature reference used by the test motherboard for box temperature adjustment is: when it is below -25 degrees, the temperature measured by the thermistor is used as the reference temperature; when it is between -25 and 120 degrees, the digital temperature sensor is used as the reference temperature; when it is above 120 degrees, the infrared temperature sensor is used as the reference temperature.

6. A sensor testing device according to claim 2, characterized in that: The sensor test device is a synchronous comparison experimental device for multiple weighing sensors, and the synchronous comparison experimental device includes a fixed object, at least one tension weighing sensor is connected in series at the bottom of the fixed object through a suspension rope, a tray is arranged below the tension weighing sensor, the bottom tension weighing sensor is connected to the edge of the tray by at least two suspension ropes to suspend the tray, at least one pressure weighing sensor is stacked on the upper surface of the tray, and the tension weighing sensor and the pressure weighing sensor are both provided with their own customized acquisition boards, which are connected to the test main board through a unified sensor interface; Use the sling and pallet to measure the same object; (1) Zero point calibration: without placing any weights, perform zero point calibration on all tension load cells and pressure load cells; (2) Range calibration: Place full-scale weights and calibrate the range of all tension load cells and pressure load cells; (3) Hysteresis characteristics: The weight of the weight gradually increases from small to large, and the measurement values ​​of each tension load cell and pressure load cell are collected. Then the weight of the weight gradually decreases from large to small, and the measurement values ​​of each tension load cell and pressure load cell are collected. The host draws the hysteresis characteristic curves of different types of load cells, and intuitively compares the hysteresis characteristics of load cells with different structures and materials. (4) Creep characteristics: Place full-scale weights, periodically read the measured values ​​of each tension load cell and pressure load cell, and draw a curve of the measured value change over time. As time goes by, the measurement results of some tension load cells or pressure load cells will gradually show errors, and the errors will gradually increase. The creep characteristics of load cells with different structures and materials can be intuitively compared. Zero point calibration and range calibration need to be re-performed after the experiment. (5) Overload characteristics: This experiment is a destructive experiment. The weight of the weight increases gradually from small to large until it exceeds the maximum bearing weight of several tension load cells or pressure load cells, causing serious deviation in the measurement value. The error change characteristics of the tension load cell or pressure load cell under overload conditions are collected.

7. A sensor testing device according to claim 3, characterized in that: The sensor test device is an intelligent access control test device, which includes an image acquisition component, a fingerprint recognition related component, and a voice recognition component; the image acquisition component includes a face recognition sensor, which is connected to the test main board via a corresponding customized acquisition board; the fingerprint recognition related component includes a fingerprint recognition sensor, which is connected to the test main board via a corresponding customized acquisition board; the voice recognition component includes a voice recognition sensor, which is connected to the test main board via a corresponding customized acquisition board; The intelligent access control experimental device provides a voice password access control method. A string of numbers and letters is set as the password. When the voice recognition component recognizes the corresponding string and there are no other numbers and letters in a period of time before and after, the password is considered correct and a signal is sent to the test mainboard. The test mainboard controls the electromagnet to be energized, and the electromagnet is energized to control the access control to open; if the password is incorrect, the electromagnet is powered off and the access control is not opened; the electromagnet is a control device.

8. A control method comprising the sensor testing device according to claim 1, characterized in that: The test mainboard is set up with a polling sensor process: The main program of the test motherboard reads the data of each sensor in turn and determines whether it is connected. Reading the data of each sensor includes the following steps: Step A1, sending a query instruction to the i-th sensor; Step A2: Set the waiting time to T di , start the timer and wait for the sensor to return data; Step A3: If the set time T di If the data returned by the sensor is received, go to step A4, otherwise go to step A5; Step A4: Adjust T according to the setting method di The sensor connection is normal, the sensor data is processed, and the process goes to step A6; Step A5, set the sensor connection failure flag, set the sensor data to invalid, and go to step A6; Step A6: The sensor query ends.

9. The control method of the sensor testing device according to claim 8, characterized in that: In step 4, T di Setup and adjustment methods include: When the test motherboard is powered on for the first time, first set T di The initial value is the same for each sensor, T di =T dinit , T dinit Able to meet the response time of any sensor; Each time the sensor is polled, if di Receive sensor data within the time, record the sensor response time T ri If the response time exceeds the longest response time T of the sensor in the previous polling rimax The value of T is updated rimax The value of T rimax The value is equal to T ri ; If T di >f s T rimax , where f s is the insurance factor, then reduce T di , the reduction each time is ΔT di , ΔT di It is a reduction.

10. A control method comprising the sensor testing device according to claim 3, characterized in that: One of the customized acquisition boards is a speech recognition module, which is connected to a microphone; one of the customized control boards is a speech generation module, which is connected to a speaker; The host is equipped with a voice interactive experiment guidance process. During the experiment, the host issues voice prompts according to the current experimental steps, listens to the students' answers, and prompts the experimental operation steps based on the answers; The voice interactive experiment guidance process includes the following steps: Step B1: During the experiment preparation: after the host is powered on, it will issue a voice prompt to prompt the student to select an experiment project, wait for the student to answer, automatically recognize the student's answer voice, and enter the corresponding experiment project program; Step B2: When the experiment starts: the host voice prompts students to connect sensors and control devices, and always reminds students of sensors that have not been connected or sensors that are connected incorrectly; Step B3: During the experiment: the host computer will give students voice prompts about the current operation precautions and the next operation content. During the experiment, if the test motherboard detects common faults or operation errors, the host computer will give students voice prompts about the troubleshooting and correction methods. Step B4: When the experiment is completed: the host voice prompts basic evaluation of the experimental results, disconnects the power supply, and organizes and stores the experimental materials.

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