Potentiometer output characteristic measuring device

Abstract

The utility model provides a potentiometer output characteristic measuring device, which belongs to the field of potentiometer detection and comprises a constant voltage source, a constant current source, a signal conditioning circuit, a signal sampling circuit, a motor control circuit and a master control circuit. The constant voltage source provides a stable voltage source for potentiometer testing. The constant current source provides a stable current source for potentiometer testing; the signal conditioning circuit applies a power supply to a potentiometer terminal of a tested product and selects a corresponding conditioning circuit according to a test mode; the signal sampling circuit mainly comprises a high-precision ADC (Analog to Digital Converter) device which is used for collecting output signals of the potentiometer; the motor control circuit is a stepping motor driving module with encoder feedback; and the main control circuit selects a set measurement mode according to a received upper computer test command, controls the loading of the power supply and the rotation of the potentiometer, acquires an output signal of the potentiometer, calculates an output characteristic result value and uploads the output characteristic result value to a test software interface.

Description

Technical Field

[0001] This utility model relates to the field of potentiometer measurement technology, and in particular to a potentiometer output characteristic measurement device. Background Technology

[0002] In the field of potentiometer production line finished product inspection, it is usually necessary to conduct quality inspection on the finished products, including the total resistance, linearity, smoothness and equivalent noise of the potentiometer. Generally, the total resistance and equivalent noise resistance are tested using the constant current method, while the linearity and smoothness are tested using the constant voltage method.

[0003] The conventional testing method involves manually applying a standard power supply to the potentiometer product. The appropriate test method is selected based on the measurement mode. This method is time-consuming, approximately 5 minutes, and is easily affected by manual operation, making it difficult to guarantee consistent measurement results.

[0004] Therefore, we have designed a new device that can automatically measure various parameters of potentiometer output characteristics, reducing the measurement time to less than 1 minute and providing good consistency of results. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a potentiometer output characteristic measurement device. The device utilizes a signal sampling circuit, primarily comprising a high-precision ADC device for acquiring the potentiometer output signal. The motor control circuit is a stepper motor drive module with encoder feedback. The main control circuit, based on received test commands from the host computer, selects the set measurement mode, controls the power supply and potentiometer rotation, acquires the potentiometer's output signal, calculates the output characteristic result value, and uploads it to the test software interface. This reduces the measurement time to less than one minute and ensures good result consistency.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A potentiometer output characteristic measuring device includes a constant voltage source, a constant current source, a signal conditioning circuit, a signal sampling circuit, a motor control circuit, and a main control circuit;

[0008] The constant voltage source is a programmable voltage source that receives commands from the main control circuit during the test and outputs a set voltage to provide a stable voltage source for potentiometer testing.

[0009] The constant current source is a programmable current source. During the test, it receives commands from the main control circuit and outputs a set current to provide a stable current source for potentiometer testing.

[0010] The signal conditioning circuit includes a measurement mode switching circuit and a signal processing circuit. It selects to apply power to the potentiometer terminal of the product under test and selects the corresponding signal processing circuit according to the test mode.

[0011] The signal sampling circuit mainly includes a high-precision ADC device, which is used to acquire the signal output after the potentiometer output is processed by the signal conditioning circuit.

[0012] The motor control circuit is a stepper motor drive module with encoder feedback;

[0013] The main control circuit selects the set measurement mode according to the received test command from the host computer, controls the loading of the power supply and the rotation of the potentiometer, and collects the output signal of the potentiometer, calculates the output characteristic result value and uploads it to the test software interface.

[0014] Preferably, the potentiometer output characteristic measuring device has a total resistance measurement function, and the measurement range covers 100Ω to 20KΩ.

[0015] Preferably, the potentiometer output characteristic measuring device has the function of measuring the output equivalent noise resistance of the potentiometer.

[0016] Preferably, the potentiometer output characteristic measuring device has a smoothness testing function.

[0017] Preferably, the potentiometer output characteristic measuring device has a linearity testing function.

[0018] The beneficial effects of this utility model are as follows:

[0019] (1) The present invention mainly includes a high-precision ADC device in the signal sampling circuit for acquiring the potentiometer output signal; the motor control circuit is a stepper motor drive module with encoder feedback; the main control circuit selects the set measurement mode according to the received upper computer test command, controls the power supply loading and potentiometer rotation, and acquires the potentiometer output signal, calculates the output characteristic result value and uploads it to the test software interface, shortening the measurement time to less than 1 minute and having good result consistency.

[0020] (2) The present invention is mainly composed of a driver, a stepper motor and an encoder through a motor control circuit, forming a closed-loop rotation control mechanism. During the test, it directly drives the potentiometer handle to rotate. Depending on the test mode, the step interval angle can be selected to run at 0.3 to 10° or to run continuously.

[0021] (3) The main control circuit of this utility model is mainly composed of a microcontroller, a power supply module and a communication interface. It is used to receive test instructions from the host computer test software, control the loading of power supply and the switching of signal mode, collect output waveform data and upload it to the test software interface. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the measuring device structure of this utility model;

[0023] Figure 2 This is a circuit diagram of the measuring device of this utility model;

[0024] Figure 3 This is a schematic diagram of the signal conditioning circuit of this utility model;

[0025] Figure 4 This is a schematic diagram of the signal sampling circuit of this utility model;

[0026] Figure 5 This is the schematic diagram of the main control circuit of this utility model. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] Example: Figures 1-5 As shown, this utility model provides a potentiometer output characteristic measuring device, which includes a constant voltage source, a constant current source, a signal conditioning circuit, a signal sampling circuit, a motor control circuit, and a main control circuit.

[0031] The constant voltage source is a programmable voltage source with an output accuracy of 1‰ and an adjustable output voltage range of 0 to 31V. In the potentiometer linearity and smoothness measurement mode, this voltage is applied to the potentiometer.

[0032] The constant current source is a programmable current source with an output accuracy of 1‰ and an adjustable output current range of 0-100mA. In the potentiometer total resistance and equivalent noise resistance measurement mode, the current is applied to the potentiometer.

[0033] The signal conditioning circuit includes a measurement mode switching circuit and a signal processing circuit. In the total resistance test mode, relays KA2 / KA6 / KA7 are closed, and the switching circuit controls the constant current source to be applied to the potentiometer power supply terminal, and the voltage signal at the power supply terminal is connected to the subsequent signal sampling circuit. In the linearity test mode, relays KA3 / KA6 are closed, and the switching circuit controls the constant voltage source to be applied to the potentiometer power supply terminal, and the sliding arm terminal of the potentiometer is connected to the signal processing circuit. In the equivalent resistance noise test mode, relays KA1 / KA5 / KA6 / KA7 are closed, and the switching circuit controls the constant current source to be applied to the sliding arm terminal of the potentiometer and one end of the power supply, and the signals at the sliding arm terminal and the other end of the power supply are connected to the subsequent signal processing circuit. In the output smoothness test, relays KA3 / KA4 / KA6 are closed, and the switching circuit controls the constant voltage source to be applied to both ends of the potentiometer power supply, and the signals at the sliding arm terminal and the potentiometer ground terminal are connected to the subsequent signal processing circuit.

[0034] The signal sampling circuit mainly consists of a high-precision, high-speed ADC with a sampling resolution of 18 bits and a sampling rate of 200K / s. It converts the potentiometer-output conditioned signal into a digital signal and transmits it to the microcontroller of the main control circuit through a parallel interface.

[0035] The motor control circuit mainly consists of a driver, a stepper motor, and an encoder, forming a closed-loop rotary control mechanism. During the test, it directly drives the potentiometer handle to rotate, and the step interval angle can be selected from 0.3 to 10° or continuous rotation operation according to the test mode.

[0036] The main control circuit consists of a microcontroller, a power module, and a communication interface. It is used to receive test commands from the host computer test software, control the power supply loading and signal mode switching, collect output waveform data, and upload it to the test software interface.

[0037] 1. Constant pressure source

[0038] The constant voltage source is a purchased standard programmable voltage source with a constant voltage accuracy of 1‰ and a voltage adjustment range of 0-31V. The voltage output of the constant voltage source is connected to the signal conditioning circuit to provide a stable voltage output for the measurement circuit; the programmable interface of the constant voltage source is connected to the first RS232 interface (U1) of the main control circuit.

[0039] 2. Constant current source

[0040] The constant current source is a purchased standard programmable current source with an output accuracy of 1‰ and an output current adjustment range of 0-100mA. The current output of the constant current source is connected to the signal conditioning circuit to provide a stable current output for the measurement circuit; the programmable interface of the constant current source is connected to the second RS232 interface (U3) of the main control circuit.

[0041] 3. Signal conditioning circuit

[0042] The signal conditioning circuit includes a measurement mode switching circuit and a signal processing circuit. Resistors RX1 / RX2, the Darlington driver chip U9 (ULQ2803LW), and relays KA1 / 2 / 3 / 4 / 5 / 6 / 7 constitute the measurement mode switching circuit; resistors 1RF1 / 1RF2 and capacitors 1CF1 / 1CF2 constitute the signal processing circuit. The OUT_A01~07 control signals from the microcontroller U15 in the main control circuit are connected to the input terminal of U9 after passing through RX1 / RX2. The amplified signals Rly_A01~07 are connected to the negative terminals of the coils of relays KA1~KA7, and the positive terminals of the relays are connected to a 24V voltage. When OUT_A01~07 outputs a high level, Rly_A01~07 outputs a low level, and the corresponding relays KA1~KA7 are energized; when OUT_A01~07 outputs a low level, Rly_A01~07 outputs a high level, and the corresponding relays KA1~KA7 are de-energized. The main control module switches the measurement modes by controlling the opening and closing of each relay. Connect the potentiometer input to terminal P2, and connect the two terminals (signals VR1_1 / VR1_3) and one sliding arm terminal (VR1_2) of the potentiometer to relays KA6 and KA1 of the signal conditioning circuit, respectively.

[0043] In the total resistance test mode, the microcontroller U15 outputs OUT_A02 / 06 / 07 at a high level and the rest at a low level, controlling the relays KA2 / KA6 / KA7 to close. The switching circuit controls the constant current source to be applied to the power supply terminal of the potentiometer, and the voltage signal of the power supply terminal is connected to the subsequent signal sampling circuit. The VR1_1 of the potentiometer is connected to the current source signal through the relay, and the VR1_3 of the potentiometer is connected to the test ground wire through the relay. The VR1_1 signal is connected to AD_01 through the relay and then connected to the signal sampling circuit.

[0044] In the linearity test mode, the microcontroller U15 outputs OUT_A03 / 06 at a high level and the rest at a low level, controls the relays KA3 / KA6 to close, and the switching circuit controls the constant voltage source to be applied to the power supply terminal of the potentiometer, and connects the slider of the potentiometer to the signal processing circuit; the voltage output of the constant voltage source of the potentiometer is connected to the VR1_1 of the potentiometer through the relay, the voltage output of the constant voltage source of the potentiometer is connected to the signal sampling circuit after being connected to AD_01 through the relay, and the voltage output of the potentiometer is connected to the test ground through the relay.

[0045] In the equivalent resistance noise test mode, the microcontroller U15 outputs OUT_A01 / 05 / 06 / 07 at a high level and the rest at a low level, closes relays KA1 / KA5 / KA6 / KA7, and switches the circuit to control the constant current source to apply to the slider end of the potentiometer and one end of the power supply. The signals from the slider end and the other end of the power supply are then connected to the subsequent signal processing circuit. The potentiometer VR1_1 is connected to the constant current source output through a relay, the potentiometer VR1_2 is connected to the test ground through a relay, and the potentiometer VR1_3 is connected to AD_01 through a relay and then connected to the signal sampling circuit.

[0046] In the output smoothness test, the microcontroller U15 outputs OUT_A03 / 04 / 06 at a high level and the rest at a low level, controlling the relays KA3 / KA4 / KA6 to close. The switching circuit controls the constant voltage source to be applied to both ends of the potentiometer power supply, and the signals from the slider end and the potentiometer ground end are connected to the subsequent signal processing circuit. The potentiometer VR1_1 is connected to the output end of the constant voltage source through a relay, the potentiometer VR1_3 is connected to the test ground through a relay, and the potentiometer VR1_2 is connected to resistors 1RF1 / 1RF2 and capacitors 1CF1 / 1CF2 through a relay to form a signal processing circuit, which is then connected to AD_01 and then connected to the signal sampling circuit.

[0047] 4. Signal sampling circuit

[0048] The signal sampling circuit mainly consists of a high-precision, high-speed ADC chip U21 (AD7609) and external capacitors. C98 is a power supply decoupling capacitor, and C94 / C95 / C96 / C97 are used to assemble the U21 chip. The sampling resolution is 18 bits, and the sampling rate is 200K / s. The digital part of the U21 chip is powered by 3.3V, and the analog part is powered by 5V. The range setting pin RANGE is connected to a high level to set the sampling range to ±10V. The reference selection fuze REF SELECT is connected to a high level to select the use of the internal reference voltage. The U21 chip connects to the main control MCU using a parallel interface, including data lines M_D00~M_D15 and control signal lines such as M_CVT / RST / RD / CS / BUSY / FD1. The main control MCU starts the analog-to-digital conversion through the control signal pins and checks whether the conversion is complete. Then, it reads the conversion data result through the 16-bit data lines (M_D00~M_D15).

[0049] 5. Motor control circuit

[0050] The motor control circuit mainly consists of a driver, a stepper motor, and an encoder, forming a closed-loop rotation control mechanism. During testing, it directly drives the potentiometer handle to rotate, selecting a step interval angle of 0.3–10° or continuous rotation operation depending on the test mode. The stepper motor driver receives the enable signal MT_EN, the direction control signal MT_DIR, and the pulse signal MT_PULSE from the main control unit microcontroller. A high-level enable signal indicates effective driver control, while a low-level enable signal indicates ineffective control. A high-level direction control signal results in clockwise rotation, and a low-level signal results in counter-clockwise rotation. One valid pulse signal corresponds to one step of motor movement. The stepper motor is a 2-phase four-wire system, connected to the driver's A+ / A- / B+ / B- output signals. The encoder is coaxially connected to the motor, powered by 5V, and used for feedback measurement of the motor's actual rotation angle. The encoder's angle output signal A / B is connected to the main control module microcontroller's counting input pins Pin-35 / 36.

[0051] 6. Main control circuit

[0052] The main control circuit consists of a microcontroller, a power module, and a communication interface. It receives test commands from the host computer's testing software, controls power loading and signal mode switching, and collects output waveform data and uploads it to the testing software interface. The microcontroller mainly consists of an ARM microcontroller U15 (GD32F103VB) and peripheral circuits (clock and debug interface). The clock crystal Y1 operates at 3.3V with an output frequency of 8MHz. Power supply noise is decoupled using capacitor C8, and the frequency output is connected to the clock input pin (Pin-12) of the U15. The debug interface is in SW mode and consists of 5 pins, resistors R77 / R78 / R79, and capacitor C42, connecting to the microcontroller's Reset / SWDIO / SWCLK pins. The microcontroller is mainly connected to the control signal conditioning circuit through OUT_A01~07 (pins 40~46), to the control signal sampling circuit through M_CVT / M_RST / M_RD / M_CS / M_BUSY / M_FD1 and M_D00~15, and to the drive motor control circuit through MT_EN / MT_DIR / MT_PULSE and EC_A / EC_B. The power supply module mainly consists of U2 (URB2405S-6WR3), U7 (CJU1117-3.3), and external capacitors. The external 24V power supply is connected to the input terminal of U2 after being filtered and stored by capacitors C12 / C13 / C14. The 5V voltage output terminal of U2 is connected to capacitors C15 / C16 and TVS diode D8. Resistor R6 and LED-D5 are used for 5V power indication. The 5V power supply is connected to the input terminal of U4 after passing through capacitors C1 / C3. The 3.3V voltage output terminal of U4 is connected to capacitors C2 / C4. Resistor R3 and LED-D7 are used for 3.3V power indication. C47~C55 are used for decoupling the 3.3V power supply devices in the circuit. The communication interface includes three RS232 interfaces. The UART terminal RX of U1 is connected to pin 48 of microcontroller U15, and the TX terminal is connected to pin 47 of U15. The TX and RX terminals of the RS232 port are connected to the communication interface of the programmable voltage source. The UART terminal RX of U3 is connected to pin 26 of U15, and the TX terminal is connected to pin 25 of U15. The TX and RX terminals of the RS232 port are connected to the communication interface of the programmable current source. The UART terminal RX of U20 is connected to pin 69 of U15, and the TX terminal is connected to pin 68 of U15. The TX and RX terminals of the RS232 port are connected to an external test host, and surge voltage suppression is performed using D66 and D67.

[0053] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A potentiometer output characteristic measuring device, characterized in that, The measuring device includes a constant voltage source, a constant current source, a signal conditioning circuit, a signal sampling circuit, a motor control circuit, and a main control circuit; The constant voltage source is a programmable voltage source with an accuracy of 1‰, which provides a stable voltage source for potentiometer testing; The constant current source is a programmable adjustable current source with an accuracy of 1‰, which provides a stable current source for potentiometer testing; The signal conditioning circuit applies power to the potentiometer terminals of the product under test and selects the corresponding conditioning circuit according to the test mode. The signal sampling circuit mainly includes a high-precision ADC device, which is used to acquire the signal after the potentiometer output signal has been processed by the signal circuit.

2. The potentiometer output characteristic measuring device according to claim 1, characterized in that, The motor control circuit is a stepper motor drive module with encoder feedback; the main control circuit selects the set measurement mode according to the received test command from the host computer.

3. The potentiometer output characteristic measuring device according to claim 2, characterized in that, The main control circuit controls the power supply loading and potentiometer rotation, and collects the potentiometer output signal.

4. The potentiometer output characteristic measuring device according to claim 3, characterized in that, The main control circuit calculates and outputs characteristic result values ​​and uploads them to the test software interface.

5. A potentiometer output characteristic measuring device according to claim 4, characterized in that, The potentiometer has a total resistance measurement range covering 100 to 20 kΩ.

6. The potentiometer output characteristic measuring device as described in claim 5, characterized in that, The potentiometer has the function of measuring the output equivalent noise resistance.

7. The potentiometer output characteristic measuring device as described in claim 6, characterized in that, The potentiometer has a smoothness test function.

8. The potentiometer output characteristic measuring device as described in claim 7, characterized in that, The potentiometer has a linearity measurement function.

Images