Program-controlled potentiometer

Abstract

The invention relates to a program-controlled potentiometer which comprises a multi-circle wire-wound potentiometer, a servo motor, a driving controller and a microprocessor, the program-controlled potentiometer further comprises an output resistance value sampling module, the microprocessor is connected to the output resistance value sampling module and the driving controller, the input end of the servo motor is connected to the driving controller, and the output resistance value sampling module is connected to the output resistance value sampling module. The output end of the microprocessor is connected to a sliding contact of the multi-turn wire-wound potentiometer, the input end of the output resistance value sampling module is connected to the output end of the multi-turn wire-wound potentiometer, and the microprocessor is configured to adjust the position of the sliding contact of the multi-turn wire-wound potentiometer according to impedance collected by the output resistance value sampling module. Compared with the prior art, the invention has the advantages of high power, high voltage resistance, high precision and the like.

Description

Technical Field

[0001] The invention relates to an adjustable potentiometer, in particular to a program-controlled potentiometer. Background Art

[0002] The commonly used controllable potentiometer is a digital potentiometer, that is, a silicon chip integrates many resistors with specific resistance values ​​in series, and the output end is connected to one end of each resistor through many internal electronic switches. Through these IO switch quantities, a certain number of resistors are output in series, and finally the change of the output resistance value is controlled by the interface command. However, this type of potentiometer has two obvious problems: the resistance value changes discontinuously, and in particular, the power and withstand voltage are relatively low, and cannot be made very high.

[0003] Another common controllable potentiometer is the sliding resistor and the rotary potentiometer. The former also has the problem of discontinuity, and the sliding head jumps between the coil resistor wires, but it has better power and voltage resistance; the latter generally has lower power and voltage resistance than the former, but is much better than the digital potentiometer. However, the commonly used sliding potentiometers and knob potentiometers are manually pre-adjusted to a fixed value.

[0004] For some applications that require continuous resistance change, relatively high power and automatic adjustment, the above-mentioned potentiometers obviously cannot meet the actual needs, especially in many applications with a high degree of test and measurement automation, such as RF power impedance matching test and variable load test and other related fields, it is almost difficult to see satisfactory products and good solutions.

[0005] For example, Chinese patent CN103996473A provides a motor potentiometer, which replaces the manual slide bar with a motor servo, but its control accuracy and voltage resistance cannot meet the actual needs; another example is Chinese patent CN115831513A, which discloses a digital control potentiometer. After research and practice, it is found that there are also many problems, such as how to accurately obtain the position of the contact point, how to accurately obtain the current output resistance, etc.; another example is Chinese patent CN107240467A, which discloses an intelligent potentiometer, which aims to solve the problem that the input and output relationship of the intelligent potentiometer cannot be set in real time by a single machine in the prior art, resulting in poor simplicity and practicality of the intelligent potentiometer. It is different from the problem set to be solved by the present invention, and its design and implementation methods are not comparable. These are not simply replaced by electromechanical manual potentiometers.

[0006] In actual use, traditional digital potentiometers, sliding resistors and knob potentiometers have the following characteristics compared:

[0007] 1) Digital potentiometer: discontinuous change, low power consumption, low voltage resistance, usually with digital interface for external program control.

[0008] 2) Sliding resistor: non-continuous change, power and voltage resistance can be very high, usually adjusted on demand through manual or mechanical action, unable to directly provide external digital interface for control.

[0009] 3) Knob-type potentiometer: It has nearly continuous change, and its power and withstand voltage can also be very high. It is usually adjusted to a preset value manually, and cannot directly provide a digital interface for external control. Summary of the invention

[0010] The purpose of the present invention is to provide a programmable potentiometer, which uses the real-time acquisition output resistance value as feedback to form a system closed loop, and provides a high-power, high-voltage and high-precision programmable potentiometer.

[0011] The purpose of the present invention can be achieved by the following technical solutions:

[0012] A programmable potentiometer comprises a multi-turn wire-wound potentiometer, a servo motor, a drive controller and a microprocessor. The programmable potentiometer further comprises an output resistance sampling module. The microprocessor is connected to the output resistance sampling module and the drive controller respectively. The input end of the servo motor is connected to the drive controller, and the output end is connected to the sliding contact of the multi-turn wire-wound potentiometer. The input end of the output resistance sampling module is connected to the output end of the multi-turn wire-wound potentiometer. The microprocessor is configured to perform the following steps:

[0013] After receiving the power-on command, monitor the control command;

[0014] After receiving the control command, the control command is parsed to obtain the target resistance value, and the target position of the sliding contact of the multi-turn wirewound potentiometer is obtained based on the target resistance value, and the target travel distance is obtained in combination with the current position of the sliding contact.

[0015] According to the obtained travel distance, the servo motor is controlled by the drive controller to drive the sliding contact to the target position, and after the sliding contact moves to the position, the actual resistance value collected by the output resistance sampling module is obtained, and the resistance comparison step is performed;

[0016] Resistance comparison step: compare the actual resistance value with the target resistance value. If the actual resistance value is within the pre-configured error range relative to the target resistance value, the execution is completed. Otherwise, the resistance correction step is executed.

[0017] Resistance correction step: adjust the position of the sliding contact according to the difference between the actual resistance and the target resistance, and perform the resistance comparison step.

[0018] The drive controller is provided with an encoder, and in the process of controlling the servo motor to drive the sliding contact, the travel distance of the sliding contact is corrected through the output closed loop of the encoder.

[0019] The control instruction contains a limited speed, and the microprocessor is configured to further perform the following steps:

[0020] After receiving the control command, the control command is parsed to obtain the limited speed;

[0021] The step of controlling the servo motor to drive the sliding contact to the target position through the driving controller according to the obtained stroke distance is specifically: controlling the servo motor to drive the sliding contact to the target position at a limited speed through the driving controller according to the obtained stroke distance;

[0022] The resistance value correction step specifically includes: adjusting the position of the sliding contact at a limited speed according to the difference between the actual resistance value and the target resistance value.

[0023] The programmable potentiometer also includes a reducer, which is arranged between the servo motor and the sliding contact.

[0024] The center rod of the reducer is integrally connected with the center rod of the multi-turn wire-wound potentiometer.

[0025] The resistance comparison step specifically includes:

[0026] Compare the actual resistance value with the target resistance value;

[0027] If the actual resistance value is within a preconfigured error range relative to the target resistance value, a locking signal is output, wherein the locking signal controls the position locking of the sliding contact;

[0028] If the actual resistance value is outside the preconfigured error range relative to the target resistance value, a resistance correction step is performed;

[0029] The locking methods include one or more of the following:

[0030] Decoupling of servo motors and sliding contacts;

[0031] Interrupt the power supply to the servo motor;

[0032] Mechanically locks the position of the sliding contact.

[0033] A second output isolation relay is provided between the multi-turn wirewound potentiometer and the output resistance sampling module, and a control signal input end of the second output isolation relay is connected to a microprocessor, and the microprocessor is configured to further perform the following steps:

[0034] When the locking signal is sent, the second output isolation relay is controlled to disconnect the connection between the multi-turn wire-wound potentiometer and the output resistance sampling module.

[0035] A first output isolation relay is provided between the output end of the multi-turn wirewound potentiometer and the main circuit, and a control signal input end of the first output isolation relay is connected to a microprocessor, and the microprocessor is configured to further perform the following steps:

[0036] When the second output isolation relay disconnects the connection between the multi-turn wire-wound potentiometer and the output resistance sampling module, the first output isolation relay is controlled to connect the output end of the multi-turn wire-wound potentiometer and the main circuit.

[0037] The communication interface between the microprocessor and the host computer is RS232, RS485, CAN, TTL232, SPI or Ethernet.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The real-time collected output resistance value is used as feedback to form a system closed loop, providing a high-power, high-voltage and high-precision programmable potentiometer.

[0040] 2. The output closed loop is realized through the encoder, thus realizing dual closed-loop control, which not only solves the problem of real-time monitoring and accuracy of system output, but also avoids the inherent errors such as starting point reset difference, stroke difference, speed difference, etc. that are usually present in pure electromechanical control systems. Compared with existing common solutions, it completely solves the demand for high-performance programmable potentiometers in the application scenarios of automated test and measurement and intelligent manufacturing processes of electronic products. These requirements include: programmable, high voltage resistance, high power, high precision, memory function, and adaptive adjustment control. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of the present invention;

[0042] Figure 2 It is a flowchart diagram of the main steps of the program executed by the microprocessor of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0044] A programmable potentiometer, such as Figure 1As shown, it includes a multi-turn wire-wound potentiometer 1, a servo motor 2, a drive controller 3 and a microprocessor 5. The programmable potentiometer also includes an output resistance sampling module 4. The microprocessor 5 is connected to the output resistance sampling module 4 and the drive controller 3 respectively. The input end of the servo motor 2 is connected to the drive controller 3, and the output end is connected to the sliding contact of the multi-turn wire-wound potentiometer 1. The input end of the output resistance sampling module 4 is connected to the output end of the multi-turn wire-wound potentiometer 1. Figure 2 As shown, the microprocessor 5 is configured to perform the following steps:

[0045] After receiving the power-on command, it will decide whether to move to the last locked position or the initial position according to the set parameters. The parameter is obtained from the external controller through the communication interface. The default is the initial position. The initial position is set according to the maximum value of the effective output of the potentiometer, and then the control command will be monitored;

[0046] After receiving the control instruction, the control instruction is parsed to obtain the target resistance value, and the target position of the sliding contact of the multi-turn wirewound potentiometer 1 is parsed based on the target resistance value, and the target travel distance is obtained in combination with the current position of the sliding contact, wherein the control instruction at least includes the target resistance value,

[0047] According to the obtained travel distance, the servo motor 2 is controlled by the driving controller 3 to drive the sliding contact to the target position, and after the sliding contact moves to the position, the actual resistance value collected by the output resistance sampling module 4 is obtained, and the resistance comparison step is performed;

[0048] Resistance comparison step: compare the actual resistance value with the target resistance value. If the actual resistance value is within the pre-configured error range relative to the target resistance value, the execution is completed. Otherwise, the resistance correction step is executed.

[0049] Resistance correction step: adjust the position of the sliding contact according to the difference between the actual resistance and the target resistance, and perform the resistance comparison step.

[0050] The real-time acquisition of the output resistance value is used as feedback to form a system closed loop, providing a high-power, high-voltage and high-precision programmable potentiometer.

[0051] In most embodiments, the drive controller 3 is provided with an encoder 31 . When the servo motor 2 is controlled to drive the sliding contact, the travel distance of the sliding contact is corrected through the output closed loop of the encoder 31 .

[0052] The overall double closed-loop structure is adopted. The innermost layer is to calculate the target position according to the set default parameters - control algorithm - drive controller control program, that is, the servo motor output closed loop, and the outer layer is real-time output resistance sampling - calculation and correction of the target position - control algorithm - correction of the drive controller control program. The high-precision output resistance sampling module samples the value in real time, and updates and corrects the target position and travel speed in real time, that is, the resistance output closed loop. The output closed loop is realized through the encoder 31, thereby realizing double closed-loop control, which not only solves the problem of real-time monitoring and accuracy of the system output, but also avoids the inherent errors of the starting point reset difference, travel difference, speed difference, etc. that are usually present in the simple electromechanical control system. Compared with the existing common solutions, it completely solves the demand for high-performance programmable potentiometers in the application scenarios of automated test and measurement and intelligent manufacturing process of electronic products. These requirements include: programmable, high voltage resistance, high power, high precision, memory function, and adaptive adjustment control.

[0053] In addition, in some embodiments, when there is a demand for resistance value change, the control instruction contains a limited speed. In this regard, the microprocessor 5 is configured to further perform the following steps: after receiving the control instruction, the control instruction is parsed to obtain the limited speed; according to the obtained stroke distance, the servo motor 2 is controlled by the driving controller 3 to drive the sliding contact to the target position, specifically: according to the obtained stroke distance, the servo motor 2 is controlled by the driving controller 3 to drive the sliding contact to the target position at the limited speed; and the resistance value correction step is specifically: according to the difference between the actual resistance value and the target resistance value, the position of the sliding contact is adjusted at the limited speed. Correspondingly, the programmable potentiometer also includes a reducer 6, which is arranged between the servo motor 2 and the sliding contact.

[0054] Of course, in other embodiments, the control instructions are not limited to the target resistance and the limited speed, but may also include other working parameters, such as the target position, PID correction parameters, interface parameters, etc.

[0055] The microprocessor 5 is connected to the host computer through a communication interface 51 to receive external control and setting instructions. The communication interface 51 between the microprocessor 5 and the host computer is RS232, RS485, CAN, TTL232, SPI or Ethernet. The servo motor 2 is driven by the drive controller 3 and drives the contact on the potentiometer to slide according to a certain precision angle and progress through the reducer 6; the microprocessor 5 calculates and obtains the travel distance of the sliding contact of the current multi-turn wire-wound potentiometer through the encoder 31;

[0056] The output resistance sampling module 4 is specifically a high-precision resistance sampling module, which can measure the output resistance and change value in real time, and then read these sampling values ​​in real time through the microprocessor to obtain the stroke position and absolute position of the potentiometer sliding contact, and calculate and update the target position.

[0057] The resistance comparison step specifically includes: comparing the actual resistance value and the target resistance value; if the actual resistance value is within a preconfigured error range relative to the target resistance value, outputting a locking signal, wherein the locking signal controls the position locking of the sliding contact; if the actual resistance value is outside the preconfigured error range relative to the target resistance value, executing a resistance correction step; in addition, in most embodiments, the locking method includes one or more of the following: decoupling the servo motor 2 and the sliding contact; interrupting the power supply to the servo motor 2; and mechanically locking the position of the sliding contact.

[0058] Once the locking task is completed, the output resistance sampling module decides whether to operate in an offline open-loop or continuously online according to user instructions. When online, the microprocessor receives the sampling information of the output resistance sampling module in real time. Once the output error is exceeded, the position lock is released and the contact position is automatically adjusted until the set error threshold is met, and the lock state is entered again.

[0059] On this basis, a second output isolation relay 8 is provided between the multi-turn wire-wound potentiometer 1 and the output resistance sampling module 4, and the control signal input end of the second output isolation relay 8 is connected to the microprocessor 5, and the microprocessor 5 is configured to also perform the following steps: when a locking signal is issued, the second output isolation relay 8 is controlled to disconnect the connection between the multi-turn wire-wound potentiometer 1 and the output resistance sampling module 4.

[0060] A first output isolation relay 7 is provided between the output end of the multi-turn wire-wound potentiometer 1 and the main circuit, and a control signal input end of the first output isolation relay 7 is connected to the microprocessor 5. The microprocessor 5 is configured to further perform the following steps: when the second output isolation relay 8 disconnects the connection between the multi-turn wire-wound potentiometer 1 and the output resistance sampling module 4, the first output isolation relay 7 is controlled to connect the output end of the multi-turn wire-wound potentiometer 1 and the main circuit.

[0061] In a specific embodiment, the multi-turn wire-wound potentiometer 1 adopts a midpoint rod type multi-turn wire-wound potentiometer, the servo motor 2 adopts a 42-step micro-servo motor, the microprocessor 5 adopts an STM32 microprocessor, and the output resistance sampling module 4 includes a constant current source and a 24-bit ADC, which together form a high-precision output resistance sampling module. To ensure the output accuracy of the potentiometer, the encoder 31 adopts a 1024-bit photoelectric encoder, and the reducer 6 adopts a 200:1 reducer. The connection relationship is as follows: the center rod of the reducer 6 is integrally connected with the center rod of the multi-turn wire-wound potentiometer 1, the end of the resistance wire is connected to a fixed contact, and the fixed contact and the sliding contact are connected to the output end of the potentiometer through a lead.

[0062] The STM32 microprocessor is responsible for generating PID control programs and control formulas according to control instructions, driving and controlling the rotation angle and stroke of the servo motor 2 through the drive controller, determining the stroke position of the servo motor through the photoelectric encoder, and further subdividing it through the reducer 6 on this basis.

[0063] A common application scenario is that the host computer controls the output resistance of the potentiometer through the system communication interface RS232 and the microprocessor 5. The implementation process is as follows:

[0064] First, when the system is initially powered on, it will be initialized according to the system's pre-set parameters, including driving the micro servo motor to the initial zero position. The initial zero position is determined based on the maximum value of the potentiometer's effective output.

[0065] Then, the loop waits to receive the RS232 control instructions of the communication port. The simplest and most commonly used control instructions are the settings of the output target resistance of the potentiometer. If the microprocessor receives the control instruction, it will generate the control task of the micro servo motor according to the built-in PID algorithm, and rotate and push the sliding contact of the potentiometer to slide along the resistance wire to the target position through the drive controller and reducer.

[0066] The system generates the target position according to the target output value and the output sampling value, generates the PID control program according to the limited speed, target position and system parameters, generates the control signal required by the drive controller, samples the actual output resistance of the potentiometer, obtains the stroke position through the encoder, and closes the loop to correct the control program.

[0067] Once the output resistance is set within the allowable error, the locking task is executed and the microprocessor records the data related to the current position for automatic restoration of the current output resistance value at the next reset.

[0068] Once the locking task is completed, the input end of the output resistance sampling module can be offline through the potentiometer output sampling isolation relay open loop, and at the same time, the isolation relay of the other output end is energized and turned on to achieve electrical isolation between sampling and output. When the potentiometer output is used as a high-voltage electrical component, this isolation is sometimes necessary; if the input electrical requirements of the sampling module are met in low-voltage situations, continuous sampling and changes can be carried out in parallel, and the final actual working mode is set by the user through control instructions.

[0069] At this point, a host PC sends control instructions through software, and the example of controlling the potentiometer application is completed.

[0070] The application demand of this type of programmable resistor in the automated testing of electronic products and product production and development is very obvious. On the one hand, traditional digital potentiometers are often limited by electrical characteristics such as voltage resistance, power, and electrical isolation, and their applications are very limited. On the other hand, although the power of traditional sliding resistors can be very high, the degree of automation and accuracy may not be very good.

[0071] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

Claims

1. A programmable potentiometer, comprising a multi-turn wire-wound potentiometer (1), a servo motor (2), a drive controller (3) and a microprocessor (5), characterized in that: The programmable potentiometer further comprises an output resistance sampling module (4), the microprocessor (5) is respectively connected to the output resistance sampling module (4) and the drive controller (3), the input end of the servo motor (2) is connected to the drive controller (3), the output end is connected to the sliding contact of the multi-turn wire-wound potentiometer (1), the input end of the output resistance sampling module (4) is connected to the output end of the multi-turn wire-wound potentiometer (1), and the microprocessor (5) is configured to perform the following steps: After receiving the power-on command, monitor the control command; After receiving the control command, the control command is parsed to obtain the target resistance value, and the target position of the sliding contact of the multi-turn wirewound potentiometer (1) is obtained based on the target resistance value, and the target travel distance is obtained in combination with the current position of the sliding contact. According to the obtained travel distance, the servo motor (2) is controlled by the drive controller (3) to drive the sliding contact to the target position, and after the sliding contact moves to the position, the actual resistance value collected by the output resistance sampling module (4) is obtained, and the resistance value comparison step is performed; Resistance comparison step: compare the actual resistance value with the target resistance value. If the actual resistance value is within the pre-configured error range relative to the target resistance value, the execution is completed. Otherwise, the resistance correction step is executed. Resistance correction step: adjust the position of the sliding contact according to the difference between the actual resistance and the target resistance, and perform the resistance comparison step.

2. A programmable potentiometer according to claim 1, characterized in that: The drive controller (3) is provided with an encoder (31). In the process of controlling the servo motor (2) to drive the sliding contact, the travel distance of the sliding contact is corrected through the output closed loop of the encoder (31).

3. A programmable potentiometer according to claim 1, characterized in that: The control instruction contains a limited speed, and the microprocessor (5) is configured to further perform the following steps: After receiving the control command, the control command is parsed to obtain the limited speed; The step of controlling the servo motor (2) to drive the sliding contact to the target position through the driving controller (3) according to the obtained stroke distance is specifically as follows: controlling the servo motor (2) to drive the sliding contact to the target position at a limited speed through the driving controller (3) according to the obtained stroke distance; The resistance value correction step specifically includes: adjusting the position of the sliding contact at a limited speed according to the difference between the actual resistance value and the target resistance value.

4. A programmable potentiometer according to claim 3, characterized in that: The programmable potentiometer also includes a reducer (6), and the reducer (6) is arranged between the servo motor (2) and the sliding contact.

5. A programmable potentiometer according to claim 4, characterized in that: The center rod of the reducer (6) is integrally connected with the center rod of the multi-turn wire-wound potentiometer (1).

6. A programmable potentiometer according to claim 1, characterized in that: The resistance comparison step specifically includes: Compare the actual resistance value with the target resistance value; If the actual resistance value is within a preconfigured error range relative to the target resistance value, a locking signal is output, wherein the locking signal controls the position locking of the sliding contact; If the actual resistance value is outside the preconfigured error range relative to the target resistance value, a resistance correction step is performed.

7. A programmable potentiometer according to claim 6, characterized in that: The locking methods include one or more of the following: Decoupling of the servo motor (2) and the sliding contact; interrupting the power supply to the servo motor (2); Mechanically locks the position of the sliding contact.

8. A programmable potentiometer according to claim 6, characterized in that: A second output isolation relay (8) is provided between the multi-turn wirewound potentiometer (1) and the output resistance sampling module (4), and a control signal input end of the second output isolation relay (8) is connected to a microprocessor (5), and the microprocessor (5) is configured to further perform the following steps: When the locking signal is sent, the second output isolation relay (8) is controlled to disconnect the connection between the multi-turn wire-wound potentiometer (1) and the output resistance sampling module (4).

9. A programmable potentiometer according to claim 8, characterized in that: A first output isolation relay (7) is provided between the output end of the multi-turn wirewound potentiometer (1) and the main circuit, and a control signal input end of the first output isolation relay (7) is connected to a microprocessor (5), and the microprocessor (5) is configured to further perform the following steps: When the second output isolation relay (8) disconnects the connection between the multi-turn wire-wound potentiometer (1) and the output resistance sampling module (4), the first output isolation relay (7) is controlled to connect the output end of the multi-turn wire-wound potentiometer (1) and the main circuit.

10. A programmable potentiometer according to claim 1, characterized in that: The communication interface between the microprocessor (5) and the host computer is RS232, RS485, CAN, TTL232, SPI or Ethernet.

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