Fully-digitally-controlled automatic control principle experimental device

Abstract

The invention provides a fully-digitally-controlled automatic control principle experimental device. The fully-digitally-controlled automatic control principle experimental device comprises a signal source circuit, an open loop / closed loop switching circuit, a typical function unit circuit, a feedback loop selection circuit, a feedback signal phase switching circuit, an upper computer, a single-chip microcomputer and a system working state indication panel. According to the utility model, the circuit function units are designed in a modular manner, and a required experimental object is built in a module combination manner instead of an element wiring manner, so that equipment faults caused by principle wiring errors are avoided, and the reliability of experimental operation is ensured; different types of functional modules can be accessed into the experiment system according to a unified interface; experiment modules with multiple functions are developed in a matched mode, and a complex experiment object is built in a series connection mode, a parallel connection mode and a feedback connection mode. Meanwhile, a real object control object or a function module developed by a user can be flexibly accessed, and the requirements of different experiment contents can be met; the experimental device is integrated with a virtual instrument module, and is small in size and simple in power supply.

Description

Technical Field

[0001] The present application relates to the technical field of teaching experiment system design, and in particular to a fully digitally controlled automatic control principle experiment device. Background Art

[0002] At present, various universities generally use analog circuit experiment boxes to arrange supporting experiments for course teaching. The experiment box contains components such as power supply, operational amplifier, resistor, capacitor and potentiometer, and needs to be equipped with signal generator and oscilloscope. By connecting various components in the experiment box to form various typical links and systems, the signal generator is used to generate the required input signal, and the response output is observed and measured through the oscilloscope.

[0003] The number of components in the experimental box is limited and it is not easy to adjust the parameters. It can only be used for verification experiments of the main knowledge points. During the experiment, students wire the circuit, observe the waveform, and measure the data according to the given "question arrangement diagram". In the limited experimental class hours, students spend a lot of time on simple wiring operations, and do not have enough time to analyze and understand the theoretical knowledge points in combination with the experimental content; there is no actual control object in the traditional experimental box, and students lack intuitive understanding of the control system during the experiment; the wiring process is prone to short-circuit faults due to errors, and the aging of analog circuit components will cause signal drift. Unreasonable wiring methods are easy to introduce interference. Students' professional basic knowledge is relatively weak in the learning stage, and these problems cannot be comprehensively analyzed and solved; there are many students in the experiment, and they need to wait in line when encountering various problems and cannot get help from the experimental instructor in time; the experimental box is used in conjunction with a signal generator and an oscilloscope, which is costly and large in size and can only be used in the laboratory. The various problems that exist have made traditional experimental teaching not have a good teaching effect, which has affected students' initiative and enthusiasm to a certain extent, making it difficult to stimulate their passion for analyzing and solving problems, and has a limited effect on improving practical ability.

[0004] Software simulation and virtual simulation experiments are also commonly used experimental teaching methods. MATLAB is a commonly used software simulation platform, which is very helpful for students to strengthen their learning of basic theoretical knowledge. However, due to its abstract concepts and ideal models, it cannot completely replace physical experiments. Virtual simulation experiments emphasize "combining virtual and real, complementing each other, and being real rather than virtual". They are often used in professional course teaching with special industry backgrounds, and are not suitable for teaching the basic theory of automatic control. Software simulation usually requires the use of large-scale commercial software, involving copyright and version tax issues, while virtual simulation experiments usually have requirements for the software operating environment and network bandwidth. There are still many problems that need to be solved when applied to the large-scale and wide-ranging experimental teaching of the basic theory of automatic control.

[0005] In the prior art, Chinese invention patent CN103985277B, with the authorization announcement date of 2016-04-27, "Network Experiment System Based on Closed-Loop Control and Its Implementation Method", proposes a networked closed-loop control system experimental scheme, which realizes the wiring and parameter adjustment of the experimental object through remote operation, and ensures the wiring safety through logical interlocking at the software level. The working principle of the experimental device itself is not substantially different from the local operation. It cannot solve the problems of high equipment cost, large space occupation, insufficient long-term operation parameter stability and device reliability.

[0006] Invention patent CN101017623B, authorization announcement date 2010-08-18, uses data acquisition card and LabVIEW software to realize virtual instrument function, mainly using virtual instrument to replace traditional instrument, making the experiment easier to operate and record, but the experimental operation process still involves manual wiring of modular unit circuits.

[0007] The utility model patent CN201829100U, with the authorization announcement date of 2011-05-11, proposes an automatic control principle experimental device based on the ELVIS virtual instrument platform. The experimental operation method still corresponds to the traditional manual wiring and potentiometer adjustment. Summary of the invention

[0008] In view of the defects in the prior art, the purpose of this application is to provide a fully digitally controlled automatic control principle experimental device. The circuit functional unit adopts a modular design, and the required experimental objects are constructed by module combination rather than component wiring. The system design ensures that equipment failures will not be caused by principle wiring errors, thereby ensuring the reliability of experimental operations.

[0009] In one aspect of the present application, there is provided a fully digital controlled automatic control principle experimental device, comprising: a signal source circuit, an open-loop / closed-loop switching circuit, a typical functional unit circuit, a feedback loop selection circuit, a feedback signal phase switching circuit, a host computer, a single-chip microcomputer and a system working status indication panel;

[0010] The single chip microcomputer includes a GPIO interface, an SPI interface and a USB / 232 interface;

[0011] The single-chip microcomputer controls the signal source circuit, the open-loop / closed-loop switching circuit, the typical functional unit circuit, the feedback loop selection circuit, the feedback signal phase switching circuit and the system working status indication panel through the GPIO interface for hardware simulation experiment operation;

[0012] The single-chip microcomputer controls the open-loop / closed-loop switching circuit, the typical functional unit circuit, the feedback loop selection circuit and the feedback signal phase switching circuit through the SPI interface to adjust the parameters of the experimental circuit;

[0013] The host computer establishes communication with the single-chip microcomputer via the USB / 232 interface to control the working state of the experimental device.

[0014] Furthermore, the typical functional unit circuit includes a proportional amplifier circuit, an inertia link circuit, a correction network circuit and an integrator circuit;

[0015] The single chip microcomputer adjusts the value of the digital potentiometer of the proportional amplifier circuit through the SPI interface to adjust the gain value of the proportional amplifier circuit;

[0016] The single chip microcomputer adjusts the value of the digital potentiometer of the inertia link circuit through the SPI interface to adjust the time constant and steady-state gain of the inertia link;

[0017] The single chip microcomputer adjusts the value of the fifth digital potentiometer of the correction network circuit through the SPI interface to change the parameters of the correction network circuit;

[0018] The single chip microcomputer controls the sixth analog switch of the integrator circuit through the GPIO interface, so as to control the integrator circuit to be in a working state of zero initial value and locked zero output.

[0019] Furthermore, the typical functional unit circuit also includes an extended network circuit;

[0020] The extended network circuit includes a circuit not connected to an object circuit state and a circuit connected to an object circuit state;

[0021] There are multiple integrator circuits, which form a Type I system or a Type II system in a closed loop according to the number of integrator circuits connected.

[0022] Further, the proportional amplification circuit includes a first proportional amplification circuit and a second proportional amplification circuit;

[0023] The inertia link circuit includes a first first-order inertia circuit and a second first-order inertia circuit;

[0024] The first proportional amplifier circuit, the first first-order inertia circuit, the second first-order inertia circuit, the correction network circuit, the expansion network circuit, the second proportional amplifier circuit and the integrator circuit are connected in sequence.

[0025] Further, the signal source circuit includes a first digital potentiometer, a first voltage follower, a second voltage follower, a first inverting integrator, a second inverting integrator and a first multi-way switch;

[0026] The digital potentiometer input end is connected to the SPI interface, the output end is connected to the input end of the first voltage follower, the output end of the first voltage follower is connected to the input end of the first inverting integrator, and the output end of the first inverting integrator is connected to the input end of the second inverting integrator;

[0027] The output end of the first voltage follower, the output end of the first inverting integrator and the output end of the second inverting integrator are respectively connected to multiple paths of the first multi-way switch, the output end of the first multi-way switch is connected to the input end of the second voltage follower, and the output end of the second voltage follower is connected to the SC port for use as an experimental excitation signal.

[0028] Furthermore, the signal source circuit further comprises a first integrating capacitor and a first analog switch, a second integrating capacitor and a second analog switch, which are respectively connected to the first inverting integrator and the second inverting integrator;

[0029] The single chip microcomputer controls the first analog switch and the second analog switch through the GPIO interface to discharge the first integral capacitor and the second integral capacitor;

[0030] The single chip microcomputer controls the multi-way switch through the GPIO interface.

[0031] Further, the feedback loop selection circuit includes a second multi-way switch;

[0032] The single chip microcomputer controls the connection states of multiple channels of the second multi-way switch through the GPIO, so as to construct four experimental objects with different structural forms.

[0033] Further, the second multi-way switch includes a first channel, a second channel, a third channel and a fourth channel;

[0034] The four different structural forms of the experimental objects include:

[0035] When the first channel is selected, it is a system composed of various typical functional circuit units;

[0036] When the second channel is selected, the link from ADC input to DAC output of the single-chip microcomputer is connected in series in the experimental circuit loop, which can simulate the experimental object or realize the control algorithm;

[0037] When the third channel is enabled, an external physical object can be connected to the experimental circuit loop to expand the application scope of the experimental platform;

[0038] When the fourth channel is selected, the system is in an open-loop mode, and can perform simple input and output characteristic experiments in the time domain and frequency domain.

[0039] Further, the GPIO interface has multiple ones, including a GPIO0 interface, which is used to control the open-loop / closed-loop switching circuit and the switching circuit in the typical functional unit circuit;

[0040] GPIO1 interface, used to control the capacitor discharge circuit in the experimental device;

[0041] GPIO2 interface, used to control the signal source circuit;

[0042] GPIO3 interface, used to control the multiplexer of the feedback loop selection circuit.

[0043] Furthermore, the single chip microcomputer also includes a PWM interface and an ENC interface for connecting to a physical object.

[0044] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0045] 1. This application adopts a modular design for circuit functional units, and builds the required experimental objects by module combination rather than component wiring. The system design ensures that equipment failures will not be caused by principle wiring errors, thereby ensuring the reliability of experimental operations; a module bus of composite DO digital quantity and SPI serial communication interface is designed to ensure that different types of functional modules can be connected to the experimental system according to a unified interface; a variety of functional experimental modules are developed to build complex experimental objects through series, parallel and feedback connections; the bus interface supports the open Modbus communication protocol, and can flexibly connect to physical control objects or functional modules developed by users, to support the needs of different experimental contents; the experimental device is integrated with a virtual instrument module, which is small in size and simple in power supply. It is no longer limited to laboratory use and can be distributed to students to flexibly arrange independent experiments; a corresponding software simulation model is developed as a tool for students to preview and compare and analyze experimental results.

[0046] 2. This application greatly simplifies the process of setting up experimental objects. The core work of system construction returns to the essence of object analysis rather than the wiring process itself. The structured design fundamentally solves the problem of short-circuit failure caused by operating errors. The experimental circuit part is driven by digital signals to avoid common problems such as poor contact after long-term use. It provides communication interfaces and standard communication protocols, which can be connected to PCs to form upper and lower computer systems, and can also be remotely operated through network access devices. Various types of experimental objects can be built by configuring common typical links, and expansion interfaces are provided to access physical control objects. The experimental device integrates virtual instruments with a low-cost solution, is small in size and easy to carry, and can be distributed to students to take out of the laboratory for independent experiments. The experimental device provides open instrument signals and can be adapted to commonly used virtual instrument equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0048] Figure 1 This is a schematic structural diagram of a fully digitally controlled automatic control principle experimental device in one embodiment of the present application.

[0049] Figure 2 1 is a schematic diagram of a signal source circuit in an embodiment of the present application.

[0050] Figure 3 This is a schematic diagram of the input and output signal connection and bus interface of a typical circuit unit in an embodiment of the present application, a is the module circuit bypass state, the circuit is not connected to the experimental object loop, b is the module circuit connected to the experimental object loop state.

[0051] Figure 4 This is a schematic diagram of a proportional amplifier circuit for performing gain adjustment via a digital potentiometer DPP of an SPI interface in an embodiment of the present application.

[0052] Figure 5 This is a schematic diagram of the inertia link circuit in one embodiment of the present application.

[0053] Figure 6 This is a schematic diagram of a correction network circuit in one embodiment of the present application.

[0054] Figure 7 1 is a schematic diagram of an inverting integrator circuit in one embodiment of the present application.

[0055] Figure 8 This is a schematic diagram of a feedback loop selection circuit controlled by a GPIO signal in an embodiment of the present application.

[0056] Fig. 9 This is a structural diagram of the software and hardware control system of the single-chip microcomputer in one embodiment of the present application.

[0057] Fig.10 This is an embodiment of a control interface in which a host computer controls a digital quantity signal of an experimental circuit through serial communication in one embodiment of the present application.

[0058] Fig.11 This is an embodiment of a control interface in which a host computer controls analog signals of an experimental circuit through serial communication in one embodiment of the present application.

[0059] Fig.12 This is a physical diagram of an embodiment adapted for NI ELVIS-2 in one embodiment of the present application.

[0060] Fig.13 This is the interface for the host computer to perform software and hardware collaborative simulation experiments in one embodiment of the present application.

[0061] In the figure: 100, signal source circuit; 100a, first digital potentiometer; 100b, first voltage follower; 100c, first inverting integrator; 100d, first analog switch; 100e, second inverting integrator; 100f, second analog switch; 100g, first multi-way switch; 100h, second voltage follower; 101, open-loop / closed-loop switching circuit; 102, first proportional amplifier circuit; 102a, second digital potentiometer; 102b, first proportional amplifier; 103, first first-order inertia circuit; 103a, first inertia circuit; 103b, third digital potentiometer; 103c, third analog switch; 104, second first-order inertia circuit; 104a, second inertia circuit; 104b, fourth digital potentiometer; 104c, fourth analog switch; 105, correction network circuit; 105a, advance correction circuit; 105b, fifth digital potentiometer; 105c, fifth analog switch; 106, Extended network circuit; 106a, schematic diagram of general circuit unit; 106b, circuit switching switch; 106c, schematic diagram of digital potentiometer; 106d, schematic diagram of capacitor discharge analog switch; 107, second proportional amplifier circuit; 107a, sixth digital potentiometer; 107b, second proportional amplifier; 108, integrator circuit; 108a, inverting integrator; 108b, sixth analog switch; 109, feedback loop selection circuit; 109a, second multi-way switch; 109b, third voltage follower; 110, feedback signal phase switching circuit; 111, host computer; 112, single-chip microcomputer; 112a, S12 single-chip microcomputer; 112b, seventh digital potentiometer; 112c, fourth voltage follower; 112d, encoder orthogonal decoding; 112e, USB / 232 communication protocol conversion; 113, motor drive and speed detection circuit; 114, DC motor and speed detection circuit; 115, system working status indication panel. DETAILED DESCRIPTION

[0062] The present application is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0063] Reference Figure 1 As shown, an automatic control principle experimental device with full digital control according to an embodiment of the present application includes: a signal source circuit 100, an open-loop / closed-loop switching circuit 101, a typical functional unit circuit, a feedback loop selection circuit 109, a feedback signal phase switching circuit 110, a host computer 111, a single-chip microcomputer 112 and a system working status indication panel 115.

[0064] The single-chip microcomputer 112 includes a GPIO interface, an SPI interface and a USB / 232 interface; the single-chip microcomputer 112 controls the signal source circuit 100, the open-loop / closed-loop switching circuit 101, the typical functional unit circuit, the feedback loop selection circuit 109, the feedback signal phase switching circuit 110 and the system working status indication panel 115 through the GPIO interface for hardware simulation experiment operation.

[0065] The single chip microcomputer 112 controls the open-loop / closed-loop switching circuit 101, the typical functional unit circuit, the feedback loop selection circuit 109 and the feedback signal phase switching circuit 110 through the SPI interface to adjust the parameters of the experimental circuit.

[0066] The host computer 111 establishes communication with the single-chip computer 112 via the USB / 232 interface to control the working state of the experimental device.

[0067] Among them, in the present application, each circuit unit can be connected to the microcontroller 112 system loop through the GPIO+SPI bus. According to the different functions of the specific circuit units, the GPIO signal is used to control the circuit module access or bypass, signal channel multi-selection routing, capacitor discharge, and the SPI communication interface is used to adjust the resistance value of the digital potentiometer, thereby constructing the experimental circuit object in a fully digital way.

[0068] The USB / 232 interface communicates with the host computer 111 via the Modbus protocol.

[0069] This application designs a module bus of GPIO interface and SPI serial communication interface to ensure that different types of functional modules can be connected to the experimental device according to a unified interface; a variety of functional experimental modules are developed to build complex experimental objects through series, parallel and feedback connections of typical functional unit circuits; the bus interface supports the open Modbus communication protocol, and can flexibly connect to physical control objects or functional modules developed by users to support the needs of different experimental contents; the experimental device is integrated with a virtual instrument module, which is small in size and simple in power supply. It is no longer limited to laboratory use and can be distributed to students to flexibly arrange independent experiments; a corresponding software simulation model is developed as a tool for students to preview and compare and analyze experimental results.

[0070] Specifically, the single-chip microcomputer 112 controls the switching circuit of the typical functional unit circuit through the GPIO interface, and can freely combine specific experimental circuit objects to realize specific transfer functions for hardware simulation experimental operations; the single-chip microcomputer 112 controls the digital potentiometer of the typical functional unit circuit through the SPI interface, and can adjust the gain, time constant and other parameters of the experimental circuit.

[0071] A feedback control system with a closed-loop structure can be formed by combining the open-loop / closed-loop switching circuit 101, the feedback loop selection circuit 109 and the feedback signal phase switching circuit 110. The feedback signal phase switching circuit 110 is used to adjust the phase of the feedback signal to ensure a negative feedback state.

[0072] The single-chip computer 112 controls the first multiplexer 100g in the signal source circuit 100 through the GPIO interface, and can select one of the four signals, namely, the step input signal SS1, the speed input signal SS2, the acceleration input signal SS3 and the virtual instrument signal generator input signal SS4, as an excitation signal to be applied to the input end of the experimental circuit. Different feedback signals can be selected by the second multiplexer 109a of the feedback loop selection circuit 109 to set different working modes of the system. The experimental device communicates with the host computer 111 through the Modbus protocol through the USB / 232 interface, and the working state of the experimental device can be controlled through the experimental host software interface.

[0073] In this application, not all functional unit circuits include digital potentiometers. Based on the needs of experimental configuration, some unit circuits have fixed parameters and only need to control the circuit connection or disconnection, or simply switch channels. The control bus includes GPIO and SPI, which can adapt to various functional unit circuits.

[0074] In some specific embodiments, the GPIO interface has multiple interfaces, including a GPIO0 interface for controlling the open-loop / closed-loop switching circuit 101 and the switching circuit in the typical functional unit circuit; a GPIO1 interface for controlling the capacitor discharge circuit in the experimental device; a GPIO2 interface for controlling the signal source circuit 100; and a GPIO3 interface for controlling the second multi-way switch 109a of the feedback loop selection circuit 109.

[0075] Among them, there are 9 GPIO0 interfaces, which respectively control the loop / closed-loop switching circuit 101 and the switching circuit in the typical functional unit circuit; there is 1 GPIO1 interface, which controls all capacitor discharge circuits; there are 2 GPIO2 interfaces, which control the multi-way switch 100g of the signal source circuit 100; there are 2 GPIO3 interfaces, which control the second multi-way switch 109a of the feedback loop selection circuit 109.

[0076] In some specific embodiments, the typical functional unit circuit includes a proportional amplifier circuit, an inertia link circuit, a correction network circuit 105 and an integrator circuit 108 .

[0077] The single-chip microcomputer 112 adjusts the value of the digital potentiometer of the proportional amplifier circuit through the SPI interface, so as to adjust the gain value of the proportional amplifier circuit; the single-chip microcomputer 112 adjusts the value of the digital potentiometer of the inertia link circuit through the SPI interface, so as to adjust the time constant and steady-state gain of the inertia link; the single-chip microcomputer 112 adjusts the value of the fifth digital potentiometer 105b of the correction network circuit 105 through the SPI interface, so as to change the parameters of the correction network circuit 105; the single-chip microcomputer 112 controls the sixth analog switch 108b of the integrator circuit 108 through the GPIO interface, so as to control the integrator circuit 108 to be in a working state of zero initial value and locked zero output.

[0078] Among them, refer to Figure 3 As shown, the extended network circuit 106 of the present application includes a general circuit unit schematic 106a, a circuit switching switch 106b, a digital potentiometer schematic 106c, and a capacitor discharge analog switch schematic 106d.

[0079] Among them, a is the bypass state of the module circuit. When the switching control signal is 0, the circuit unit is disconnected from the experimental loop, the circuit is not connected to the experimental object loop, and the output signal of the previous circuit is directly connected to the input port of the next circuit; b is the state of the module circuit connected to the experimental object loop. When the switching control signal is 1, the output signal of the previous circuit is connected to the input port of this circuit unit, the output signal of the circuit is connected to the input port of the next circuit, and the circuit is connected to the experimental object loop.

[0080] In some specific embodiments, the typical functional unit circuit also includes an extended network circuit 105 and an integrator circuit 108; the extended network circuit 105 includes a circuit not connected to an object loop state and a circuit connected to an object loop state; there are multiple integrator circuits, and according to the number of connections, a Type I system or a Type II system is formed in a closed-loop manner.

[0081] In the above embodiments, one implementation method is to construct corresponding experimental circuit objects according to different knowledge points according to the needs of automatic control principle experimental teaching. In a simple closed-loop mode, a forward channel is connected in series with a proportional amplifier, an inertial link and an integrator to form a typical second-order system; a forward channel is connected in series with an integrator to obtain a type I system, and two integrators are connected in series to obtain a type II system.

[0082] Reference Figures 4 to 7 As shown, there are four basic forms of typical functional unit circuits (typical transfer function functional unit circuits), namely Figure 4 The proportional amplifier circuit unit (i.e., proportional amplifier circuit) shown in FIG. Figure 5The inertia link circuit unit (i.e., inertia link circuit) shown in the figure, wherein the GPIO signal is used to set the initial state of the capacitor discharge, and the SPI interface is used to adjust the digital potentiometer DPP to change the inertia link time constant and steady-state gain, Figure 6 The correction network circuit unit (i.e., correction network circuit 105) shown in FIG. 1 , wherein the SPI interface is used to adjust the DPP resistance value of the digital potentiometer 106c, the GPIO1 signal is used to control the fifth analog switch 105c to discharge the correction capacitor, and Figure 7 In the integrator circuit unit (ie, the integrator circuit 108 ) shown, the GPIO signal controls the sixth analog switch 108 b to discharge the integration capacitor.

[0083] Specifically, the fully digitally controlled proportional amplifier circuit unit uses AD5293-100 as the digital potentiometer. The gain adjustment range of each proportional amplifier is [0, 9.99], and the adjustment step value is 0.009766, which can configure the gain value of the system transfer function with sufficient accuracy.

[0084] For the fully digitally controlled inertia link circuit unit, when a 1uF feedback loop parallel capacitor is used, the time constant adjustment range is [0.01, 0.1099], and the step value is 9.77*10-5. By changing the capacity of the parallel capacitor, the time constant of the inertia link can also be adjusted within a larger range, fully meeting the parameter requirements of the transfer function of the experimental object.

[0085] The correction network circuit 105 unit can be active or passive, leading or lagging, etc. The resistance value of the fifth digital potentiometer 105b is precisely adjusted through the SPI interface to change the corner frequency of the correction network.

[0086] The integrator circuit 108 and other circuit units, all circuit modules can be added to the system loop through the GPIO+SPI bus interface.

[0087] Specifically, the proportional amplifier circuit includes a first proportional amplifier circuit 102 and a second proportional amplifier circuit 107; the inertia link circuit includes a first first-order inertia circuit 103 and a second first-order inertia circuit 104; the first proportional amplifier circuit 102, the first first-order inertia circuit 103, the second first-order inertia circuit 104, the correction network circuit 105, the expansion network circuit 106, the second proportional amplifier circuit 107 and the integrator circuit 108 are connected in sequence.

[0088] Under the GPIO+SPI bus architecture, this application can easily expand new circuit units to realize different transfer function functions, such as active or passive correction networks, nonlinear networks, etc., and realize full digital control. Through multiple different types of functional modules, they can be connected to the experimental system according to a unified interface. Multiple different functional modules can flexibly configure the types, quantities and connection sequences of different functional circuit units, build various forms of system transfer function models, and select different types of input signals as excitations to meet the experimental needs of different courses.

[0089] For the proportional amplifier circuit, the single-chip microcomputer 112 adjusts the values ​​of the second digital potentiometer 102a and the sixth digital potentiometer 107a through the SPI interface, and can correspondingly adjust the gain values ​​of the first proportional amplifier circuit 102b and the second proportional amplifier 107b; for the inertia link circuit, the single-chip microcomputer 112 adjusts the values ​​of the third digital potentiometer 103b and the fourth digital potentiometer 104b through the SPI interface, and correspondingly adjusts the time constant and steady-state gain of the inertia link, and controls the third analog switch 103c and the fourth analog switch 104c to switch the two through the GPIO1 interface. Capacitors C3 and C4 are discharged to put the circuit in a zero initial value state; for the correction network circuit 105, the single-chip microcomputer 112 adjusts the value of the fifth digital potentiometer 105b through the SPI interface to change the circuit parameters of the correction network accordingly, and controls the fifth analog switch 105c through the GPIO1 interface to discharge the correction capacitor C5 to put the circuit in a zero initial value state; for the integrator circuit 108, the single-chip microcomputer 112 controls the sixth analog switch 108b through the GPIO1 interface to discharge the integration capacitor C6 to put the inverting integrator 108a in a zero initial value and lock the zero output working state.

[0090] Signals are input and output through the first inertia circuit 103a, the second inertia circuit 104a, the advance correction circuit 105a and the general circuit unit 106a.

[0091] All typical circuit units can be controlled through a unified GPIO and SPI interface. The required modules are selected and connected to the experimental circuit loop according to the target system needs of the simulation experiment, and the circuit parameters are adjusted according to the experimental requirements. The circuit switching and interconnection method ensures that the output of any circuit unit will only be open or only connected to the input of another circuit unit at any time, fundamentally avoiding the common situation of circuit short circuit due to wiring errors in traditional experimental methods, greatly improving the safety of the experimental device. Circuit switching and parameter adjustment do not use traditional knob switches and potentiometers, but are achieved through the control of long-life signal relays, the second multi-way switch chip and digital potentiometers by a single-chip microcomputer, which greatly improves the reliability and signal stability of the experimental device.

[0092] In the above embodiment, the proportional amplifier circuit, the inertia link circuit, the correction network circuit and the inverting integrator circuit are all fully digitally controlled.

[0093] In some specific embodiments, the signal source circuit 100 includes a first digital potentiometer 100a, a first voltage follower 100b, a second voltage follower 100h, a first inverting integrator 100c, a second inverting integrator 100e and a first multi-way switch 100g.

[0094] The input end of the first digital potentiometer 100a is connected to the SPI interface, and the output end is connected to the input end of the first voltage follower 100b. The output end of the first voltage follower 100b is connected to the input end of the first inverting integrator 100c. The output end of the first inverting integrator 100c is connected to the input end of the second inverting integrator 100e.

[0095] The output end of the first voltage follower 100b, the output end of the first inverting integrator 100c and the output end of the second inverting integrator 100e are respectively connected to multiple paths of the first multi-way switch 100g, the output end of the first multi-way switch 100g is connected to the input end of the second voltage follower 100h, and the output end of the second voltage follower 100h is connected to the SC (actual experimental excitation signal) port to be used as an experimental excitation signal.

[0096] Reference Figure 2 As shown, specifically, the signal source circuit 100 is as shown in Figure 2 As shown, 100a is a precision digital potentiometer AD5293-20 with 1024 gears. The resistance value can be adjusted through the SPI interface to accurately adjust the amplitude of the output signal in the voltage range of [-2V, +2V] according to the step value of 3.9mV. The output signal generates a step signal SS1 after passing through the voltage follower 100b, and SS1 generates a speed signal SS2 after passing through the first inverting integrator 100c. SS2 generates an acceleration signal SS3 after passing through the second inverting integrator 100e. The SS4 port is connected to the signal generator channel of the virtual instrument adapted by the experimental device. The single-chip microcomputer 112 controls the first multi-way switch 100g through the GPIO2 signal, and selects a signal from SS1 to SS4 to output to SC as the actual experimental excitation signal.

[0097] In some specific embodiments, the signal source circuit 100 also includes a first integrating capacitor and a first analog switch 100d, a second integrating capacitor and a second analog switch 100f, which are respectively connected to the first inverting integrator 100c and the second inverting integrator 100e; the single-chip microcomputer 112 controls the first analog switch 100d and the second analog switch 100f through the GPIO interface to discharge the first integrating capacitor and the second integrating capacitor; the single-chip microcomputer 112 controls the first multi-way switch 100g through the GPIO interface.

[0098] The single chip microcomputer 112 controls the first analog switch 100d and the second analog switch 100f through the GPIO1 signal to discharge the integration capacitors of the first inverting integrator 100c and the second inverting integrator 100e, so that the system can return to the zero initial value state.

[0099] In some specific embodiments, the feedback loop selection circuit 109 includes a second multi-way switch 109a; the single-chip microcomputer 112 controls the connection states of multiple channels of the second multi-way switch 109a through GPIO to construct four experimental objects with different structural forms.

[0100] Specifically, the second multi-way switch 109a includes a first channel SY1, a second channel SY2, a third channel SY3 and a fourth channel SY4; the experimental objects of four different structural forms include: when the first channel SY1 is selected, it is a system composed of various typical functional circuit units; when the second channel SY2 is selected, the link from ADC input to DAC output of the single-chip microcomputer is connected in series in the experimental circuit loop, which can simulate the experimental object or implement the control algorithm; when the third channel SY3 is selected, the experimental circuit loop can be connected to an external physical object to expand the application scope of the experimental platform; when the fourth channel SY4 is selected, the system is in an open-loop mode, and simple input and output characteristic experiments in time domain and frequency domain can be performed.

[0101] Different types of closed-loop control experimental systems can be constructed by using the second multi-way switch 109a on the feedback channel. The internal multi-way structure is as follows: Figure 8 As shown. The single-chip microcomputer 112 controls the second multi-way switch 109aADG1204 through GPIO3, and the following four different structural forms of experimental objects can be constructed: when the SY1 channel is selected, the experimental object is a system composed of various functional circuit units; when the SY2 channel is selected, the single-chip microcomputer 112 is connected in series in the experimental circuit loop from ADC input to DAC output, and specific functions can be realized through the software model, which can simulate the experimental object and realize the control algorithm; when the SY3 channel is selected, the experimental circuit loop can be connected to an external physical object to expand the application scope of the experimental platform; when the SY4 channel is selected, the system is in an open-loop mode, and simple input and output characteristic experiments in the time domain and frequency domain can be performed.

[0102] The four gears of the second multi-way switch 109a correspond to four different structural forms of the experimental system, and the third voltage follower 109b ensures that the loop signal is not affected by the load effect.

[0103] More specifically, the single-chip microcomputer 112 can construct four different types of experimental objects, namely, open loop, closed loop, single-chip microcomputer software-in-the-loop (MIL / SIL), and external physical object expansion, by simply controlling the connection state of the second multi-way switch 109a of the feedback channel through GPIO.

[0104] Open-loop system: When the SY4 channel is selected, multiple circuit units in the forward channel are connected in series to form transfer functions of different orders, which are used for time domain input and output characteristic experiments and time domain Bode plot tests;

[0105] Closed-loop system: When the SY1 channel is selected, multiple circuit units in the forward channel are connected in series, and the feedback channel is connected as negative feedback, which can constitute typical experimental objects such as overdamped / critically damped / underdamped second-order systems, type I systems or type II systems, etc., and are used for dynamic characteristics and steady-state characteristics experiments of dynamic system time domain analysis;

[0106] Single-chip microcomputer software-in-the-loop system: When the SY2 channel is selected, after the single-chip microcomputer 112 is connected in series to the experimental loop through the ADC / DAC interface, the single-chip microcomputer program can be used to simulate the specific transfer function function to form a model-in-the-loop (MIL) experimental object, or the single-chip microcomputer program can be used to implement a typical control algorithm, such as PID control, to form a software-in-the-loop (SIL) experimental object.

[0107] External physical object expansion system: When the SY3 channel is selected, the single-chip microcomputer 112 control circuit, in addition to controlling the operation of each circuit unit through the GPIO and SPI interfaces, is also equipped with a motor drive circuit driven by a PWM interface, which can be used to control physical objects other than the DC motor supporting the control device. The working status signal of the physical object is connected to the feedback channel through the external sensor signal interface, so that the external physical object can be controlled by the circuit of the experimental device and the single-chip microcomputer program.

[0108] In some specific embodiments, the single chip microcomputer 112 further includes a PWM interface and an ENC interface for connecting to a physical object.

[0109] Among them, in this application, this embodiment uses the motor drive circuit and speed detection 113 and the DC motor 114 as physical objects to implement closed-loop control of the DC motor speed in the SY2 working mode.

[0110] Reference Fig. 9 As shown, the single-chip microcomputer 112 communicates data with the host computer 111 through the communication interface SCI0 on the one hand, and controls the connection status of each module circuit and sets the resistance value of the digital potentiometer through the GPIO and SPI interfaces on the other hand.

[0111] The single chip computer 112 selects the MC9S12XS128 single chip computer 112a.

[0112] The device further includes a seventh digital potentiometer 112 b and a fourth voltage follower 112 c for outputting a DAC signal.

[0113] The experimental device communicates with the host computer 111 through the communication interface 112e. All relays, analog switches and digital potentiometers on the experimental device can be controlled locally or on the experimental host connected through the network according to the specified communication protocol, thereby completing localized or networked experimental operations. Fig.10 and Fig.11 They are software interfaces for the host computer to control the switch quantity of the experimental board (used to control the access or bypass of each circuit module, the channel selection of the second multi-way switch 109a, and the capacitor discharge control) and the analog quantity (used to adjust the resistance value of the digital potentiometer and control the status LED and digital tube).

[0114] Fig.12 This is a photo of the physical device of this embodiment, which is adapted to the NI ELVIS-2 virtual instrument platform for the experimental teaching of the "Principles of Automatic Control" course. The specific embodiments of the basic invention are described above.

[0115] It should be understood that based on the technical principles of the present invention, various forms of experimental platforms can be constructed without being limited to the above-mentioned specific implementation methods, including adapting different types of instrument platforms through different signal connection forms, setting functional circuit units of different numbers, types and connection orders to form experimental objects with different complexities, using different microcontroller models to design control circuit boards, communicating with the host computer through different communication interfaces, and integrating different types of physical objects.

[0116] The above describes the specific embodiments of the present application. It should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the substantive content of the present application. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. A fully digital controlled automatic control principle experimental device, characterized in that: include: Signal source circuit, open-loop / closed-loop switching circuit, typical functional unit circuit, feedback loop selection circuit, feedback signal phase switching circuit, host computer, single-chip microcomputer and system working status indication panel; The single chip microcomputer includes a GPIO interface, an SPI interface and a USB / 232 interface; The single-chip microcomputer controls the signal source circuit, the open-loop / closed-loop switching circuit, the typical functional unit circuit, the feedback loop selection circuit, the feedback signal phase switching circuit and the system working status indication panel through the GPIO interface for hardware simulation experiment operation; The single-chip microcomputer controls the open-loop / closed-loop switching circuit, the typical functional unit circuit, the feedback loop selection circuit and the feedback signal phase switching circuit through the SPI interface to adjust the parameters of the experimental circuit; The host computer establishes communication with the single-chip microcomputer via the USB / 232 interface to control the working state of the experimental device.

2. According to claim 1, a fully digital controlled automatic control principle experimental device is characterized in that: The typical functional unit circuit includes a proportional amplifier circuit, an inertia link circuit, a correction network circuit and an integrator circuit; The single chip microcomputer adjusts the value of the digital potentiometer of the proportional amplifier circuit through the SPI interface to adjust the gain value of the proportional amplifier circuit; The single chip microcomputer adjusts the value of the digital potentiometer of the inertia link circuit through the SPI interface to adjust the time constant and steady-state gain of the inertia link; The single chip microcomputer adjusts the value of the fifth digital potentiometer of the correction network circuit through the SPI interface to change the parameters of the correction network circuit; The single chip microcomputer controls the sixth analog switch of the integrator circuit through the GPIO interface, so as to control the integrator circuit to be in a working state of zero initial value and locked zero output.

3. The fully digital controlled automatic control principle experimental device according to claim 2 is characterized in that: The typical functional unit circuit also includes an extended network circuit; The extended network circuit includes a circuit not connected to an object circuit state and a circuit connected to an object circuit state; There are multiple integrator circuits, which form a Type I system or a Type II system in a closed loop according to the number of integrator circuits connected.

4. The fully digital controlled automatic control principle experimental device according to claim 3 is characterized in that: The proportional amplification circuit includes a first proportional amplification circuit and a second proportional amplification circuit; The inertia link circuit includes a first first-order inertia circuit and a second first-order inertia circuit; The first proportional amplifier circuit, the first first-order inertia circuit, the second first-order inertia circuit, the correction network circuit, the expansion network circuit, the second proportional amplifier circuit and the integrator circuit are connected in sequence.

5. The fully digital controlled automatic control principle experimental device according to claim 1 is characterized in that: The signal source circuit includes a first digital potentiometer, a first voltage follower, a second voltage follower, a first inverting integrator, a second inverting integrator and a first multi-way switch; The digital potentiometer input end is connected to the SPI interface, the output end is connected to the input end of the first voltage follower, the output end of the first voltage follower is connected to the input end of the first inverting integrator, and the output end of the first inverting integrator is connected to the input end of the second inverting integrator; The output end of the first voltage follower, the output end of the first inverting integrator and the output end of the second inverting integrator are respectively connected to multiple paths of the first multi-way switch, the output end of the first multi-way switch is connected to the input end of the second voltage follower, and the output end of the second voltage follower is connected to the SC port for use as an experimental excitation signal.

6. The fully digital controlled automatic control principle experimental device according to claim 5 is characterized in that: The signal source circuit further includes a first integrating capacitor and a first analog switch, a second integrating capacitor and a second analog switch, which are respectively connected to the first inverting integrator and the second inverting integrator; The single chip microcomputer controls the first analog switch and the second analog switch through the GPIO interface to discharge the first integral capacitor and the second integral capacitor; The single chip microcomputer controls the multi-way switch through the GPIO interface.

7. The fully digital controlled automatic control principle experimental device according to claim 1 is characterized in that: The feedback loop selection circuit includes a second multi-way switch; The single chip microcomputer controls the connection states of multiple channels of the second multi-way switch through the GPIO, so as to construct four experimental objects with different structural forms.

8. The fully digital controlled automatic control principle experimental device according to claim 7 is characterized in that: The second multi-way switch includes a first channel, a second channel, a third channel and a fourth channel; The four different structural forms of the experimental objects include: When the first channel is selected, it is a system composed of various typical functional circuit units; When the second channel is selected, the link from ADC input to DAC output of the single-chip microcomputer is connected in series in the experimental circuit loop, which can simulate the experimental object or realize the control algorithm; When the third channel is enabled, an external physical object can be connected to the experimental circuit loop to expand the application scope of the experimental platform; When the fourth channel is selected, the system is in an open-loop mode, and can perform simple input and output characteristic experiments in the time domain and frequency domain.

9. The fully digital controlled automatic control principle experimental device according to claim 1 is characterized in that: The GPIO interface has multiple interfaces, including a GPIO0 interface, which is used to control the open-loop / closed-loop switching circuit and the switching circuit in the typical functional unit circuit; GPIO1 interface, used to control the capacitor discharge circuit in the experimental device; GPIO2 interface, used to control the signal source circuit; GPIO3 interface, used to control the multiplexer of the feedback loop selection circuit.

10. The fully digital controlled automatic control principle experimental device according to claim 1 is characterized in that: The single chip microcomputer further comprises a PWM interface and an ENC interface for connecting to a physical object.

Images