An electric lifting table resistance detection method and current acquisition circuit

Abstract

The present invention relates to the field of smart home device control technology, and in particular to a method for detecting resistance of an electric lifting table, comprising: before a single-chip microcomputer samples the output current of a motor, the single-chip microcomputer pre-acquires the current current of the motor, and judges whether the electric lifting table is in an ascending state or a descending state according to an input direction control signal: if the electric lifting table is in an ascending state, the single-chip microcomputer control circuit acquisition circuit amplifies the output current of the motor by a first preset multiple and then performs sampling; if the electric lifting table is in a descending state, the single-chip microcomputer control circuit acquisition circuit amplifies the output current of the motor by a second preset multiple and then performs sampling. The beneficial effects of the present invention: according to the ascending or descending state of the lifting table, the different amplification multiples of the operational amplifier are adjusted, so that the current sampling circuit outputs a voltage signal suitable for the single-chip microcomputer to more easily identify and judge, so that the judgment of the resistance retreat device is more sensitive and accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of smart home device control, and in particular to an resistance detection method and a current acquisition circuit for an electric lifting table. Background Art

[0002] With the rapid development of society, smart furniture has been widely used in people's work and life. For example, a smart lifting table is a relatively common type of smart furniture. The resistance retraction device of the electric lifting table mainly determines whether it encounters resistance by detecting the change of current during the collision process. However, the amplification factor of the operational amplifier in the current sampling circuit of the resistance retraction device in the prior art is not dynamically adjusted according to the current size, and the judgment sensitivity is low. Especially when the lifting table is running downward with a heavy load, since the motor running current is small, the current change is not obvious when encountering resistance, and the resistance retraction device may not be able to judge. Summary of the invention

[0003] In view of the above problems existing in the prior art, a method for detecting resistance of an electric lifting table and a current collection circuit are provided.

[0004] The specific technical solutions are as follows:

[0005] The present invention includes a method for detecting an obstruction of an electric lifting table, comprising:

[0006] Before the single-chip microcomputer samples the output current of the motor, the single-chip microcomputer obtains the current current of the motor in advance, and determines whether the electric lifting table is in the ascending state or the descending state according to the input direction control signal:

[0007] If the current current of the motor is not less than the first preset threshold value, and it is determined that the electric lifting table is in the ascending state, the single-chip control circuit acquisition circuit amplifies the output current of the motor by a first preset multiple and then performs sampling;

[0008] If the current current of the motor is less than the first preset threshold value and it is determined that the electric lifting table is in a descending state, the single chip microcomputer controls the circuit acquisition circuit to amplify the output current of the motor by a second preset multiple and then perform sampling;

[0009] The single chip microcomputer calculates and processes the amplified current sampling value and compares it with a second preset threshold value. When the current sampling value is greater than the second preset threshold value, the single chip microcomputer determines that resistance is encountered.

[0010] Optionally, the single chip microcomputer calculates and processes the current sampling value including:

[0011] The single chip microcomputer collects a plurality of current sampling values ​​at a preset frequency, and performs weighting and filtering processing on the plurality of current sampling values;

[0012] A portion of the current sampling values ​​is selected from the plurality of current sampling values ​​for averaging processing.

[0013] Optionally, the plurality of current sampling values ​​are weighted according to the following formula:

[0014] I AD =I 2 *0.1+I 1 *0.9

[0015] in,

[0016] I AD Used to represent the current sampling value obtained after weighted processing;

[0017] I 1 Used to indicate the current sampling value obtained by the last sampling;

[0018] I 2 Used to represent the current sampling value obtained in this sampling.

[0019] Optionally, the current sampling value obtained after the current calculation is compared with the current sampling value obtained last time, and when the current current sampling value is not less than the current sampling value obtained last time, the current current sampling value is weighted and then the second preset threshold is updated.

[0020] Optionally, the current sampling value is weighted according to the following formula:

[0021] b 2 =b 1 *0.97+a*0.03

[0022] in,

[0023] b 2 used to indicate the updated second preset threshold;

[0024] b 1 used to indicate the second preset threshold before updating;

[0025] a is used to represent the current sampling value.

[0026] The present invention also provides a current acquisition circuit of a device for retreating when encountering an obstacle, comprising:

[0027] An operational amplifier, wherein the first input end of the operational amplifier is connected to the output end of the motor through a first resistor and a second resistor, the second input end of the operational amplifier is connected to a switching module capable of switching the current amplification factor, the output end of the motor is also connected between the switching module and the second input end of the operational amplifier through a third resistor and a fourth resistor, and the output end of the operational amplifier is connected to the current collection end of the single-chip microcomputer.

[0028] Optionally, the switching module includes a single-pole double-throw switch, a first amplifying unit, and a second amplifying unit;

[0029] The first pin of the single-pole double-throw switch is connected to one end of the first amplifying unit, the second pin of the single-pole double-throw switch is grounded, the third pin of the single-pole double-throw switch is connected to one end of the second amplifying unit, the fourth pin of the single-pole double-throw switch is connected to the second input end of the operational amplifier, the fifth pin of the single-pole double-throw switch is connected to the power supply, the sixth pin of the single-pole double-throw switch is connected to the control output end of the single-chip microcomputer, and the other ends of the first amplifying unit and the second amplifying unit are connected between the output end of the operational amplifier and the current collection end of the single-chip microcomputer through a first fulcrum.

[0030] Optionally, the first amplification unit includes:

[0031] a fifth resistor, connected between the first pin of the single-pole double-throw switch and the first fulcrum;

[0032] The first capacitor is connected to two ends of the fifth resistor via the second support point and the third support point respectively.

[0033] The second amplification unit comprises:

[0034] a sixth resistor, connected between the third pin of the single-pole double-throw switch and the first fulcrum;

[0035] The second capacitor is connected to two ends of the sixth resistor via the fourth support point and the fifth support point respectively.

[0036] Optionally, a third capacitor is further included, connected between the first resistor and the ground terminal.

[0037] Optionally, a seventh resistor is further included, connected between the first support point and the current collection terminal of the single chip microcomputer;

[0038] A fourth capacitor, one end of the fourth capacitor is connected between the seventh resistor and the current collection end of the single-chip microcomputer through a sixth fulcrum, and the other end of the fourth capacitor is grounded.

[0039] The technical solution of the present invention has the following advantages or beneficial effects: it provides a method for detecting resistance in an electric lifting table and a current acquisition circuit of a device for retreating in the event of resistance, and adjusts the different amplification factors of the operational amplifier according to the current rising or falling working state of the electric lifting table, so that the current sampling circuit outputs a voltage signal suitable for recognition and judgment by a single-chip microcomputer, making the judgment method for retreating in the event of resistance more sensitive and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The embodiments of the present invention will be described more fully with reference to the attached drawings, which are provided for illustration and description only and are not intended to limit the scope of the present invention.

[0041] Figure 1 It is a circuit structure diagram of a current acquisition circuit of a device for retreating when encountering an obstacle in an embodiment of the present invention;

[0042] Figure 2 4 is a flowchart of the steps of the obstruction detection method in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0046] The present invention provides a method for detecting an electric lifting table encountering resistance, such as Figure 2 As shown, including:

[0047] Step S1, before the single-chip microcomputer samples the output current of the motor, the single-chip microcomputer obtains the current current of the motor in advance, and determines whether the electric lifting table is in the ascending state or the descending state according to the input direction control signal:

[0048] If the current current of the motor is not less than the first preset threshold value, and it is determined that the electric lifting table is in the ascending state, the single-chip control circuit acquisition circuit amplifies the output current of the motor by a first preset multiple and then performs sampling;

[0049] If the current current of the motor is less than the first preset threshold value, and it is determined that the electric lifting table is in a descending state, the single-chip control circuit acquisition circuit amplifies the output current of the motor by a second preset multiple and then performs sampling;

[0050] Step S2, the single chip microcomputer calculates and processes the amplified current sampling value;

[0051] Step S3, comparing the current sampling value obtained after calculation with the second preset threshold value, when the current sampling value is greater than the second preset threshold value, the single chip microcomputer determines that the lifting table encounters resistance during movement.

[0052] Specifically, if a button is provided on the lifting table to adjust the direction of the lifting table, the direction control signal can be input through the button. The first preset threshold in this embodiment is used to judge the working state of the lifting table. When the motor current is less than the first preset threshold and the lifting table is in a descending state, it is judged that the motor current is small at this time. If the amplification factor is not enough, no obvious current changes can be collected. In this embodiment, at least two amplification factors are provided. Taking two switchable amplification factors as an example, the second preset factor is greater than the first preset factor. When the lifting table is in a descending state, it can be switched to the second preset factor so that the single-chip microcomputer can collect more obvious current changes. The second preset threshold is the resistance judgment threshold. If the current sampling value is greater than the second preset threshold for multiple consecutive times, it can be judged that the lifting table encounters resistance.

[0053] As an optional implementation, the calculation process of the current sampling value by the single chip microcomputer includes:

[0054] The single chip microcomputer collects a number of current sampling values ​​according to a preset frequency, and performs weighting and filtering on the number of current sampling values;

[0055] Some current sampling values ​​are selected from a plurality of current sampling values ​​for averaging processing.

[0056] Specifically, in this embodiment, the processing process of the collected current sampling values ​​includes weighted processing and filtering processing, and weighted processing is performed on a plurality of current sampling values ​​according to the following formula:

[0057] I AD =I 2 *0.1+I 1 *0.9

[0058] in,

[0059] I AD Used to represent the current sampling value obtained after weighted processing;

[0060] I 1 Used to indicate the current sampling value obtained from the last sampling;

[0061] I 2 Used to indicate the current sampling value obtained in this sampling.

[0062] Furthermore, after weighting and filtering, the current sampling values ​​are averaged. For example, 40 I AD The values ​​in the array are updated in real time, and the oldest data in the array is squeezed out when new data comes in. The middle 20 values ​​are intercepted to find the average value, and the values ​​after averaging the 5 consecutive median values ​​are averaged again to obtain the final current sampling value a used to determine whether there is resistance.

[0063] As an optional implementation, the current sampling value a obtained after the current calculation is compared with the current sampling value a obtained last time. When the current current sampling value is not less than the current sampling value obtained last time, the current current sampling value is weighted and then the second preset threshold value b is updated.

[0064] Specifically, in this embodiment, the current current sampling value a is weighted according to the following formula:

[0065] b 2 =b 1 *0.97+a*0.03

[0066] in,

[0067] b 2 Used to indicate the updated second preset threshold;

[0068] b 1 Used to indicate a second preset threshold before updating;

[0069] a is used to represent the current sampling value.

[0070] The present invention obtains the change trend of the current sampling value by averaging the current sampling value, and judges whether the second preset threshold needs to be updated according to the change trend, so that the result of the resistance judgment is more accurate. The above calculation process realizes multiple filtering, reduces the interference of noise, increases the stability of data, and reduces the possibility of false alarm.

[0071] The present invention provides a current collection circuit of a device for retreating when encountering an obstacle, such as Figure 1 As shown, including:

[0072] An operational amplifier U1, wherein a first input terminal of the operational amplifier U1 is connected to a motor M via a first resistor R1 and a second resistor R2, a second input terminal of the operational amplifier U1 is connected to a switching module capable of switching a current amplification factor, an output terminal of the motor M is further connected between the switching module and the second input terminal of the operational amplifier U1 via a third resistor R3 and a fourth resistor R4, and an output terminal of the operational amplifier U1 is connected to a current collection terminal (MCU ADC) of a single-chip computer.

[0073] Specifically, in this embodiment, the sampling current of the motor M is divided into two paths, one of which is transmitted to the first input terminal of the operational amplifier U1 through resistors R1 and R2, and the other is transmitted to the second input terminal of the operational amplifier U1 through R3 and R4. At the same time, the second input terminal of the operational amplifier U1 is also connected to the switching module, which can provide at least two different current magnifications to control the input size of the second input terminal of the operational amplifier, thereby changing the output sampling current of the operational amplifier. The switching method is determined according to the current current of the motor. For example, when the lifting table rises, the current of the motor is large, and the switching module provides a smaller magnification; when the lifting table falls, the current of the motor is small, and it is switched to a larger magnification for the single-chip microcomputer to collect. By dynamically adjusting the operational amplifier according to the working state of the motor through the above-mentioned switching module, the accuracy of the resistance retreat device in judging resistance can be improved, thereby improving the sensitivity of the resistance retreat device.

[0074] As an optional implementation, Figure 1 As shown, the switching module includes a single-pole double-throw switch U2, a first amplifying unit 1, and a second amplifying unit 2; the first pin of the single-pole double-throw switch U2 is connected to one end of the first amplifying unit 1, the second pin of the single-pole double-throw switch U2 is grounded, the third pin of the single-pole double-throw switch U2 is connected to one end of the second amplifying unit 2, the fourth pin of the single-pole double-throw switch U2 is connected to the second input end of the operational amplifier U1, the fifth pin of the single-pole double-throw switch U2 is connected to the power supply VCC, the sixth pin of the single-pole double-throw switch U2 is connected to the control output end (MCU SWITCH) of the single-chip microcomputer MCU, and the other ends of the first amplifying unit 1 and the second amplifying unit 2 are both connected between the output end of the operational amplifier U1 and the current collection end of the single-chip microcomputer MCU through the first fulcrum F1.

[0075] Specifically, the switching module in this embodiment uses a single-chip microcomputer to control a single-pole double-throw switch to switch and connect the first amplification unit 1 or the second amplification unit 2. The first amplification unit 1 and the second amplification unit 2 can provide different current amplification factors respectively. First, the single-chip microcomputer can determine whether the lifting table is currently rising or falling by collecting the current of the motor M. For example, when the motor current is greater than the first preset threshold, it is judged that the lifting table is currently in an ascending state. When the motor current is less than the first preset threshold, it is judged that the lifting table is currently in a descending state. Then the single-chip microcomputer controls the switching of the single-pole double-throw switch according to this judgment result. The first pin NO of the single-pole double-throw switch U2 is a normally open contact (Normal Open). The first amplification unit 1 can be used to provide a conventional current amplification factor. The third pin NC of the single-pole double-throw switch U2 is a normally closed contact (Normal Close). The second amplification unit 2 can be used to provide a larger current amplification factor, so that when the lifting table is in a descending state, the single-chip microcomputer can collect more obvious current changes, thereby improving the sensitivity of the device for retreating when encountering resistance.

[0076] As an optional implementation, Figure 1 As shown, the first amplifying unit 1 includes: a fifth resistor R5 connected between the first pin NO of the single-pole double-throw switch U2 and the first fulcrum F1; a first capacitor C1 connected to both ends of the fifth resistor R5 through the second fulcrum F2 and the third fulcrum F3 respectively.

[0077] The second amplifying unit 2 includes: a sixth resistor R6 connected between the third pin NC of the single-pole double-throw switch U2 and the first fulcrum F1; a second capacitor C2 connected to both ends of the sixth resistor R6 through the fourth fulcrum F4 and the fifth fulcrum F5 respectively.

[0078] The current collection circuit of the present invention also includes a third capacitor C3, connected between the first resistor R1 and the ground terminal; a seventh resistor R7, connected between the first fulcrum F1 and the current collection terminal of the single-chip microcomputer (MCU ADC); a fourth capacitor C4, one end of the fourth capacitor C4 is connected between the seventh resistor R7 and the current collection terminal of the single-chip microcomputer through the sixth fulcrum F6, and the other end of the fourth capacitor C4 is grounded.

[0079] Specifically, since the first amplifying unit 1 and the second amplifying unit 2 in the embodiment of the present invention provide different current amplification factors, the resistance values ​​of the fifth resistor R5 and the sixth resistor R6 should be different.

[0080] The beneficial effects of the embodiments of the present invention are as follows: A current acquisition circuit for a resistance detection method and a resistance return device of an electric lifting table is provided. The different amplification factors of an operational amplifier are adjusted according to the current rising or falling working state of the electric lifting table, so that the current sampling circuit outputs a voltage signal suitable for the single-chip microcomputer to identify and judge, making the judgment method of resistance return more sensitive and accurate.

[0081] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and drawings of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting resistance of an electric lifting table. It is characterized in that include: Before the single-chip microcomputer samples the output current of the motor, the single-chip microcomputer obtains the current current of the motor in advance, and determines whether the electric lifting table is in the ascending state or the descending state according to the input direction control signal: If the current current of the motor is not less than the first preset threshold value, and it is determined that the electric lifting table is in the ascending state, the single-chip control circuit acquisition circuit amplifies the output current of the motor by a first preset multiple and then performs sampling; If the current current of the motor is less than the first preset threshold value and it is determined that the electric lifting table is in a descending state, the single chip microcomputer controls the circuit acquisition circuit to amplify the output current of the motor by a second preset multiple and then perform sampling; The single chip microcomputer calculates and processes the amplified current sampling value, and compares it with a second preset threshold value. When the current sampling value is greater than the second preset threshold value, the single chip microcomputer determines that resistance is encountered; The single chip microcomputer performs calculation processing on the amplified current sampling value to perform average processing on the current sampling value.

2. The method for detecting an obstruction according to claim 1, It is characterized in that The calculation and processing process of the current sampling value by the single chip microcomputer includes: The single chip microcomputer collects a plurality of current sampling values ​​at a preset frequency, and performs weighting and filtering processing on the plurality of current sampling values; A portion of the current sampling values ​​are selected from the plurality of current sampling values ​​for averaging processing.

3. The method for detecting an obstruction according to claim 2, It is characterized in that The plurality of current sampling values ​​are weighted according to the following formula: I AD =I 2 *0.1+I 1 *0.9 in, I AD Used to represent the current sampling value obtained after weighted processing; I 1 Used to indicate the current sampling value obtained by the last sampling; I 2 Used to represent the current sampling value obtained in this sampling.

4. The method for detecting an obstruction according to claim 1, It is characterized in that The current sampling value obtained after the current calculation process is compared with the current sampling value obtained last time. When the current sampling value is not less than the current sampling value obtained last time, the second preset threshold is updated after weighted processing of the current current sampling value.

5. The method for detecting an obstruction according to claim 4, It is characterized in that The current sampling value is weighted according to the following formula: b 2 =b 1 *0.97+a*0.03 in, b 2 used to indicate the updated second preset threshold; b 1 used to indicate the second preset threshold before updating; a is used to represent the current sampling value.

6. A current collection circuit for a device that retreats when encountering an obstacle, It is characterized in that include: An operational amplifier, wherein a first input end of the operational amplifier is connected to an output end of the motor through a first resistor and a second resistor, a second input end of the operational amplifier is connected to a switching module capable of switching a current amplification factor, the output end of the motor is further connected between the switching module and the second input end of the operational amplifier through a third resistor and a fourth resistor, and the output end of the operational amplifier is connected to a current collection end of a single-chip microcomputer; Before the single-chip microcomputer samples the output current of the motor, the single-chip microcomputer obtains the current current of the motor in advance, and determines whether the electric lifting table is in the ascending state or the descending state according to the input direction control signal: If the current current of the motor is not less than the first preset threshold value, and it is determined that the electric lifting table is in the ascending state, the single-chip control circuit acquisition circuit amplifies the output current of the motor by a first preset multiple and then performs sampling; If the current current of the motor is less than the first preset threshold value and it is determined that the electric lifting table is in a descending state, the single chip microcomputer controls the circuit acquisition circuit to amplify the output current of the motor by a second preset multiple and then perform sampling.

7. The current acquisition circuit according to claim 6, It is characterized in that The switching module includes a single-pole double-throw switch, a first amplifying unit, and a second amplifying unit; The first pin of the single-pole double-throw switch is connected to one end of the first amplifying unit, the second pin of the single-pole double-throw switch is grounded, the third pin of the single-pole double-throw switch is connected to one end of the second amplifying unit, the fourth pin of the single-pole double-throw switch is connected to the second input end of the operational amplifier, the fifth pin of the single-pole double-throw switch is connected to the power supply, the sixth pin of the single-pole double-throw switch is connected to the control output end of the single-chip microcomputer, and the other ends of the first amplifying unit and the second amplifying unit are connected between the output end of the operational amplifier and the current collection end of the single-chip microcomputer through a first fulcrum.

8. The current acquisition circuit according to claim 7, It is characterized in that The first amplification unit comprises: a fifth resistor, connected between the first pin of the single-pole double-throw switch and the first fulcrum; A first capacitor connected to two ends of the fifth resistor via a second fulcrum and a third fulcrum respectively; The second amplification unit comprises: a sixth resistor, connected between the third pin of the single-pole double-throw switch and the first fulcrum; The second capacitor is connected to two ends of the sixth resistor via the fourth support point and the fifth support point respectively.

9. The current acquisition circuit according to claim 6, It is characterized in that The device also includes a third capacitor connected between the first resistor and the ground terminal.

10. The current acquisition circuit according to claim 7, It is characterized in that It also includes a seventh resistor connected between the first support point and the current collection terminal of the single chip microcomputer; A fourth capacitor, one end of the fourth capacitor is connected between the seventh resistor and the current collection end of the single-chip microcomputer through a sixth fulcrum, and the other end of the fourth capacitor is grounded.

Images