Torque sensor information acquisition circuit

Abstract

A torque sensor information acquisition circuit relates to the technical field of detection devices. The problem that an existing torque sensor cannot meet the requirements of wide range and high resolution at the same time is solved. Four bridge arm resistors of the full-bridge strain circuit are pasted or integrated on an elastic body of the torque sensor for signal acquisition, two differential amplification circuits with different gains are adopted to carry out differential amplification on received differential voltage signals respectively, and after the two signals are converted through an AD conversion circuit, the two signals are transmitted to the full-bridge strain circuit. Judging whether the absolute value of the converted high-gain channel signal is smaller than a preset saturation threshold value or not by adopting a microcontroller; if yes, a digital high-gain channel signal value is selected for calculation, and torque information is obtained; and if the absolute value of the digital high-gain channel signal reaches or exceeds a saturation threshold value, calculating by adopting a low-gain channel signal value to obtain torque information. The method is mainly used for torque acquisition.

Description

Technical Field

[0001] This invention relates to the field of detection device technology, and in particular to torque sensors. Background Technology

[0002] Torque sensors, also known as torque measurement sensors, are used to measure one-dimensional torque and are widely used in the field of robotics. This type of sensor employs the traditional method of attaching resistance strain gauges to the surface of an elastic beam. When physical quantities such as torque are applied to the elastic beam, it causes changes in the stress and strain of the element, which in turn causes changes in the resistance of the strain gauges.

[0003] Changes in resistance can be converted into an analog signal, which is then amplified and converted into a digital signal by an analog-to-digital converter (ADC). Due to the limitation of the ADC's data bit width, there is a conflict between the sensor's measurement range and resolution. Traditional solutions often use single-gain amplifier circuits, which cannot simultaneously meet the requirements of a large measurement range and high resolution. Although there are solutions that use analog switches to switch the measurement range, these suffer from problems such as switching delay, contact lifespan, and signal transients.

[0004] Therefore, there is an urgent need for a torque sensor information acquisition solution that can simultaneously achieve high resolution and wide measurement range. Summary of the Invention

[0005] The present invention addresses the problem that existing torque sensors cannot simultaneously meet the requirements of large range and high resolution, and provides a torque sensor information acquisition circuit.

[0006] The torque sensor information acquisition circuit of the present invention includes a full-bridge strain gauge circuit, a first differential amplifier circuit, a second differential amplifier circuit, an AD conversion circuit, and a microcontroller;

[0007] The four bridge arm resistors of the full-bridge strain gauge circuit are attached or integrated onto the elastic body of the torque sensor; the force deformation of the elastic body of the torque sensor is converted into a change in the resistance value of the bridge arm of the full-bridge strain gauge circuit, generating a differential voltage signal proportional to the torque between the first and second output terminals of the full-bridge strain gauge circuit.

[0008] The first and second output terminals of the full-bridge strain gauge circuit are simultaneously connected to the two signal input terminals of the first differential amplifier circuit and the two signal input terminals of the second differential amplifier circuit.

[0009] The gain of the first differential amplifier circuit is greater than the gain of the second differential amplifier circuit;

[0010] The first differential amplifier circuit and the second differential amplifier circuit respectively perform differential amplification on the received differential voltage signal to obtain the high-gain channel signal Vout1 and the low-gain channel signal Vout2;

[0011] The high-gain channel signal Vout1 and the low-gain channel signal Vout2 are respectively transmitted to the AD conversion circuit;

[0012] The AD conversion circuit synchronously performs analog-to-digital conversion on the high-gain channel signal Vout1 and the low-gain channel signal Vout2 through two analog sampling input channels; and transmits the digital signals after analog-to-digital conversion to the microcontroller respectively.

[0013] The microcontroller determines whether the absolute value of the digital high-gain channel signal Vout1 is less than a preset saturation threshold; if so, it uses the value of the digital high-gain channel signal Vout1 for calculation to obtain torque information.

[0014] If the absolute value of the digital high-gain channel signal Vout1 reaches or exceeds the saturation threshold, the value of the low-gain channel signal Vout2 is used for calculation to obtain torque information.

[0015] Furthermore, in this invention, the four bridge arm resistors of the full-bridge strain gauge circuit are connected in the form of a Wheatstone bridge.

[0016] Furthermore, in this invention, the first output terminal of the full-bridge strain gauge circuit is the connection point of the first bridge arm resistor R1 and the third bridge arm resistor R3, and the second output terminal is the connection point of the second bridge arm resistor R2 and the fourth bridge arm resistor R4.

[0017] Furthermore, in this invention, the AD conversion circuit is implemented using the ADS1256 chip, or using a microcontroller with a built-in multi-channel ADC.

[0018] Furthermore, in this invention, the formula for calculating and obtaining torque information using the high-gain digital channel signal Vout1 is the same as the formula for calculating and obtaining torque information using the low-gain channel signal Vout2, specifically:

[0019] Torque = (ADC_Value - Offset) Scale_Factor;

[0020] Wherein, ADC_Value is the value of the digital high-gain channel signal Vout1 or the value of the low-gain channel signal Vout2; Offset is the zero-point offset value of the high or low gain channel; and Scale_Factor is the scaling factor of the high or low gain channel.

[0021] Furthermore, in this invention, both the first differential amplifier circuit and the second differential amplifier circuit are implemented using instrumentation amplifiers.

[0022] Furthermore, in this invention, a filter circuit is connected in series between the signal output terminals of the first differential amplifier circuit and the input terminal of the AD conversion circuit, respectively, to perform low-pass filtering on the high-gain channel signal Vout1 and the low-gain channel signal Vout2 before transmitting them to the AD conversion circuit.

[0023] This invention achieves both wide measurement range and high resolution by processing signals with different gains in parallel at the hardware level, fundamentally solving the contradiction that traditional single-channel circuits cannot balance range and resolution. It features delay-free switching, as the dual channels are always in a synchronous acquisition state, and the processor makes software judgments and selections based on the sampled values, eliminating the delay, jitter, and lifespan issues caused by mechanical or analog switch switching, resulting in faster response speeds. It also boasts high reliability and anti-interference capabilities, employing an instrumentation amplifier as the core amplification component, supplemented by subsequent filtering circuits, significantly improving the signal-to-noise ratio and common-mode rejection capability, enhancing the overall anti-interference performance and measurement accuracy of the system. Furthermore, it offers high flexibility, with the range switching threshold configurable via software, allowing adaptation to different sensors and application scenarios without hardware modifications, demonstrating strong versatility. Attached Figure Description

[0024] Figure 1 This is a block diagram of the torque sensor information acquisition circuit described in this invention.

[0025] Figure 2 This is a circuit diagram showing the connection between the full-bridge strain gauge circuit, the first differential amplifier circuit, and the second differential amplifier circuit. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0027] Specific implementation method one: Refer to Figure 1 This embodiment describes a torque sensor information acquisition circuit, which includes a full-bridge strain gauge circuit 1, a first differential amplifier circuit 2, a second differential amplifier circuit 3, an AD conversion circuit 4, and a microcontroller 5.

[0028] The four bridge arm resistors of the full-bridge strain circuit 1 are attached or integrated onto the elastic body of the torque sensor; the force deformation of the elastic body of the torque sensor is converted into the change of the resistance value of the bridge arm of the full-bridge strain circuit 1, and a differential voltage signal proportional to the torque is generated between the first output terminal and the second output terminal of the full-bridge strain circuit 1.

[0029] The first and second output terminals of the full-bridge strain gauge circuit 1 are simultaneously connected to the two signal input terminals of the first differential amplifier circuit 2 and the two signal input terminals of the second differential amplifier circuit 3.

[0030] The gain of the first differential amplifier circuit 2 is greater than the gain of the second differential amplifier circuit 3;

[0031] The first differential amplifier circuit 2 and the second differential amplifier circuit 3 respectively perform differential amplification on the received differential voltage signal to obtain the high-gain channel signal Vout1 and the low-gain channel signal Vout2;

[0032] The high-gain channel signal Vout1 and the low-gain channel signal Vout2 are respectively transmitted to the AD conversion circuit 4;

[0033] The AD conversion circuit 4 synchronously performs analog-to-digital conversion on the high-gain channel signal Vout1 and the low-gain channel signal Vout2 through two analog sampling input channels; and transmits the digital signals after analog-to-digital conversion to the microcontroller 5 respectively.

[0034] The microcontroller 5 determines whether the absolute value of the digital high-gain channel signal Vout1 is less than a preset saturation threshold; if so, it uses the value of the digital high-gain channel signal Vout1 for calculation to obtain torque information.

[0035] If the absolute value of the digital high-gain channel signal Vout1 reaches or exceeds the saturation threshold, the value of the low-gain channel signal Vout2 is used for calculation to obtain torque information.

[0036] In this embodiment, the preset saturation threshold is set according to the actual application requirements.

[0037] Furthermore, in this invention, the four bridge arm resistors of the full-bridge strain gauge circuit 1 are connected in the form of a Wheatstone bridge.

[0038] Furthermore, in this invention, the first output terminal of the full-bridge strain gauge circuit 1 is the connection point of the first bridge arm resistor R1 and the third bridge arm resistor R3, and the second output terminal is the connection point of the second bridge arm resistor R2 and the fourth bridge arm resistor R4.

[0039] Furthermore, in this invention, the AD conversion circuit 4 is implemented using the ADS1256 chip, or using a microcontroller with a built-in multi-channel ADC.

[0040] Furthermore, in this invention, the formula for calculating and obtaining torque information using the high-gain digital channel signal Vout1 is the same as the formula for calculating and obtaining torque information using the low-gain channel signal Vout2, specifically:

[0041] Torque = (ADC_Value - Offset) Scale_Factor;

[0042] Wherein, ADC_Value is the value of the digital high-gain channel signal Vout1 or the value of the low-gain channel signal Vout2; Offset is the zero-point offset value of the high or low gain channel; and Scale_Factor is the scaling factor of the high or low gain channel.

[0043] Furthermore, in this invention, both the first differential amplifier circuit 2 and the second differential amplifier circuit 3 are implemented using instrumentation amplifiers.

[0044] Furthermore, in this invention, a filter circuit is connected in series between the signal output terminals of the first differential amplifier circuit 2 and the second differential amplifier circuit 3 and the input terminal of the AD conversion circuit 4, respectively, to perform low-pass filtering on the high-gain channel signal Vout1 and the low-gain channel signal Vout2 before transmitting them to the AD conversion circuit 4.

[0045] like Figure 1 and 2 As shown, a torque sensor information acquisition circuit mainly includes: a full-bridge strain gauge circuit 1, a first differential amplifier circuit 2, and a second differential amplifier circuit 3.

[0046] The full-bridge strain gauge circuit 1 consists of four strain resistors R1, R2, R3, and R4. In practice, these resistors are metal foil strain gauges or semiconductor piezoresistive elements, which are attached or integrated onto the elastic body of the sensor and connected in a Wheatstone bridge configuration. When the elastic body deforms under stress, the resistance of the bridge arms changes, thereby generating a millivolt-level differential voltage signal proportional to the torque between the first and second output terminals. The first output terminal of the bridge is the connection point of the first resistor R1 and the third resistor R3, and the second output terminal is the connection point of the second resistor R2 and the fourth resistor R4.

[0047] The input terminals of the first differential amplifier circuit 2 and the second differential amplifier circuit 3 are connected in parallel to the first and second output terminals of the full-bridge strain gauge circuit 1. In this embodiment, both are built using integrated instrumentation amplifiers (such as AD620, INA128, etc.). By setting different external gain resistors, the gain G1 of the first differential amplifier circuit 2 is set to be greater than the gain G2 of the second differential amplifier circuit 3, which is used to amplify small torque signals within a certain range; the gain G2 of the second differential amplifier circuit 3 is used to amplify large torque signals within a larger range.

[0048] The analog-to-digital converter (ADC) can be implemented using a microcontroller (MCU) with a built-in multi-channel ADC, or it can be implemented using a separate high-precision ADC chip (such as ADS1256). Its two analog input channels are respectively connected to the output terminals of the first differential amplifier circuit 2 and the second differential amplifier circuit 3, and are configured in synchronous sampling mode to capture the two signals at the same time, thereby eliminating calculation errors caused by asynchronous signal changes.

[0049] The microcontroller 5 has a built-in signal processing algorithm, and its workflow is as follows: It synchronously samples and reads the ADC values ​​output from two independent differential amplifier circuits; it then determines whether the absolute value of the high-gain channel signal Vout1 is less than a preset saturation threshold. If it is less, it indicates that the current torque is within a small-range, high-precision measurement range, and Vout1 is selected for calculation. If the absolute value of Vout1 reaches or exceeds the saturation threshold, it indicates that the current torque is too large, and the high-gain channel is saturated or about to saturate, so it immediately switches to the low-gain channel signal Vout2 for calculation.

[0050] During power-on or periodic calibration, the system applies a standard torque for calibration, calculating the zero-point offset and scale factor for both high and low gain channels. In actual measurements, regardless of the signal selected, the corresponding calibration parameters are used for initial correction: Torque = (ADC_Value - Offset) Scale_Factor, where ADC_Value is the voltage signal value obtained by processing the outputs Vout1 and Vout2 from two independent differential amplifier circuits using the signal processing algorithm described above. Through fine calibration, it can be ensured that the calculated torque value is smooth, continuous, and without jumps near the switching point between high and low gain channels.

[0051] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A torque sensor information acquisition circuit, characterized in that, The full-bridge strain circuit (1), the first differential amplification circuit (2), the second differential amplification circuit (3), the AD conversion circuit (4) and the microcontroller (5) are included. The four bridge arm resistors of the full-bridge strain circuit (1) are pasted or integrated on the elastic body of the torque sensor; the stress deformation of the torque sensor elastic body is converted into the bridge arm resistor value change of the full-bridge strain circuit (1), and a differential voltage signal proportional to the torque is generated between the first output end and the second output end of the full-bridge strain circuit (1). The first output end and the second output end of the full-bridge strain circuit (1) are simultaneously connected to the two signal input ends of the first differential amplification circuit (2) and the two signal input ends of the second differential amplification circuit (3). The gain of the first differential amplification circuit (2) is greater than the gain of the second differential amplification circuit (3). The first differential amplification circuit (2) and the second differential amplification circuit (3) respectively perform differential amplification on the received differential voltage signal to obtain a high-gain channel signal Vout1 and a low-gain channel signal Vout2. The high-gain channel signal Vout1 and the low-gain channel signal Vout2 are transmitted to the AD conversion circuit (4) respectively. The AD conversion circuit (4) synchronously converts the high-gain channel signal Vout1 and the low-gain channel signal Vout2 through two analog sampling input channels; and the digital signals after analog-to-digital conversion are transmitted to the microcontroller (5) respectively. The microcontroller (5) judges whether the absolute value of the digital high-gain channel signal Vout1 is less than a preset saturation threshold; if yes, the digital high-gain channel signal Vout1 value is selected for calculation to obtain torque information. If the absolute value of the digital high-gain channel signal Vout1 reaches or exceeds the saturation threshold, the low-gain channel signal Vout2 value is used for calculation to obtain torque information.

2. The torque sensor information acquisition circuit according to claim 1, characterized by The four bridge arm resistors of the full-bridge strain circuit (1) are connected in the form of a Wheatstone bridge.

3. The torque sensor information acquisition circuit according to claim 2, characterized by The first output end of the full-bridge strain circuit (1) is the connection point of the first bridge arm resistor R1 and the third bridge arm resistor R3, and the second output end is the connection point of the second bridge arm resistor R2 and the fourth bridge arm resistor R4.

4. A torque sensor information acquisition circuit according to claim 1, 2 or 3, characterized in that, The AD conversion circuit (4) is implemented by using a chip ADS1256 or a microcontroller with a built-in multi-channel ADC.

5. The torque sensor information acquisition circuit according to claim 1, characterized by, The formula for calculating torque information by selecting the digital high-gain channel signal Vout1 value and the low-gain channel signal Vout2 value is the same, which is specifically: Torque = (ADC_Value - Offset) Scale_Factor; Wherein, ADC_Value is the digital high-gain channel signal Vout1 value or the low-gain channel signal Vout2 value; Offset is the zero point offset value of the high or low gain channel, and Scale_Factor is the proportional coefficient of the high or low gain channel.

6. A torque sensor information acquisition circuit according to claim 1, 2 or 5, characterized in that, The first differential amplification circuit (2) and the second differential amplification circuit (3) are implemented by using an instrument amplifier.

7. A torque sensor information acquisition circuit according to claim 1, 2 or 5, characterized in that, The signal output ends of the first differential amplification circuit (2) and the second differential amplification circuit (3) are respectively connected with an input end of an AD conversion circuit (4) in series with a filter circuit, and the high-gain channel signal Vout1 and the low-gain channel signal Vout2 are transmitted to the AD conversion circuit (4) after low-pass filtering.

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