A six-axis moment sensor system

Abstract

This utility model relates to a six-dimensional torque sensor system. Through integrated circuit design and packaging within the six-dimensional torque sensor, high-precision and highly sensitive deformation sensing and electrical signal conversion output are achieved via strain gauges on the elastic beams of the main frame structure. After specific measurement using a half-bridge differential Wheatstone bridge, the measured signal is amplified, filtered, and converted from digital to analog data by an ADC chip before being sent to a lower-level computer. The lower-level computer then reads the acquired sensor measurement signal, forming a high-precision circuit design specifically matched to the six-dimensional torque sensor. The coordinated installation of the strain gauges, half-bridge differential Wheatstone bridge, and ADC chip makes it less susceptible to environmental factors and effectively suppresses noise interference while achieving high signal gain, effectively realizing the measurement output function of the six-dimensional torque sensor.

Description

Technical Field

[0001] This utility model belongs to the field of sensor circuit technology and relates to a six-dimensional torque sensor system. Background Technology

[0002] Six-dimensional torque sensors play a crucial role in meeting the real-time and accurate force perception requirements of high-performance robots. High-precision, high-sensitivity, and reliable hardware circuits are the key foundation for achieving the performance indicators of six-dimensional torque sensors and also the basis for decoupling algorithm analysis after data acquisition. After the mechanical structure design of the six-dimensional torque sensor is completed, its hardware circuit needs to be designed. Its main function is to convert externally applied force or torque into an electrical signal, which is then read by the sensor. In practical applications, this is usually achieved by attaching a resistance strain gauge to the sensor and representing the signal by the change in its resistance value. The change in resistance causes a change in voltage, which is amplified by an appropriate factor before being read. Finally, the amplified voltage value is transmitted to the host computer via serial communication for subsequent decoupling calculations. During the acquisition process, it is also important to suppress noise interference while maintaining high gain and to minimize the influence of environmental factors (such as temperature and humidity). However, how to design a high-precision and reliable circuit for a six-dimensional torque sensor remains a technical challenge. Utility Model Content

[0003] To address the problems existing in the above-mentioned traditional technologies, this utility model proposes a six-dimensional torque sensor system that can effectively realize the high-precision and reliable circuit required for a six-dimensional torque sensor.

[0004] To achieve the above objectives, the embodiments of this utility model adopt the following technical solutions:

[0005] A six-dimensional torque sensor system is provided, including a main frame structure of the six-dimensional torque sensor, a circuit board, a lower-level machine, a set number of ADC chips, a set number of half-bridge differential Wheatstone bridges, and a set number of resistance strain gauges multiplied by 2, wherein the set number is not less than 3.

[0006] Each strain gauge is attached to its designated patch position on the beam of the elastic body within the main frame structure. The leads of each strain gauge are connected to a half-bridge differential Wheatstone bridge via soldered extension wires. Each pair of strain gauges is connected to the resistor positions on the two arms of a half-bridge differential Wheatstone bridge. The output pins of each half-bridge differential Wheatstone bridge are connected to the positive and negative input terminals of a corresponding ADC chip. The output terminals of each ADC chip are connected to the corresponding input ports of the lower-level machine. Each strain gauge, each half-bridge differential Wheatstone bridge, each ADC chip, and the lower-level machine are all soldered onto a circuit board, which is mounted within the elastic body. The elastic body is a three-spoke structure.

[0007] The resistance strain gauge is used to convert the deformation of the elastic body caused by external force into an electrical signal output. The half-bridge differential Wheatstone bridge is used to measure the bridge voltage signal that indirectly reflects the resistance change of the resistance strain gauge. The ADC chip is used to acquire the bridge voltage signal and convert it into a digital signal after signal amplification and filtering. The lower-level computer is used to read the digital signal obtained from the ADC chip and transmit it to the upper-level computer through the serial port.

[0008] In one embodiment, the strain gauges include 12, the half-bridge differential Wheatstone bridge includes 6, the ADC chip includes 6, and 4 strain gauges are attached to each beam of the elastomer.

[0009] In one embodiment, each patch position on the beam is polished with cross-shaped grooves at a 45° angle to the direction of force, and the surface of the patch position is free of paint, rust, and plating.

[0010] In one embodiment, the resistance strain gauge is a BE120-3AA resistance strain gauge.

[0011] In one embodiment, the ADC chip is an HX711 chip.

[0012] In one embodiment, the resistance strain gauge, the strain gauge leads, and the welding extension wires are sealed with protective silicone.

[0013] One of the above technical solutions has the following advantages and beneficial effects:

[0014] The aforementioned six-dimensional torque sensor system, through its design, comprises a sensor circuit consisting of a main lower-level machine, an ADC chip, a half-bridge differential Wheatstone bridge, and resistance strain gauges. This circuit is integrated onto an elastic body via a circuit board, facilitating seamless integration with the six-dimensional torque sensor. The resistance strain gauges on the beams of the elastic body within the main frame structure of the six-dimensional torque sensor achieve high-precision and high-sensitivity deformation sensing and electrical signal conversion output. After specific measurement via the half-bridge differential Wheatstone bridge, the measured signal is amplified, filtered, and converted from digital to analog by the ADC chip before being sent to the lower-level machine. The lower-level machine then reads the acquired sensor measurement signal, forming a high-precision circuit design specifically matched to the six-dimensional torque sensor. The coordinated installation of the resistance strain gauges, half-bridge differential Wheatstone bridge, and ADC chip is less susceptible to environmental factors and effectively suppresses noise interference while maintaining high signal gain, effectively realizing the measurement output function of the six-dimensional torque sensor. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structural composition of a six-dimensional torque sensor system in one embodiment;

[0017] Figure 2 This is an exploded view of the main frame structure of a six-dimensional torque sensor in one embodiment;

[0018] Figure 3 This is a schematic diagram of the components of an elastomer in one embodiment;

[0019] Figure 4 This is a schematic diagram of the bonding structure of a resistance strain gauge on an elastomer in one embodiment;

[0020] Figure 5 This is a physical diagram of the overall circuit of a six-dimensional torque sensor system in one embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model. Unless otherwise defined, all technical and scientific terms used in this utility model have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present utility model.

[0022] It should be noted that the reference to "embodiment" in this utility model means that a specific feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of this utility model. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand that the embodiments described in this utility model can be combined with other embodiments. The term "and / or" as used in this utility model specification refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0023] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0024] In one embodiment, such as Figure 1 As shown, a six-dimensional torque sensor system is provided, including a main frame structure of the six-dimensional torque sensor, a circuit board, a lower-level machine, a predetermined number of ADC chips, a predetermined number of half-bridge differential Wheatstone bridges, and a predetermined number of resistance strain gauges 12 multiplied by two, with the predetermined number not less than three. Each resistance strain gauge 12 is respectively attached to a patch position on the beam of the elastic body 101 in the main frame structure. The leads of each resistance strain gauge 12 are connected to the half-bridge differential Wheatstone bridges via soldered extension wires, and every two resistance strain gauges 12 are connected to the resistor positions on the two arms of each half-bridge differential Wheatstone bridge. The output pins of each half-bridge differential Wheatstone bridge are connected to the positive and negative input terminals of a corresponding ADC chip. The output terminals of each ADC chip are respectively connected to the corresponding input ports of the lower-level machine. Each resistance strain gauge 12, each half-bridge differential Wheatstone bridge, each ADC chip, and the lower-level machine are all soldered onto the circuit board, which is mounted in the elastic body 101. The elastic body 101 is a three-spoke structure. The resistance strain gauge 12 converts the deformation of the elastic body 101 under external force into an electrical signal output. A half-bridge differential Wheatstone bridge is used to measure the bridge voltage signal, which indirectly reflects the resistance change of the resistance strain gauge 12. An ADC chip is used to acquire the bridge voltage signal and convert it into a digital signal after signal amplification and filtering. The lower-level computer reads the digital signal obtained from the ADC chip and transmits it to the upper-level computer via a serial port.

[0025] Understandable, such as Figure 2 The diagram shown is an exploded view of the main frame structure of the six-dimensional torque sensor, which mainly includes a top cover, a three-spoke elastic body 101, and a base. Figure 3 The diagram shows the components of the elastic body, mainly including the beams, inner flange, and outer flange. Resistance strain gauges 12 are installed on each beam to convert the deformation of the elastic body under external force into an electrical signal output in the form of resistance changes.

[0026] The resistance strain gauge 12 can be a wire strain gauge or a foil strain gauge, used to linearly map mechanical strain to a change in resistance value. For example, the resistance strain gauge 12 can be a 120Ω strain gauge with a sensitivity coefficient of 2.1. The resistance strain gauge 12 is attached to the elastic body of the three-spoke structure of the six-dimensional torque sensor at a location (the location range is larger than the area of ​​the resistance strain gauge 12). The back of the resistance strain gauge 12 is attached to the object being measured at the designated location using adhesive. The leads of the resistance strain gauge 12 are connected to a half-bridge differential Wheatstone bridge via soldered extension wires. The resistance on both arms of each half-bridge differential Wheatstone bridge is replaced by the resistance strain gauge 12.

[0027] In this design, each half-bridge differential Wheatstone bridge is paired with two resistance strain gauges 12 mounted on opposite sides of the same beam of the three-spoke elastic body to form a differential signal loop. The half-bridge differential Wheatstone bridge indirectly reflects the resistance change of the strain gauges 12 by measuring the change in its bridge voltage, thereby indirectly representing the magnitude of the external force on the elastic body by the magnitude of the deformation. For a detailed explanation of the specific functions and signal conversion principles of the half-bridge differential Wheatstone bridge, please refer to the basic circuit principle of the bridge; further details are omitted here. Figure 4 The diagram shows a schematic of the bonding structure of a resistance strain gauge on an elastomer.

[0028] The lower-level machine can use the existing STM32F103C8T6 microprocessor, which has 37 GPIO ports, some of which are multiplexed. It also has two built-in 12-bit ADC modules. The lower-level machine can power the entire circuit system and handle data downloading via the built-in Type-C circuit. For a detailed explanation of the specific functions and port structure of the STM32F103C8T6 microprocessor, please refer to the chip circuit description; similarly, this description will not elaborate further.

[0029] To simultaneously acquire multiple signals and compensate for the insufficient number of ADC modules built into the lower-level chip, additional ADC chips are needed to supplement the channels. Existing analog-to-digital converter chips can be used, which typically integrate a clock oscillator, are compatible with external clocks, and are easy to assemble and use. Furthermore, they can amplify the output signal by a certain gain using their built-in programmable amplifiers, allowing direct connection to the corresponding input ports of the lower-level device without the need for separate programming of the chip's internal registers, resulting in high efficiency. In practical applications, the output pins of each half-bridge differential Wheatstone bridge are connected to the positive and negative input terminals (such as INA+ and INA-) of the corresponding ADC chip to achieve differential input.

[0030] During the signal acquisition process between the lower-level machine and the data transmission between the upper-level machine, the lower-level machine uses the existing USB CDC virtual serial port to transmit data with the upper-level machine. USB CDC is a communication standard that allows USB devices to simulate serial port devices on a computer, enabling the upper-level machine to communicate with the STM32 like a traditional serial port device without the need to install special USB drivers, thus achieving high-speed and long-term stable and reliable data transmission. All the aforementioned strain gauges 12, half-bridge differential Wheatstone bridges, ADC chips, and the lower-level machine are soldered onto the same circuit board. The physical circuit diagram is shown below. Figure 5 As shown.

[0031] The aforementioned six-dimensional torque sensor system, through its design, comprises a sensor circuit consisting of a main lower-level machine, an ADC chip, a half-bridge differential Wheatstone bridge, and resistance strain gauges. This circuit is integrated onto an elastic body via a circuit board, facilitating seamless integration with the six-dimensional torque sensor. The resistance strain gauges on the beams of the elastic body within the main frame structure of the six-dimensional torque sensor achieve high-precision and high-sensitivity deformation sensing and electrical signal conversion output. After specific measurement via the half-bridge differential Wheatstone bridge, the measured signal is amplified, filtered, and converted from digital to analog by the ADC chip before being sent to the lower-level machine. The lower-level machine then reads the acquired sensor measurement signal, forming a high-precision circuit design specifically matched to the six-dimensional torque sensor. The coordinated installation of the resistance strain gauges, half-bridge differential Wheatstone bridge, and ADC chip is less susceptible to environmental factors and effectively suppresses noise interference while maintaining high signal gain, effectively realizing the measurement output function of the six-dimensional torque sensor.

[0032] In one embodiment, the strain gauges include 12, the half-bridge differential Wheatstone bridge includes 6, the ADC chip includes 6, and 4 strain gauges are attached to each beam of the elastomer.

[0033] It is understandable that, since the three-spoke elastic body of the six-dimensional torque sensor has three beams, and in this embodiment, four resistance strain gauges can be attached to each beam, a single six-dimensional torque sensor requires six ADC chips. Therefore, the built-in ADC module of the lower-level machine cannot meet the requirements for the quantity and accuracy of strain measurement. External ADC chips must be used to measure the circuit through pin settings, and it must be ensured that each ADC chip can read and output simultaneously and independently without generating interference signals when externally connected. Each ADC chip is electrically connected to the respective GPIO port of the lower-level machine, and the lower-level machine transmits the signals acquired by the ADC chips to the upper-level machine through its own UART communication serial port.

[0034] This embodiment attaches four resistance strain gauges to each beam, and simultaneously arranges six half-bridge differential Wheatstone bridges and six ADC chips. By distributing the four resistance strain gauges evenly on each beam—for example, attaching two resistance strain gauges as a group, symmetrically at two opposite surfaces on the radial side of the beam, and equidistantly distributing the two groups of resistance strain gauges along the axial direction of the beam—and ensuring that each resistance strain gauge is not coplanar, this uniform distribution makes the deformation sensing on each beam more precise and accurate, thereby further improving measurement accuracy and sensitivity.

[0035] In one embodiment, each patch position on the beam is ground with cross-shaped patterns at a 45° angle to the direction of force, and the surface of the patch position is free of paint, rust, and plating.

[0036] It is understood that in this embodiment, at each patch position on each beam, a cross pattern at a 45° angle to the direction of force can be formed by sanding with fine sandpaper. Moreover, the surface of the patch position is free of dirt, paint, rust, and plating. This is to maximize the friction between the surface of the patch position and the resistance strain gauge, further enhance the adhesion effect of the resistance strain gauge, and thus more precisely sense the deformation transmitted to the beam, achieve a more sensitive deformation sensing effect, and promote the improvement of measurement accuracy.

[0037] In one embodiment, the resistance strain gauge is a BE120-3AA resistance strain gauge. It is understood that the BE120-3AA resistance strain gauge can be used in this embodiment because it has a larger wire grid size and better meets the size requirements of the elastic beam, allowing for a wider range of deformation detection and thus further improving the sensitivity of deformation sensing.

[0038] In one embodiment, the resistance strain gauge, the strain gauge leads, and the welding extension wires are sealed with protective silicone.

[0039] Specifically, in this embodiment, the resistance strain gauge, the strain gauge leads, and the welding extension wires can also be sealed with protective silicone to protect them from moisture and external forces, thereby improving circuit reliability and avoiding measurement interference caused by environmental factors.

[0040] In one embodiment, the ADC chip is an HX711 chip.

[0041] It is understood that in this embodiment, the ADC chip can be the existing HX711 chip. This chip is a 24-bit analog-to-digital converter with two differential inputs. It integrates a clock oscillator, is compatible with external clocks, and can amplify the output signal by 32x, 64x, or 128x through its built-in programmable amplifier. It can be directly connected to the corresponding input port of the lower-level machine without the need for separate programming of the internal registers, ensuring high efficiency.

[0042] It should be noted that in the specific circuit diagrams of the above circuit parts, if the pins in different circuit diagrams are marked with the same label, it means that the pins with the same label are connected.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of protection of this utility model. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this utility model, and all of these modifications and improvements fall within the scope of protection of this utility model.

Claims

1. A six-dimensional torque sensor system, characterized in that, It includes the main frame structure of the six-dimensional torque sensor, circuit board, lower-level machine, a set number of ADC chips, a set number of half-bridge differential Wheatstone bridges, and a set number of resistance strain gauges multiplied by 2, with a set number of not less than 3. Each strain gauge is attached to its designated patch position on the beam of the elastic body within the main frame structure. The leads of each strain gauge are connected to a half-bridge differential Wheatstone bridge via soldered extension wires. Each pair of strain gauges is connected to the resistor positions on the two arms of a half-bridge differential Wheatstone bridge. The output pins of each half-bridge differential Wheatstone bridge are connected to the positive and negative input terminals of a corresponding ADC chip. The output terminals of each ADC chip are connected to the corresponding input ports of the lower-level machine. Each strain gauge, each half-bridge differential Wheatstone bridge, each ADC chip, and the lower-level machine are all soldered onto a circuit board, which is mounted within the elastic body. The elastic body is a three-spoke structure. The resistance strain gauge is used to convert the deformation of the elastic body caused by external force into an electrical signal output. The half-bridge differential Wheatstone bridge is used to measure the bridge voltage signal that indirectly reflects the resistance change of the resistance strain gauge. The ADC chip is used to acquire the bridge voltage signal and convert it into a digital signal after signal amplification and filtering. The lower-level computer is used to read the digital signal obtained from the ADC chip and transmit it to the upper-level computer through the serial port.

2. The six-dimensional torque sensor system according to claim 1, characterized in that, The system includes 12 resistance strain gauges, 6 half-bridge differential Wheatstone bridges, 6 ADC chips, and 4 resistance strain gauges attached to each beam of the elastomer.

3. The six-dimensional torque sensor system according to claim 2, characterized in that, The patch positions on the beam are polished with cross-shaped patterns at a 45° angle to the direction of force. The surfaces of the patch positions are free of paint, rust, and plating.

4. A six-dimensional torque sensor system according to claim 3, characterized in that, The resistance strain gauge is a BE120-3AA resistance strain gauge.

5. A six-dimensional torque sensor system according to any one of claims 1 to 4, characterized in that, The ADC chip is an HX711 chip.

6. A six-dimensional torque sensor system according to claim 5, characterized in that, The resistance strain gauge, its leads, and the welding extension wires are sealed with protective silicone.

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