Full-resistance zero compensation method for six-dimensional force sensor

Abstract

The invention discloses a full-resistance zero compensation method for a six-dimensional force sensor, and the method comprises the steps: building a Wheatstone bridge corresponding to each measurement dimension of the six-dimensional force sensor, and enabling the Wheatstone bridge to comprise a bridge switching circuit; the connection between each single-pole double-throw switch in the Wheatstone bridge needing zero compensation and the bridge switching circuit is controlled, the bridging mode of the Wheatstone bridge is changed, and a first output voltage, a second output voltage, a third output voltage and a fourth output voltage are obtained in sequence; according to the first input voltage, the first output voltage, the second output voltage, the third output voltage and the fourth output voltage, initial resistance values of four strain gauges corresponding to the Wheatstone bridge are obtained; according to the initial resistance values of the four strain gauges, the short-circuit welding spots of the corresponding strain gauges are connected through electric welding, so that the resistance difference value between the strain gauges does not exceed a first difference value threshold value. According to the invention, the zero compensation can reduce the inter-dimensional coupling and improve the measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of six-dimensional force sensors, and in particular to a method for zero-point compensation of the total resistance of a six-dimensional force sensor. Background Technology

[0002] A multidimensional force sensor is a force sensor capable of simultaneously measuring force and torque components in two or more directions. In a Cartesian coordinate system, force and torque can each be decomposed into three components. Therefore, the most complete form of multidimensional force is a six-dimensional force / torque sensor, which can simultaneously measure three force components and three torque components. Widely used multidimensional force sensors are of this type. Because six-dimensional force sensors can simultaneously detect three-dimensional force and three-dimensional torque in space, they can serve as fundamental components for precision assembly, precision operation, precision control, and human-machine interaction control. Simultaneously, six-dimensional force sensors are also essential for robots to perform contact-based tasks, such as space exploration technology, force control of space manipulators, industrial robots, and remote control operation of underwater robots, all of which require large-range, high-precision six-dimensional force sensors.

[0003] Traditional one-dimensional force sensors achieve zero-point compensation by adding a compensation resistor to the Wheatstone bridge, allowing the bridge to rebalance under no-load conditions, thus improving force measurement accuracy. However, six-dimensional force sensors need to consider the coupling effects between different dimensions. Adding a compensation resistor may increase these coupling effects, causing the measurement data from different dimensions to interfere with each other and reducing accuracy. Summary of the Invention

[0004] In view of the aforementioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a method for zero-point compensation of the total resistance of a six-dimensional force sensor, which aims to compensate each strain gauge in the Wheatstone bridge accordingly, so as to reduce inter-dimensional coupling and improve measurement accuracy.

[0005] To achieve the above objectives, this invention discloses a method for zero-point compensation of the total resistance of a six-dimensional force sensor, the method comprising: Step S1: Construct Wheatstone bridges corresponding to each measurement dimension of the six-dimensional force sensor; wherein, the six-dimensional force sensor further includes multiple bridge switching circuits corresponding to the Wheatstone bridges, each bridge switching circuit includes two input terminals and two output terminals, each Wheatstone bridge includes a first terminal, a second terminal, a third terminal and a fourth terminal, and all four terminals are connected to a single-pole double-throw switch, the single-pole double-throw switch is used to switch the connection relationship between the corresponding terminals and the input terminals and the output terminals of the bridge switching circuit; Step S2: Control each of the single-pole double-throw switches in the Wheatstone bridge that requires zero-point compensation, so that the first and third diagonally opposite endpoints are respectively connected to the two input terminals of the bridge switching circuit, and the second and fourth diagonally opposite endpoints are respectively connected to the two output terminals of the bridge switching circuit; and apply positive and negative first input voltages sequentially between the two input terminals, and measure the corresponding first and second output voltages at the two output terminals. Step S3: Control each of the single-pole double-throw switches in the Wheatstone bridge that requires zero-point compensation, so that the first and third diagonally opposite endpoints are respectively connected to the two output terminals of the bridge switching circuit, and the second and fourth diagonally opposite endpoints are respectively connected to the two input terminals of the bridge switching circuit; and apply the first positive and negative input voltages sequentially between the two input terminals, and measure the corresponding third and fourth output voltages at the two output terminals; Step S4: Based on the first input voltage, the first output voltage, the second output voltage, the third output voltage, and the fourth output voltage, obtain the initial resistance values ​​of the four strain gauges corresponding to the Wheatstone bridge; wherein, some of the grid bars of the strain gauges are provided with shorting solder joints; Step S5: Based on the initial resistance values ​​of the four strain gauges, weld the short-circuit joints corresponding to the strain gauges so that the resistance difference between the strain gauges does not exceed a first difference threshold.

[0006] Optionally, in step S2, the first output voltage and the second output voltage satisfy the following conditions: in, The first output voltage, This is the second output voltage. The first input voltage, , , and These are the four strain gauges of the Wheatstone bridge, and Located between the first endpoint and the second endpoint, Located between the second endpoint and the third endpoint, Located between the third endpoint and the fourth endpoint, It is located between the fourth endpoint and the first endpoint.

[0007] Optionally, in step S3, the third output voltage and the fourth output voltage satisfy the following conditions: in, The third output voltage, The fourth output voltage, The first input voltage, , , and These are the four strain gauges of the Wheatstone bridge, and Located between the first endpoint and the second endpoint, Located between the second endpoint and the third endpoint, Located between the third endpoint and the fourth endpoint, It is located between the fourth endpoint and the first endpoint.

[0008] Optionally, step S4 includes: according to Solve , , and .

[0009] Optionally, step S5 includes: The minimum initial resistance value is obtained based on the initial resistance values ​​of the four strain gauges; Based on the minimum initial resistance value, the short-circuit solder joints of the strain gauges other than the strain gauge corresponding to the minimum initial resistance value are electrically welded, such that the resistance difference between the resistance values ​​of the other strain gauges and the minimum initial resistance value does not exceed a first difference threshold.

[0010] Optionally, after step S5, the method further includes: Reapply the test input voltage to the first endpoint and the third endpoint, and obtain the corresponding test output voltage; determine whether the test output voltage is less than the first test threshold. If it is, determine that the zero-point compensation is completed; otherwise, perform compensation again.

[0011] Optionally, the strain gauge is connected to the corresponding short-circuit solder joint by electric welding to shield part of the grid resistance, thereby reducing the resistance of the strain gauge.

[0012] Optionally, after step S5, the method further includes: Repeat steps S2 to S5 for each Wheatstone bridge corresponding to each measurement dimension to complete the zero-point compensation of the total resistance of all Wheatstone bridges.

[0013] The beneficial effects of this invention are as follows: 1. This invention uses a bridge switching circuit and a single-pole double-throw switch to change the input and output of the corresponding Wheatstone bridge, thereby obtaining different outputs. Based on these outputs, the resistance values ​​of each strain gauge can be calculated, and then zero-point compensation of the total resistance can be performed on each strain gauge. On the one hand, this invention achieves precise compensation in this way. Since it is a total resistance compensation, it avoids the interdimensional coupling effect that may be caused by adding only a compensation resistor in the prior art. On the other hand, this invention can accurately obtain the strain gauge resistance for corresponding compensation without adding other equipment, avoiding redundancy, simplifying the process, and making it easier to streamline. 2. Some grid bars of the strain gauge in this invention are provided with short-circuit solder joints. Based on the initial resistance values ​​of the four strain gauges, the short-circuit solder joints of the corresponding strain gauges are connected by electric welding, so that the resistance difference between the strain gauges does not exceed a first difference threshold. Compared to existing methods that add compensation resistors for zero-point compensation, this invention does not introduce new compensation resistors. Zero-point compensation is achieved by adjusting the resistance of the strain gauge itself. This avoids the failure caused by the compensation resistor not changing its resistance with the deformation or changing its resistance with a different magnitude than the strain gauge, which leads to changes in the strain gauge resistance but still maintaining bridge balance in the Wheatstone bridge. This reduces interdimensional coupling, increases the accuracy of zero-point compensation, and improves the accuracy of subsequent force measurement.

[0014] In summary, this invention can compensate each strain gauge in a Wheatstone bridge accordingly, thereby reducing interdimensional coupling caused by conventional zero-point compensation and improving measurement accuracy. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a method for zero-point compensation of the total resistance of a six-dimensional force sensor according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit structure of a Wheatstone bridge provided in a specific embodiment of the present invention; Figure 3 This is a schematic diagram of the equivalent circuit structure of the Wheatstone bridge corresponding to the first voltage output provided in a specific embodiment of the present invention; Figure 4 This is a schematic diagram of the equivalent circuit structure of the Wheatstone bridge corresponding to the second voltage output provided in a specific embodiment of the present invention; Figure 5 This is a schematic diagram of the equivalent circuit structure of the Wheatstone bridge corresponding to the third voltage output provided in a specific embodiment of the present invention; Figure 6 This is a schematic diagram of the equivalent circuit structure of the Wheatstone bridge corresponding to the fourth voltage output provided in a specific embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a strain gauge with short-circuit solder joints on the grid strips according to a specific embodiment of the present invention. Detailed Implementation

[0016] This invention discloses a method for zero-point compensation of the total resistance of a six-dimensional force sensor. Those skilled in the art can refer to the content of this document and appropriately modify the technical details to implement it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can obviously make modifications or appropriate changes and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0017] The applicant's research revealed that traditional one-dimensional force sensors achieve zero-point compensation by adding a compensation resistor to the Wheatstone bridge, allowing the bridge to rebalance under no-load conditions, thus improving force measurement accuracy. However, six-dimensional force sensors require consideration of the coupling effects between different dimensions. Adding a compensation resistor may increase these coupling effects, causing the measurement data from different dimensions to interfere with each other and reducing accuracy.

[0018] Therefore, embodiments of the present invention provide a method for zero-point compensation of the total resistance of a six-dimensional force sensor, such as... Figure 1 As shown, the method includes: Step S1: Construct the Wheatstone bridges corresponding to each measurement dimension of the six-dimensional force sensor.

[0019] The six-dimensional force sensor also includes multiple bridge switching circuits corresponding to Wheatstone bridges. Each bridge switching circuit has two input terminals and two output terminals. Each Wheatstone bridge has a first terminal, a second terminal, a third terminal, and a fourth terminal, and all four terminals are connected to a single-pole double-throw switch. The single-pole double-throw switch is used to switch the connection relationship between the corresponding terminals and the input and output terminals of the bridge switching circuit.

[0020] Step S2: Control each single-pole double-throw switch in the Wheatstone bridge that requires zero-point compensation, so that the first and third diagonally opposite endpoints are connected to the two input terminals of the bridge switching circuit, and the second and fourth diagonally opposite endpoints are connected to the two output terminals of the bridge switching circuit, respectively; and apply positive and negative first input voltages sequentially between the two input terminals, and measure the corresponding first and second output voltages at the two output terminals.

[0021] It should be noted that the input and output of the Wheatstone bridge can be switched using a single-pole double-throw switch, thereby changing its bridge configuration. With the same input voltage (which can be positive or negative), different output voltages can be obtained, allowing for the determination of the resistance values ​​of each strain gauge. This enables accurate measurement of strain gauge resistance values ​​and precise compensation without the addition of other instruments.

[0022] Step S3: Control each single-pole double-throw switch in the Wheatstone bridge that requires zero-point compensation, so that the first and third diagonally opposite endpoints are connected to the two output terminals of the bridge switching circuit, and the second and fourth diagonally opposite endpoints are connected to the two input terminals of the bridge switching circuit, respectively; and apply positive and negative first input voltages sequentially between the two input terminals, and measure the corresponding third and fourth output voltages at the two output terminals.

[0023] Step S4: Obtain the initial resistance values ​​of the four strain gauges corresponding to the Wheatstone bridge based on the first input voltage, first output voltage, second output voltage, third output voltage, and fourth output voltage. Some of the strain gauge bars are provided with shorting solder joints.

[0024] In this specific embodiment, the Wheatstone bridge can be as follows: Figure 2 As shown, the bridge switching circuit includes two input terminals 201 and 202 and two output terminals 203 and 204. The Wheatstone bridge includes a first terminal 205, a second terminal 206, a third terminal 207, and a fourth terminal 208. 209 is a single-pole double-throw switch.

[0025] In this specific embodiment, the equivalent circuit structure diagram of the Wheatstone bridge corresponding to the first voltage output in step S2 is shown below. Figure 3 As shown, the equivalent circuit structure diagram of the Wheatstone bridge corresponding to the second voltage output in step S2 is as follows. Figure 4 As shown, in step S2, the first output voltage and the second output voltage satisfy the following conditions: in, This is the first output voltage. This is the second output voltage. The first input voltage, , , and These are four strain gauges of a Wheatstone bridge, and Located between the first endpoint and the second endpoint, Located between the second and third endpoints, Located between the third and fourth endpoints, It is located between the fourth endpoint and the first endpoint.

[0026] In this specific embodiment, the equivalent circuit structure diagram of the Wheatstone bridge corresponding to the third voltage output in step S3 is shown below. Figure 5 As shown, the equivalent circuit structure diagram of the Wheatstone bridge corresponding to the second voltage output in step S3 is as follows. Figure 6 As shown, the third and fourth output voltages in step S3 satisfy the following conditions: in, This is the third output voltage. This is the fourth output voltage. The first input voltage, , , and These are four strain gauges of a Wheatstone bridge, and Located between the first endpoint and the second endpoint, Located between the second and third endpoints, Located between the third and fourth endpoints, It is located between the fourth endpoint and the first endpoint.

[0027] In this specific embodiment, step S4 includes: according to Solve , , and .

[0028] Step S5: Based on the initial resistance values ​​of the four strain gauges, weld the short-circuit joints of the corresponding strain gauges to ensure that the resistance difference between each strain gauge does not exceed the first difference threshold.

[0029] In this specific embodiment, step S5 includes: The minimum initial resistance value is obtained based on the initial resistance values ​​of the four strain gauges; Based on the minimum initial resistance value, short-circuit welds are made to the strain gauges other than the strain gauge corresponding to the minimum initial resistance value, so that the resistance difference between the resistance values ​​of the other strain gauges and the minimum initial resistance value does not exceed the first difference threshold.

[0030] It should be noted that the embodiments of the present invention compensate by reducing the resistance value, therefore zero-point compensation needs to be performed based on the minimum initial resistance value.

[0031] In this specific embodiment, the strain gauge is connected to the corresponding short-circuit solder joints by electric welding to shield part of the grid resistance, thereby reducing the strain gauge resistance.

[0032] In this specific embodiment, a schematic diagram of the strain gauge's grid strips with short-circuit solder joints is shown below. Figure 7 As shown, Figure 7 In the diagram, 701 is a strain gauge, and 702 is a shorting solder joint. Connecting these solder joints partially shields the strain gauge resistance, thus achieving zero-point compensation. Simultaneously, this compensation method avoids introducing a new compensation resistor, thereby preventing inter-dimensional coupling caused by such a resistor.

[0033] In this specific embodiment, after step S5, the method further includes: Reapply the test input voltage to the first and third endpoints and obtain the corresponding test output voltage; determine whether the test output voltage is less than the first test threshold. If it is, determine that the zero-point compensation is completed; otherwise, perform compensation again.

[0034] It should be noted that testing is one of the factory steps and can effectively improve the quality of the finished product.

[0035] In this specific embodiment, after step S5, the method further includes: Repeat steps S2 to S5 for each Wheatstone bridge corresponding to each measurement dimension to complete the zero-point compensation of the total resistance of all Wheatstone bridges.

[0036] This invention, through the inclusion of a bridge switching circuit and a single-pole double-throw switch, alters the input and output of a corresponding Wheatstone bridge to obtain different outputs. Based on these outputs, the resistance values ​​of each strain gauge can be calculated, enabling zero-point compensation of the strain gauge's resistance. On one hand, this method achieves precise compensation; since it's full resistance compensation, it avoids the interdimensional coupling effects that might arise from adding only a single compensation resistor in existing technologies. On the other hand, this structure allows for accurate acquisition of strain gauge resistances for compensation without adding other equipment, avoiding redundancy, simplifying the process, and facilitating streamlined production.

[0037] In this embodiment of the invention, some bars of the strain gauge are provided with short-circuit solder joints. Based on the initial resistance values ​​of the four strain gauges, the short-circuit solder joints of the corresponding strain gauges are electrically welded together, ensuring that the resistance difference between the strain gauges does not exceed a first difference threshold. Compared to existing methods that add compensation resistors for zero-point compensation, this embodiment of the invention does not introduce new compensation resistors. Zero-point compensation is achieved through the adjustment and change of the strain gauge's own resistance value. This avoids the failure situation where the strain gauge resistance changes but the bridge balance is maintained due to the compensation resistor not changing with the deformation or the change amplitude differing from that of the strain gauge. This reduces interdimensional coupling, increases the accuracy of zero-point compensation, and improves the accuracy of subsequent force measurement.

[0038] In summary, the embodiments of the present invention can compensate each strain gauge in the Wheatstone bridge accordingly, thereby reducing interdimensional coupling caused by conventional zero-point compensation and improving measurement accuracy.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0040] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A six-dimensional force sensor full resistance zero point compensation method, characterized in that: The method comprises: Step S1, constructing a Wheatstone bridge corresponding to each measurement dimension of the six-dimensional force sensor; wherein the six-dimensional force sensor also includes a plurality of bridge switching circuits corresponding to the Wheatstone bridges, the bridge switching circuit includes two input terminals and two output terminals, each of the Wheatstone bridges includes a first terminal, a second terminal, a third terminal and a fourth terminal, and the four terminals are all connected to a single-pole double-throw switch, and the single-pole double-throw switch is used to switch the connection relationship between the input terminal and the output terminal of the bridge switching circuit corresponding to the terminal; Step S2, controlling each of the single-pole double-throw switches in the Wheatstone bridge that requires zero-point compensation, so that the first end point and the third end point located at the diagonal are respectively connected to the two input ends of the bridge switching circuit, and the second end point and the fourth end point located at the diagonal are respectively connected to the two output ends of the bridge switching circuit; and applying a positive and a negative first input voltage in sequence between the two input ends, and measuring at the two output ends to obtain the corresponding first output voltage and second output voltage; Step S3, controlling each of the single-pole double-throw switches in the Wheatstone bridge that requires zero-point compensation, so that the first end point and the third end point located at the diagonal are respectively connected to the two output ends of the bridge switching circuit, and the second end point and the fourth end point located at the diagonal are respectively connected to the two input ends of the bridge switching circuit; and applying the first input voltage in a positive direction and a negative direction in a negative direction in sequence between the two input ends, and measuring at the two output ends to obtain the corresponding third output voltage and fourth output voltage; Step S4, obtaining initial resistance values ​​of four strain gauges corresponding to the Wheatstone bridge according to the first input voltage, the first output voltage, the second output voltage, the third output voltage and the fourth output voltage; wherein some bars of the strain gauge are provided with short-circuit solder joints; Step S5: according to the initial resistance values ​​of the four strain gauges, welding the short-circuit welding points corresponding to the strain gauges so that the resistance difference between the strain gauges does not exceed a first difference threshold.

2. The six-dimensional force sensor full resistance zero point compensation method according to claim 1, characterized in that: In step S2, the first output voltage and the second output voltage satisfy: in, is the first output voltage, is the second output voltage, is the first input voltage, , , and are the four strain gauges of the Wheatstone bridge, and is located between the first endpoint and the second endpoint, is located between the second endpoint and the third endpoint, is located between the third endpoint and the fourth endpoint, Located between the fourth endpoint and the first endpoint.

3. The six-dimensional force sensor full resistance zero point compensation method according to claim 2 is characterized in that: In step S3, the third output voltage and the fourth output voltage satisfy: in, is the third output voltage, is the fourth output voltage, is the first input voltage, , , and are the four strain gauges of the Wheatstone bridge, and is located between the first endpoint and the second endpoint, is located between the second endpoint and the third endpoint, is located between the third endpoint and the fourth endpoint, Located between the fourth endpoint and the first endpoint.

4. The six-dimensional force sensor full resistance zero point compensation method according to claim 3 is characterized in that: The step S4 comprises: according to Solution , , and .

5. The six-dimensional force sensor full resistance zero point compensation method according to claim 1, characterized in that: The step S5 comprises: According to the initial resistance values ​​of the four strain gauges, obtaining the minimum initial resistance value; According to the minimum initial resistance, the short-circuit welding points of the other strain gauges except the strain gauge corresponding to the minimum initial resistance are connected by electric welding, so that the resistance difference between the resistance of the other strain gauges and the minimum initial resistance does not exceed the first difference threshold.

6. The six-dimensional force sensor full resistance zero point compensation method according to claim 1, characterized in that: After step S5, the method further includes: Reapply the test input voltage to the first endpoint and the third endpoint, and obtain the corresponding test output voltage; determine whether the test output voltage is less than the first test threshold, if so, determine that the zero point compensation is completed, if not, re-compensate.

7. The six-dimensional force sensor full resistance zero point compensation method according to claim 1, characterized in that: The strain gauge is connected to the corresponding short-circuit welding point by electric welding to shield part of the grid resistance, thereby reducing the resistance of the strain gauge.

8. The six-dimensional force sensor full resistance zero point compensation method according to claim 1, characterized in that: After step S5, the method further includes: Repeat steps S2 to S5 for the Wheatstone bridges corresponding to each measurement dimension to complete full resistance zero point compensation of all the Wheatstone bridges.

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