Method and system for realizing accurate measurement of six-dimensional force based on second-order generalized integrator

Abstract

The invention relates to the technical field of six-dimensional force measurement, and discloses a method and a system for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator (SOGI), through effective suppression of the second-order generalized integrator (SOGI) on specific frequency interference and accurate extraction of weak signals, the anti-interference capability of the six-dimensional force measurement system is greatly improved, and the measurement accuracy of the six-dimensional force is improved. Through the multi-frequency characteristic and flexible parameter configuration of the SOGI, the system can adapt to dynamic changes of forces and moments with different frequency components, can accurately measure both low-frequency components of static forces and high-frequency components of transient force impact, meets the six-dimensional force measurement requirements under complex working conditions, and has a wide application prospect. Through optimization of an SOGI algorithm, decoupling processing of a multi-dimensional force signal and optimization of dynamic response, the change of the force signal can be quickly responded in a dynamic scene, the control precision and stability of equipment such as a robot in the movement process are effectively improved, and misoperation caused by untimely response of the force signal is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of six-dimensional force measurement, in particular to a method and system for realizing precise six-dimensional force measurement based on a second-order generalized integrator. BACKGROUND

[0002] In many fields such as industrial automation, robot control, medical rehabilitation equipment, and aerospace, six-dimensional force sensors play a key role, which can accurately measure forces (F x ,Fᵧ,F z ) and moments (M x ,Mᵧ,M z ) in three-dimensional space.

[0003] However, current six-dimensional force sensors face many challenges in practical applications. On the one hand, the resistance value of the six-dimensional force sensor is usually small, resulting in extremely weak output signals, which are easily disturbed by external environmental noise, such as electromagnetic interference and mechanical vibration noise, which seriously affects the measurement accuracy. On the other hand, the dynamic changes of force and moment may exhibit complex frequency characteristics, and existing detection techniques are difficult to simultaneously consider accurate measurement of different frequency components.

[0004] Traditional signal processing methods have limitations in dealing with these problems. For example, some simple filtering methods cannot effectively filter out disturbances of specific frequencies, while simultaneously causing distortion to useful signals. For multi-frequency signal detection, traditional methods often require complex hardware circuit reconstruction, which not only increases cost but also reduces system reliability and flexibility. Therefore, there is an urgent need for a new technology to improve the measurement accuracy and environmental adaptability of six-dimensional force sensors. Based on this, the present application proposes a method and system for realizing precise six-dimensional force measurement based on a second-order generalized integrator to solve the above problems. SUMMARY

[0005] (I) Technical problems to be solved

[0006] In view of the deficiencies of the prior art, the present application provides a method and system for realizing precise six-dimensional force measurement based on a second-order generalized integrator to solve the problems of large interference, small resistance value, weak signal, and difficulty in considering multi-frequency signal measurement of existing six-dimensional force sensors, thereby realizing high-precision and high-reliability measurement of six-dimensional force.

[0007] (II) Technical solutions

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a method for realizing precise six-dimensional force measurement based on a second-order generalized integrator, comprising the following steps:

[0009] S1, the six-dimensional force sensor module perceives force and torque and converts it into resistance change signal;

[0010] S2, the signal conditioning module is preliminarily processed;

[0011] S3, the SOGI-based signal processing module is entered for filtering and signal extraction;

[0012] S4, then the microcontroller unit (MCU) is used for data calculation and analysis;

[0013] S5, finally, the six-dimensional force data is output to external equipment through the data output module.

[0014] Preferably, the six-dimensional force sensor module adopts a strain body structure, which perceives force and torque on three spatial coordinate axes XYZ through high-precision strain gauges and converts it into resistance change.

[0015] Preferably, the signal conditioning module is used to preliminarily process the weak resistance change signal output by the six-dimensional force sensor, including amplification, filtering and other operations.

[0016] Preferably, the microcontroller unit (MCU) calculates the specific value of the six-dimensional force according to the mathematical model of force and resistance change.

[0017] Preferably, the data output module outputs the six-dimensional force data calculated by the microcontroller unit (MCU) in a standard communication protocol for data interaction with external equipment.

[0018] Preferably, the SOGI-based signal processing module processes the conditioned signal using a second-order generalized integrator (SOGI), which constructs an adaptive filter to phase-shift the input signal by 90° and eliminate harmonic interference, realizing accurate extraction of specific frequency signals.

[0019] Preferably, the SOGI-based signal processing module processes the conditioned signal using a second-order generalized integrator (SOGI) includes the following steps:

[0020] (1) According to the conversion model of force signal and electric signal, the target detection frequency range of SOGI is determined, the multi-frequency characteristics of SOGI are used to assign different detection frequencies to different dimensions of force / torque, and signal decoupling is realized through frequency differentiation;

[0021] (2) By establishing the mathematical model of force / torque and resistance change, the corresponding relationship between the excitation signal frequency and the force signal is determined, combined with the hardware multiplexing circuit, different frequency excitation signals are injected in time, at a certain moment, only the excitation signal corresponding to a certain dimension of force / torque is injected into the six-dimensional force sensor, the signal of this dimension is extracted through SOGI, then the data processing and storage are carried out through the microcontroller unit (MCU), at the next moment, the excitation signal injection and signal extraction of another dimension are switched, and so on, so as to realize the time-sharing decoupling measurement of six-dimensional force signal;

[0022] (3) The parameters of SOGI are set, the filtering effect and response speed are balanced by adjusting the parameter k of SOGI, in the scene with high requirement for dynamic response, the value of k is appropriately reduced, so that SOGI can track the change of force signal faster, and the stability of signal is ensured by increasing the additional anti-aliasing filter in the signal conditioning module.

[0023] Preferably, the discretization of the SOGI algorithm is realized in the microcontroller unit (MCU), since H1(s) and H2(s) are both second-order filters, the continuous domain SOGI transfer function is discretized through bilinear Tustin transformation, and is converted into a time domain difference equation for digital signal processing in the MCU.

[0024] A system for realizing precise measurement of six-dimensional force based on a second-order generalized integrator, comprising:

[0025] A six-dimensional force sensor module adopts a strain body structure, perceives the force and torque on the three spatial coordinate axes XYZ through high-precision strain gauges, and converts them into resistance change;

[0026] A signal conditioning module is used to preliminarily process the weak resistance change signal output by the six-dimensional force sensor, including amplification, filtering and other operations, so as to improve the quality of the signal and facilitate subsequent signal processing;

[0027] An excitation source generation module is used to inject excitation signals of different frequencies;

[0028] A signal processing module based on SOGI processes the conditioned signal by using a second-order generalized integrator, constructs an adaptive filter to perform 90° phase shift on the input signal, eliminates harmonic interference, and realizes accurate extraction of signals of specific frequencies;

[0029] A microcontroller unit (MCU) is used to further operate and analyze the signals processed based on SOGI, calculates the specific values of six-dimensional force according to the mathematical model of force and resistance change;

[0030] Data output module, for outputting six-dimensional force data calculated by microcontroller unit (MCU) in standard communication protocol, and interacting with external equipment.

[0031] (Three) beneficial effects

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] 1. The effective suppression of specific frequency interference by the second-order generalized integrator (SOGI) and the accurate extraction of weak signals greatly improve the anti-interference ability of the six-dimensional force measurement system. In an environment with strong electromagnetic interference (such as 50Hz power frequency interference), the absolute error of force measurement can be controlled within 0.1%FS (full scale) using the method of the present application, which is more than 50% lower than the traditional method.

[0034] 2. The multi-frequency characteristics and flexible parameter configuration of SOGI enable the system to adapt to dynamic changes in force and torque with different frequency components. Whether it is a low-frequency component of static force or a high-frequency component of transient force impact, it can be accurately measured, meeting the six-dimensional force measurement requirements in complex working conditions.

[0035] 3. Through optimization of the SOGI algorithm, decoupling processing of multi-dimensional force signals, and optimization of dynamic response, the present application realizes high-precision measurement of six-dimensional force. The measurement accuracy of the system is improved by more than 30% compared with the prior art, providing reliable data support for fields with extremely high force detection requirements such as industrial robots and aerospace.

[0036] 4. In dynamic scenarios, the six-dimensional force measurement system of the present application can quickly respond to changes in force signals, with a response time reduced by more than 40%, effectively improving the control accuracy and stability of robots and other equipment during motion, and avoiding operation errors caused by delayed force signal response. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the architecture diagram of the six-dimensional force precision measurement system of the present application;

[0038] Figure 2 is the SOGI algorithm flowchart of the present application;

[0039] Figure 3 is the multi-dimensional force signal decoupling principle diagram of the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0041] The present application aims to provide a method and system for realizing precise measurement of six-dimensional force based on a second-order generalized integrator, so as to solve the problems of large interference, small resistance value, weak signal and difficulty in measuring multiple frequency signals existing in the prior art six-dimensional force sensor, and to realize high-precision and high-reliability measurement of six-dimensional force.

[0042] In the prior art, the basic principle of the second-order generalized integrator (SOGI) is to simulate the pure integration behavior in an ideal sense by designing a pair of mutually perpendicular first-order low-pass filters, and given any form of periodic excitation source (V(t)) , the SOGI after proper configuration can output the instantaneous power factor angle and effective value size corresponding to the excitation (V(t)) , where K is the proportional coefficient, and the process does not depend on the prior knowledge of the specific frequency parameter (f) , and has good adaptive ability.

[0043] Based on this, please refer to Figure 1-3 The method for realizing precise measurement of six-dimensional force comprises the following steps:

[0044] S1, perceiving force and torque through a six-dimensional force sensor module and converting them into resistance change signals;

[0045] S2, performing preliminary processing through a signal conditioning module;

[0046] S3, entering a SOGI-based signal processing module to perform filtering and signal extraction;

[0047] S4, then performing data calculation and analysis by a microcontroller unit (MCU);

[0048] S5, finally outputting six-dimensional force data to external equipment through a data output module.

[0049] The six-dimensional force sensor module adopts a strain body structure, perceives force and torque on XYZ three spatial coordinate axes through high-precision strain gauges, and converts them into resistance changes, and the module has good overload resistance and durability, and the maximum safe overload during work can reach 3.5 times.

[0050] The signal conditioning module performs preliminary processing on the weak resistance change signal output by the six-dimensional force sensor, including amplification, filtering and other operations, to improve the quality of the signal and facilitate subsequent signal processing.

[0051] The SOGI-based signal processing module is the core part of the application, which uses a second-order generalized integrator to process the conditioned signal. Specifically, SOGI can perform 90° phase shift on the input signal and eliminate harmonic interference by constructing an adaptive filter, thereby achieving accurate extraction of specific frequency signals.

[0052] The microcontroller unit (MCU) is responsible for further calculation and analysis of the signals processed based on SOGI, and calculates the specific values of the six-dimensional force according to the mathematical model of force and resistance change.

[0053] The data output module outputs the six-dimensional force data calculated by the MCU in a standard communication protocol (such as Ethernet / EtherCAT / RS-485, etc.) for data interaction with external devices (such as robot control systems, industrial automation production lines, etc.).

[0054] The six-dimensional force sensor needs to measure three-dimensional force and three-dimensional torque simultaneously, and there is a coupling phenomenon between the signals, which will affect the detection accuracy. In the application, the SOGI algorithm is optimized according to the signal characteristics of the six-dimensional force sensor. By determining the target detection frequency range of SOGI according to the conversion model of force signal and electric signal, using the multi-frequency characteristics of SOGI, different detection frequencies are assigned to different dimensions of force / torque, signal decoupling is achieved through frequency differentiation. At the same time, by establishing the mathematical model of force / torque and resistance change, the corresponding relationship between excitation signal frequency and force signal is determined, combined with the hardware multiplexing circuit, different frequency excitation signals are injected in time division, at a certain moment, only the excitation signal corresponding to a certain dimension of force / torque is injected into the six-dimensional force sensor, the signal of this dimension is extracted through SOGI, then the data is processed and stored through the microcontroller unit (MCU), at the next moment, the excitation signal injection and signal extraction of another dimension are switched, and so on, to realize the time-sharing decoupling measurement of six-dimensional force signal.

[0055] Specifically, through a large number of experimental data fitting, the frequency distribution law of resistance change under the action of different types of force and torque is obtained, which is used as the basis to set the center frequency \omega0 of SOGI. At the same time, the force in the X-axis direction is set as frequency f1, the force in the Y-axis direction is set as frequency f2, the force in the Z-axis direction is set as frequency f3, the torque in the X-axis direction is set as frequency f4, the torque in the Y-axis direction is set as frequency f5, and the torque in the Z-axis direction is set as frequency f6. These frequencies are independent of each other and do not interfere with each other.

[0056] Secondly, the parameters of the SOGI are also set in the application, and the value of the parameter k directly affects the filtering performance and dynamic response of the system, and the experience value 1.414 is usually taken, but in the application, the optimal k value is determined by simulation and experimental test in combination with the actual needs of the six-dimensional force measurement scene, the filtering effect and response speed are balanced by adjusting the parameter k of the SOGI, in the scene with high requirements for dynamic response, the k value is appropriately reduced, so that the SOGI can track the change of the force signal faster, and at the same time, an additional anti-aliasing filter is added in the signal conditioning module to ensure the stability of the signal. For example, in the environment with strong electromagnetic interference, the k value is appropriately increased to enhance the suppression ability of high-frequency noise, and in the scene with high requirements for dynamic force response, the k value is appropriately reduced to improve the response speed of the system.

[0057] In addition, the discretization of the SOGI algorithm is implemented in a microcontroller unit (MCU), since H1(s) and H2(s) are both second-order filters, the continuous-domain SOGI transfer function is discretized by a bilinear Tustin transformation, and is converted into a time-domain difference equation for digital signal processing in the MCU, and the specific implementation code is as follows (taking C language as an example):

[0058]

[0059]

[0060] It should be noted that in order to meet the dynamic scene of the six-dimensional force sensor, the scheme of the application adopts a high-speed data acquisition chip and a high-performance microcontroller to improve the speed of signal acquisition and processing. For example, a data acquisition chip with 24Bit high-speed ADC sampling function is selected, which can realize a data output frequency of 2700Hz, ensuring that the dynamic change of the force signal can be captured quickly. In the microcontroller unit (MCU), efficient algorithms and data structures are used to reduce the time delay of data processing, and ensure that the system can output six-dimensional force data in real time and accurately.

[0061] The application also provides a system for implementing the above method, which comprises a six-dimensional force sensor module, a signal conditioning module, an excitation source generation module, a SOGI-based signal processing module, a microcontroller unit (MCU) and a data output module.

[0062] Among them, the six-dimensional force sensor module adopts a strain body structure, perceives the force and torque on the XYZ three spatial coordinate axes through high-precision strain gauges, and converts them into resistance changes. Specifically, a six-dimensional force sensor with high-precision strain gauges and good structural design is selected, such as the HPS-FT series sensor. According to the actual application scene, the sensor is installed in the appropriate position to ensure that the target force and torque can be accurately perceived. For example, the sensor is installed on the end effector of an industrial robot to accurately measure the force and torque when grabbing an object.

[0063] The signal conditioning module is used to preliminarily process the weak resistance change signal output by the six-dimensional force sensor, including amplification, filtering and other operations, to improve the quality of the signal and facilitate subsequent signal processing. Specifically, it includes a preamplifier circuit and a filter circuit. The preamplifier circuit uses a high-precision instrument amplifier to amplify the weak resistance change signal output by the six-dimensional force sensor to an appropriate voltage range. The filter circuit uses a combination of low-pass and band-pass filters to preliminarily filter out high-frequency noise and low-frequency interference, improving signal quality.

[0064] The excitation source generation module is used to inject excitation signals of different frequencies.

[0065] The SOGI-based signal processing module uses a second-order generalized integrator to process the conditioned signal. By constructing an adaptive filter, it performs 90° phase shift on the input signal while eliminating harmonic interference, achieving accurate extraction of specific frequency signals. Specifically, SOGI-based signal processing code is written in the microcontroller unit (MCU) to realize the discretization of the SOGI algorithm. According to the characteristics of the six-dimensional force sensor and the actual application environment, the parameters k and center frequency \omega0 of SOGI are adjusted. For example, in an industrial environment with 50Hz power frequency interference, after multiple experimental tests, the k value is adjusted to 1.2, and the \omega0 is set to a value corresponding to the main frequency component of the force signal.

[0066] The microcontroller unit (MCU) is used to further operate and analyze the signals processed based on SOGI. According to the mathematical model of force and resistance change, the specific value of six-dimensional force is calculated. Specifically, an STM32 series chip is used to develop data processing programs in the MCU, including further operation of the signals processed by SOGI, calculation of six-dimensional force values according to the mathematical model of force and resistance change, and control of hardware multiplexing circuit to realize decoupling measurement of multi-dimensional force signals.

[0067] The data output module is used for outputting the six-dimensional force data calculated by the micro control unit (MCU) in a standard communication protocol to interact with external devices, and specifically, the data output module is configured according to the interface requirement of the external device, if the external device adopts an Ethernet interface, an Ethernet controller chip is integrated in the data output module to realize the Ethernet transmission of the six-dimensional force data, if an RS-485 interface is adopted, a corresponding RS-485 transceiver chip is configured to ensure that the data can be accurately and stably output to the external device.

[0068] The application greatly improves the anti-interference ability of the six-dimensional force measurement system through the effective suppression of specific frequency interference by the second-order generalized integrator (SOGI) and the accurate extraction of weak signals, and in the environment with strong electromagnetic interference (such as 50Hz power frequency interference), the absolute error of force measurement can be controlled within 0.1%FS (full scale) by using the method of the application, which is more than 50% lower than the traditional method, the multi-frequency characteristics and flexible parameter configuration of SOGI enable the system to adapt to the dynamic changes of forces and torques with different frequency components, whether it is the low-frequency component of static force or the high-frequency component of transient force impact, it can be accurately measured, meeting the six-dimensional force measurement requirements under complex working conditions, through the optimization of SOGI algorithm, the decoupling processing of multi-dimensional force signal and the optimization of dynamic response, the application realizes high-precision measurement of six-dimensional force, the measurement accuracy of the system is more than 30% higher than that of the prior art, which can provide reliable data support for the fields with extremely high force detection requirements such as industrial robots and aerospace, in the dynamic scene, the six-dimensional force measurement system of the application can quickly respond to the change of force signal, the response time is shortened by more than 40%, effectively improving the control accuracy and stability of robots and other equipment in the motion process, avoiding the operation errors caused by the untimely response of force signal.

[0069] Although the embodiments of the application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made without departing from the principles and spirit of the application, the scope of the application being defined by the appended claims and their equivalents.

Claims

1. A method for achieving precise measurement of six-dimensional forces based on a second-order generalized integrator, characterized in that: The following steps are involved: S1, sense force and torque through the six-dimensional force sensor module and convert them into resistance change signals; S2, preliminary processing is performed by the signal conditioning module; S3, enter the SOGI-based signal processing module for filtering and signal extraction; S4, then the microcontroller unit (MCU) performs data calculation and analysis; S5. Finally, the six-dimensional force data is output to an external device through the data output module.

2. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 1, characterized in that: The six-dimensional force sensor module adopts a strain gauge structure, which senses the force and torque on the three spatial coordinate axes of XYZ through high-precision strain gauges and converts them into resistance changes.

3. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 2, characterized in that: The signal conditioning module is used to perform preliminary processing on the weak resistance change signal output by the six-dimensional force sensor, including operations such as amplification and filtering.

4. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 3, characterized in that: The microcontroller unit (MCU) calculates the specific value of the six-dimensional force based on the mathematical model of force and resistance change.

5. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 4, characterized in that: The data output module outputs the six-dimensional force data calculated by the microcontroller unit (MCU) using a standard communication protocol for data interaction with external devices.

6. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 5, characterized in that: The SOGI-based signal processing module uses a second-order generalized integrator (SOGI) to process the conditioned signal. It constructs an adaptive filter to perform a 90-degree phase shift on the input signal and eliminate harmonic interference, thereby accurately extracting the specific frequency signal.

7. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 6, characterized in that: The SOGI-based signal processing module processes the conditioned signal using a second-order generalized integrator (SOGI) and includes the following steps: (1) Based on the conversion model between force signals and electrical signals, the target detection frequency range of SOGI is determined. By utilizing the multi-frequency characteristics of SOGI, different detection frequencies are assigned to forces / torques of different dimensions, and signal decoupling is achieved through frequency differentiation. (2) By establishing a mathematical model of force / torque and resistance change, the corresponding relationship between the excitation signal frequency and the force signal is clarified. Combined with the hardware multiplexing circuit, excitation signals of different frequencies are injected in a time-sharing manner. At a certain moment, only the excitation signal corresponding to a certain dimension of force / torque is injected into the six-dimensional force sensor. The signal of this dimension is extracted separately through SOGI, and then the data is processed and stored by the microcontroller unit (MCU). At the next moment, the excitation signal injection and signal extraction of the other dimension are switched, and so on, to achieve time-sharing decoupling measurement of the six-dimensional force signal; (3) Adjust the parameters of SOGI. By adjusting the parameter k of SOGI, the filtering effect and response speed are balanced. In scenarios with high requirements for dynamic response, the k value is appropriately reduced so that SOGI can track the changes in force signals faster. At the same time, the stability of the signal is ensured by adding an additional anti-aliasing filter in the signal conditioning module.

8. The method for realizing accurate measurement of six-dimensional force based on a second-order generalized integrator according to claim 7, characterized in that: The discretization implementation of the SOGI algorithm is performed in a microcontroller unit (MCU). Since H1(s) and H2(s) are both second-order filters, the SOGI transfer function in the continuous domain is discretized through a bilinear Tustin transform and converted into a time-domain difference equation for digital signal processing in the MCU.

9. A system for implementing the method according to any one of claims 1 to 8, characterized in that: include: The six-dimensional force sensor module uses a strain gauge structure to sense the force and torque on the three spatial coordinate axes of XYZ through high-precision strain gauges and converts them into resistance changes; The signal conditioning module is used to perform preliminary processing on the weak resistance change signal output by the six-dimensional force sensor, including amplification, filtering and other operations to improve the signal quality and facilitate subsequent signal processing; Excitation source generation module, used to inject excitation signals of different frequencies; The SOGI-based signal processing module uses a second-order generalized integrator to process the conditioned signal and constructs an adaptive filter to perform a 90° phase shift on the input signal while eliminating harmonic interference to achieve accurate extraction of specific frequency signals. A microcontroller unit (MCU) is used to perform further operations and analysis on the SOGI-processed signals and calculate the specific value of the six-dimensional force based on the mathematical model of force and resistance changes; The data output module is used to output the six-dimensional force data calculated by the microcontroller unit (MCU) using a standard communication protocol and to interact with external devices.

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