Microcontroller unit-based contact force soft measurement system for excavator

Abstract

The application discloses a kind of based on micro control unit (hereinafter referred to as MCU) excavator contact force soft measurement system.The system is composed of four parts of sensor array, signal conditioning circuit, signal pre-processing system and PC host computer.Signal conditioning circuit converts various signals output by sensor, and is uniformly adjusted to the signal format that MCU can receive.Temperature sensor and pressure sensor output analog signal, which is converted into digital signal by A / D conversion module and then input into MCU.Inclination sensor directly outputs inclination data, which is converted into TTL level by CAN transceiver and communicated with MCU.Displacement encoder outputs pulse signal, which is converted into pulse voltage that MCU can receive by signal conditioning circuit and then input into the pulse counter of MCU.The application is a kind of installation sensor at each joint and hydraulic cylinder of hydraulic excavator, pre-process sensor information by MCU and send to host computer, and finally estimate the real-time contact force of excavator by the operation of host computer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of embedded systems, sensor technology and computer science, in particular to a microcontroller-based contact force soft measurement system for excavators. BACKGROUND

[0002] As one of the most widely used earthwork construction machinery, hydraulic excavators play an extremely important role in the fields of farmland water conservancy, urban construction, national defense engineering, etc. At present, the traditional excavating method controlled by manpower often faces the defects of large consumption of operator's brain and physical strength, easy fatigue after long time work, low control precision and efficiency, high cost, and difficulty in adapting to dangerous, harsh or harmful environment. Therefore, it is a feasible method to solve the above problems and realize unmanned control of excavation by comprehensively using advanced control technology, computer technology and sensor technology to realize intelligent motion control of excavators.

[0003] The hydraulic mechanical arm is one of the core components of the modern excavator, and the control of the end motion precision and stability is an important indicator to measure the working performance of the excavator. Precise contact force control requires accurate force feedback. The traditional contact force feedback method of the mechanical arm is to install a six-degree-of-freedom force / torque sensor on the end effector. However, if it is used for large-torque devices such as excavators and needs to be frequently contacted, the force sensor is easily damaged. Therefore, many researchers at home and abroad have proposed many force estimation methods for mechanical arms. However, due to the single sensor, accurate dynamic parameters cannot be obtained, resulting in low estimation accuracy and inability to be applied to actual production. Moreover, the related hardware circuit scheme of the measurement system is not found in foreign related literature, and more improvements are made in the algorithm direction. The conventional type of sensor is commonly used for industrial computer connection, so the measurement system needs to use a specific industrial computer. Especially in the case of a large number of non-bus protocol sensors, the demand for industrial computer interface is further improved, and the requirement for computer expandability is increased. SUMMARY

[0004] To solve the above problems, the present application discloses a microcontroller-based contact force soft measurement system for excavators. The system is composed of a sensor array, a signal conditioning circuit, a signal preprocessing system and a PC upper computer, realizes the functions of automatic measurement of the contact force at the end (bucket side) of the excavator and real-time display, expands the upper limit of the number of sensors of the excavator measurement system, improves the precision of the contact force measurement, reduces the hardware requirements of the measurement system, improves the flexibility of the measurement system, and solves the soft measurement problem of the contact force at the end of the excavator.

[0005] The application is a micro control unit based excavator contact force soft measurement system, which is composed of a sensor array, a signal conditioning circuit, an MCU and a PC upper computer; the sensor array transmits signals to the signal conditioning circuit through a wired mode, and is responsible for temperature, pressure, position, attitude and other parameter acquisition functions of the excavator; the signal conditioning circuit transmits signals to the sensor array and the MCU through a wired mode, and is responsible for signal conversion function from the sensor to the MCU; the MCU transmits data to the signal conditioning circuit through a wired mode, and exchanges data with the upper computer through a network, and is responsible for the pretreatment function of the data collected by the sensor; the PC upper computer realizes bidirectional data exchange with the MCU through a network, and is responsible for the calculation of contact force and the data visualization function;

[0006] The sensor array is composed of four types of sensors, i.e., temperature sensors, pressure sensors, displacement sensors and inclination sensors. Each type of sensor is installed in the bucket, the arm and the boom. The temperature and pressure sensors are integrated temperature and pressure sensors, which are used to measure the pressure of the two side cavities of the hydraulic cylinder. The hydraulic cylinder has a piston, which divides the entire hydraulic cylinder cavity into two parts. Two integrated temperature and pressure sensors measure the hydraulic pressure and oil temperature of the two side cavities.

[0007] Each hydraulic cylinder is provided with two integrated temperature and pressure sensors, which transmit signals to the A / D conversion circuit. The sensor outputs an analog signal to the A / D conversion circuit, which is used to measure the pressure of the two side cavities of the hydraulic cylinder and the oil temperature. The displacement sensor is an incremental wire displacement encoder, which is installed in the bucket, the arm and the boom hydraulic cylinder position, and transmits signals to the signal conditioning circuit. The sensor outputs a pulse signal, which is used to measure the position of the piston rod when the hydraulic cylinder moves. The inclination sensor is a super high precision single axis inclination sensor, which is installed in the joint hinge of the bucket, the arm and the boom, and transmits signals to the CAN transceiver. The sensor outputs a digital signal, which is used to measure the current pose of the excavator mechanical arm.

[0008] The signal conditioning circuit is composed of an A / D conversion circuit, a signal conditioning circuit and a CAN transceiver. The temperature and pressure integrated sensor transmits signals to the A / D conversion circuit, the A / D conversion circuit transmits signals to the MCU, and the temperature and pressure data is converted from an analog signal to a digital signal via the A / D conversion circuit, and is input into the MCU through SPI communication; the displacement encoder transmits signals to the signal conditioning circuit, the signal conditioning circuit transmits signals to the MCU, and after the signal conditioning circuit obtains the pulse signal, the signal conditioning circuit is adjusted to convert into a pulse signal that can be received by the MCU and is input into the MCU; the inclination sensor and the CAN transceiver perform bidirectional data exchange, the CAN transceiver and the MCU perform bidirectional data exchange, the MCU sends a control instruction to the CAN transceiver, the inclination sensor sends a digital signal to the CAN transceiver, and the CAN transceiver converts the voltage into a TTL level and then sends it to the MCU for reception.

[0009] The MCU module is composed of a low-pass filter, a viscous friction coefficient calculation, a pulse counter, a displacement speed calculation, a CAN bus, an angle and angular velocity calculation, a cylinder pressure calculation, a data integration, and a network transmission module. The A / D conversion circuit delivers data to the low-pass filter, the low-pass filter delivers data to the viscous friction coefficient calculation module, the low-pass filter obtains temperature data sent by the A / D conversion circuit, removes high-frequency burrs in the collected data after processing, and sends the data to the viscous friction coefficient calculation module; the low-pass filter delivers data to the viscous friction coefficient calculation module, the viscous friction coefficient calculation module delivers data to the data integration module, and the viscous friction coefficient calculation module calculates and outputs the viscous friction coefficient according to the temperature data; the signal conditioning circuit delivers signals to the pulse counter, the pulse counter delivers data to the displacement speed calculation module, the pulse counter receives the adjusted pulse signal, and the pulse counter performs addition and subtraction operations on the counter according to the signal characteristics, and extracts the value in the counter when needed; the pulse counter delivers data to the displacement speed calculation module, the displacement speed calculation module delivers data to the data integration module, the displacement speed calculation module is triggered after the timer overflows, receives the pulse counter data, and then converts the obtained data into actual displacement and speed data and outputs; the CAN transceiver delivers data to the CAN bus, the CAN bus delivers data to the angle and angular velocity calculation, the CAN bus obtains the inclination data converted by the CAN transceiver, and sends the data to the angle and angular velocity calculation module via the bus; the CAN bus delivers data to the angle and angular velocity calculation, the angle and angular velocity calculation delivers data to the data integration module, the angle and angular velocity calculation module obtains angle data from the CAN bus, and outputs angle and angular velocity data to the data integration module after calculation and processing; the A / D conversion module delivers data to the cylinder pressure calculation module, the cylinder pressure calculation module delivers data to the data integration module, the cylinder pressure conversion module obtains hydraulic data on both sides of the hydraulic cylinder from the A / D conversion module, calculates the pressure difference between both sides of the hydraulic cylinder after processing and conversion, calculates the actual cylinder pressure data through compensation correction, and outputs to the data integration module; the viscous friction coefficient calculation module, the speed and displacement calculation module, the angle and angular velocity calculation module, and the cylinder pressure calculation module deliver data to the data integration module, the data integration module delivers data to the network transmission module, the integration module classifies, arranges, and compresses the data calculated by all previous modules, and sends the compressed data to the network transmission module; the data integration module delivers data to the network transmission module, the network transmission module realizes bidirectional data exchange with the upper computer, the network transmission module obtains the data integrated by the data integration module and sends it to the upper computer, and simultaneously receives the control instructions from the upper computer so that the upper computer can control the MCU.

[0010] The low-pass filter algorithm module is composed of temperature data, register 1, register 2 coefficient 1, coefficient 2, multiplication 1, multiplication 2, summation and data fusion part. The temperature data delivers data to the register 1, which is responsible for inputting the temperature data to the low-pass filter algorithm; the temperature data delivers data to the register 1, the register 1 delivers data to the multiplication 1, the register 1 acquires the temperature data and stores, and waits for input to the multiplication 1; coefficient 1 delivers data to multiplication 1, the value of coefficient 1 is determined according to the low-pass filter requirement, and is used for filtering high-frequency signal interference in the acquisition process; register 1, coefficient 1 deliver data to multiplication 1, multiplication 1 delivers data to summation, which is used for weighting processing of the current temperature data; coefficient 2 delivers data to multiplication 2, the value of coefficient 2 is determined according to the low-pass filter requirement, and is usually (coefficient 1+coefficient 2)=1, which is used for filtering high-frequency signal interference in the acquisition process; summation delivers data to register 2, register 2 delivers data to multiplication 2, which is used for storing the summation result of the last round and participating in the weighted summation operation of this round; register 2 delivers data to coefficient 2 and multiplication 2, multiplication 2 delivers data to summation, which is used for weighting processing of the summation result of the last round; multiplication 1 delivers data to multiplication 2 and summation, summation delivers data to register 2 and data fusion, summation is used for summing two groups of temperature data after weighting, and generates filtered temperature data, and after calculation, the summation result covers the data of register 2 and outputs to the data fusion module;

[0011] The pulse counter module is composed of input signal 1, input signal 2, direction judgment, accumulation / decrement, register 1 and register 2. Input signal 1 delivers data to direction judgment, which is responsible for inputting pulse signal to the direction judgment module; input signal 2 delivers data to direction judgment, which is responsible for inputting pulse signal with 90° phase shift to the direction judgment module; input signal 1 and input signal 2 deliver data to direction judgment, which delivers data to accumulation / decrement, which judges the displacement direction of the current pulse according to the level of input signal 1 and input signal 2, and outputs the judgment result to the accumulation / decrement module; direction judgment and register 1 deliver data to the accumulation / decrement module, which delivers data to register 1 and register 2, which calls the data of register 1 for addition and subtraction operation after obtaining the direction judgment result, and stores the output result in register 1 and register 2; accumulation / decrement and register 1 realize bidirectional data exchange, register 1 outputs stored data to the accumulation / decrement module, and accumulation / decrement outputs calculation result to register 1 to cover the original data, and register 1 stores the current pulse count value; accumulation / decrement delivers data to register 2, and register 2 stores the pulse count calculation result of the accumulation / decrement module, and waits for the displacement speed calculation module to read;

[0012] The cylinder pressure conversion module is composed of rod side cylinder pressure, non-rod side cylinder pressure, rod side area, non-rod side area, pressure calculation formula 1, pressure calculation formula 2, pressure difference calculation formula, compensation correction, output force module; the rod side cylinder pressure sends data to the pressure calculation formula 1, and the rod side cylinder pressure is responsible for inputting the rod side pressure data of the hydraulic cylinder into the module; the non-rod side cylinder pressure sends data to the pressure calculation formula 2, and the non-rod side cylinder pressure is responsible for inputting the non-rod side pressure data of the hydraulic cylinder into the module; the rod side area sends data to the pressure calculation formula 1, and is responsible for inputting the rod side area of the hydraulic cylinder into the pressure calculation formula; the non-sensing area sends data to the pressure calculation formula 2, and is responsible for inputting the non-rod side area of the hydraulic cylinder into the pressure calculation formula; the rod side cylinder pressure and the rod side area send data to the pressure calculation formula 1, the pressure calculation formula 1 sends data to the pressure difference calculation formula, the pressure calculation formula 1 converts the pressure data into pressure data and sends it to the pressure difference calculation formula; the non-rod side cylinder pressure and the non-rod side area send data to the pressure calculation formula 2, the pressure calculation formula 2 sends data to the pressure difference calculation formula, the pressure calculation formula 2 converts the pressure data into pressure data and sends it to the pressure difference calculation formula; the pressure calculation formula 1 and the pressure calculation formula 2 send data to the pressure difference calculation formula, the pressure difference calculation formula sends data to the compensation correction, and the pressure difference calculation formula is responsible for calculating the difference between the rod side pressure and the non-rod side pressure and outputting to the compensation correction module; the pressure difference calculation formula sends data to the compensation correction module, the compensation correction module sends data to the output force, the compensation correction module corrects the output result of the pressure difference calculation formula through the model and outputs to the output force module; the compensation correction sends data to the output force module, and the output force is responsible for sending data to the data integration module for next operation;

[0013] The speed displacement calculation module is composed of a timer signal, a pulse counter count, an upper edge detection, a timer overflow interval, a speed operation, a register, a pulse displacement conversion, a speed, and a displacement module. The timer signal delivers data to the upper edge monitoring, which is responsible for periodic output of a high-level pulse signal; the pulse counter count delivers data to the speed operation and the pulse-displacement conversion, which is responsible for providing count data in the pulse counter; the timer signal delivers data to the upper edge detection, which delivers data to the speed operation, and is responsible for capturing the rising edge signal and activating the module; the timer overflow interval delivers data to the speed operation, which provides time data of the timer interval period; the upper edge detection, the timer overflow interval, the pulse counter count, and the register deliver data to the speed operation, which delivers data to the speed, and calculates the current hydraulic cylinder moving speed through a conversion formula according to the timer overflow interval and the pulse counter count value stored in the register; the pulse and the counter count deliver data to the register, which delivers data to the speed operation, and is responsible for storing the pulse counter count value of the last round, and the count value of the pulse counter of the current round will overwrite the original data in the register after the speed operation is completed; the pulse counter count delivers data to the pulse-displacement conversion, which delivers data to the displacement, and is responsible for converting the pulse counter count into the actual hydraulic cylinder displacement; the speed operation delivers data to the speed, which is responsible for outputting the speed data from the module; the pulse-displacement conversion delivers data to the displacement, which is responsible for outputting the displacement data from the module;

[0014] The viscous friction coefficient calculation module is composed of a temperature signal, a viscous friction coefficient and temperature relationship formula, and a temperature coefficient. The temperature signal delivers data to the viscous friction coefficient and temperature relationship formula, which is processed by the low-pass filter module and sent to the module for data calculation; the temperature signal delivers data to the viscous friction coefficient and temperature relationship formula, which delivers data to the temperature coefficient, and is responsible for calculating the current hydraulic oil viscous friction coefficient according to the temperature; the viscous friction coefficient and temperature relationship formula delivers data to the temperature coefficient, which is responsible for outputting the viscous friction coefficient calculation result based on the temperature;

[0015] The PC host computer is composed of a network module, data processing, motion parameter processing, a database, a shovel model, contact force calculation and a graphical interface. The MCU and the network module realize bidirectional data exchange, the network module transmits data to the data processing module, the network module receives MCU data and sends host computer instructions to the MCU, and sends the received MCU data to the data processing module for further processing; the network module transmits data to the data processing module, the data processing transmits data to the motion parameter processing, contact force calculation and graphical interface, which is used to decompress the compressed data in the transmission process, and classify and send various data to different data processing modules for further operation; the data processing module transmits data to the motion parameter processing module, the motion parameter processing module transmits data to the database and the shovel model, which is used to re-group the decompressed motion parameters according to the mechanical structure, and store them in the database for subsequent graphical interface extraction, and send the motion parameters to the shovel model for subsequent calculation; the motion parameter processing transmits data to the shovel model, the shovel model transmits data to the contact force calculation and the graphical interface, which is used to provide the position information of the mechanical structure of the shovel required in the contact force measurement and graphical drawing process; the data processing, the shovel model transmit data to the contact force calculation, the contact force calculation transmits data to the database and the graphical interface, the contact force calculation calculates the contact force data of each hydraulic cylinder according to the data provided by the data processing and the shovel model module, and sends them to the database for storage, and to the graphical interface for presentation; the data processing, contact force calculation, shovel model, database transmit data to the graphical interface, the graphical interface transmits data to the network module, the graphical interface receives real-time data of the data processing, contact force calculation, shovel model to draw a 2D shovel model, displays real-time measurement data, and draws a line graph according to user instructions to obtain historical data of a certain parameter from the database, the graphical interface outputs control instructions to the network module according to user instructions to realize control of the MCU.

[0016] The measurement system patent includes hardware circuit and software algorithm two parts, the hardware circuit level has more rich sensor types compared with similar patents, because of the existence of temperature sensor and displacement encoder, the hydraulic oil temperature and hydraulic cylinder displacement data can be directly obtained, further improve the modeling accuracy of force measurement model, improve the measurement accuracy of contact force; compared with the general measurement patent using sensor direct measurement data means, the contact force soft measurement calculation algorithm is added, not simply using temperature, pressure data for alarm and control, but through a series of data calculation (i.e. soft measurement) contact force data, using the way of derivation to indirectly measure data, avoid the sensor damage caused by the force data of hydraulic system dramatic change, at the same time, the use of multiple sensor parameters also improves the indirect measurement accuracy of measured data.

[0017] The scheme adopts the data exchange mode of MCU plus network transmission, so that general PC can also calculate and process parameters, on the one hand, the high cost required for purchasing industrial computers is avoided, on the other hand, PC provides customization possibility for contact force measurement systems with different computing power requirements, which helps to further reduce the cost and improve the upper limit of contact force precision, network provides guarantee for real-time data exchange between MCU and PC as a high-speed data exchange means, and since wireless network transmission is allowed, MCU can realize wireless remote data exchange with PC, which provides a solution for lightweight excavator measurement system.

[0018] Advantages of the present application:

[0019] (1) The MCU measurement system has the characteristics of small size, low power consumption and strong expandability, the network transmission has the characteristics of strong real-time and high bandwidth, which reduces the expandability requirement of the upper computer and improves the flexibility of the measurement system;

[0020] (2) The temperature sensor provides accurate values for the determination of the viscous friction coefficient, the accuracy of the viscous friction directly affects the contact force measurement accuracy, and the determination of the viscous friction coefficient can improve the estimation accuracy of the viscous friction;

[0021] (3) The displacement sensor provides a calculation basis for the piston moving speed of the hydraulic cylinder, the piston moving speed directly affects the estimation of viscous friction, and the accurate estimation of viscous friction helps to improve the accuracy of contact force measurement;

[0022] (4) The real-time drawing of the excavator 2D motion model and the data change broken line graph improves the usability of the man-machine interaction system, and makes the data more intuitive.

[0023] (5) The scheme adopts the data exchange mode of MCU plus network transmission, so that general PC can also calculate and process parameters, on the one hand, the high cost required for purchasing industrial computers is avoided, on the other hand, PC provides customization possibility for contact force measurement systems with different computing power requirements, which helps to further reduce the cost and improve the upper limit of contact force precision, network provides guarantee for real-time data exchange between MCU and PC as a high-speed data exchange means, and since wireless network transmission is allowed, MCU can realize wireless remote data exchange with PC, which provides a solution for lightweight excavator measurement system. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the present application;

[0025] Figure 2 It is a low-pass filtering algorithm flowchart of the present application;

[0026] Figure 3 Flow chart of the cylinder pressure conversion module of the present application;

[0027] Figure 4 Flow chart of the cylinder pressure conversion module of the present application;

[0028] Figure 5 Flow chart of the speed displacement calculation module of the present application;

[0029] Figure 6 Flow chart of the viscous friction coefficient calculation module of the present application;

[0030] Figure 7 Flow chart of the PC host computer operation of the present application. DETAILED DESCRIPTION

[0031] The present application will be further clarified by the following examples and figures, which should not be taken as limiting the scope of the present application. It should be noted that the terms "front", "back", "left", "right", "up" and "down" used in the following description refer to the directions in the figures, and the terms "inner" and "outer" refer to the directions towards or away from the geometric center of a particular component.

[0032] Figure 1 The present application is a whole structure schematic diagram. The embodiment is a kind of excavator contact force soft measurement system based on embedded system. The system is composed of sensor array, signal conditioning circuit, MCU and PC host computer four parts;Sensor array sends signal to signal conditioning circuit through wired mode, is responsible for the temperature, pressure, position, attitude and other parameter acquisition functions of excavator;Signal conditioning circuit sends signal to sensor array and MCU through wired mode, is responsible for the signal conversion function from sensor to MCU;MCU sends data to signal conditioning circuit through wired mode, realizes two-way data exchange with host computer through network, is responsible for the pre-processing function of data collected by sensor;PC host computer realizes two-way data exchange with MCU through network, is responsible for the calculation of contact force and data visualization function;

[0033] The sensor array is composed of four types of sensors, temperature sensors, pressure sensors, displacement sensors and inclination sensors. Each type of sensor is installed in the bucket, the bucket rod and the boom respectively. The temperature and pressure sensors adopt a temperature and pressure integrated sensor, two temperature and pressure integrated sensors are installed on each hydraulic cylinder, the temperature and pressure integrated sensor transmits signals to the A / D conversion circuit, the sensor outputs an analog signal to the A / D conversion circuit, which is used to measure the pressure of the two side cavities of the hydraulic cylinder and the oil temperature of the hydraulic oil; the displacement sensor adopts an incremental wire displacement encoder, which is installed in the bucket, the bucket rod and the boom hydraulic cylinder position, transmits signals to the signal conditioning circuit, the sensor outputs a pulse signal, which is used to measure the position of the piston rod when the hydraulic cylinder moves; the inclination sensor adopts a super-high-precision single-axis inclination sensor, which is installed in the joint hinge of the bucket, the bucket rod and the boom, transmits signals to the CAN transceiver, the sensor outputs a digital signal, which is used to measure the current pose of the excavator mechanical arm;

[0034] The signal conditioning circuit is composed of an A / D conversion circuit, a signal conditioning circuit and a CAN transceiver. The temperature and pressure integrated sensor transmits signals to the A / D conversion circuit, the A / D conversion circuit transmits signals to the MCU, the temperature and pressure data are converted from analog signals to digital signals via the A / D conversion circuit, and are input to the MCU through SPI communication; the displacement encoder transmits signals to the signal conditioning circuit, the signal conditioning circuit transmits signals to the MCU, after the signal conditioning circuit obtains the pulse signal, it is converted to a pulse signal that can be received by the MCU via the signal conditioning circuit and is input to the MCU; the inclination sensor and the CAN transceiver perform bidirectional data exchange, the CAN transceiver and the MCU perform bidirectional data exchange, the MCU sends control instructions to the CAN transceiver, the inclination sensor sends digital signals to the CAN transceiver, and the CAN transceiver converts the voltage to TTL level and sends it to the MCU for reception;

[0035] The MCU module is composed of a low-pass filter, a viscous friction coefficient calculation, a pulse counter, a displacement speed calculation, a CAN bus, an angle and angular velocity calculation, a cylinder pressure calculation, a data integration, and a network transmission module. The A / D conversion circuit delivers data to the low-pass filter, the low-pass filter delivers data to the viscous friction coefficient calculation module, the low-pass filter obtains temperature data sent by the A / D conversion circuit, removes high-frequency burrs in the collected data after processing, and sends the data to the viscous friction coefficient calculation module; the low-pass filter delivers data to the viscous friction coefficient calculation module, the viscous friction coefficient calculation module delivers data to the data integration module, and the viscous friction coefficient calculation module calculates and outputs the viscous friction coefficient according to the temperature data; the signal conditioning circuit delivers signals to the pulse counter, the pulse counter delivers data to the displacement speed calculation module, the pulse counter receives the adjusted pulse signal, and the pulse counter performs addition and subtraction operations on the counter according to the signal characteristics, and extracts the value in the counter when needed; the pulse counter delivers data to the displacement speed calculation module, the displacement speed calculation module delivers data to the data integration module, the displacement speed calculation module is triggered after the timer overflows, receives the pulse counter data, and then converts the obtained data into actual displacement and speed data and outputs; the CAN transceiver delivers data to the CAN bus, the CAN bus delivers data to the angle and angular velocity calculation, the CAN bus obtains the inclination data converted by the CAN transceiver, and sends the data to the angle and angular velocity calculation module via the bus; the CAN bus delivers data to the angle and angular velocity calculation, the angle and angular velocity calculation delivers data to the data integration module, the angle and angular velocity calculation module obtains angle data from the CAN bus, and outputs angle and angular velocity data to the data integration module after calculation and processing; the A / D conversion module delivers data to the cylinder pressure calculation module, the cylinder pressure calculation module delivers data to the data integration module, the cylinder pressure conversion module obtains hydraulic data on both sides of the hydraulic cylinder from the A / D conversion module, calculates the pressure difference between both sides of the hydraulic cylinder after processing and conversion, calculates the actual cylinder pressure data through compensation correction, and outputs to the data integration module; the viscous friction coefficient calculation module, the speed and displacement calculation module, the angle and angular velocity calculation module, and the cylinder pressure calculation module deliver data to the data integration module, the data integration module delivers data to the network transmission module, the integration module classifies, arranges, and compresses the data calculated by all previous modules, and sends the compressed data to the network transmission module; the data integration module delivers data to the network transmission module, the network transmission module realizes bidirectional data exchange with the upper computer, the network transmission module obtains the data integrated by the data integration module and sends it to the upper computer, and simultaneously receives the control instructions from the upper computer so that the upper computer can control the MCU.

[0036] Figure 2A flow chart for the low-pass filtering algorithm of the application is implemented. The low-pass filtering algorithm module is composed of temperature data, register 1, register 2 coefficient 1, coefficient 2, multiplication 1, multiplication 2, summation and data fusion part. The temperature data delivers data to register 1, which is responsible for inputting temperature data to the low-pass filtering algorithm; the temperature data delivers data to register 1, and register 1 delivers data to multiplication 1, register 1 acquires temperature data and stores, and waits to be input into multiplication 1; coefficient 1 delivers data to multiplication 1, the value of coefficient 1 is determined according to the low-pass filtering requirement, and is used to filter out high-frequency signal interference in the collection process; register 1 and coefficient 1 deliver data to multiplication 1, and multiplication 1 delivers data to summation, which is used for weighted processing of the current temperature data; coefficient 2 delivers data to multiplication 2, the value of coefficient 2 is determined according to the low-pass filtering requirement, and generally (coefficient 1+coefficient 2)=1, which is used to filter out high-frequency signal interference in the collection process; summation delivers data to register 2, and register 2 delivers data to multiplication 2, which is used to store the summation result of the last round and participate in the weighted summation operation of the current round; register 2 delivers data to coefficient 2 and multiplication 2, and multiplication 2 delivers data to summation, which is used for weighted processing of the summation result of the last round; multiplication 1 delivers data to multiplication 2 and summation, and summation delivers data to register 2 and data fusion, and summation is used to sum the two groups of temperature data after weighted processing, and generate filtered temperature data, and after calculation, the summation result covers the data of register 2 and outputs to the data fusion module;

[0037] Figure 3 A flow chart for the pulse counter module of the application is implemented. The pulse counter module is composed of input signal 1, input signal 2, direction judgment, accumulation / decrement, register 1 and register 2. Input signal 1 delivers data to direction judgment, which is responsible for inputting pulse signals to the direction judgment module; input signal 2 delivers data to direction judgment, which is responsible for inputting pulse signals with 90° phase shift from input signal 1 to the direction judgment module; input signal 1 and input signal 2 deliver data to direction judgment, and direction judgment delivers data to accumulation / decrement, which judges the displacement direction of the current pulse according to the level of input signal 1 and input signal 2, and outputs the judgment result to the accumulation / decrement module; direction judgment and register 1 deliver data to the accumulation / decrement module, and accumulation / decrement delivers data to register 1 and register 2, which acquires the direction judgment result and calls the data of register 1 for addition and subtraction operation, and outputs the result to register 1 and register 2; accumulation / decrement and register 1 realize bidirectional data exchange, register 1 outputs stored data to the accumulation / decrement module, and accumulation / decrement outputs the calculation result to register 1 to cover the original data, and register 1 stores the current pulse count value; accumulation / decrement delivers data to register 2, and register 2 stores the pulse count calculation result of the accumulation / decrement module, and waits to be read by the displacement speed calculation module;

[0038] Figure 4 A flow chart is implemented for the cylinder pressure conversion module of the present application. The cylinder pressure conversion module is composed of rod side cylinder pressure, non-rod side cylinder pressure, rod side area, non-rod side area, pressure calculation formula 1, pressure calculation formula 2, pressure difference calculation formula, compensation correction, output force module; the rod side cylinder pressure sends data to the pressure calculation formula 1, and the rod side cylinder pressure is responsible for inputting the rod side pressure data of the hydraulic cylinder into the module; the non-rod side cylinder pressure sends data to the pressure calculation formula 2, and the non-rod side cylinder pressure is responsible for inputting the non-rod side pressure data of the hydraulic cylinder into the module; the rod side area sends data to the pressure calculation formula 1, and is responsible for inputting the rod side area of the hydraulic cylinder into the pressure calculation formula; the non-sensing area sends data to the pressure calculation formula 2, and is responsible for inputting the non-rod side area of the hydraulic cylinder into the pressure calculation formula; the rod side cylinder pressure and the rod side area send data to the pressure calculation formula 1, the pressure calculation formula 1 sends data to the pressure difference calculation formula, the pressure calculation formula 1 converts the pressure data into pressure data and sends it to the pressure difference calculation formula; the non-rod side cylinder pressure and the non-rod side area send data to the pressure calculation formula 2, the pressure calculation formula 2 sends data to the pressure difference calculation formula, the pressure calculation formula 2 converts the pressure data into pressure data and sends it to the pressure difference calculation formula; the pressure calculation formula 1 and the pressure calculation formula 2 send data to the pressure difference calculation formula, the pressure difference calculation formula sends data to the compensation correction, and the pressure difference calculation formula is responsible for calculating the difference between the rod side pressure and the non-rod side pressure and outputting to the compensation correction module; the pressure difference calculation formula sends data to the compensation correction module, the compensation correction module sends data to the output force, the compensation correction module corrects the output result of the pressure difference calculation formula through the model and outputs to the output force module; the compensation correction sends data to the output force module, and the output force is responsible for sending data to the data integration module for next operation;

[0039] Figure 5A flow chart is realized for the speed displacement calculation module of the application. The speed displacement calculation module is composed of a timer signal, a pulse counter count, an upper edge detection, a timer overflow interval, a speed operation, a register, a pulse displacement conversion, a speed, and a displacement module. The timer signal delivers data to the upper edge monitoring, which is responsible for periodic output of a high-level pulse signal; the pulse counter count delivers data to the speed operation and the pulse-displacement conversion, and is responsible for providing count data in the pulse counter; the timer signal delivers data to the upper edge detection, which delivers data to the speed operation, and is responsible for capturing the rising edge signal and activating the module; the timer overflow interval delivers data to the speed operation, which provides time data of the timer interval period; the upper edge detection, the timer overflow interval, the pulse counter count, and the register deliver data to the speed operation, which delivers data to the speed, and calculates the current hydraulic cylinder moving speed through a conversion formula according to the timer overflow interval and the pulse counter count value stored in the register; the pulse and the counter count deliver data to the register, which delivers data to the speed operation, and is responsible for storing the pulse counter count value of the last round, and the count value of the pulse counter of the current round will overwrite the original data in the register after the speed operation is completed; the pulse counter count delivers data to the pulse-displacement conversion, which delivers data to the displacement, and is responsible for converting the pulse counter count into the actual hydraulic cylinder displacement; the speed operation delivers data to the speed, which is responsible for outputting the speed data from the module; the pulse-displacement conversion delivers data to the displacement, which is responsible for outputting the displacement data from the module.

[0040] Figure 6 A flow chart is realized for the viscous friction coefficient calculation module of the application. The viscous friction coefficient calculation module is composed of a temperature signal, a viscous friction coefficient and temperature relationship formula, and a temperature coefficient. The temperature signal delivers data to the viscous friction coefficient and temperature relationship formula, which is processed by the low-pass filter module and then sent to the module for data calculation; the temperature signal delivers data to the viscous friction coefficient and temperature relationship formula, which delivers data to the temperature coefficient, and is responsible for calculating the current hydraulic oil viscous friction coefficient according to the temperature; the viscous friction coefficient and temperature relationship formula delivers data to the temperature coefficient, which is responsible for outputting the viscous friction coefficient calculation result based on the temperature.

[0041] Figure 7The PC host computer of the application is realized as a structural diagram. The PC host computer is composed of a network module, data processing, motion parameter processing, a database, a shovel model, contact force calculation and a graphical interface. The MCU and the network module realize bidirectional data exchange, the network module transmits data to the data processing module, the network module receives MCU data and sends host computer instructions to the MCU, and sends the received MCU data to the data processing module for further processing; the network module transmits data to the data processing module, the data processing transmits data to the motion parameter processing, contact force calculation and graphical interface, which is used to decompress the compressed data in the transmission process, and classify and send various data to different data processing modules for further operation; the data processing module transmits data to the motion parameter processing module, the motion parameter processing module transmits data to the database and the shovel model, which is used to re-group the decompressed motion parameters according to the mechanical structure, and store them in the database for subsequent graphical interface extraction, and send the motion parameters to the shovel model for subsequent calculation; the motion parameter processing transmits data to the shovel model, the shovel model transmits data to the contact force calculation and the graphical interface, which is used to provide the position information of the mechanical structure of the shovel required in the contact force measurement and graphical drawing process; the data processing, the shovel model transmit data to the contact force calculation, the contact force calculation transmits data to the database and the graphical interface, the contact force calculation calculates the contact force data of each hydraulic cylinder according to the data provided by the data processing and the shovel model module, and sends them to the database for storage, and to the graphical interface for presentation; the data processing, contact force calculation, shovel model, database transmit data to the graphical interface, the graphical interface transmits data to the network module, the graphical interface receives real-time data of the data processing, contact force calculation and shovel model to draw a 2D shovel model, displays real-time measurement data, and draws a line chart according to user instructions to obtain historical data of a certain parameter from the database, the graphical interface outputs control instructions to the network module according to user instructions to realize control of the MCU; the embodiment adopts the data exchange mode of MCU plus network transmission, so that general PC can also calculate and process parameters, which helps to further reduce the cost and improve the upper limit of contact force measurement accuracy, the network provides guarantee for real-time data interaction between MCU and PC as a high-speed data exchange means, and since wireless network transmission is allowed, MCU can realize wireless remote data exchange with PC, and a lighter measurement system is provided for the shovel.

[0042] The technical means disclosed in the application scheme is not limited to the technical means disclosed in the above embodiments, but also includes technical solutions composed of any combination of the above technical features.

Claims

1. A micro-control unit-based contact force soft measurement system for excavators, the system being composed of a sensor array, a signal conditioning circuit, a signal preprocessing system, and a PC host computer; the sensor array transmits signals to the signal conditioning circuit through a wired mode; the signal conditioning circuit transmits signals to the signal preprocessing system through a wired mode; the signal preprocessing system and the host computer realize bidirectional data exchange through a wired / wireless network mode; characterized in that: The sensor array is composed of four types of sensors, temperature sensors, pressure sensors, displacement sensors and inclination sensors; each type of sensor is installed in the three parts of the bucket, the bucket rod and the boom; wherein the temperature and pressure sensors are all temperature and pressure integrated sensors, two temperature and pressure integrated sensors are installed on each hydraulic cylinder, the temperature and pressure integrated sensors transmit signals to the A / D conversion circuit, the sensor outputs analog signals to the A / D conversion circuit, and the two temperature and pressure integrated sensors are used to measure the hydraulic pressure and the hydraulic oil temperature of the two sides of the hydraulic cylinder respectively; the displacement sensor is installed at the hydraulic cylinder position of the bucket, the bucket rod and the boom, and transmits signals to the signal conditioning circuit, the sensor outputs pulse signals, and is used to measure the position of the piston rod when the hydraulic cylinder moves; the inclination sensor is installed at the joint hinge of the bucket, the bucket rod and the boom, and transmits signals to the CAN transceiver, the sensor outputs digital signals, and is used to measure the current pose of the mechanical arm of the excavator; The signal conditioning circuit is composed of an A / D conversion circuit, a signal conditioning circuit and a CAN transceiver; the temperature and pressure integrated sensor transmits signals to the A / D conversion circuit, the A / D conversion circuit transmits signals to the MCU, the temperature and pressure data are converted from analog signals to digital signals via the A / D conversion circuit, and are input into the MCU through SPI communication; the displacement encoder transmits signals to the signal conditioning circuit, the signal conditioning circuit transmits signals to the MCU, after the signal conditioning circuit obtains the pulse signal, the signal conditioning circuit adjusts and converts it into a pulse signal that can be received by the MCU and inputs it into the MCU; the inclination sensor and the CAN transceiver perform bidirectional data exchange, the CAN transceiver and the MCU perform bidirectional data exchange, the MCU sends control instructions to the CAN transceiver, the inclination sensor sends digital signals to the CAN transceiver, and the CAN transceiver converts the voltage into TTL level and sends it to the MCU for reception; The MCU is composed of a low-pass filter, a viscous friction coefficient calculation, a pulse counter, a displacement speed calculation, a CAN bus, an angle and angular velocity calculation, a cylinder pressure calculation, a data integration and a network transmission module; the A / D conversion circuit transmits data to the low-pass filter, the low-pass filter transmits data to the viscous friction coefficient calculation module, the low-pass filter obtains the temperature data sent by the A / D conversion circuit, removes the high-frequency burrs in the collected data after processing, and sends the data to the viscous friction coefficient calculation module; The low-pass filter delivers data to the viscous friction coefficient calculation module, which delivers data to the data integration module, and the viscous friction coefficient calculation module calculates and outputs the viscous friction coefficient according to the temperature data; the signal conditioning circuit delivers signals to the pulse counter, which delivers data to the displacement speed calculation module, the pulse counter receives the conditioned pulse signal, and according to the signal characteristics, the counter is added or subtracted, and the value in the counter is extracted when needed; the pulse counter delivers data to the displacement speed calculation module, which delivers data to the data integration module, the displacement speed calculation module is triggered after the timer overflows, receives the pulse counter data, and then converts the obtained data into actual displacement and speed data through calculation and outputs; the CAN transceiver delivers data to the CAN bus, which delivers data to the angle and angular velocity calculation, and the CAN bus sends the angle data converted by the CAN transceiver to the angle and angular velocity calculation module via the bus after obtaining the angle data; the CAN bus delivers data to the angle and angular velocity calculation, which delivers data to the data integration module, and the angle and angular velocity calculation module obtains angle data from the CAN bus and outputs angle and angular velocity data to the data integration module after calculation and processing; the A / D conversion module delivers data to the cylinder pressure calculation module, which delivers data to the data integration module, the cylinder pressure conversion module obtains hydraulic data on both sides of the hydraulic cylinder from the A / D conversion module, calculates the pressure difference on both sides of the hydraulic cylinder after processing and conversion, and calculates the actual cylinder pressure data through compensation correction, and outputs to the data integration module; the viscous friction coefficient calculation module, the speed and displacement calculation module, the angle and angular velocity calculation module, and the cylinder pressure calculation module deliver data to the data integration module, and the data integration module delivers data to the network transmission module, the integration module classifies, arranges and compresses the data calculated by all previous modules, and sends the compressed data to the network transmission module; The data integration module delivers data to the network transmission module, and the network transmission module realizes bidirectional data exchange with the upper computer, obtains the data integrated by the data integration module and sends it to the upper computer, and receives the control instructions of the upper computer to enable the upper computer to control the MCU.

2. The microcontroller unit based contact force soft sensing system for excavator as claimed in claim 1 wherein: The low-pass filter algorithm module is composed of temperature data, register 1, register 2, coefficient 1, coefficient 2, multiplication 1, multiplication 2, summation and data fusion; the temperature data delivers data to the register 1, which is responsible for inputting the temperature data to the low-pass filter algorithm; the temperature data delivers data to the register 1, which delivers data to the multiplication 1, and the register 1 obtains and stores the temperature data, waiting to be input into the multiplication 1; the coefficient 1 delivers data to the multiplication 1, and the value of the coefficient 1 is determined according to the low-pass filter requirement, which is used to filter out high-frequency signal interference in the collection process; The register 1 and the coefficient 1 deliver data to the multiplication 1, and the multiplication 1 delivers data to the summation, which is used for weighted processing of the current temperature data; Coefficient 2 delivers data to multiplication 2, the value of coefficient 2 is determined according to the low-pass filtering requirement, generally coefficient 1+coefficient 2=1, for filtering high-frequency signal interference in the acquisition process; summation delivers data to register 2, register 2 delivers data to multiplication 2, for storing the last round summation result and participating in the current round weighted summation operation; register 2 delivers data to coefficient 2 and multiplication 2, multiplication 2 delivers data to summation, multiplication 2 is used for weighting processing of the last round summation result; multiplication 1 delivers data to multiplication 2 and summation, summation delivers data to register 2 and data fusion, summation is used for summing two groups of temperature data after weighting, and generates filtered temperature data, and after calculation, the summation result covers the data of register 2 and outputs to the data fusion module.

3. The microcontroller unit based contact force soft sensor system for excavator according to claim 1, wherein: The pulse counter is composed of input signal 1, input signal 2, direction judgment, accumulation / decrement, register 3 and register 4; input signal 1 delivers data to direction judgment, and input signal 1 is responsible for inputting pulse signals to the direction judgment module; input signal 2 delivers data to direction judgment, and input signal 2 is responsible for inputting pulse signals with 90° phase shift from input signal 1 to the direction judgment module; input signal 1 and input signal 2 deliver data to direction judgment, and direction judgment delivers data to accumulation / decrement, and direction judgment judges the displacement direction of the current pulse according to the level of input signal 1 and input signal 2, and outputs the judgment result to the accumulation / decrement module; Direction judgment and register 3 deliver data to the accumulation / decrement module, and accumulation / decrement delivers data to register 3 and register 4, and accumulation / decrement calls the data of register 1 for addition and subtraction operation after obtaining the direction judgment result, and the output result is stored in register 3 and register 4; Accumulation / decrement and register 3 realize bidirectional data exchange, register 3 outputs stored data to the accumulation / decrement module, accumulation / decrement outputs calculation result to register 3 to cover the original data, and register 3 stores the current pulse count value; Accumulation / decrement delivers data to register 4, and register 4 stores the pulse count calculation result of the accumulation / decrement module, and waits for the displacement speed calculation module to read.

4. The microcontroller unit based contact force soft sensing system for excavator as claimed in claim 1 wherein: The cylinder pressure conversion module is composed of rod side cylinder pressure, non-rod side cylinder pressure, rod side area, non-rod side area, pressure calculation formula 1, pressure calculation formula 2, pressure difference calculation formula, compensation correction, and output force module; the rod side cylinder pressure sends data to the pressure calculation formula 1, and is responsible for inputting the rod side pressure data of the hydraulic cylinder into the module; the non-rod side cylinder pressure sends data to the pressure calculation formula 2, and is responsible for inputting the non-rod side pressure data of the hydraulic cylinder into the module; the rod side area sends data to the pressure calculation formula 1, and is responsible for inputting the rod side area of the hydraulic cylinder into the pressure calculation formula; the non-sensing area sends data to the pressure calculation formula 2, and is responsible for inputting the non-rod side area of the hydraulic cylinder into the pressure calculation formula; the rod side cylinder pressure and the rod side area send data to the pressure calculation formula 1, the pressure calculation formula 1 sends data to the pressure difference calculation formula, the pressure calculation formula 1 converts the pressure data into pressure data and sends it to the pressure difference calculation formula; the non-rod side cylinder pressure and the non-rod side area send data to the pressure calculation formula 2, the pressure calculation formula 2 sends data to the pressure difference calculation formula, the pressure calculation formula 2 converts the pressure data into pressure data and sends it to the pressure difference calculation formula; the pressure calculation formula 1 and the pressure calculation formula 2 send data to the pressure difference calculation formula, the pressure difference calculation formula sends data to the compensation correction, and the pressure difference calculation formula is responsible for calculating the difference between the rod side pressure and the non-rod side pressure and outputting to the compensation correction module; the pressure difference calculation formula sends data to the compensation correction module, the compensation correction module sends data to the output force, the compensation correction module corrects the output result of the pressure difference calculation formula through the model and outputs to the output force module; the compensation correction sends data to the output force module, and the output force is responsible for sending data to the data integration module for the next operation.

5. The microcontroller unit based contact force soft sensing system for excavator as claimed in claim 1 wherein: The speed displacement calculation module is composed of a timer signal, a pulse counter count, an upper edge detection, a timer overflow interval, a speed operation, a register, a pulse displacement conversion, a speed, and a displacement module; the timer signal delivers data to the upper edge monitoring, which is responsible for periodic output of a high-level pulse signal; the pulse counter count delivers data to the speed operation and the pulse-displacement conversion, which is responsible for providing count data in the pulse counter; the timer signal delivers data to the upper edge detection, which delivers data to the speed operation, and is responsible for capturing the rising edge signal and activating the module; the timer overflow interval delivers data to the speed operation, which provides time data of the timer interval period; the upper edge detection, the timer overflow interval, the pulse counter count, and the register deliver data to the speed operation, which delivers data to the speed, and calculates the current hydraulic cylinder moving speed through a conversion formula according to the timer overflow interval and the pulse counter count value of the current and the last time stored in the register; the pulse and the counter count deliver data to the register, which delivers data to the speed operation, and is responsible for storing the pulse counter count value of the last round, and the count value of the pulse counter of the current round will overwrite the original data in the register after the speed operation is completed; the pulse counter count delivers data to the pulse-displacement conversion, which delivers data to the displacement, and is responsible for converting the pulse counter count into the actual hydraulic cylinder displacement; the speed operation delivers data to the speed, which is responsible for outputting the speed data from the module; the pulse-displacement conversion delivers data to the displacement, which is responsible for outputting the displacement data from the module.

6. The microcontroller unit based contact force soft sensing system for excavator as claimed in claim 1 wherein: The viscosity friction coefficient calculation is composed of a temperature signal, a viscosity friction coefficient and temperature relationship formula, and a temperature coefficient; the temperature signal delivers data to the viscosity friction coefficient and temperature relationship formula, which is processed by the low-pass filter module and sent to the module, and is used for data calculation of the module; the temperature signal delivers data to the viscosity friction coefficient and temperature relationship formula, which delivers data to the temperature coefficient, and is responsible for calculating the viscosity friction coefficient of the current hydraulic oil according to the temperature; the viscosity friction coefficient and temperature relationship formula delivers data to the temperature coefficient, which is responsible for outputting the viscosity friction coefficient calculation result based on the temperature.

7. The microcontroller unit based contact force soft sensing system for excavator as claimed in claim 1 wherein: The PC host computer is composed of a network module, a data processing module, a motion parameter processing module, a database, a shovel model, a contact force calculation module and a graphical interface; the MCU and the network module realize bidirectional data exchange, the network module transmits data to the data processing module, the network module receives MCU data and sends host computer instructions to the MCU, and sends the received MCU data to the data processing module for further processing; the network module transmits data to the data processing module, the data processing module transmits data to the motion parameter processing module, the motion parameter processing module transmits data to the database and the shovel model, which is used to re-group the decompressed motion parameters according to the mechanical structure, store them in the database for subsequent graphical interface extraction, and send the motion parameters to the shovel model for subsequent calculation; the motion parameter processing module transmits data to the shovel model, the shovel model transmits data to the contact force calculation module and the graphical interface, which is used to provide the position information of the mechanical structure of the shovel required in the contact force measurement and graphical drawing process; the data processing module, the shovel model transmit data to the contact force calculation module, the contact force calculation module transmits data to the database and the graphical interface, the contact force calculation module calculates the contact force data of each hydraulic cylinder according to the data provided by the data processing module and the shovel model module, and sends them to the database for storage, and sends them to the graphical interface for presentation; the data processing module, the contact force calculation module, the shovel model and the database transmit data to the graphical interface, the graphical interface transmits data to the network module, the graphical interface receives real-time data of the data processing module, the contact force calculation module and the shovel model to draw a 2D shovel model, displays real-time measurement data, and draws a line chart according to user instructions to obtain historical data of a certain parameter from the database, the graphical interface outputs control instructions to the network module according to user instructions to realize control of the MCU. ​

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