WO2021248681A1

WO2021248681A1 - Six-dimensional force sensor integrating data acquisition system and inertia force compensation system

Info

Publication number: WO2021248681A1
Application number: PCT/CN2020/108753
Authority: WO
Inventors: 李晨; 黄肖飞; 相立峰; 戴振东
Original assignee: 南京神源生智能科技有限公司; 南京溧航仿生产业研究院有限公司
Priority date: 2020-06-12
Filing date: 2020-08-13
Publication date: 2021-12-16
Also published as: CN111531566A

Abstract

Disclosed is a six-dimensional force sensor integrating a data acquisition system and an inertia force compensation system, comprising an upper cover plate, an elastic body, and a lower cover plate. The upper cover plate and the lower cover plate are respectively arranged on upper and lower ends of the elastic body. The elastic body is provided with a bridging PCB, an analog quantity PCB, and a communication PCB. The bridging PCB is in welded connection to the analog quantity PCB by means of an enameled wire. The analog quantity PCB is inserted and connected to the communication PCB by means of a pin header. The bridging PCB is bonded on the elastic body. A differential signal of a Wheatstone bridge in the elastic body is connected to the analog quantity PCB. An attitude angle sensor is integrated on the analog quantity PCB. An output of the analog quantity PCB is externally connected by a communication port of the communication PCB. The advantages are: the six-dimensional force sensor integrates the data acquisition system and the inertia force compensation system, reduces the influence of the inertia force on the measurement error of the measurement of the six-dimensional force sensor, improves the measurement accuracy, reduces the measurement error, and improves the repeatability of the sensor.

Description

A six-dimensional force sensor integrating data acquisition system and inertial force compensation system

Technical field

The invention relates to the field of robot application, especially a six-dimensional force sensor used in the field of automation and industrial robots, and specifically a six-dimensional force sensor integrating a data acquisition system and an inertial force compensation system.

Background technique

Multi-dimensional force sensor and torque sensor refer to a force sensor that can measure force and torque components in more than two directions at the same time. In the Cartesian coordinate system, force and torque can each be decomposed into three components, and six-dimensional force sensors can measure space. Three-dimensional orthogonal forces (Fx, Fy, Fz) and three-dimensional orthogonal moments (Tx, Ty, Tz) in any force system. Six-dimensional force sensors are widely used in robotics, industrial automation, military industry and other fields. In various fields of application, six-dimensional force sensors play a pivotal role, which is equivalent to the human brain.

Under static conditions, the force and torque measured by the six-dimensional force sensor on the robot wrist generally consist of four parts, namely: ①, the influence of the weight of the sensor body; ②, the influence of the load's own weight; ③, the influence of the load inertial force; ④The load is affected by the external contact force. Because the six-dimensional force sensor is usually installed at the end of the robotic arm in the application field of industrial robots, and then connected to the end actuator through a series of adapters, the posture of the load changes during the movement of the robot, and the gravity The direction of the load is always vertical downwards. Therefore, the load’s own weight or inertial force will affect the test data of the six-dimensional force sensor, resulting in inaccurate data measured by the six-dimensional force sensor, large measurement errors, and poor data repeatability. And so on related issues.

technical problem

The purpose of the present invention is to provide a six-dimensional force sensor integrating a data acquisition system and an inertial force compensation system, which can reduce the influence of gravity or inertial force on the measurement error of the six-dimensional force sensor and improve the measurement accuracy of the six-dimensional force sensor. , Reduce the measurement error and improve the repeatability of the sensor.

Technical solutions

The technical scheme adopted by the present invention is: a six-dimensional force sensor integrating a data acquisition system and an inertial force compensation system, comprising an upper cover plate, an elastic body and a lower cover plate, the upper cover plate and the lower cover plate are respectively arranged on the elastic body At the upper and lower ends, the elastic body is the sensitive element of the sensor. The bridge PCB, the analog PCB and the communication PCB are set on the elastic body. The bridge PCB and the analog PCB are connected by enameled wire welding, and the analog PCB and the communication PCB are connected through the header pins. Connect, the group bridge PCB is glued to the elastic body.

Metal strain gauges are pasted on the strain beam in the elastic body and wiring terminals are pasted on the bridge PCB to form a Wheatstone bridge. The differential signal of the Wheatstone bridge is connected to the analog PCB through the connecting line. The analog PCB integrates an attitude angle sensor, analog The output of the quantity PCB is connected to the outside by the communication port of the communication PCB.

The six-dimensional force sensor of the technical scheme of the present invention is a measurement method in which the mechanical quantity is converted into an electrical signal through the sensitive element strain gauge, the strain gauge is pasted on the elastic body, and the bridge is formed by the connecting terminal.

The six-dimensional force sensor of the technical scheme of the present invention integrates a posture angle sensor on an analog PCB to realize inertial force compensation, which can improve the accuracy and precision of measurement when the six-dimensional force sensor is used on a robot, and reduce measurement errors.

As a further preference to the technical solution of the present invention, the processing circuit of the six-dimensional force sensor includes an amplifying circuit, an analog/digital conversion circuit, a microcontroller circuit and a communication circuit. The differential signal of the Wheatstone bridge is connected and amplified by the amplifying circuit. The signal from the analog/digital conversion circuit converts the analog signal into a digital signal, enters the microcontroller circuit for data collection, and the collected data is transmitted through the communication circuit.

The amplifying circuit is integrated on the analog PCB. The amplifying circuit includes instrumentation amplifier AD8222ACPZ, amplifying multiple matching resistor R3 and differential low-pass filter to form a fixed gain multiple to amplify weak differential signals.

The analog/digital conversion circuit, micro-controller circuit and communication circuit are all integrated on the communication PCB. The analog/digital conversion circuit adopts the 16-bit, 8-channel high-precision conversion circuit AD7606, which can convert 8-channel signals at the same time, and the sampling rate is up to 200KSPS , Fast response and high real-time performance; the microcontroller uses STM32F103RET6 to transmit data with AD7606 through SPI, and connects to the communication circuit through the URAT\RMII interface.

As a further preference to the technical solution of the present invention, the communication circuit is an RS485 communication circuit, a CAN communication circuit, a UDP communication circuit or an Ether Cat communication circuit.

The RS485 communication circuit is composed of a transceiver converter MAX485, a digital isolator ADuM1301 and a communication port. The communication port is used for external connection.

The CAN communication circuit is composed of a transceiver converter TJA1042T, a digital isolator ADuM1301, and a communication port. The communication port is used for external connection.

The UDP communication circuit is composed of a transceiver converter DP83848C, a network isolation transformer HR601680, and a network interface. The network interface is used for external connection.

The Ether Cat communication circuit is composed of a transceiver converter LAN9252, a network isolation transformer HR601680, and a network interface. The network interface is used for external connection.

In the technical scheme of the present invention, the communication PCB covers the current common communication methods, mainly including: UDP, Ether Cat, CAN and 485, which can meet the current needs of various industries.

For the preferred technical solution of the present invention, the elastic body is composed of 12 strain beams. Elastomers are known products in the technical field.

Preferably, the technical solution of the present invention is provided with a crimping block for fixing the cable on the elastic body.

In the preferred technical solution of the present invention, the attitude angle sensor is a WT931 attitude angle sensor. The WT931 attitude angle sensor is a purchased part, directly purchased and soldered on the analog PCB.

Beneficial effect

Compared with the prior art, the present invention has the following beneficial effects.

The six-dimensional force sensor of the present invention integrates a data acquisition system and an inertial force compensation system, can reduce the influence of gravity or inertial force on the measurement error caused by the six-dimensional force sensor measurement, can improve the measurement accuracy of the six-dimensional force sensor, and reduce the measurement Error, improve the repeatability of the sensor, and so on.

Description of the drawings

Fig. 1 is an exploded view of the overall structure of the six-dimensional force sensor of this embodiment.

Fig. 2 is a schematic diagram of the elastic body and the strain gauge cloth in the six-dimensional force sensor of this embodiment.

Fig. 3 is a schematic diagram of the bridge assembly of the six-dimensional force sensor of this embodiment.

FIG. 4 is a schematic diagram of the bonding position of the bridge PCB and the strain gauge of the six-dimensional force sensor of this embodiment.

Fig. 5 is a schematic diagram of the assembly bridge PCB of the six-dimensional force sensor of this embodiment installed in the annular groove under the elastic body force platform.

FIG. 6 is a schematic diagram of the group bridge PCB, the analog PCB and the communication PCB 5 of the six-dimensional force sensor of this embodiment are all integrated into the elastic body.

Fig. 7 is a schematic diagram of the WT931 attitude angle sensor used in the six-dimensional force sensor of this embodiment.

Figure 8 is a schematic diagram of the WT931 attitude angle sensor integrated on the analog PCB.

Fig. 9 is a schematic circuit diagram of the amplifying circuit on the analog PCB in the six-dimensional force sensor of this embodiment.

FIG. 10 is a schematic circuit diagram of the analog/digital conversion circuit on the communication PCB in the six-dimensional force sensor of this embodiment.

FIG. 11 is a schematic circuit diagram of the microcontroller on the communication PCB in the six-dimensional force sensor of this embodiment.

Figure 12 is a schematic circuit diagram of the RS485 communication circuit on the communication PCB.

Figure 13 is a schematic circuit diagram of the CAN communication circuit on the communication PCB.

Figure 14 is a circuit diagram of the UDP communication circuit on the communication PCB.

Figure 15 is a circuit diagram of the Ether Cat communication circuit on the communication PCB.

Embodiments of the present invention

The technical solution of the present invention will be described in detail below, but the protection scope of the present invention is not limited to the embodiments.

In order to make the content of the present invention more obvious and understandable, further description will be made below in conjunction with Figures 1 to 15 and specific implementations.

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

As shown in Figure 1, a six-dimensional force sensor integrating a data acquisition system and an inertial force compensation system includes an upper cover 1, an elastic body 2 and a lower cover 4. The upper cover 1 and the lower cover 4 are respectively arranged on The upper and lower ends of the elastic body 2, the upper cover plate 1 and the elastic body 2 are connected by 4 M4 screws, the elastic body 2 and the lower cover plate 4 are first positioned by 2 cylindrical pins, and then connected by 8 M5 bolts.

As shown in Figure 2, the elastic body 2 is the sensitive element of the sensor, and the elastic body 2 is a known technology in the technical field; in this embodiment, the elastic body 2 is composed of 12 strain beams. After finite element calculation, the elastic body 2 is Paste metal strain gauges on appropriate positions to form a Wheatstone bridge to measure force or moment in all directions.

As shown in Figures 2 and 3, the elastomer 2 selected in this embodiment is a known elastomer 2 in the technical field. A total of 24 strain gauges are attached to the 12 strain beams of elastomer 2, and the 24 strain gauges are marked as R1-R24, respectively.

As shown in Figure 1, the elastic body 2 is equipped with a bridge PCB7, an analog PCB6 and a communication PCB5. The bridge PCB7 and the analog PCB6 are connected by enameled wire welding, the analog PCB6 and the communication PCB5 are connected by pin headers, and the bridge PCB7 is connected Bonded to the elastic body 2.

As shown in Figures 1, 2 and 3, a metal strain gauge is pasted on the strain beam in the elastic body 2 and a connection terminal is pasted on the bridge PCB to form a Wheatstone bridge. The differential signal of the Wheatstone bridge is connected to the analog signal through the connecting line. PCB6, an attitude angle sensor is integrated on the analog PCB6, and the output of the analog PCB6 is connected to the outside through the communication port of the communication PCB5.

As shown in Figures 1 and 4, the terminal blocks are pasted on the bridge PCB7. The terminal blocks must be pasted to the designated position on the bridge PCB7. After the terminal blocks are pasted, the bridge is grouped according to Figure 3. After the bridge is completed, the white 704 is used after the inspection is correct. The glue is sealed in the annular groove under the force platform of the elastic body 2.

As shown in Figures 1, 5 and 6, the analog PCB6 is fixed inside the elastomer 2 by four M2 screws, and is connected to the bridge PCB7 by welding through two power lines. The analog PCB6 and the communication PCB5 are plugged in through pin headers. The communication PCB5 covers the current commonly used communication methods, mainly including: UDP, Ether Cat, CAN and RS485. The cables are soldered on the designated solder joints of the communication PCB5, and finally lead out of the sensor. The elastic body 2 is provided with a crimping block 3 for fixing the cable, and the crimping block 3 and the elastic body 2 are connected by two M2 bolts.

When the six-dimensional force sensor is used on the robot, it is usually installed on the flange at the end of the robot arm, and then connected to the end effector through a series of adapters. In this way, the load is The posture changes, and the direction of gravity is always vertical downwards. Therefore, the measurement of the six-dimensional force sensor by the load gravity will change with the continuous changes of the robot, which will inevitably affect the accuracy and precision of the six-dimensional force sensor. At the same time, acceleration will inevitably occur during the robot movement, and the inertial force generated by acceleration will also affect the accuracy and precision of the six-dimensional force sensor measurement. Therefore, the gravity compensation system and inertial force compensation are integrated in the six-dimensional force sensor. The system can improve the accuracy and precision of the measurement of the six-dimensional force sensor when used on the robot, and reduce the measurement error. There are two schemes for integrating the gravity compensation system and the inertial force compensation system in the six-dimensional force sensor.

One is to measure the robot's relative posture during the festival, obtain the displacement, velocity, and acceleration related data in various postures through the data acquisition system, and use related algorithms for gravity compensation and inertial force compensation to achieve the above objectives.

The other is to integrate a 9-axis attitude angle sensor in the system. The 9-axis attitude angle sensor is integrated into the above-mentioned analog quantity board, and the displacement, velocity and acceleration related data in various attitudes are also obtained through the data acquisition system. Relevant algorithms perform gravity compensation and inertial force compensation to achieve the above goals.

In this embodiment, in order to overcome the influence of gravity (or inertial force) on the measurement results of the sensor, the present invention integrates a 9-axis attitude angle sensor, namely the WT931 attitude angle sensor, in the analog PCB6. As shown in Figure 6, the WT931 attitude angle sensor The angle sensor is integrated in the analog PCB6, and the displacement, velocity and acceleration related data in various postures are also obtained through the data acquisition system, and the relevant algorithms are used for gravity compensation and inertial force compensation to achieve the above objectives.

As shown in Fig. 7, the WT931 attitude angle sensor selected in this embodiment is an outsourcing part, which is directly soldered on the analog PCB6 after purchase. As shown in Figure 8.

The processing circuit of the six-dimensional force sensor in this embodiment includes an amplifier circuit, an analog/digital conversion circuit, a microcontroller circuit, and a communication circuit. The differential signal of the Wheatstone bridge is connected and amplified by the amplifier circuit. The /digital conversion circuit converts the analog signal into a digital signal, and enters the microcontroller circuit for data collection, and the collected data is transmitted through the communication circuit.

As shown in Figure 9, the amplifying circuit is integrated on the analog PCB6. The amplifying circuit includes instrumentation amplifier AD8222ACPZ, amplifying multiple matching resistor R3 and differential low-pass filter to form a fixed gain multiple to amplify weak differential signals.

As shown in Figure 10, the analog/digital conversion circuit, the microcontroller circuit and the communication circuit are all integrated on the communication PCB5. The analog/digital conversion circuit adopts the 16-bit, 8-channel high-precision conversion circuit AD7606, which can simultaneously respond to 8-channel signals. Conversion, sampling rate up to 200KSPS, fast response and high real-time performance.

As shown in Figure 11, the microcontroller uses STM32F103RET6 to transmit data with AD7606 through SPI, and is connected to the communication circuit through the URAT\RMII interface.

In this embodiment, the communication PCB covers the currently commonly used communication methods, mainly including: UDP, Ether Cat, CAN, and RS485, which can meet the current needs of various industries. The communication PCB5 is RS485 communication circuit, CAN communication circuit, UDP communication circuit or Ether Cat communication circuit.

As shown in Figure 12, the RS485 communication circuit is composed of a transceiver converter MAX485, a digital isolator ADuM1301 and a communication port. The communication port is used for external connection.

As shown in Figure 13, the CAN communication circuit is composed of a transceiver converter TJA1042T, a digital isolator ADuM1301, and a communication port. The communication port is used for external connections.

As shown in Figure 14, the UDP communication circuit consists of a transceiver converter DP83848C, a network isolation transformer HR601680, and a network interface. The network interface is used for external connections.

As shown in Figure 15, the Ether Cat communication circuit consists of a transceiver converter LAN9252, a network isolation transformer HR601680, and a network interface. The network interface is used for external connections.

In the six-dimensional force sensor in this embodiment, a measurement method in which the mechanical quantity is converted into an electrical signal through the sensitive element strain gauge, the strain gauge is pasted on the elastic body, and the bridge is formed through the connection terminal. There are three PCB boards inside the sensor body, one is the bridge board, the second is the analog board, and the third is the communication board. The bridge board and the analog board are connected by enameled wire welding, and the analog board and the communication board are connected by pin headers. Plug connection. The wiring terminal is pasted on the designated position on the bridge board to form a Wheatstone bridge. The differential signal of the Wheatstone circuit in elastomer 2 is connected to the analog PCB through the connecting wire, and is amplified by the instrument amplifying circuit on the analog PCB. The amplified signal is then converted by the analog-to-digital conversion circuit to convert the analog signal into a digital signal. Data acquisition is carried out through the MCU circuit. The collected data is transmitted through the communication circuit UDP/Ether Cat/CAN/RS485. The communication board covers the current common communication methods, mainly including: UDP, Ether Cat, CAN and 485 can meet the current needs of all walks of life.

The parts not involved in the present invention are all the same as the prior art or can be realized by using the prior art.

As mentioned above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details can be made without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

A six-dimensional force sensor integrating a data acquisition system and an inertial force compensation system, which is characterized by comprising an upper cover (1), an elastic body (2) and a lower cover (4), an upper cover (1) and a lower cover The cover plate (4) is respectively arranged on the upper and lower ends of the elastic body (2). The elastic body (2) is the sensitive element of the sensor. The elastic body (2) is provided with a bridge PCB (7), an analog PCB (6) and The communication PCB (5), the bridge PCB (7) and the analog PCB (6) are connected by enameled wire welding, the analog PCB (6) and the communication PCB (5) are connected by pin headers, and the bridge PCB (7) is glued. Connected to the elastomer (2),

The elastic body (2) paste the metal strain gauge on the inner strain beam and paste the connecting terminal on the bridge PCB to form a Wheatstone bridge. The differential signal of the Wheatstone bridge is connected to the analog PCB (6) through the connecting line, and the analog PCB (6) The posture angle sensor is integrated, and the output of the analog PCB (6) is connected to the outside by the communication port of the communication PCB (5).
The six-dimensional force sensor integrated with a data acquisition system and an inertial force compensation system according to claim 1, wherein the processing circuit of the six-dimensional force sensor includes an amplifier circuit, an analog/digital conversion circuit, a microcontroller circuit, and a communication circuit, The differential signal access of the Wheatstone bridge is amplified by the amplifier circuit, and the amplified signal is converted by the analog/digital conversion circuit to convert the analog signal into a digital signal, and enters the microcontroller circuit for data collection, and the collected data is carried out through the communication circuit data transmission;

The amplifying circuit is integrated on the analog PCB (6). The amplifying circuit includes instrumentation amplifier AD8222ACPZ, amplification matching resistor R3 and differential low-pass filter to form a fixed gain multiple to amplify weak differential signals;

The analog/digital conversion circuit, the microcontroller circuit and the communication circuit are all integrated on the communication PCB (5). The analog/digital conversion circuit adopts the 16-bit, 8-channel high-precision conversion circuit AD7606, which can convert and sample 8-channel signals at the same time The rate is up to 200KSPS, fast response and high real-time performance; the microcontroller uses STM32F103RET6 to transmit data with AD7606 through SPI, and connects to the communication circuit through the URAT\RMII interface.
The six-dimensional force sensor integrated with a data acquisition system and an inertial force compensation system according to claim 3, wherein the communication circuit is an RS485 communication circuit, a CAN communication circuit, a UDP communication circuit or an Ether Cat communication circuit,

The RS485 communication circuit is composed of a transceiver converter MAX485, a digital isolator ADuM1301 and a communication port. The communication port is used for external connection;

CAN communication circuit is composed of transceiver converter TJA1042T, digital isolator ADuM1301, communication port, communication port is used for external connection;

The UDP communication circuit is composed of a transceiver converter DP83848C, a network isolation transformer HR601680, and a network interface. The network interface is used for external connection;

The Ether Cat communication circuit is composed of a transceiver converter LAN9252, a network isolation transformer HR601680, and a network interface. The network interface is used for external connection.
The six-dimensional force sensor integrated with a data acquisition system and an inertial force compensation system according to claim 1, wherein the elastic body (2) is composed of 12 strain beams.
The six-dimensional force sensor integrated with a data acquisition system and an inertial force compensation system according to claim 4, characterized in that the elastic body (2) is provided with a crimping block (3) for fixing the cable.
The six-dimensional force sensor integrating a data acquisition system and an inertial force compensation system according to claim 1, wherein the attitude angle sensor is a WT931 attitude angle sensor.