Dexterous hand distal finger force transducer for robot and calibration method

Abstract

The invention discloses a dexterous hand distal finger force transducer for a robot and a calibration method. The dexterous hand distal finger force transducer comprises a phalanx, a base plate, an elastic body, a cover plate and a protective layer which are sequentially arranged from bottom to top, the base plate is connected with the top of the phalanx, the top of the base plate is provided with a supporting boss, the geometric center of the elastic body is connected with the supporting boss, the elastic body extends from the geometric center to form a plurality of blades, the blades are provided with sensors, the bottoms of the blades and the base plate are arranged at intervals, and the geometric center of the elastic body coincides with the geometric center of the upper cover plate. A contact is arranged at the tail end of the blade at the bottom of the cover plate and makes contact with the top of the tail end of the blade, and the top of the cover plate is connected with the protective layer. The position and size information of the applied force value can be obtained, and the sensitivity detection of the detection assembly on the force is realized.

Description

Technical Field

[0001] The invention belongs to the field of strain gauges, and relates to a distal finger force sensor for a dexterous hand of a robot and a calibration method. Background Art

[0002] As a new type of end effector for robots, the distal fingers of dexterous hands for robots are an important topic in robot research. In recent years, research progress has accelerated at home and abroad. Since the 1970s, a large number of studies have been carried out on dexterous hands at home and abroad, from three fingers to five fingers, from industry to life, from simple grasping to dexterous operation. Market-related entities have continuously promoted the research on dexterous hands in order to solve increasingly complex practical operation problems.

[0003] The dexterous hand is a new type of end effector for robots. Generally speaking, the ways in which robots interact with the environment mainly include: moving and walking, obtaining visual and other information, and executing and outputting decisions. The end effector is a general term for the robot's execution parts. It is generally installed at the end of the robot's wrist and is a device that directly executes tasks. As the final link and execution part of the interaction between the robot and the environment, the end effector plays an extremely important role in improving the flexibility and ease of use of the robot. The quality of its performance largely determines the working performance of the entire robot.

[0004] Dexterous hands imitate the structure and function of human hands and play a key role in the interaction between robots and the environment. As the environments that robot hands need to adapt to increase and the tasks they need to perform become more and more complex, simple end effectors can no longer meet the needs. Robot hands need to be small and light, but the existing structural components on the market cannot accurately reflect the position and force value information of the contact surface. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and to provide a distal finger force sensor for a robot and a calibration method, which can obtain the position information of the applied force value and realize the sensitivity detection of the detection component to the force.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A force sensor for distal finger of a dexterous hand for a robot, comprising a finger bone, a pad, an elastic body, a cover plate and a protective layer arranged in sequence from bottom to top; The pad is connected to the top of the finger bone, a supporting boss is arranged on the top of the pad, the geometric center of the elastomer is connected to the supporting boss, a plurality of blades are extended from the geometric center of the elastomer, sensors are arranged at the ends of the blades, the bottom of the blades are spaced apart from the top of the pad, the geometric center of the elastomer coincides with the geometric center of the upper cover plate, a contact is arranged at the end of the blade at the bottom of the cover plate, the contact is in contact with the top of the end of the blade, and the top of the cover plate is connected to the protective layer.

[0007] Preferably, a protruding ball head is provided on the top of the cover plate, and the protruding ball head is cooperatively connected with the protective layer.

[0008] Preferably, the material of the protective layer is rubber.

[0009] Preferably, the phalanx is connected to the middle finger segment of the robot.

[0010] Preferably, the blades of the elastic body are in a Y-shape, a sensor is made on each blade, and the three sensors are arranged evenly divided at 120°.

[0011] Preferably, the blades of the elastic body are in a cross shape, a sensor is made on each blade, and the four sensors are arranged at 90° evenly divided.

[0012] Preferably, the blade of the elastic body is in an X-shape, a sensor is made on each blade, two adjacent sensors are arranged at an angle of 45° to 60°, and another two adjacent sensors are arranged at an angle of 135° to 120°.

[0013] Preferably, the blade of the elastic body is in an H shape, and a sensor is made on each blade. Two adjacent sensors are arranged in parallel, and two opposite sensors are arranged at 180 degrees.

[0014] Preferably, a limiting boss is arranged on the top of the pad below each blade, and a gap is arranged between the limiting boss and the bottom of the blade.

[0015] A calibration method for a distal finger force sensor for a robot dexterous hand includes the following steps: Divide the loading area into multiple determination areas; Perform zero point and full scale calibration on each sensor in turn; The divided judgment area is loaded at the boundary position, and the coefficients of each sensor when loaded to the boundary are obtained. The range between the upper and lower limits of the coefficients is the corresponding judgment area.

[0016] Compared with the prior art, the present invention has the following beneficial effects: When the protective layer of the present invention is subjected to force, through the cover plate and the elastomer, each blade sensor has a good perception ability to the force value change. The elastomer is provided with a sensor on each blade, and its different deformation differences make each sensor have different output signals. The closer the force loading position is to the blade center position of the sensor, the smaller the output difference is. Through the difference in the output signals of each blade sensor, it is possible to obtain the position information of the applied force value by judging it, thereby realizing the sensitivity detection of the detection component to the force, so that the component can be widely used in the fields of humanoid robots, dexterous mechanical fingers, fingertip sensors, etc., to improve the detection and judgment of the perception signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a distal finger force sensor for a robot dexterous hand of the present invention; Figure 2 It is a schematic diagram of assembling the phalanges and the backing plate of the present invention; Figure 3 It is a schematic diagram of the assembly of the elastic body and the backing plate of the present invention; Figure 4 It is a schematic diagram of the cooperation between the elastic body and the cover plate of the present invention; Figure 5 This is a schematic diagram of the cooperation between the cover plate and the rubber cap of the present invention; Figure 6 It is a block diagram of the peripheral circuit principle of the present invention; Figure 7 It is a schematic diagram of 4 determination areas of the present invention; Figure 8 Schematic diagram of 6 determination areas of the present invention; Fig. 9 Schematic diagram of 8 determination areas of the present invention; Fig.10 It is a schematic diagram of 9 determination areas of the present invention.

[0018] Among them: 1-finger bone; 2-pad; 3-elastic body; 4-cover plate; 5-rubber finger sleeve; 6-peripheral circuit; 7-mounting bolt; 8-support boss. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" used in this article includes any and all combinations of one or more related listed items. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0022] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplicity and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0023] like Figure 1As shown in the figure, the robot dexterous hand distal finger force sensor of the present invention is applicable to the fields of humanoid robots, dexterous mechanical fingers, fingertip sensors, etc. Its structural components include finger bones 1, pads 2, elastic bodies 3, cover plates 4 and rubber finger sleeves 5 from bottom to top.

[0024] like Figure 2 As shown, the phalange 1 is connected to the middle finger section of the robot and serves as a support. The pad 2 is connected to the top of the phalange 1 by means of mounting bolts 7. The position positioning during the connection process can be arbitrarily selected according to the size and position of the sensor and the phalange 1.

[0025] like Figure 3 As shown, a triangular support boss 8 is provided on the top of the pad 2, and the support boss 8 is fitted with the triangular inner cavity of the geometric center of the elastic body 3 and laser welded; the specific connection mode can also use mechanical assembly interference or secondary screw installation, so as to achieve reliable assembly and installation. The pad 2 has an anti-overload limit function. A limit boss is designed on the top of the pad 2 under each blade. The gap between the limit boss and the bottom of the blade is set to ensure normal use of long-term overload 200%FS and instantaneous overload 500%FS.

[0026] The elastic body 3 extends a plurality of blades from the geometric center, sensors are arranged at the ends of the blades, and the bottom of the blades is spaced apart from the top of the pad 2 .

[0027] like Figure 4 As shown, the geometric center of the elastic body 3 coincides with the geometric center of the upper cover plate 4, and a contact is provided at the bottom of the cover plate 4 at the position of the blade end, and the contact is in contact with the top of the blade end.

[0028] like Figure 5 As shown, the cover plate 4 forms a tight fit connection with the rubber finger sleeve 5 through the protruding ∅2mm protruding ball head; the specific connection mode can be bonding, vulcanization, interference fit, etc., which can achieve reliable assembly and installation. The rubber finger sleeve 5 serves as a protective layer for the entire sensor.

[0029] The rear end of the phalanx 1 is provided with a peripheral circuit 6. When the rubber finger sleeve 5 is subjected to force, the cover plate 4 and the elastic body 3 are compressed, so that the multiple groups of pressure sensors have different output signals, and the signals are transmitted to the rear peripheral circuit 6. The peripheral circuit 6 determines and feeds back the size and position of the loading force value based on the different change values ​​output by each sensor.

[0030] like Figure 6As shown, the peripheral circuit 6 realizes multi-channel tiny signal data acquisition, uses an amplifier circuit to amplify the sensor output voltage signal, and the amplified signal is connected to the integrated ADC conversion chip for acquisition. The collected signal is transmitted and summarized to the MCU through the SPI interface. The MCU then filters, converts the voltage, and decouples the data of each channel in turn, and then outputs the pressure value and position information.

[0031] In the present application, the blades of the elastic body 3 are in four forms, which are respectively the following structures.

[0032] The first type is that the blade shape of the elastic body 3 is "Y" shaped, and a sensor is made on each blade, and the three sensors are arranged at 120°. The closer the force loading position is to the center position of the sensor blade, the smaller the output difference is. When the loading force value is far away from the center position, the output difference of the three sensors is used as the judgment standard. The peripheral circuit 6 judges and feedbacks the size and position of the loading force value based on the different change values ​​of the outputs of the three sensors.

[0033] When the blade shape of the elastic body 3 is "Y" shaped, a limiting boss is designed under each blade, and the three limiting bosses are arranged evenly divided at 120°. At the same time, the design height of the limiting boss is considered to ensure normal deformation and reasonable output of each sensor.

[0034] The second type is that the blade shape of the elastic body 3 is a "+" shape, and a sensor is made on each blade, and the four sensors are arranged at 90°. The closer the force loading position is to the center position of the sensor blade, the smaller the output difference is. When the loading force value is far away from the center position, the output difference of the four sensors is used as the judgment standard. The peripheral circuit 6 judges and feedbacks the size and position of the loading force value based on the different change values ​​of the outputs of the four sensors.

[0035] The blade shape of the elastomer 3 is "+" shaped, and a limit boss is designed under each blade. The four limit bosses are evenly divided at 90°. At the same time, the design height of the limit boss is considered to ensure normal deformation and reasonable output of each sensor.

[0036] The third type is that the blade shape of the elastic body 3 is "X" shaped, and a sensor is made on each blade. The layout of two adjacent sensors is evenly divided according to 45° to 60°, and the layout of two adjacent sensors is evenly divided according to 135° to 120°. The closer the force loading position is to the center position of the sensor blade, the smaller the output difference is. When the loading force value is far away from the center position, the output difference of the four sensors is used as the judgment standard. The peripheral circuit 6 judges and feedbacks the size and position of the loading force value based on the different change values ​​of the output of the four sensors.

[0037] The blade shape of the elastomer 3 is "X" shaped, and a limiting boss is designed under each blade. The layout of two adjacent limiting bosses is evenly divided according to 45° to 60°, and the layout of two adjacent limiting bosses is evenly divided according to 135° to 120°. At the same time, the design height of the limiting boss is considered to ensure the normal deformation and reasonable output of each sensor.

[0038] In the fourth type, the blade shape of the elastic body 3 is "H" shaped, and a sensor is made on each blade. Two adjacent sensors are arranged in parallel, and the two relative sensors are arranged at 180 degrees. The closer the force loading position is to the center position of the blade of the sensor, the smaller the output difference is. When the loading force value is far away from the center position, the output difference of the four sensors is used as the judgment standard. The peripheral circuit 6 judges and feedbacks the size and position of the loading force value based on the different change values ​​of the outputs of the four sensors.

[0039] The blade shape of the elastomer 3 is "H" shaped, and a limiting boss is designed under each blade. The two adjacent limiting bosses are arranged in parallel, and the two relative limiting bosses are arranged at 180°. At the same time, the design height of the limiting boss is considered to ensure the normal deformation and reasonable output of each sensor.

[0040] The supporting boss 8 used for assembly in the backing plate 2 can be designed to be triangular, square, polygonal, etc., and the central inner cavity hole of the blade of the corresponding set elastomer 3 can be triangular, square, polygonal, etc.

[0041] In this embodiment, taking the “Y” shape of the blade of the elastic body 3 as an example, the position of the loading force value is determined by the output difference of the three sensors.

[0042] Calibration 4 area: like Figure 7 As shown, the loading area is divided into four quadrants. When the center point is loaded, the loading force value is close to being evenly divided. The position control accuracy of each area is about 1% to 3%. The peripheral circuit 6 determines and feeds back the size and position change of the loading force value based on the different change values ​​output by the three sensors. The algorithm determines the position of the loading point according to Table 1. The actual position of the loading point in the four areas, namely the first, second, third and fourth quadrants, can be effectively reflected through software algorithm processing, thereby obtaining the size and position information of the force value.

[0043] The specific process is: 1. When the upper computer software of the distal finger force sensor of the dexterous hand is not loaded, the zero point value 0 is written, and when 1kg is loaded, the calibration value 10000 is written, and automatic calibration is performed, and the zero point and full range calibration are performed on each sensor in turn.

[0044] 2 After calibration, check whether the calibration values ​​of each channel are written successfully.

[0045] 3. Load the boundary position of the divided four-quadrant area, obtain the output coefficient of each sensor when the four-quadrant is loaded to the boundary through software, and write it into the upper computer for execution.

[0046] 4 After measuring each boundary condition three times, take the average value of the coefficient, summarize the product into a coefficient list as shown in Table 1, and write it into the host computer software.

[0047] Table 1 Criteria for determining the location of the 4 regions

[0048] The standard output sum is the average of the output values ​​of multiple sensors obtained during the calibration process.

[0049] For example, the actual outputs of the three sensors for measuring the force of the distal finger of the dexterous hand are 999, 1000, and 1001 respectively, and the total is 3000. The standard output sum is 3000 / 3=1000. During calibration, the load is placed in the exact center of the sensor, and the zero value 0 is written in the software. The three full scales are calibrated to 1000 respectively. Therefore, their standard output sum is 1000.

[0050] The range between the upper and lower limits of the coefficient corresponds to the area in the quadrant. When determining the area and force value, the peripheral circuit 6 determines and feedbacks the size and position change of the loading force value based on the different change values ​​output by the three sensors. As shown in Table 2, the actual position of the loading point in the four areas, namely the first, second, third and fourth quadrants, is specifically reflected, and the size and position information of the force value is obtained.

[0051] Table 24 Determination of regional position and force value results

[0052] Calibration 6 area: like Figure 8 As shown, the loading area is divided into 6 judgment areas, and 6 positions are represented by A~F respectively. When the center point is loaded, the loading force value is close to being evenly divided, and the position control accuracy of each area is about 2.5%~4.5%. The judgment criteria of the 6 area positions are shown in Table 3.

[0053] Table 36 Criteria for determining regional location

[0054] The peripheral circuit 6 determines and feeds back the size and position change of the loading force value according to the different change values ​​of the three sensor outputs, and performs algorithmic determination on the loading point position according to Table 3. Through software algorithm processing, the actual position of the loading point in the six areas, namely the marked areas A to F, can be effectively reflected, and then the size and position information of the force value can be obtained. The verification results are shown in Table 4.

[0055] Table 46 Regional loading position results verification

[0056] Calibration 8 area: like Fig. 9 As shown, the loading area is divided into 8 judgment areas, and A~H represent the 8 positions respectively. When the center point is loaded, the loading force value tends to be evenly divided, and the position control accuracy of each area is about 4.5%~5%. The judgment criteria of the 6 area positions are shown in Table 5.

[0057] Table 58 Criteria for determining regional location

[0058] The peripheral circuit 6 determines and feeds back the size and position change of the loading force value according to the different change values ​​of the three sensor outputs, and performs algorithm determination on the loading point position according to Table 5. Through software algorithm processing, the actual position of the loading point in the 8 areas, namely the marked areas A to H, can be effectively reflected, and then the size and position information of the force value can be obtained. The verification results are shown in Table 6.

[0059] Table 68 Regional loading position results verification

[0060] Calibration 9 area: like Fig.10 As shown in Table 7, the loading area is divided into 9 judgment areas, and A~I represent the 9 positions respectively. When the center point is loaded, the loading force value is close to being evenly divided, and the position control accuracy of each area is about 5%~6%. The judgment criteria for the positions of the 6 areas are shown in Table 7.

[0061] Table 78 Criteria for determining regional location

[0062] The peripheral circuit 6 determines and feeds back the size and position change of the loading force value according to the different change values ​​of the three sensor outputs, and performs algorithmic determination on the loading point position according to Table 7. Through software algorithm processing, the actual position of the loading point in the eight areas, namely the marked areas A to I, can be effectively reflected, and then the size and position information of the force value can be obtained. The verification results are shown in Table 8.

[0063] Table 89 Regional loading position results verification

[0064] When the rubber finger sleeve 5 of the top protective layer is stressed in different areas, the blades of the pressurized elastomer 3 are deformed respectively through the different stress points of the cover plate 4, and the three sensors have different output signals. This signal is transmitted to the peripheral circuit 6 at the rear end, and the peripheral circuit 6 classifies and decouples the sensor signal and converts the voltage signal into a digital signal. The algorithm determines the position of the loading point and finally realizes the actual position information of the loading point in areas 4, 6, 8, and 9 through software algorithm processing, thereby obtaining the force value information. Of course, when the area division is subdivided, more judgment criteria will be required, and the accuracy of the judgment result will gradually decrease.

[0065] For the blade shapes of the elastic body 3 being "+", "X" and "H", the loading area can be divided into 4, 6, 8 and 9 areas according to the above method, and calibrated and determined.

[0066] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0067] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this patent should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A robot dexterous hand distal finger force sensor, characterized in that: It comprises finger bones (1), a backing plate (2), an elastic body (3), a cover plate (4) and a protective layer which are arranged in sequence from bottom to top; The pad (2) is connected to the top of the phalanx (1), a supporting boss (8) is provided on the top of the pad (2), the geometric center of the elastic body (3) is connected to the supporting boss (8), a plurality of blades are extended from the geometric center of the elastic body (3), sensors are provided at the ends of the blades, the bottom of the blades are spaced from the top of the pad (2), the geometric center of the elastic body (3) coincides with the geometric center of the upper cover plate (4), a contact is provided at the bottom of the cover plate (4) at the end of the blade, the contact is in contact with the top of the blade end, and the top of the cover plate (4) is connected to the protective layer.

2. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: A protruding ball head is provided on the top of the cover plate (4), and the protruding ball head is cooperatively connected with the protective layer.

3. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: The material of the protective layer is rubber.

4. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: The phalanx (1) is connected to the middle finger segment of the robot.

5. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: The blades of the elastic body (3) are in a Y-shape, a sensor is made on each blade, and the three sensors are arranged at an angle of 120 degrees.

6. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: The blades of the elastic body (3) are in the shape of a cross, a sensor is made on each blade, and the four sensors are arranged at 90° evenly spaced.

7. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: The blade shape of the elastic body (3) is X-shaped, and a sensor is made on each blade. The layout of two adjacent sensors is evenly divided according to 45° to 60°, and the layout of two adjacent sensors is evenly divided according to 135° to 120°.

8. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: The blade shape of the elastic body (3) is H-shaped, and a sensor is made on each blade. Two adjacent sensors are arranged in parallel, and two relative sensors are arranged at 180 degrees.

9. The robot dexterous hand distal finger force sensor according to claim 1, characterized in that: A limiting boss is arranged on the top of the pad (2) below each blade, and a gap is arranged between the limiting boss and the bottom of the blade.

10. A calibration method for a distal finger force sensor for a robot based on any one of claims 1 to 9, characterized in that: The process includes: Divide the loading area into multiple determination areas; Carry out zero point and full scale calibration for each sensor in turn; The divided judgment area is loaded at the boundary position, and the coefficients of each sensor when loaded to the boundary are obtained. The range between the upper and lower limits of the coefficients is the corresponding judgment area.

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