Intelligent end effector and fastening state sensing method

Abstract

The application discloses an intelligent end effector and a buckling state sensing method, and relates to the technical field of 3C assembly.The lower part of a pressing head is located in a base, an elastic structure is arranged between the pressing head and the base, the upper part of the pressing head is located outside the base, a sensor mainboard is located on the base, a sensor sensitive head is located on the upper part of the pressing head, the sensor sensitive head is used for measuring force information of a contact surface when the pressing head contacts a flat cable, the sensor sensitive head transmits the collected force information of the contact surface to the sensor mainboard, the sensor mainboard is used for transmitting the force information of the contact surface to a computer for processing, the inside of the pressing head is provided with a first air path, the upper end of the first air path extends to the upper part of the pressing head, the first air path is in communication with a second air path of the base, and the first air path and the second air path form a negative pressure air path.The application can adaptively complete an assembly task when an assembly scene is not fixed, and has the advantages of high dexterity and high operation precision.

Description

Technical Field

[0001] This invention relates to the field of 3C assembly technology, and in particular to an intelligent end effector and a fastening state sensing method, which is applicable to the intelligent autonomous operation of robots to replace manual labor in wiring assembly work, and meets the practical application needs of using robots to intelligently realize wiring assembly tasks in 3C assembly. Background Technology

[0002] The 3C assembly manufacturing industry is characterized by rapid product iteration, complex operational tasks, and a high degree of non-standardization of the objects being handled, resulting in significant uncertainties in its production and precision assembly environment. Most 3C parts are small, lightweight, and non-standard components with complex and easily deformable shapes, placing high demands on the dexterity and adaptability of actuators during assembly. Simultaneously, 3C assembly places high demands on the assembly operation itself, and traditional automated assembly methods lacking sensing capabilities struggle to achieve adaptive operation. While the widespread application of automated actuators in the 3C assembly field has led to the automation of some simple assembly tasks, complex and precision assembly tasks still rely on manual labor.

[0003] In recent years, with increasing demand, various end effectors have emerged both domestically and internationally for specific 3C assembly scenarios. For tasks involving the assembly of small ribbon cables, there are combined end effectors using gripping and pressing mechanisms, and automated actuators that fix the device to be assembled on a platform and use push rods to insert the ribbon cable. These actuators can complete assembly tasks in a single, unchanging, fixed environment. However, because ribbon cable assembly requires high operational precision, if the actuator lacks tactile sensing capabilities, it cannot detect the cable engagement status, thus lacking the ability to make fine adjustments during assembly. This can easily damage the ribbon cable during assembly, and the success rate of cable engagement is low. Furthermore, these actuators require a fixed assembly environment, exhibiting poor intelligent autonomy, which necessitates adjustments to the assembly system when the assembly task and environment change, resulting in low production efficiency.

[0004] Numerous research findings have emerged both domestically and internationally regarding the application of tactile sensing in industrial scenarios. A research team at MIT used the Gelsight visual-tactile sensor to obtain force information from the contact surface, analyzing it to estimate the cable's pose and friction vector, thus adaptively performing cable straightening operations. A research team at the Max Planck Institute in Germany used visual-tactile sensors to create a three-dimensional tactile image of the contact surface, establishing the shape features of the grasped object. However, due to the difficulty in integrating visual-tactile sensors into miniaturized actuators and the lack of practical and feasible tactile information analysis methods, there are currently no instances of tactile sensing being applied in actual 3C assembly production. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent end effector and a method for sensing the engagement state, which can intelligently, autonomously, adaptively, skillfully and with high precision perform assembly operations on ribbon cables, thereby solving the problems of existing automated assembly technologies in ribbon cable assembly applications and meeting the practical application needs of using robots to intelligently complete the assembly of small ribbon cables.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides an intelligent end effector, including a base, a pressing head, an elastic structure, and a tactile sensor. The tactile sensor includes a sensor motherboard and a sensor sensing head electrically connected to each other. The lower part of the pressing head is located in the base, and the elastic structure is disposed between the pressing head and the base. The upper part of the pressing head is located outside the base. The sensor motherboard is located on the base, and the sensor sensing head is located on the upper part of the pressing head. The sensor sensing head is used to measure the force information of the contact surface when the pressing head contacts the ribbon cable. The sensor sensing head transmits the collected force information of the contact surface to the sensor motherboard, which transmits the force information of the contact surface to a computer for processing. The pressing head has a first air passage inside, the upper end of which extends to the upper part of the pressing head. The first air passage is connected to a second air passage of the base, and the first air passage and the second air passage form a negative pressure air passage.

[0008] Preferably, the base includes an upper base, a lower base, and a mounting ring. The sensor motherboard is mounted on the mounting ring. The mounting ring and the upper base are detachably connected. The upper base and the lower base are detachably connected. The mounting ring is provided with a through hole for the pressing head to pass through. The symmetrical protruding structures on both sides of the lower base are used to cooperate with the flange of the general-purpose robotic arm.

[0009] Preferably, the pressing head includes a first connecting part and a second connecting part, the first connecting part has a rectangular cross-section, the second connecting part has a circular cross-section, the first connecting part is located outside the base, and the second connecting part is located inside the base.

[0010] Preferably, the upper end of the first connecting part is provided with a groove and a first vent hole, the first vent hole is connected to the first air passage, the groove is used to place the sensor sensitive head, and a second vent hole is provided on the sensor sensitive head at a position corresponding to the first vent hole.

[0011] Preferably, the sensor sensing head includes a lower flexible circuit board, a dielectric layer, and an upper flexible circuit board arranged sequentially from bottom to top;

[0012] The lower flexible circuit board includes a main flexible circuit board bottom layer, a second inner layer, a first inner layer, and a main flexible circuit board top layer arranged sequentially from bottom to top. The main flexible circuit board top layer is provided with a plurality of first electrodes. The lower surface of the main flexible circuit board bottom layer is provided with a first pad. The signal of the first electrode is transmitted to the first pad through the first inner layer. The main flexible circuit board top layer is provided with a reinforcement layer. The reinforcement layer is used for the first pad to be inserted into the sensor motherboard to realize the signal transmission between the sensor motherboard and the first pad.

[0013] The upper flexible circuit board includes a sub-flexible circuit board bottom layer and a sub-flexible circuit board top layer. The sub-flexible circuit board bottom layer is disposed below the sub-flexible circuit board top layer. A plurality of second electrodes are disposed on the lower surface of the sub-flexible circuit board bottom layer. The second electrodes and the first electrodes form a capacitor. The dielectric layer is located between the first electrodes and the second electrodes. Second pads are disposed on both the sub-flexible circuit board top layer and the main flexible circuit board top layer. The second pads on the sub-flexible circuit board top layer and the second pads on the main flexible circuit board top layer are connected to realize signal transmission between the lower flexible circuit board and the upper flexible circuit board.

[0014] Preferably, the sensor sensitive head is provided with a bristle structure, and the bristles of the bristle structure are wedge-shaped.

[0015] Preferably, the elastic structure is an annular spring sheet, which is embedded in the nested cavity of the base, and the lower end of the pressing head contacts the annular spring sheet;

[0016] A sealing ring is provided between the pressing head and the base.

[0017] This invention also discloses a method for sensing engagement state, which is applied to the aforementioned intelligent end effector. The method for sensing engagement state includes:

[0018] Acquire force information collected by a tactile sensor; the force information includes arrayed tangential force and arrayed normal force;

[0019] Based on the force information, the deviation state of the cable is determined; the deviation state is no deviation, positive deviation, reverse deviation, or failure.

[0020] If the deviation is a positive deviation or a negative deviation, the intelligent end effector is controlled to move the male connector of the cable in the alignment direction according to the deviation.

[0021] During the movement, the alignment status of the cabling is determined based on the force information; the alignment status is either the start of alignment or the end of alignment.

[0022] If the alignment state is "alignment complete", the ribbon cable stops moving and returns to the step of "determining the deviation state of the ribbon cable based on the force information".

[0023] If the deviation state is not deviation, then the intelligent end effector is controlled to perform a fastening operation.

[0024] Preferably, determining the deviation state of the cabling based on the force information specifically includes:

[0025] If the array-type tangential force is greater than the first tangential force setting threshold, then the deviation state of the cabling is determined to be a failure.

[0026] If the arrayed tangential force is less than or equal to the first tangential force threshold, then the arrayed normal force is projected onto the direction to be determined to obtain a scatter plot of the normal force distribution.

[0027] The scatter plot of the normal force distribution is fitted with a straight line using the least squares method to obtain the fitted straight line.

[0028] Determine whether the absolute value of the slope of the fitted line is less than the slope threshold;

[0029] If so, then the deviation state of the cable is determined to be no deviation;

[0030] If not, then determine whether the absolute value of the slope is positive;

[0031] If so, then the deviation state of the cable is determined to be a positive deviation;

[0032] If not, then the deviation state of the cable is determined to be a reverse deviation.

[0033] Preferably, determining the alignment state of the cabling based on the force information specifically includes:

[0034] Based on the array-type normal force of the current frame, determine the average normal force of the three frames of the current frame;

[0035] Based on the array-type normal force described in the previous frame, determine the average normal force of the three frames in the previous frame;

[0036] Determine the ratio of the average normal force of the three frames in the current frame to the average normal force of the three frames in the previous frame;

[0037] Determine whether the ratio is less than the normal force setting threshold;

[0038] If so, then the alignment state of the ribbon cable is determined to be the start of alignment;

[0039] Based on the array-type tangential force of the current frame, determine the average tangential force of the three frames of the current frame;

[0040] Based on the array-type tangential force described in the previous frame, determine the average tangential force of the three frames in the previous frame;

[0041] Based on the array-type tangential force described in the first two frames, determine the average tangential force of the three frames in the first two frames;

[0042] Determine the ratio of the average tangential force of the three frames in the current frame to the average tangential force of the three frames in the previous frame;

[0043] Determine the ratio of the average tangential force of the three frames in the previous frame to the average tangential force of the three frames in the two previous frames.

[0044] Determine whether the ratio of the average tangential force of the three frames in the current frame to the average tangential force of the three frames in the previous frame, and the ratio of the average tangential force of the three frames in the previous frame to the average tangential force of the three frames in the two previous frames, are both greater than the second tangential force setting threshold.

[0045] If so, then the alignment status of the ribbon cable is determined to be the end of alignment.

[0046] The present invention achieves the following technical effects compared to the prior art:

[0047] The intelligent end effector of this invention combines negative pressure adsorption and operates on tiny ribbon cables through a small pressing head. A tactile sensor collects tactile information and uses it to sense the engagement state, providing feedback on the robotic arm's movements. Furthermore, the pressing head has a certain degree of planar adaptability, which improves the stability and dexterity of the actuator when assembling tiny ribbon cables. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is an isometric view of the intelligent end effector of the present invention;

[0050] Figure 2 This is an exploded view of the intelligent end effector of the present invention;

[0051] Figure 3 This is a cross-sectional plan view of the intelligent end effector of the present invention (the arrows indicate the direction of the negative pressure airflow);

[0052] Figure 4 This is a cross-sectional axonometric view of the intelligent end effector of the present invention;

[0053] Figure 5 This is an exploded view of the sensor sensor head of the present invention;

[0054] Figure 6 for Figure 5 Enlarged view of section I;

[0055] Figure 7 for Figure 5 Enlarged view of section II;

[0056] Figure 8 This is a schematic diagram showing the relative posture of the male connector and the female connector of the ribbon cable when the male connector is in an misaligned state.

[0057] Figure 9 This is a flowchart of the deviation state judgment process of the present invention;

[0058] Figure 10 This is a schematic diagram showing the relative posture of the male connector and the female connector of the ribbon cable when the male connector of the ribbon cable enters the alignment state.

[0059] Figure 11 This is a schematic diagram showing the relative postures of the male connector of the ribbon cable and the female connector of the ribbon cable after they enter the alignment state and are subjected to tangential compression.

[0060] Wherein: 1-1: Upper base, 1-2: Lower base, 1-3: Mounting ring, 2: Press head, 3: Annular spring, 4: Negative pressure air path, 5: Sealing ring, 6-1: Sensor sensitive head, 6-1-1: Lower flexible board, 6-1-1-1: Main flexible board bottom layer, 6-1-1-2: Second inner layer, 6-1-1-3: First inner layer, 6-1-1-4: Main flexible board top layer, 6-1-2: First electrode, 6-1-3: First pad, 6-1-4: Reinforcement layer, 6-1-5: Dielectric layer, 6-1-6: Upper flexible board, 6-1-6-1: Sub-flexible board bottom layer, 6-1-6-2: Sub-flexible board top layer, 6-1-7: Second pad, 6-2: Sensor main board, 7: Bristle structure. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] The purpose of this invention is to provide an intelligent end effector that can intelligently, autonomously, adaptively, skillfully and with high precision perform assembly operations on ribbon cables, thereby solving the problems of existing automated assembly technologies in ribbon cable assembly applications and meeting the practical application needs of using robots to intelligently complete the assembly of small ribbon cables.

[0063] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0064] like Figures 1 to 7As shown: This embodiment provides an intelligent end effector for assembling a miniature ribbon cable with dimensions of 3mm × 8mm. It includes a base, a pressing head 2, an elastic structure, and a tactile sensor. The intelligent end effector is fixed to the end of a robotic arm via the base and a flange connection. The tactile sensor includes a sensor motherboard 6-2 and a sensor sensing head 6-1. The lower part of the pressing head 2 is located within the base, and an elastic structure is provided between the pressing head 2 and the base. The upper part of the pressing head 2 is located outside the base. The sensor motherboard 6-2 is located on the base, and the sensor sensing head 6-1 is located above the pressing head 2. The sensor sensing head 6-1 is used to measure the force information of the contact surface when the pressing head 2 contacts the ribbon cable, including the tangential force value and the normal force value. The force value is used to sense the engagement status of the ribbon cable. The sensor motherboard 6-2 and the sensor sensitive head 6-1 are connected by a ribbon cable to transmit information. The ribbon cable extends downward along one side of the pressing head 2. The sensor sensitive head 6-1 transmits the force information of the contact surface to the sensor motherboard 6-2. The sensor motherboard 6-2 is used to transmit the force information of the contact surface to the computer for processing. The pressing head 2 has a first air passage inside. The upper end of the first air passage extends to the upper part of the pressing head 2. The first air passage is connected to the second air passage of the base. The base is provided with a quick-connect air pipe that is threaded to the base. The quick-connect air pipe is used to connect to an external air pump. The first air passage, the second air passage and the quick-connect air pipe form a negative pressure air passage 4, realizing the negative pressure adsorption function.

[0065] Specifically, in this embodiment, the base includes an upper base 1-1, a lower base 1-2, and a mounting ring 1-3. The sensor main board 6-2 is mounted on the mounting ring 1-3. The mounting ring 1-3 and the upper base 1-1 are detachably connected by bolts and nuts. The upper base 1-1 and the lower base 1-2 are also detachably connected by bolts and nuts. Both the mounting ring 1-3 and the sensor main board 6-2 are provided with through holes for the pressing head 2 to pass through. The symmetrical protruding structures on both sides of the lower base 1-2 are used to connect with the flange of the general-purpose robotic arm by bolts.

[0066] In this embodiment, the pressing head 2 includes a first connecting part and a second connecting part. The cross-section of the first connecting part is rectangular, that is, the first connecting part is a square column. The cross-section of the second connecting part is circular, that is, the second connecting part is a cylinder. The first connecting part is located outside the base, and the second connecting part is located inside the base.

[0067] In this embodiment, the upper end of the first connecting part is provided with a groove and a first vent hole. The first vent hole communicates with the first air passage. The groove is used to place the sensor sensitive head 6-1. A second vent hole is provided on the sensor sensitive head 6-1 at a position corresponding to the first vent hole. The negative pressure air passage 4 starts from the second vent hole, enters the first air passage of the pressing head 2 and the second air passage of the base through the first vent hole of the pressing head 2, then leads out of the base in a horizontal direction, and finally leads out of the intelligent end effector of this embodiment from the quick connector of the air pipe. The negative pressure airflow in the negative pressure air passage 4 is driven by an external air pump to realize the negative pressure adsorption function of the actuator.

[0068] In this embodiment, the sensor sensing head 6-1 includes a lower flexible circuit board 6-1-1, a dielectric layer 6-1-5, and an upper flexible circuit board 6-1-6 arranged sequentially from bottom to top, specifically including:

[0069] The lower flexible circuit board 6-1-1 is the main flexible circuit board. The lower flexible circuit board 6-1-1 includes four FPC layers arranged from bottom to top: the bottom layer 6-1-1-1, the second inner layer 6-1-1-2, the first inner layer 6-1-1-3, and the top layer 6-1-1-4. Above the top layer 6-1-1-4 of the main flexible circuit board, there are two rows of six columns of 0.8mm×0.8mm square first electrodes 6-1-2. The signal of the first electrode 6-1-2 is transmitted through the first inner layer 6-1-1-3 to the first pad 6-1-3 below the bottom layer 6-1-1-1 of the main flexible circuit board. A 0.3mm reinforcement layer 6-1-4 is provided above the top layer 6-1-1-4 of the main flexible circuit board to facilitate the connection between the first pad 6-1-3 below the bottom layer 6-1-1-1 of the main flexible circuit board and the sensor motherboard 6-2 to realize the signal transmission between the sensor motherboard 6-2 and the first pad 6-1-3.

[0070] The dielectric layer 6-1-5 is made of 0.1mm thick silicone rubber;

[0071] The upper flexible printed circuit board 6-1-6 is the secondary flexible printed circuit board. It comprises two FPC layers arranged sequentially from bottom to top: a bottom layer 6-1-6-1 and a top layer 6-1-6-2. Below the bottom layer 6-1-6-1 is a row of three columns of 1.4mm × 2.5mm square second electrodes. These second electrodes, acting as a common electrode, together with the square first electrode 6-1-2 above the top layer 6-1-1-4 of the main flexible printed circuit board, form a capacitor for force detection. The dielectric layer 6-1... -5 is located between the first electrode 6-1-2 and the second electrode. The capacitor dielectric is the dielectric layer 6-1-5 made of silicone rubber. The second pad 6-1-7 is provided on both the top layer 6-1-6-2 of the sub-flex PCB and the top layer 6-1-1-4 of the main flexible PCB. The second pad 6-1-7 on the top layer 6-1-6-2 of the sub-flex PCB and the second pad 6-1-7 on the top layer 6-1-1-4 of the main flexible PCB are soldered together to realize the signal transmission between the lower flexible PCB 6-1-1 and the upper flexible PCB 6-1-6.

[0072] In this embodiment, a bristle structure 7 is provided on the contact surface of the sensor sensitive head 6-1. The bristle structure 7 is located at the position where the second vent is not provided. The bristles of the bristle structure 7 are wedge-shaped and are microstructures. The bristle structure 7 is used to increase the friction force during tangential loading and enhance the stability of tangential loading during the wiring operation.

[0073] In this embodiment, the elastic structure is an annular spring 3. The annular spring 3 is embedded in the nested structure cavity of the base. The lower end of the pressing head 2 is in full contact with the annular spring 3. When the pressing head 2 is pressed down by the normal force, the annular spring 3 is compressed. Its compression stroke makes the annular spring 3 have a certain range of motion relative to the base, that is, it ensures that the pressing head 2 has a certain range of motion relative to the base, so that the pressing head 2 has a certain planar adaptability.

[0074] In this embodiment, a sealing ring 5 is provided between the pressing head 2 and the base. The sealing ring 5 is embedded in the base and fixed by the nested structure cavity in the middle of the base. The sealing ring 5 is in close contact with the pressing head 2. The tight connection between the upper base 1-1 and the lower base 1-2 ensures the airtightness of the connection between the pressing head 2 and the base, and ensures the airtightness of the negative pressure air passage 4 when passing through the base and the pressing head 2. The sealing ring 5 has a certain degree of deformability, ensuring that the pressing head 2 has a certain range of motion relative to the base.

[0075] The robotic arm and intelligent end effector work together to assemble the micro-wire. During operation, the intelligent end effector needs to drive the male connector of the wire, adjust its position to align it, and complete the pressing and fastening operation. In this process, it is necessary to ensure that the intelligent end effector has good adhesion to the male connector and that the adhesion remains stable under tangential loading. In the intelligent end effector, the negative pressure air path 4 and the bristle structure 7, combined with negative pressure adsorption and bristle adhesion, ensure the adhesion capability of the actuator. Meanwhile, during operation, due to the limitations of the robotic arm's operational precision, the contact surface of the pressing head 2 may have a small angle with the wire mounting plane. In the intelligent end effector, the annular spring 3 and the sealing ring 5 together ensure that the pressing head 2 has a certain range of motion relative to the base, providing a certain degree of planar adaptability and passive compliance when performing the pressing action.

[0076] This embodiment also provides a method for sensing engagement state, which is applied to the aforementioned intelligent end effector. The method for sensing engagement state includes:

[0077] The force information collected by the tactile sensor is acquired; the force information includes arrayed tangential force and arrayed normal force.

[0078] Based on the force information, the deviation state of the cabling is determined; the deviation state is no deviation, positive deviation, reverse deviation, or failure.

[0079] If the deviation is a positive or negative deviation, the intelligent end effector is controlled to move the male connector of the cable in the alignment direction according to the deviation.

[0080] During the movement, the alignment status of the cabling is determined based on the force information; the alignment status is either the start of alignment or the end of alignment.

[0081] If the alignment state is "alignment complete", the ribbon cable stops moving and returns to the step of "determining the deviation state of the ribbon cable based on the force information".

[0082] If the deviation state is not deviation, then the intelligent end effector is controlled to perform a fastening operation.

[0083] As an optional implementation, determining the deviation state of the cabling based on the force information specifically includes:

[0084] If the array-type tangential force is greater than the first tangential force setting threshold, then the deviation state of the cabling is determined to be a failure.

[0085] If the arrayed tangential force is less than or equal to the first tangential force threshold, then the arrayed normal force is projected onto the direction to be determined to obtain a scatter plot of the normal force distribution.

[0086] The scatter plot of the normal force distribution is fitted with a straight line using the least squares method to obtain the fitted straight line.

[0087] Determine whether the absolute value of the slope of the fitted line is less than the slope threshold.

[0088] If so, then the deviation state of the cable is determined to be no deviation.

[0089] If not, then determine whether the absolute value of the slope is positive.

[0090] If so, the deviation state of the cabling is determined to be a positive deviation.

[0091] If not, then the deviation state of the cable is determined to be a reverse deviation.

[0092] In practical applications, the method for determining the deviation direction of the cabling uses the arrayed tangential and normal force distribution information obtained by the tactile sensor. After eliminating the interference of failure cases with excessive tangential force, the normal force distribution of the direction to be determined is fitted, and the determination result is obtained from the slope of the fitted line.

[0093] As an optional implementation, determining the alignment state of the cabling based on the force information specifically includes:

[0094] Based on the array-type normal force of the current frame, determine the average normal force of the three frames of the current frame.

[0095] Based on the array-type normal force of the previous frame, determine the average normal force of the three frames of the previous frame.

[0096] Determine the ratio of the average normal force of the three frames in the current frame to the average normal force of the three frames in the previous frame.

[0097] Determine whether the ratio is less than the normal force setting threshold.

[0098] If so, then the alignment state of the ribbon cable is determined to be the start of alignment.

[0099] Based on the array-type tangential force of the current frame, determine the average tangential force of the three frames of the current frame.

[0100] Based on the array-type tangential force described in the previous frame, determine the average tangential force of the three frames in the previous frame.

[0101] Based on the array-type tangential force described in the first two frames, determine the average tangential force of the three frames in the first two frames.

[0102] Determine the ratio of the average tangential force of the three frames in the current frame to the average tangential force of the three frames in the previous frame.

[0103] Determine the ratio of the average tangential force of the three frames in the previous frame to the average tangential force of the three frames in the two previous frames.

[0104] Determine whether the ratio of the average tangential force of the three frames in the current frame to the average tangential force of the three frames in the previous frame, and the ratio of the average tangential force of the three frames in the previous frame to the average tangential force of the three frames in the two previous frames, are both greater than the second tangential force setting threshold.

[0105] If so, then the alignment status of the ribbon cable is determined to be the end of alignment.

[0106] In practical applications, the alignment status of the ribbon cable is determined by the array-type tangential and normal force distribution information obtained by the tactile sensor, taking the average value of the normal and tangential forces across multiple frames to detect their changing characteristics, judging the start of the alignment phase based on the characteristic of a sudden decrease in normal force, and judging the end of the alignment phase based on the characteristic of a continuous increase in tangential force.

[0107] In practical applications, the fastening state sensing method is based on an intelligent end effector, and the fastening state sensing method includes: a method for judging the deviation direction of the cabling and a method for judging the alignment state of the cabling.

[0108] The intelligent end effector performs the following operation for cable assembly: under a given pre-pressure condition, the deviation direction is determined. Based on the obtained deviation direction, the actuator drives the male cable connector to move in the alignment direction. During the movement, the alignment status is determined in real time. If alignment characteristics are found, the movement stops, and the deviation direction is determined again. If the deviation direction is determined to be not deviated, the fastening operation is performed; otherwise, the above process is repeated.

[0109] The principle behind the method for determining the deviation direction (deviation state) of the cabling is as follows: Figure 8 As shown, if the male and female connectors of the cable are not aligned, the male connector will contact the edge of the female connector under a given preload. The normal force distribution on the contact surface will show concentration near the contact point. Different deviation directions result in different contact point positions, leading to a more concentrated normal force distribution on one side. The process for determining the deviation direction of the cable is as follows: Project the array of normal force values ​​onto the direction to be determined to obtain a scatter plot of the normal force distribution. A concentration of normal force near the contact point will be represented by a higher normal force value near the contact point in the scatter plot. Perform least-squares linear fitting on this scatter plot. The slope of the resulting line can classify the concentration of the normal force distribution into three categories: if the absolute value of the slope is less than a slope threshold, it is judged as no deviation; if the slope is positive and the absolute value is greater than the slope threshold, it is defined as a positive deviation; if the slope is negative and the absolute value is greater than the slope threshold, it is defined as a negative deviation. If the tangential force on the contact surface is large during the deviation direction judgment process, it will cause the measured normal force at the tangential loading end to be too large, thus concentrating the normal force distribution at the tangential loading end and interfering with the judgment of the cable deviation direction. Therefore, a tangential force threshold condition needs to be added. If the tangential force is greater than the tangential force threshold (the first tangential force setting threshold), it is judged as a failure. If the tangential force is less than the tangential force threshold, the judgment result is obtained from the slope condition of the fitted straight line of the normal force distribution. The deviation direction judgment process is as follows: Figure 9 As shown.

[0110] The principle of the alignment status judgment method for the ribbon cable is as follows: The actuator drives the male connector of the ribbon cable to move in the alignment direction, and the alignment status is judged in real time during the movement. At the instant when the male connector of the ribbon cable goes from being unaligned to being aligned and entering the groove of the female connector, such as... Figure 10 As shown, under a given preload, the male and female connectors of the cable change from full contact to insufficient contact. The normal force on the contact surface decreases and the occurrence time is short, manifested as a significant jump in the normal force on the contact surface. After the male connector enters the groove of the female connector, the actuator continues to drive the male connector to move tangentially, and the sidewall of the male connector is squeezed against the sidewall of the female connector, as shown... Figure 11As shown, the tangential force on the contact surface increases and continues to increase with the continuation of tangential movement. The process of the alignment state judgment method for the cabling is as follows: In order to eliminate small fluctuations and noise in the force signal, the average value of the current frame and the two previous frames (a total of three frames) is used to detect the force characteristics; the force characteristics are judged in real time during the movement, and the alignment state is judged frame by frame; the detection method of the normal force change characteristics is as follows: if the ratio of the average normal force value of the current frame (referring to the average normal force of the current frame and the average normal force of the two previous frames) to the average normal force value of the previous frame (referring to the average normal force of the previous frame and the average normal force of the two frames before the previous frame) is less than the normal force set threshold, it indicates that the normal force value has changed. If the jump decreases, the result indicates that the alignment phase has begun. The detection method for the tangential force change feature is as follows: if the ratio of the average tangential force of the current frame (referring to the average tangential force of the current frame and the average tangential force of the previous two frames) to the average tangential force of the previous frame (referring to the average tangential force of the previous frame and the average tangential force of the two frames before the previous frame), and the ratio of the average tangential force of the previous frame to the average tangential force of the two frames before the previous frame (referring to the average tangential force of the two frames before the previous two frames) are both greater than the second tangential force setting threshold, it indicates that the tangential force value has continuously increased, and the result indicates that the alignment phase has ended.

[0111] This invention presents a method for sensing the engagement state. By analyzing the contact state between the male and female ends of the cable during the pressing and engaging process of the actuator, the characteristics of the normal and tangential forces on the contact surface are obtained, along with the correspondence between these forces and different engagement states. Based on this, the normal and tangential force information of the contact surface is obtained through the sensor of the tactile sensor at the end of the actuator's pressing head. The computer then determines the engagement state and provides feedback to the actuator and robotic arm's operational behavior. An intelligent end effector incorporating this engagement state sensing capability can adaptively complete assembly tasks even in variable assembly scenarios, improving production efficiency while maintaining high operational precision.

[0112] In this embodiment, the intelligent end effector combines negative pressure adsorption and bristle adhesion to operate on the fine ribbon cable through a small pressing head 2. The tactile sensor collects tactile information and uses it to sense the engagement state, providing feedback on the robotic arm's movements. Furthermore, the pressing head 2 has a certain degree of planar adaptability, which improves the stability and dexterity of the actuator when assembling the tiny ribbon cable.

[0113] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An intelligent end effector, characterized in that: The device includes a base, a pressing head, an elastic structure, and a tactile sensor. The tactile sensor includes a sensor motherboard and a sensor sensitive head that are electrically connected to each other. The lower part of the pressing head is located in the base, and the elastic structure is provided between the pressing head and the base. The upper part of the pressing head is located outside the base. The sensor motherboard is located on the base, and the sensor sensitive head is located on the upper part of the pressing head. The sensor sensitive head is used to measure the force information of the contact surface when the pressing head contacts the ribbon cable. The sensor sensitive head transmits the collected force information of the contact surface to the sensor motherboard, and the sensor motherboard is used to transmit the force information of the contact surface to a computer for processing. The pressing head has a first air passage inside, and the upper end of the first air passage extends to the upper part of the pressing head. The first air passage is connected to a second air passage of the base, and the first air passage and the second air passage form a negative pressure air passage. The elastic structure is a ring-shaped spring sheet, which is embedded in the nested structure cavity of the base, and the lower end of the pressing head contacts the ring-shaped spring sheet; When the pressing head is pressed down by a normal force, the annular spring is compressed, and its compression stroke gives the annular spring a range of motion relative to the base, thus giving the pressing head planar adaptability. A sealing ring is provided between the pressing head and the base; The pressing head includes a first connecting part and a second connecting part. The first connecting part has a rectangular cross-section, and the second connecting part has a circular cross-section. The first connecting part is located outside the base, and the second connecting part is located inside the base. The upper end of the first connecting part is provided with a groove and a first vent hole. The first vent hole is connected to the first air passage. The groove is used to place the sensor sensitive head. The sensor sensitive head is provided with a second vent hole at a position corresponding to the first vent hole.

2. The intelligent end effector according to claim 1, characterized in that: The base includes an upper base, a lower base, and a mounting ring. The sensor motherboard is mounted on the mounting ring. The mounting ring and the upper base are detachably connected. The upper base and the lower base are detachably connected. The mounting ring is provided with a through hole for the pressing head to pass through. The symmetrical protruding structures on both sides of the lower base are used to cooperate with the flange of the general-purpose robotic arm.

3. The intelligent end effector according to claim 1, characterized in that: The sensor's sensitive head is provided with a bristle structure, and the bristles of the bristle structure are wedge-shaped.

4. The intelligent end effector according to claim 1, characterized in that: The sensor sensing head includes a lower flexible circuit board, a dielectric layer and an upper flexible circuit board arranged sequentially from bottom to top; The lower flexible circuit board includes a main flexible circuit board bottom layer, a second inner layer, a first inner layer, and a main flexible circuit board top layer arranged sequentially from bottom to top. The main flexible circuit board top layer is provided with a plurality of first electrodes. The lower surface of the main flexible circuit board bottom layer is provided with a first pad. The signal of the first electrode is transmitted to the first pad through the first inner layer. The main flexible circuit board top layer is provided with a reinforcement layer. The reinforcement layer is used for the first pad to be inserted into the sensor motherboard to realize the signal transmission between the sensor motherboard and the first pad. The upper flexible circuit board includes a sub-flexible circuit board bottom layer and a sub-flexible circuit board top layer. The sub-flexible circuit board bottom layer is disposed below the sub-flexible circuit board top layer. A plurality of second electrodes are disposed on the lower surface of the sub-flexible circuit board bottom layer. The second electrodes and the first electrodes form a capacitor. The dielectric layer is located between the first electrodes and the second electrodes. Second pads are disposed on both the sub-flexible circuit board top layer and the main flexible circuit board top layer. The second pads on the sub-flexible circuit board top layer and the second pads on the main flexible circuit board top layer are connected to realize signal transmission between the lower flexible circuit board and the upper flexible circuit board.

5. A method for sensing engagement state, characterized in that: The method is applied to the intelligent end effector according to any one of claims 1-4, wherein the engagement state sensing method includes: Acquire force information collected by a tactile sensor; the force information includes arrayed tangential force and arrayed normal force; Based on the force information, the deviation state of the cable is determined; the deviation state is no deviation, positive deviation, reverse deviation, or failure. If the deviation is a positive deviation or a negative deviation, the intelligent end effector is controlled to move the male connector of the cable in the alignment direction according to the deviation. During the movement, the alignment status of the cabling is determined based on the force information; the alignment status is either the start of alignment or the end of alignment. If the alignment state is "alignment complete", the ribbon cable stops moving and returns to the step of "determining the deviation state of the ribbon cable based on the force information"; If the deviation state is not deviation, then control the intelligent end effector to perform the engagement operation; Based on the force information, the deviation state of the cable is determined, specifically including: If the array-type tangential force is greater than the first tangential force setting threshold, then the deviation state of the cabling is determined to be a failure. If the arrayed tangential force is less than or equal to the first tangential force threshold, then the arrayed normal force is projected onto the direction to be determined to obtain a scatter plot of the normal force distribution. The scatter plot of the normal force distribution is fitted with a straight line using the least squares method to obtain the fitted straight line. Determine whether the absolute value of the slope of the fitted line is less than the slope threshold; If so, then the deviation state of the cable is determined to be no deviation; If not, then determine whether the absolute value of the slope is positive; If so, then the deviation state of the cable is determined to be a positive deviation; If not, then the deviation state of the cable is determined to be a reverse deviation.

6. The fastening state sensing method according to claim 5, characterized in that: Based on the force information, the alignment status of the cabling is determined, specifically including: Based on the array-type normal force of the current frame, determine the average normal force of the three frames of the current frame; Based on the array-type normal force described in the previous frame, determine the average normal force of the three frames in the previous frame; Determine the ratio of the average normal force of the three frames in the current frame to the average normal force of the three frames in the previous frame; Determine whether the ratio is less than the normal force setting threshold; If so, then the alignment state of the ribbon cable is determined to be the start of alignment; Based on the array-type tangential force of the current frame, determine the average tangential force of the three frames of the current frame; Based on the array-type tangential force described in the previous frame, determine the average tangential force of the three frames in the previous frame; Based on the array-type tangential force described in the first two frames, determine the average tangential force of the three frames in the first two frames; Determine the ratio of the average tangential force of the three frames in the current frame to the average tangential force of the three frames in the previous frame; Determine the ratio of the average tangential force of the three frames in the previous frame to the average tangential force of the three frames in the two previous frames. Determine whether the ratio of the average tangential force of the three frames in the current frame to the average tangential force of the three frames in the previous frame, and the ratio of the average tangential force of the three frames in the previous frame to the average tangential force of the three frames in the two previous frames, are both greater than the second tangential force setting threshold. If so, then the alignment status of the ribbon cable is determined to be the end of alignment.

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