Variable stiffness flexible disassembly end effector and feedback control method thereof

Abstract

The application discloses a variable stiffness flexible disassembly end effector and a feedback control method thereof. The effector comprises a mounting base, a flexible clamping arm, a stiffness adjusting assembly, a sensing and detecting assembly and a control module. The movable constraint in the stiffness adjusting assembly moves along the length direction of the flexible clamping arm, which can change the effective deformation length of the flexible deformation section in the flexible clamping arm and adjust the local equivalent stiffness. The control module identifies the disassembly stage, controls the first stiffness state in the contact positioning stage, controls the second stiffness state in the constraint breaking stage, and switches back to the first stiffness state and links the short distance unloading when detecting the connection constraint release transient characteristic, so as to buffer the release impact. When disassembling the connection structure, the application can reduce the impact load, rebound, target damage and mechanical arm vibration risk generated at the connection constraint release moment through low stiffness contact positioning, high stiffness buckle breaking, active stiffness reduction buffer at the release moment and separation and removal.

Description

Technical Field

[0001] This invention relates to the field of robotic automated dismantling equipment technology, specifically to a variable stiffness flexible dismantling end effector and its feedback control method. Background Technology

[0002] With the rapid pace of industrial product upgrades, a large number of decommissioned power equipment, electronic devices, instruments, and electromechanical products are entering the recycling and processing stage. The recycling process for decommissioned electricity meters, electronic metering terminals, and other products typically involves steps such as disassembling the meter cover, separating the bottom shell, removing the terminal blocks, taking out the circuit board, separating the display module, and disassembling internal connectors. After long-term use and storage, the plastic casing of these products is prone to aging, embrittlement, deformation, and contamination. Furthermore, differences exist between different batches of products in terms of clip positions, assembly gaps, screw tightness, adhesive residue, and insertion resistance. These factors introduce significant uncertainty into the disassembly process.

[0003] Existing automated dismantling equipment for waste electricity meters or similar electronic products mostly uses conveyor lines in conjunction with fixed workstations. Common processes include loading and positioning, screw removal, meter cover separation, circuit board removal, terminal block removal, and component sorting and recycling. This type of equipment is suitable for processing products with relatively uniform structures and small positional errors, and can improve dismantling efficiency. However, its end tools are mostly fixed-rigidity grippers, pry bars, suction cups, screwdrivers, or cutting tools, which usually perform actions according to preset trajectories, and are not adaptable to situations such as shell deformation, jamming, and changes in connection strength.

[0004] In actual disassembly, the end effector must both make compliant contact with the target and provide sufficient disassembly force. Existing technologies still have shortcomings in terms of tooling adaptability, flexible gripper disassembly force, end effector local stiffness adjustment, and connection release buffering.

[0005] The existing technology mainly has the following problems:

[0006] First, existing flexible grippers, soft grippers, or compliant end effectors can adapt to different shapes and reduce contact impact through structures such as flexible fingers, airbag actuation, particle blocking, and friction plates. These technologies have good adaptability in scenarios such as gripping, handling, and non-destructive clamping, and can also achieve stiffness adjustment to a certain extent. However, disassembly operations differ from ordinary gripping. Prying open latches, separating shells, peeling off adhesive residue, or pulling out connectors typically require significant local support stiffness and stable force transmission capabilities. If the end effector structure is too flexible overall, problems such as excessive deformation, insufficient disassembly force, slippage of the gripping point, or unstable prying angle can easily occur. Therefore, although existing flexible gripping structures can improve contact safety, their adaptability to high-resistance disassembly stages remains limited. Related technology can be found in patent CN112025749A, which discloses a soft gripper with a wide range of variable stiffness.

[0007] Secondly, existing technologies such as robot compliance control, impedance control, admittance control, and variable stiffness joints can improve the compliance of robots during contact with the environment and, to some extent, achieve force control or stiffness adjustment. For example, some solutions achieve variable stiffness control by using electromagnetic springs, Lorentz motors, elastic actuators, or contactors combined with flexible components. These technologies mainly adjust the force-position relationship at the robot control algorithm, joint, or actuator level to make the robot exhibit overall compliance characteristics. However, in the disassembly of meter housing clips, connectors, or adhesive connections, what truly needs adjustment is the local structural stiffness of the end effector. If the stiffness change mainly occurs at the joint or general actuator level, it is difficult to directly change the effective deformation length and force transmission characteristics of the end effector contact position. Related technologies can be found in patents CN117621144B and CN109476023A.

[0008] Third, existing automated dismantling equipment for waste electricity meters or similar electronic products mostly uses conveyor lines, fixed workstations, and specialized tools to complete processes such as feeding, positioning, screw removal, meter cover separation, circuit board removal, and sorting and recycling. This type of solution is suitable for products with relatively uniform structures and fixed dismantling locations, and can improve dismantling efficiency. However, when the snap-fit, plug-in, or housing fastening structure is pried open, the connection constraint often releases suddenly at a certain moment, and the contact force, torque, or force-displacement slope drops rapidly. If the end effector maintains high stiffness and continues to apply load, problems such as the meter cover popping open, tool rebounding, housing edge breakage, parts falling off, or robotic arm vibration can easily occur. Existing dismantling equipment focuses more on the positioning, clamping, and dismantling actions themselves, and does not adequately consider the active stiffness reduction buffer at the moment of connection release. Related technology can be found in patent CN205551065U.

[0009] In summary, among the existing technologies mentioned above, flexible grippers mainly address the issues of gripping adaptability and contact safety, robot compliant control mainly addresses the adjustment of force-position relationships during contact, and collision protection technology mainly addresses the safety protection issue after abnormal collisions. None of these technologies address the phased contradictions encountered during the disassembly of the casing connection structure of retired electronic products—namely, the need for low stiffness in positioning, high stiffness in breaking, and the need for rapid stiffness reduction and buffering during release—by proposing a technical solution that combines variable stiffness of the end-effector structure with transient unloading during connection release. Therefore, the core innovation of this invention lies in forming a closed-loop control system that integrates variable stiffness of the local structure, identification of disassembly stages, and active unloading during release. Summary of the Invention

[0010] To address the problems of the prior art, the present invention aims to provide a variable stiffness flexible disassembly end effector and its feedback control method for disassembling the shell connection structures of retired electronic products such as decommissioned energy meters and electronic metering terminals. This invention is applicable to situations where there are contact positioning errors, changes in connection resistance, and connection release impacts between the end effector and the target to be disassembled during the disassembly of retired electronic products with snap-fit ​​connections, plug-in connections, and adhesive edge connections. By adjusting the local equivalent stiffness of the flexible clamping arm, it achieves staged disassembly control during the contact positioning, constraint breaking, and connection release buffering processes. When disassembling connection structures such as snap-fit, plug-in, adhesive, or interference fits, this invention, while ensuring contact compliance and constraint breaking force transmission capability, can reduce the impact load, rebound, target damage, and robotic arm vibration risks generated at the moment of connection constraint release.

[0011] The technical solution of the present invention is described in detail below.

[0012] This invention provides a variable stiffness flexible disassembly end effector, which includes: a mounting base, at least two flexible clamping arms, a stiffness adjustment component, a sensing and detection component, and a control module;

[0013] One end of the flexible clamping arm is connected to the mounting base, and the other end is used to contact, clamp, support, pry, or pull the target to be disassembled;

[0014] The stiffness adjustment component includes a driving component, a transmission component, and a movable constraint component. The movable constraint component cooperates with the flexible clamping arm and can move along the length direction of the flexible clamping arm under the action of the driving component and the transmission component to change the effective deformation length of the flexible deformation segment, thereby adjusting the local equivalent stiffness of the flexible clamping arm.

[0015] The sensing and detection component is used to collect contact force signals, displacement signals, and / or torque signals between the end effector and the target to be disassembled;

[0016] The control module is connected to the sensing and detection component and the stiffness adjustment component respectively. The control module is used to determine the current disassembly stage based on the contact force signal, displacement signal and / or torque signal, and control the stiffness adjustment component to adjust the equivalent stiffness of the flexible clamping arm to form a staged control closed loop of contact positioning, constraint breaking and release buffering.

[0017] In this invention, the movable constraint member is a constraint sleeve fitted onto the outside of the flexible clamping arm, a slider abutting against the side of the flexible clamping arm, or a clamping member capable of limiting local deformation of the flexible clamping arm. When the movable constraint member moves towards the end of the flexible clamping arm, the effective deformation length of the flexible deformation segment decreases, and the equivalent stiffness of the flexible clamping arm increases. When the movable constraint member moves away from the end of the flexible clamping arm, the effective deformation length of the flexible deformation segment increases, and the equivalent stiffness of the flexible clamping arm decreases. By changing the effective deformation length of the flexible deformation segment of the flexible clamping arm through the movable constraint member, the local equivalent stiffness of the end-effector can be actively adjusted.

[0018] In this invention, the driving component is a servo motor, stepper motor, linear motor, electric actuator, cylinder, hydraulic cylinder, or shape memory alloy driving component; the transmission component is a lead screw transmission mechanism, gear and rack transmission mechanism, linkage transmission mechanism, synchronous belt transmission mechanism, linear slide, cam mechanism, or flexible transmission mechanism.

[0019] In this invention, the flexible clamping arm includes a rigid connecting section, a flexible deformable section, and an end contact section; the rigid connecting section is connected to the mounting base, the flexible deformable section is disposed between the rigid connecting section and the end contact section, and the end contact section is provided with a flexible contact layer; the flexible clamping arm is an elastic beam structure, a flexible hinge structure, a leaf spring structure, a sheet elastic structure, or an elastic composite structure.

[0020] In this invention, the sensing and detection component includes at least one of a force sensor, a torque sensor, a displacement sensor, an acceleration sensor, a vibration sensor, a current sensor, a proximity sensor, or a tactile sensor; wherein, the force sensor is preferably a multi-axis force / torque sensor, and the control module can obtain the normal contact force Fn and the tangential contact force Ft based on the output of the multi-axis force / torque sensor for use in determining slippage trends and identifying disassembly stages.

[0021] In this invention, the transient characteristics of the release of the connection constraint include at least one of the following: the decrease in contact force within a preset time window is greater than a first force decrease threshold; the decrease in torque within a preset time window is greater than a first torque decrease threshold; the force-displacement slope abruptly changes from being greater than a first slope threshold to being less than a second slope threshold; or the relative displacement of the target to be disassembled increases rapidly within a preset time window.

[0022] In this invention, the control module controls the flexible clamping arm to be in a first stiffness state during the contact positioning stage and to be in a second stiffness state during the constraint breaking stage, wherein the equivalent stiffness of the second stiffness state is greater than that of the first stiffness state; when a transient characteristic of connection constraint release is detected, the flexible clamping arm is controlled to switch from the second stiffness state to the first stiffness state and a short-distance unloading action is triggered to form a staged control closed loop of contact positioning, constraint breaking and release buffering.

[0023] In this invention, after determining that the connection constraint has been released, the control module is also used to control the robotic arm or end effector to perform a short-distance unloading action. The short-distance unloading action is one or more of the following: retraction, lateral offset, rotational release, deceleration along the disassembly direction, or stopping the application of load.

[0024] In this invention, each of the at least two flexible clamping arms is provided with an independent stiffness adjustment component, so that different flexible clamping arms can form differentiated equivalent stiffness. Some flexible clamping arms can be in a low-stiffness fitting state to adapt to the target shape; some flexible clamping arms can be in a high-stiffness support state to provide dismantling force, so as to achieve the synergy of local low-stiffness fitting and local high-stiffness breaking.

[0025] The present invention also includes a vibration assist module, which is disposed on the mounting base, the flexible clamping arm or the end contact section, and is used to apply axial, radial or tangential micro-vibration to the target to be disassembled when a periodic obstruction or jamming state is detected, so as to reduce the peak separation force of the target connection structure; the vibration assist module can be a piezoelectric vibrator, an electromagnetic vibrator, an eccentric wheel vibrator, an ultrasonic vibrator or a micro linear vibration module.

[0026] This invention also includes a limiting protection component and a quick-change interface; the limiting protection component is used to restrict the movement range of the movable constraint member, thereby limiting the maximum and minimum equivalent stiffness of the flexible clamping arm.

[0027] To prevent damage to the target due to excessive stiffness or instability due to insufficient stiffness, a quick-change interface is provided on the mounting base for connection to the end effector of the robot arm.

[0028] This invention also provides a feedback control method for the aforementioned variable stiffness flexible disassembly end effector. This method uses contact force, displacement, and / or torque feedback for stiffness adjustment control, enabling the end effector to automatically switch stiffness states according to disassembly stages such as contact positioning, constraint breaking, and connection release. The method includes the following steps:

[0029] S1, collects contact force, displacement and / or torque signals between the end effector and the target to be disassembled;

[0030] S2, based on the changes in contact force, displacement, and / or torque within a preset time window, obtain the rate of change of contact force, the rate of change of displacement, the rate of change of torque, and / or the force-displacement slope.

[0031] S3, based on the contact force change rate, displacement change rate, torque change rate and / or force-displacement slope, determine the current disassembly stage, and control the stiffness adjustment component (3) to adjust the equivalent stiffness of the flexible clamping arm (2) to form a staged control closed loop of contact positioning, constraint breaking and release buffer.

[0032] In this invention, in step S2, the force-displacement slope is obtained according to the following formula: Kc=ΔF / Δx, where Kc is the estimated value of contact stiffness, ΔF is the change in contact force within a preset time window, and Δx is the change in displacement within a preset time window.

[0033] In this invention, in step S3, when it is determined that the current stage is contact positioning, the stiffness adjustment component is controlled to make the flexible clamping arm in a first stiffness state to improve contact compliance and reduce the risk of target damage; when it is determined that the current stage is constraint breaking, the stiffness adjustment component is controlled to make the flexible clamping arm in a second stiffness state, the equivalent stiffness of the second stiffness state being greater than the equivalent stiffness of the first stiffness state, to improve force transmission capability and disassembly stability; when a transient characteristic of connection constraint release is detected, the stiffness adjustment component is controlled to switch the flexible clamping arm from the second stiffness state to the first stiffness state, and a short-distance unloading control command is output simultaneously to reduce the impact load at the moment of connection release through the short-distance unloading action.

[0034] In this invention, in step S3, when the contact force is less than a first force threshold and the displacement change rate is less than a first displacement threshold, it is determined that the current stage is contact positioning, and the movable constraint member is controlled to move away from the end of the flexible clamping arm to reduce the equivalent stiffness of the flexible clamping arm; when the contact force continues to increase and the force-displacement slope is greater than a first slope threshold, it is determined that the current stage is constraint breaking, and the movable constraint member is controlled to move closer to the end of the flexible clamping arm to increase the equivalent stiffness of the flexible clamping arm.

[0035] In this invention, in step S3, the connection constraint of the target to be disassembled is determined to be released when at least one of the following conditions is met: the decrease in contact force within a preset time window is greater than a first force decrease threshold; the decrease in torque within a preset time window is greater than a first torque decrease threshold; the force-displacement slope changes abruptly from being greater than a first slope threshold to being less than a second slope threshold; or the relative displacement of the target to be disassembled increases rapidly within a preset time window.

[0036] In this invention, in step S3, after the connection constraint is released, the robotic arm or end effector is controlled to perform a short-distance unloading action. The short-distance unloading action is one or more of the following: retraction, lateral offset, rotational release, deceleration along the disassembly direction, or stopping the application of load.

[0037] In this invention, in step S3, when a periodic peak is detected in the contact force or torque within a preset time window and the displacement change is less than the second displacement threshold, it is determined that there is a periodic obstruction state, and the vibration auxiliary module is activated to apply micro-vibration; when the ratio of tangential contact force to normal contact force is greater than the slippage threshold, it is determined that there is a slippage trend, and the equivalent stiffness of at least one flexible clamping arm is increased or the clamping force is adjusted.

[0038] Furthermore, the present invention provides a disassembly robot system, including a robotic arm, a controller, and the aforementioned variable stiffness flexible disassembly end effector; the variable stiffness flexible disassembly end effector is connected to the robotic arm via a quick-change interface; the controller is communicatively connected to the control module and is used to control the movement of the robotic arm based on contact force signals, displacement signals, and / or torque signals, and to control the equivalent stiffness of the flexible gripping arm; when a transient characteristic of connection constraint release is detected, the controller synchronously outputs a stiffness switching command and a robotic arm unloading trajectory correction command to drive the flexible gripping arm to switch from a second stiffness state to a first stiffness state and perform a short-distance unloading action.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. This invention changes the effective deformation length of the flexible deformation section of the flexible clamping arm by using movable constraint components, thereby achieving active adjustment of the local equivalent stiffness of the end effector, rather than relying solely on robot joint compliance control or overall impedance adjustment, so that the stiffness change directly acts on the disassembly contact area.

[0041] 2. In the contact positioning stage, the present invention adopts a first stiffness state, which can absorb the contact impact caused by visual positioning error, clamping error and local deformation of the shell, and reduce the risk of damage to the target surface; in the constraint breaking stage, a second stiffness state is adopted, which can reduce excessive bending of the flexible clamping arm and improve the disassembly force transmission efficiency of connection structures such as buckles, plugs, adhesives or interference fits; after detecting the transient characteristics of connection constraint release, it actively switches from the second stiffness state to the first stiffness state, and combined with the short-distance unloading action, it can buffer the impact load generated at the moment of connection release, and reduce the risk of tool rebound, shell breakage, part ejection and robot arm vibration.

[0042] 3. This invention determines the disassembly stage by using contact force, displacement, and / or torque signals, without relying on a single visual positioning result. It can adapt to complex working conditions such as positional deviations of the object to be disassembled, structural aging, and inconsistent connection states. By controlling the differential stiffness of multiple flexible clamping arms, it can achieve synergy between local first stiffness state contact and local second stiffness state breaking, improving the disassembly adaptability of irregular targets and complex connection structures. By applying micro-vibration through the micro-vibration auxiliary module under jammed or periodically obstructed conditions, it can reduce peak disassembly force and improve the continuity and stability of the disassembly process. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall structure of the variable stiffness flexible disassembly end effector of the present invention.

[0044] Figure 2 This is a schematic diagram of the flexible clamping arm structure of the present invention.

[0045] Figure 3 This is a schematic diagram illustrating the principle of changing the effective length of the flexible deformation segment using the movable constraint component of the present invention.

[0046] Figure 4 This is a schematic diagram of the constraint sleeve stiffness adjustment component of the present invention.

[0047] Figure 5 This is a comparison diagram of the first and second stiffness states of the flexible clamping arm of the present invention.

[0048] Figure 6 This is a schematic diagram of the arrangement of the sensing and detection components of the present invention.

[0049] Figure 7 This is a flowchart of the feedback control method of the present invention.

[0050] Figure 8 This is a schematic diagram of the active stiffness reduction buffer during the connection release of the present invention. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] like Figure 1 As shown, this embodiment provides a variable stiffness flexible disassembly end effector, including a mounting base 1, a flexible clamping arm 2, a stiffness adjustment component 3, a sensing and detection component 4, a control module 5, a vibration auxiliary module 6, a limit protection component 7, and a quick-change interface 8.

[0053] Mounting base 1 is used to connect to the end flange of the robot arm. Mounting base 1 can be made of aluminum alloy, stainless steel, titanium alloy, engineering plastic, or composite material. Mounting base 1 is provided with mounting holes, locating pin holes, cable channels, and drive component mounting cavities.

[0054] A quick-change interface 8 is located on one side of the mounting base 1 and is used to enable quick connection and disconnection between the end effector and the robot arm. The quick-change interface 8 can be a mechanical locking interface, a pneumatic locking interface, an electromagnetic locking interface, or a standard robot end effector quick-change interface.

[0055] At least two flexible clamping arms 2 are provided; in other embodiments, three, four or more flexible clamping arms 2 may be provided. Multiple flexible clamping arms 2 are arranged symmetrically, in a ring, in parallel, or asymmetrically around the mounting base 1. The flexible clamping arms 2 are used to contact, clamp, support, pry, or pull the target to be disassembled.

[0056] Each flexible clamping arm 2 includes a rigid connecting section 21, a flexible deformable section 22, and an end contact section 23. The rigid connecting section 21 is connected to the mounting base 1, the flexible deformable section 22 is disposed between the rigid connecting section 21 and the end contact section 23, the flexible deformable section 22 can generate elastic deformation under the action of contact force, and a flexible contact layer 24 is provided on the end contact section 23.

[0057] like Figure 3 and Figure 4 As shown, the stiffness adjustment component 3 adopts a constraint sleeve stiffness adjustment structure, which includes a driving component 31, a transmission component 32, and a movable constraint component 33. The movable constraint component 33 is a constraint sleeve fitted on the outside of the flexible clamping arm 2. The flexible deformation section 22 of the flexible clamping arm 2 is a long strip-shaped elastic beam. The constraint sleeve has an inner cavity that matches the shape of the flexible clamping arm 2, allowing it to slide along the length direction of the flexible clamping arm 2. When the movable constraint component 33 moves towards the end of the flexible clamping arm 2, the effective deformation length of the flexible deformation section 22 decreases, and the equivalent stiffness of the flexible clamping arm 2 increases; when the movable constraint component 33 moves away from the end of the flexible clamping arm 2, the effective deformation length of the flexible deformation section 22 increases, and the equivalent stiffness of the flexible clamping arm 2 decreases.

[0058] The driving component 31 is a miniature servo motor. The transmission component 32 is a lead screw and nut mechanism. The servo motor drives the lead screw to rotate, and the lead screw drives the nut to move along the lead screw axis. The nut is connected to the constraint sleeve, thereby driving the constraint sleeve to move along the flexible clamping arm 2.

[0059] When the constraint sleeve moves to a position near the end of the flexible clamping arm 2, the portion of the flexible deformation section 22 covered by the constraint sleeve is restricted, and the effective length actually participating in elastic deformation decreases. At this time, the equivalent stiffness of the flexible clamping arm 2 increases, making it suitable for constraint breaking, prying, peeling, or high-resistance disassembly stages.

[0060] When the constraint sleeve moves to a position away from the end of the flexible clamping arm 2, the freely deformable length in the flexible deformation section 22 increases. At this time, the equivalent stiffness of the flexible clamping arm 2 decreases, making it suitable for contact positioning, compliant fitting, release buffering, and removal stages.

[0061] In one embodiment, the effective deformation length of the flexible deformation segment 22 is denoted as . . The smaller the value, the greater the equivalent stiffness of the flexible clamping arm 2; The larger the value, the smaller the equivalent stiffness of the flexible clamping arm 2. For an approximate cantilever beam structure, with other parameters remaining constant, its equivalent bending stiffness can be approximately expressed as:

[0062]

[0063] in, The equivalent stiffness of the flexible clamping arm, This is the effective deformation length of the flexible deformation segment.

[0064] like Figure 6 As shown, the sensing and detection assembly 4 includes a force sensor 41, a torque sensor 42, a displacement sensor 43, and an acceleration sensor 44. The force sensor 41 is used to acquire the normal and / or tangential contact forces between the end effector and the target to be disassembled. The torque sensor 42 is used to acquire torque changes during the disassembly process of the end effector. The displacement sensor 43 is used to acquire the deformation of the flexible gripping arm 2, the position of the movable constraint 33, or the displacement of the end effector relative to the target. The acceleration sensor 44 is used to acquire vibration response or impact signals.

[0065] After receiving the aforementioned sensor signals, control module 5 calculates the changes in contact force, displacement, torque, rate of change of contact force, rate of change of displacement, rate of change of torque, and force-displacement slope within a preset time window. The preset time window can range from 5ms to 500ms, and the specific value can be determined based on the robot control cycle, sensor sampling frequency, and characteristics of the object being disassembled.

[0066] The control module 5 determines the current disassembly stage based on the above parameters.

[0067] Furthermore, such as Figures 7-8 As shown, this embodiment provides a feedback control method for a variable stiffness flexible disassembly end effector, including the following steps:

[0068] Step 1: Collect the contact force, displacement, and / or torque signals between the end effector and the target to be disassembled.

[0069] Step 2: Based on the changes in contact force, displacement, and / or torque within the preset time window, obtain the rate of change of contact force, the rate of change of displacement, the rate of change of torque, and / or the force-displacement slope.

[0070] The rate of change of force, the rate of change of displacement, the rate of change of torque, and the force-displacement slope can be expressed as follows:

[0071]

[0072]

[0073]

[0074]

[0075] Step 3: Determine the current disassembly stage based on the contact force change rate, displacement change rate, torque change rate, and / or force-displacement slope. When it is determined that the current stage is the contact positioning stage, control the stiffness adjustment component to put the flexible clamping arm in the first stiffness state to improve contact compliance and reduce the risk of target damage. When it is determined that the current stage is the constraint breaking stage, control the stiffness adjustment component to put the flexible clamping arm in the second stiffness state to improve force transmission capability and disassembly stability. When a sudden drop in contact force, a sudden drop in torque, a sudden change in force-displacement slope, and / or a rapid increase in the relative displacement of the target are detected, it is determined that the connection constraint of the target to be disassembled is released. Control the stiffness adjustment component to switch the flexible clamping arm from the second stiffness state to the first stiffness state, and coordinate with a short-distance unloading action to reduce the impact load at the moment of connection release.

[0076] In one embodiment, the force-displacement slope is obtained according to the following formula: Kc = ΔF / Δx; Where Kc is the estimated contact stiffness, ΔF is the change in contact force within the preset time window, and Δx is the change in displacement within the preset time window.

[0077] When the contact force is less than the first force threshold and the rate of change of displacement is less than the first displacement threshold, it is determined that the current stage is the contact positioning stage. When the contact force continues to increase and the force-displacement slope is greater than the first slope threshold, it is determined that the current stage is the constraint breaking stage.

[0078] When the decrease in contact force within a preset time window is greater than the first force decrease threshold, or the decrease in torque within a preset time window is greater than the first torque decrease threshold, or the force-displacement slope changes abruptly from being greater than the first slope threshold to being less than the second slope threshold, it is determined that the connection constraint of the target to be disassembled is released.

[0079] When the ratio of tangential force to normal force is greater than the slippage threshold, a slippage trend is detected, and the control module improves clamping stability or adjusts the stiffness distribution of the flexible clamping arm. When the contact force or torque exhibits multiple periodic peaks within a preset time window, and the target displacement change is less than the second displacement threshold, a periodic obstruction state is detected, and the vibration assistance module is activated.

[0080] In one embodiment, the first force threshold, first displacement threshold, first force decrease threshold, first torque decrease threshold, first slope threshold, second slope threshold, slip threshold, and preset time window are obtained through prototype calibration. During calibration, several disassembly tests are repeatedly performed for the target connection type to collect data on contact force, displacement, torque, and deformation of the flexible clamping arm. The characteristic change ranges before and after connection release are statistically analyzed, and each threshold is determined accordingly. The preset time window is preferably a time window containing N consecutive sampling points, where N is set according to the sensor sampling frequency and the duration of target connection release.

[0081] During the approach and contact positioning phase, the control module 5 controls the stiffness adjustment component 3 to bring the flexible gripping arm 2 to a first stiffness state. In this state, the flexible gripping arm 2 can compensate for visual positioning errors, clamping errors, and local deformation of the housing, reducing the risk of rigid collisions.

[0082] During the constraint breaking phase, control module 5 controls the movable constraint 33 to move to shorten the effective deformation length. The position allows the flexible gripping arm 2 to be in a second stiffness state. In this state, the disassembly force output by the robotic arm can be applied more effectively to the latches, connectors, adhesive edges, or housing separation points.

[0083] Upon detection of connection release, control module 5 controls the movable constraint 33 to move to the first stiffness position, while simultaneously controlling the robotic arm or end effector to perform short-distance unloading, retraction, deceleration, or lateral offset actions. If periodic obstruction or jamming is detected, control module 5 can activate vibration assistance module 6 to assist disassembly with axial, radial, or tangential micro-vibrations.

[0084] Regarding the active stiffness reduction buffer control at the moment of connection release: During the constraint breaking phase, the flexible clamping arm 2 is in a second stiffness state. At this time, if the connection structure has not yet been released, the contact force F and / or torque T will typically continue to increase with end displacement or disassembly action.

[0085] When the connection structure is suddenly released, the contact force F or torque T will drop significantly within a short period of time. If the actuator is still in a state of secondary stiffness at this time, impact and rebound may occur.

[0086] To address the aforementioned issues, control module 5 continuously monitors the decrease in contact force, decrease in torque, and changes in force-displacement slope within a preset time window. The connection constraint is released when any of the following conditions are met:

[0087]

[0088]

[0089]

[0090] in, For the force reduction threshold, The torque reduction threshold, The first slope threshold, This is the second slope threshold.

[0091] When the connection constraint is released, the control module 5 sends a stiffness reduction command to the stiffness adjustment component 3, causing the movable constraint 33 to move away from the end of the flexible gripping arm 2; at the same time, it controls the robot arm to perform a short-distance unloading action and reduces the movement speed of the end effector along the disassembly direction.

[0092] Step 5: After the connection constraint is released, control the robot arm or end effector to perform a short-distance unloading action. The short-distance unloading action includes retraction, lateral offset, rotational release, deceleration movement along the dismantling direction, or a combination thereof.

[0093] Step 6: When a periodic peak is detected in the contact force or torque within a preset time window, and the displacement change is less than the set threshold, it is determined that there is a periodic obstruction or jamming state, and the vibration auxiliary module is activated to apply micro-vibration.

[0094] The following example, using the disassembly process of a decommissioned power equipment housing assembly as an example, illustrates the working process of the variable stiffness flexible disassembly end effector of this invention. It should be understood that this embodiment is only used to illustrate a specific application of this invention in the disassembly scenario of a snap-fit ​​connection structure and does not constitute a limitation on the applicable objects, disassembly path, connection form, or control parameters of this invention.

[0095] In this embodiment, the target to be disassembled is a housing assembly, which includes a first housing portion, a second housing portion, and a snap-fit ​​connection structure disposed between the two. The snap-fit ​​connection structure may include a snap-fit ​​tongue, a snap-fit ​​groove, an elastic snap claw, a limiting protrusion, or a snap-fit ​​structure. Because decommissioned power equipment may experience aging, deformation, contamination, or changes in assembly gaps during long-term use, storage, and recycling, the snap-fit ​​position, snap-fit ​​strength, and release resistance may vary for different targets to be disassembled.

[0096] Before disassembly begins, the control module 5 controls the movable constraint 33 to be in the initial first stiffness position. At this time, the flexible deformation segment 22 has a large effective deformation length, and the equivalent stiffness of the flexible clamping arm 2 is low, which is suitable for compliant contact and position error compensation.

[0097] The robot system first acquires the position, orientation, and snap-fit ​​area information of the housing component to be disassembled through a vision inspection device. The controller generates an approach path for the end effector based on the vision inspection results. The robotic arm moves the end effector to the vicinity of the snap-fit ​​area and aligns the end contact section 23 of the flexible gripping arm 2 with the predetermined contact area of ​​the target to be disassembled.

[0098] During the approach process, the control module 5 controls the flexible clamping arm 2 to be in a first stiffness state. In this state, even if there is a certain deviation in the position of the target to be disassembled, the flexible clamping arm 2 can absorb slight contact errors through elastic deformation, reducing the risk of rigid collision.

[0099] When the end effector approaches the target to be disassembled, the robotic arm moves at a low speed to bring the flexible contact layer 24 into contact with the shell surface. The sensing and detection component 4 collects contact force, displacement, and / or torque signals in real time. When the contact force reaches a preset contact threshold, the control module 5 determines that the flexible gripping arm 2 has made contact with the target to be disassembled. At this time, the control module 5 does not immediately increase the stiffness, but keeps the flexible gripping arm 2 in a first stiffness state, so that the flexible gripping arm 2 can conform to the shell surface and compensate for local unevenness, deformation, or clamping errors on the target surface.

[0100] After contact positioning is completed, the control module 5 controls multiple flexible clamping arms 2 to clamp or support the housing assembly to be disassembled. At least one flexible clamping arm 2 contacts the edge of the housing near the latch, and at least another flexible clamping arm 2 contacts the opposite side of the housing surface to form a stable clamping and support relationship.

[0101] The control module 5 determines the clamping state based on the normal contact force, tangential contact force, clamping displacement, and deformation of the flexible clamping arm 2. If the clamping force reaches the preset clamping threshold and the relative slippage of the target is less than the set threshold, the clamping is determined to be stable.

[0102] Once clamping is confirmed, control module 5 controls stiffness adjustment component 3 to enter the stiffness enhancement process. Drive component 31 drives movable constraint component 33 to move towards the end of flexible clamping arm 2 via transmission component 32, thereby reducing the effective deformation length of flexible deformation section 22 and gradually increasing the equivalent stiffness of flexible clamping arm 2.

[0103] Once the flexible clamping arm 2 reaches a moderate stiffness state, the robotic arm drives the end effector to apply a preload force to the snap-fit ​​connection structure along a preset direction. The preload direction can be a prying direction, a lateral offset direction, a pulling direction, a rotation direction, or a combination thereof. The control module calculates the force-displacement slope in real time.

[0104]

[0105] As the contact force continues to increase, and the force-displacement slope... When the slope exceeds the first slope threshold, the control module 5 determines that the buckle breaking stage has begun. At this time, the control module 5 controls the movable constraint 33 corresponding to the main load-bearing flexible clamping arm 2 to continue moving towards the end of the flexible clamping arm 2, so that the main load-bearing flexible clamping arm 2 switches to the second stiffness state.

[0106] In the second stiffness state, the effective deformation length of the flexible deformation segment 22 is relatively small, and the flexible clamping arm 2 can provide a high force transmission capability. At the same time, the control module 5 can control the auxiliary flexible clamping arm 2 to maintain a low or medium stiffness state, which is used to conform to the target shell surface and maintain overall clamping stability. Thus, the end effector forms a differential stiffness distribution of "local high stiffness breaking and local low stiffness conforming".

[0107] In the second stiffness state, the robotic arm performs a snap-lock breaking action. The snap-lock breaking action may include a prying action along the snap-lock opening direction, a pulling action along the housing separation direction, a slight rotation action around the snap-lock edge, a lateral offset action along the housing seam direction, or a combination of the above actions.

[0108] If a sustained increase in contact force or torque is detected during the buckle breaking stage, but the target displacement change is small, control module 5 determines that a jamming state may exist. In this case, control module 5 can activate vibration assistance module 6 to apply micro-vibration to the buckle area. The vibration direction can be along the buckle opening direction, along the shell seam direction, or perpendicular to the shell surface.

[0109] During the buckle release process, control module 5 continuously monitors the contact force, torque, and force-displacement slope. When the buckle connection structure is released, phenomena such as a sudden drop in contact force, a sudden drop in torque, a sudden change in force-displacement slope, or a rapid change in target displacement usually occur.

[0110] When the decrease in contact force within a preset time window is greater than the first force decrease threshold, or the decrease in torque within a preset time window is greater than the first torque decrease threshold, or the force-displacement slope changes abruptly from being greater than the first slope threshold to being less than the second slope threshold, the control module 5 determines that the snap-fit ​​connection structure has been released.

[0111] When the control module 5 determines that the snap-fit ​​connection structure has been released, it immediately sends a stiffness reduction command to the stiffness adjustment component 3. The drive component 31 drives the movable constraint component 33 to move away from the end of the flexible clamping arm 2 through the transmission component 32, thereby increasing the effective deformation length of the flexible deformation section 22, and thus switching the flexible clamping arm 2 from the second stiffness state to a low stiffness or medium first stiffness state.

[0112] Meanwhile, control module 5 controls the robotic arm to perform a short-distance unloading action. The short-distance unloading action may include retracting in the opposite direction of disassembly, unloading in the lateral offset direction, rotating at a small angle around the release direction of the latch, reducing the movement speed of the end effector in the disassembly direction, or stopping the application of load.

[0113] In one implementation, the short-distance retraction distance can be from 1mm to 10mm, and the lateral offset distance can be from 1mm to 5mm. These values ​​are merely examples; specific parameters can be set according to the target structure to be disassembled, the clamping strength, and the robot's control precision.

[0114] During the active stiffness reduction process, the flexible clamping arm 2 can absorb part of the released impact energy through elastic deformation, thereby reducing the impact peak at the moment of release of the latch, reducing shell cracking, target ejection and end effector vibration.

[0115] After the latch release buffer is completed, the control module 5 determines whether the latch is completely disengaged based on the contact force and target displacement. If the contact force remains at a low level and the relative displacement of the target component reaches the set separation distance, it is determined that the latch connection has been completely released. At this time, the flexible clamping arm 2 maintains a low stiffness or medium-first stiffness state, and the robotic arm drives the end effector to move along the housing separation direction, separating the first housing part from the second housing part.

[0116] If the contact force increases again during the separation and removal process, the control module 5 determines that there may be a second latch that has not been fully released or a partial jamming. At this time, the control module 5 can pause the removal action and re-enter the contact positioning, stiffness enhancement and latch breaking process to disassemble the remaining latches.

[0117] Once the housing components are completely separated, the robotic arm moves the disassembled components to the designated placement position. Subsequently, the control module 5 controls the movable constraint 33 to reset to the initial first stiffness position, and the end effector enters the preparation state for the next disassembly.

[0118] Through the above working process, this embodiment can achieve low-stiffness contact positioning, high-stiffness buckle breaking, active stiffness reduction buffering at the moment of release, and separation and removal, which better reflects the technical effects of the present invention of "compliant contact, high-stiffness breaking, release buffering and stable removal".

[0119] In summary, this invention modifies the effective deformation length of the flexible deformation section of the flexible clamping arm through a movable constraint component, and combines contact force, displacement, and / or torque feedback to achieve disassembly stage identification, stiffness state switching, and short-distance unloading control after connection release. This forms an integrated technical solution for the automated disassembly of the housing connection structure of retired electronic products, featuring flexible contact, high-stiffness breaking, and release buffering. The above embodiments are merely illustrative of the technical concept of this invention and do not constitute a limitation on the scope of protection of this invention; any equivalent substitutions, modifications, or improvements made based on the technical concept of this invention should fall within the scope of protection of this invention.

[0120] It should be understood that the above embodiments are for illustrative purposes only and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make adaptive adjustments to the specific structural form, driving method, sensor arrangement, and control parameters without departing from the concept of the present invention.

Claims

1. A variable stiffness flexible disassembly end effector, characterized in that, It includes a mounting base (1), at least two flexible clamping arms (2), a stiffness adjustment assembly (3), a sensing and detection assembly (4), and a control module (5); One end of the flexible clamping arm (2) is connected to the mounting base (1), and the other end is used to contact, clamp, support, pry or pull the target to be disassembled; The stiffness adjustment component (3) includes a driving member (31), a transmission member (32), and a movable constraint member (33). The movable constraint member (33) cooperates with the flexible clamping arm (2) and can move along the length direction of the flexible clamping arm (2) under the action of the driving member (31) and the transmission member (32) to change the effective deformation length of the flexible deformation segment (22), thereby adjusting the local equivalent stiffness of the flexible clamping arm (2). The sensing and detection component (4) is used to collect contact force signals, displacement signals and / or torque signals between the end effector and the target to be disassembled; The control module (5) is connected to the sensing and detection component (4) and the stiffness adjustment component (3) respectively. The control module (5) is used to determine the current disassembly stage based on the contact force signal, displacement signal and / or torque signal, and control the stiffness adjustment component (3) to adjust the equivalent stiffness of the flexible clamping arm (2) to form a staged control closed loop of contact positioning, constraint breaking and release buffer.

2. The variable stiffness flexible disassembly end effector according to claim 1, characterized in that, The movable constraint member (33) is a constraint sleeve sleeved on the outside of the flexible clamping arm (2), a slider abutting against the side of the flexible clamping arm (2), or a clamping member that can limit the local deformation of the flexible clamping arm (2); the flexible clamping arm (2) includes a rigid connecting section (21), a flexible deformation section (22) and an end contact section (23), the flexible deformation section (22) is disposed between the rigid connecting section (21) and the end contact section (23), the rigid connecting section (21) is connected to the mounting base (1), and the end contact section (23) is provided with a flexible contact layer (24).

3. The variable stiffness flexible disassembly end effector according to claim 1, characterized in that, The at least two flexible clamping arms (2) are respectively provided with independent stiffness adjustment components (3), so that different flexible clamping arms (2) can form differentiated equivalent stiffness, so as to achieve the synergy of local low stiffness fitting and local high stiffness breaking.

4. The variable stiffness flexible disassembly end effector according to claim 1, characterized in that, The control module (5) controls the flexible gripping arm to be in a first stiffness state during the contact positioning stage and to be in a second stiffness state during the constraint breaking stage, and the equivalent stiffness of the second stiffness state is greater than the equivalent stiffness of the first stiffness state; when the transient characteristics of the connection constraint release are detected, the flexible gripping arm (2) is controlled to switch from the second stiffness state to the first stiffness state and to perform a short-distance unloading action in conjunction with it, so as to form a staged control closed loop of contact positioning, constraint breaking and release buffer; after the connection constraint is determined to be released, the control module is also used to control the robotic arm or end effector to perform a short-distance unloading action.

5. The variable stiffness flexible disassembly end effector according to claim 1, characterized in that, It also includes a vibration assist module (6); the vibration assist module (6) is disposed on the mounting base (1) or the flexible clamping arm (2) and is used to apply axial, radial or tangential micro-vibration to the target to be disassembled when a periodic obstruction or jamming state is detected.

6. A feedback control method based on the variable stiffness flexible disassembly end effector according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1, collects contact force, displacement and / or torque signals between the end effector and the target to be disassembled; S2, based on the changes in contact force, displacement, and / or torque within a preset time window, obtain the rate of change of contact force, the rate of change of displacement, the rate of change of torque, and / or the force-displacement slope. S3, based on the contact force change rate, displacement change rate, torque change rate and / or force-displacement slope, determine the current disassembly stage, and control the stiffness adjustment component (3) to adjust the equivalent stiffness of the flexible clamping arm (2) to form a staged control closed loop of contact positioning, constraint breaking and release buffer.

7. The feedback control method according to claim 6, characterized in that, In step S3, when the contact force is less than the first force threshold and the displacement change rate is less than the first displacement threshold, it is determined that the current stage is the contact positioning stage; when the contact force continues to increase and the force-displacement slope is greater than the first slope threshold, it is determined that the current stage is the constraint breaking stage; when at least one of the following conditions is met, it is determined that the connection constraint of the target to be disassembled is released: the decrease in contact force within a preset time window is greater than the first force decrease threshold; the decrease in torque within a preset time window is greater than the first torque decrease threshold. The force-displacement slope abruptly changes from being greater than the first slope threshold to being less than the second slope threshold; or the relative displacement of the target to be disassembled increases rapidly within a preset time window.

8. The feedback control method according to claim 6, characterized in that, In step S3, when it is determined that the current position is in the contact positioning stage, the stiffness adjustment component (3) is controlled to make the flexible clamping arm (2) in the first stiffness state; when it is determined that the current position is in the constraint breaking stage, the stiffness adjustment component (3) is controlled to make the flexible clamping arm (2) in the second stiffness state, the equivalent stiffness of the second stiffness state is greater than the equivalent stiffness of the first stiffness state; when the transient characteristics of connection constraint release are detected, the stiffness adjustment component (3) is controlled to switch the flexible clamping arm (2) from the second stiffness state to the first stiffness state, and a short-distance unloading control command is output simultaneously to reduce the impact load at the moment of connection release; after the connection constraint is released, the robotic arm or end effector is controlled to perform a short-distance unloading action.

9. The feedback control method according to claim 6, characterized in that, In step S3, when a periodic peak is detected in the contact force or torque within a preset time window and the displacement change is less than the second displacement threshold, it is determined that there is a periodic obstruction state and the vibration auxiliary module (6) is activated to apply micro-vibration; when the ratio of tangential contact force to normal contact force is greater than the slip threshold, it is determined that there is a slip trend and the equivalent stiffness of at least one flexible clamping arm (2) is increased or the clamping force is adjusted.

10. A disassembly robot system, characterized in that, The device includes a robotic arm, a controller, and a variable stiffness flexible disassembly end effector as described in any one of claims 1 to 5; the variable stiffness flexible disassembly end effector is connected to the robotic arm via a quick-change interface (8); the controller is communicatively connected to the control module (5) and is used to control the movement of the robotic arm based on contact force signals, displacement signals, and / or torque signals, and to control the equivalent stiffness of the flexible gripping arm (2); when a transient characteristic of connection constraint release is detected, the controller synchronously outputs a stiffness switching command and a robotic arm unloading trajectory correction command to drive the flexible gripping arm (2) to switch from a second stiffness state to a first stiffness state and perform a short-distance unloading action.

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