Active flexible assembling mechanism based on air floatation and zero rigidity

Abstract

The invention provides an active compliant assembly mechanism based on air floatation and zero rigidity. The active compliant assembly mechanism comprises a parallel mechanism, a supporting platform and a visual detection system. The parallel mechanism comprises an upper platform, a base, an air floating ball assembly, a zero-rigidity mechanism, a plane air cushion and an electric cylinder. The upper platform and the base are connected through an electric cylinder assembly, and the upper platform and the base are connected through an air floating ball assembly, a zero-rigidity mechanism and a plane air cushion in sequence. The electric cylinder assembly, the air floating ball assembly, the zero-rigidity mechanism and the plane air cushion can provide three rotational degrees of freedom and three translational degrees of freedom for the supporting platform; the visual inspection system is mounted on an upper platform of the parallel mechanism; the visual detection system is used for judging the distance and position relation between the assembly body and the assembly target; a control system is further arranged on the lower surface of the supporting platform, the large-load characteristic and the high-friction-force characteristic brought by the heavy-load working condition are both reduced to the extremely low level, pose adjustment of an object under the heavy-load working condition can be achieved only by one person, and therefore the labor cost is greatly saved.

Description

Technical Field

[0001] The invention belongs to the field of assembly mechanisms, and in particular relates to an active compliant assembly mechanism based on air flotation and zero stiffness. Background Art

[0002] Adjusting the multi-degree-of-freedom posture of large components to meet assembly conditions is a key technology in the equipment development and production process, and belongs to heavy-load assembly. Due to the large weight and size of large components, manual operation is extremely difficult. It is difficult for operators to stably maintain the relative position and contact force between them and the target body, and there is a high risk of collision during the installation process. Heavy-duty assembly refers to the operation of heavy components to assemble mechanical equipment, such as the docking and assembly of rocket compartments, large satellites and other spacecraft components. Due to the large mass of the assembled parts, the large number of degrees of freedom required for the assembly operation, and the high assembly precision requirements, the assembly is extremely difficult. There are currently two assembly methods for heavy components. One is to complete the assembly through the cooperation of multiple people. This method is inefficient, labor-intensive, and difficult to ensure assembly reliability. The second is to assemble by controlling the automated assembly mechanism. The current automated assembly mechanisms include guide rail brackets, CNC positioners, parallel mechanisms, and series mechanisms. However, these mechanisms have the disadvantages of poor adaptability, complex assembly procedures, large force control errors, poor load-bearing capacity, and low positioning accuracy for the assembly needs of heavy components. In addition, due to the large mass of the assembly, if errors occur during the assembly process, it is easy to cause damage to the assembled components. Summary of the invention

[0003] In view of this, the present invention aims to propose an active compliant assembly mechanism based on air flotation and zero stiffness, which reduces the high load characteristics and high friction characteristics brought by heavy-load conditions to an extremely low level. Only one person is needed to adjust the position of an object under heavy-load conditions, thereby greatly saving labor costs.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows: An active compliant assembly mechanism based on air flotation and zero stiffness, comprising a parallel mechanism, a support platform and a visual inspection system; The parallel mechanism comprises an upper platform, a base, an air float assembly, a zero stiffness mechanism, a plane air cushion and an electric cylinder assembly; The edges between the upper platform and the base are connected by an electric cylinder assembly, and the upper platform and the middle of the base are connected in sequence by an air float assembly, a zero stiffness mechanism and a plane air cushion; The electric cylinder assembly, air float assembly, zero stiffness mechanism and plane air cushion can work together to provide 3 rotational degrees of freedom and 3 translational degrees of freedom for the support platform; The visual inspection system is installed on the upper platform of the parallel mechanism through the support platform; The visual inspection system is used to determine the distance and position relationship between the assembly and the assembly target; The lower surface of the support platform is also provided with a control system for inputting information transmitted by the visual detection system and outputting a driving signal for controlling the movement of the electric cylinder, thereby achieving position and posture adjustment with six degrees of freedom.

[0005] Furthermore, the air flotation ball assembly includes an air flotation ball body and an air flotation ball seat, the upper platform is connected to the air flotation ball body, and an air film exists between the air flotation ball body and the air flotation ball seat, thereby providing the upper platform with three degrees of rotational freedom without friction.

[0006] Furthermore, the zero-stiffness mechanism is used to provide a constant force in the vertical direction, thereby accurately offsetting the gravity of the upper structure and providing the upper platform with a vertical translational degree of freedom.

[0007] Furthermore, the plane air cushion is arranged on a smooth contact surface of the base, and an air film exists between the contact surface of the plane air cushion and the base, so that the two can realize frictionless relative motion; The air flotation ball assembly and the plane air cushion can provide support for the upper platform and also achieve gas lubrication, thereby reducing friction.

[0008] Furthermore, the electric cylinder assembly includes 6 electric cylinder bodies, which are evenly arranged between the upper platform and the base, and the two ends of the electric cylinder bodies are respectively hinged to the upper platform and the base; the electric cylinder contains a force sensor inside, which can perform force feedback.

[0009] Furthermore, the electric cylinder assembly and the visual detection assembly are connected to a control system.

[0010] Compared with the prior art, the active compliant assembly mechanism based on air flotation and zero stiffness described in the present invention has the following advantages: (1) The active compliant assembly mechanism based on air flotation and zero stiffness described in the present invention realizes single-person rapid operation through an automatic control system, reducing manpower consumption; the combination of the parallel mechanism and the zero stiffness mechanism enables the assembly to move in six degrees of freedom, thereby improving the flexibility and efficiency of the operation.

[0011] (2) The present invention discloses an active compliant assembly mechanism based on air flotation and zero stiffness. The zero stiffness mechanism can offset the gravity of heavy-loaded components, avoiding impact or extrusion forces caused by excessive movement or misoperation during the assembly process, thereby protecting the assembly and the assembly system from damage.

[0012] (3) The active compliant assembly mechanism based on air flotation and zero stiffness described in the present invention, the use of a spherical air flotation device and a planar air flotation device, not only provides three rotational degrees of freedom and two translational degrees of freedom, but also significantly reduces the friction during the movement of the system, improves the load-bearing capacity of the system, and makes the assembly of heavy parts easier and safer.

[0013] (4) The active compliant assembly mechanism based on air flotation and zero stiffness described in the present invention introduces a visual inspection system, which can monitor the positional relationship between the assembly and the target in real time, providing guidance for completing the assembly process accurately and safely, thereby improving the accuracy and reliability of the assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 It is a three-dimensional schematic diagram of an active compliant assembly mechanism based on air flotation and zero stiffness according to an embodiment of the present invention; Figure 2 A side view of an active compliant assembly mechanism based on air flotation and zero stiffness according to an embodiment of the present invention; Figure 3 It is a modular schematic diagram of the parallel mechanism described in an embodiment of the present invention.

[0015] Description of reference numerals: 1. Parallel mechanism; 11. Upper platform; 12. Air float assembly; 121. Air float body; 122. Air float seat; 13. Zero stiffness mechanism; 14. Plane air cushion; 15. Electric cylinder assembly; 16. Base; 2. Support platform; 3. Visual inspection system; 4. Control system. DETAILED DESCRIPTION

[0016] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0020] An active compliant assembly mechanism based on air flotation and zero stiffness, such as Figure 1-Figure 3 As shown, it includes a parallel mechanism 1, a support platform 2 and a visual detection system 3; The parallel mechanism 1 includes an upper platform 11, a base 16, an air-floating ball assembly 12, a zero-stiffness mechanism 13, a plane air cushion 14 and an electric cylinder assembly 15; The upper platform 11 and the base 16 are connected at their edges by an electric cylinder assembly 15, and the upper platform 11 and the middle of the base 16 are connected in sequence by an air float assembly 12, a zero stiffness mechanism 13 and a plane air cushion 14; The electric cylinder assembly 15, the air floating ball assembly 12, the zero stiffness mechanism 13 and the plane air cushion 14 cooperate together to provide the support platform 2 with 3 rotational degrees of freedom and 3 translational degrees of freedom; The visual inspection system 3 is mounted to the upper platform 11 of the parallel mechanism 1 through the support platform 2; The visual inspection system 3 is used to determine the distance and positional relationship between the assembly and the assembly target; the distance and positional relationship between the assembly and the assembly target is determined according to the built-in algorithm, thereby determining whether the assembly action is correct, and providing guidance for accurately and safely completing the assembly process. The visual inspection system 3 is an existing device.

[0021] The lower surface of the support platform 2 is also provided with a control system 4, which is composed of a servo driver and a controller. The system input is the information transmitted by the visual inspection system 3, and the output drive signal is used to control the movement of the electric cylinder, thereby realizing the position and posture adjustment of six degrees of freedom and finally completing the assembly process.

[0022] A compliant control algorithm based on perception power assistance is embedded in the control system, which can sense the operator's intention by collecting force information inside the electric cylinder for force feedback and control the mechanism to perform compliant movement.

[0023] Preferably, the air flotation ball assembly 12 includes an air flotation ball body 121 and an air flotation ball seat 122 , the upper platform 11 is connected to the air flotation ball body 121 , and an air film exists between the air flotation ball body 121 and the air flotation ball seat 122 , thereby providing the upper platform 11 with three degrees of rotational freedom without friction.

[0024] Preferably, the zero stiffness mechanism 13 is used to provide a constant force in the vertical direction, thereby accurately offsetting the gravity of the upper structure and providing the upper platform 11 with a vertical translational degree of freedom; the mechanism can be implemented by constant force hydraulics, constant force pneumatics and other technologies; The zero-rigidity mechanism 13 is designed based on different methods such as constant-force air pressure and constant-force hydraulic technology. Its implementation principle is to provide a constant upward force in the vertical direction to accurately offset the gravity of its upper structure including the assembly, thereby reducing the difficulty of the mechanism's vertical movement.

[0025] Preferably, the plane air cushion 14 is arranged on a smooth contact surface of the base 16, and there is an air film between the contact surfaces of the plane air cushion 14 and the base 16, so that the two can realize frictionless relative motion; The air float assembly 12 and the plane air cushion 14 can provide support for the upper platform 11 and also realize gas lubrication, thereby reducing friction; thereby greatly reducing friction, which is conducive to the assembly of heavy-loaded components.

[0026] Preferably, the electric cylinder assembly 15 includes 6 electric cylinder bodies, which are evenly arranged between the upper platform 11 and the base 16, and the two ends of the electric cylinder body are respectively hinged to the upper platform 11 and the base 16; the electric cylinder contains a force sensor inside, which can perform force feedback; the electric cylinder assembly 15 constitutes a motion branch of the parallel mechanism 1, which is used to drive the mechanism to achieve two translational degrees of freedom and three rotational degrees of freedom; because the air flotation device provides the main bearing capacity for the parallel mechanism 1 and reduces the friction force encountered when the system moves, the driving force required for the movement of the electric cylinder drive mechanism can be reduced; when performing assembly operations, the upper platform 11 is driven to move by controlling the action of the electric cylinder, thereby adjusting the posture of the assembly with the above-mentioned degrees of freedom.

[0027] Preferably, the electric cylinder assembly 15 and the visual detection assembly are connected to the control system 4 .

[0028] Working Principle,Before the process, i.e. during the equipment commissioning, it is necessary to input the ,assembly features into the control system 4, to ensure that the system can accurately identify the ,installation requirements and make control decisions; The assembly is placed on top of the mechanism motion platform and clamped, and the mechanism is transferred to the specified position by a loader; the visual inspection system 3 on the top of the motion platform performs real-time detection of the position of the assembly; the control system 4 integrated inside the base 16 controls the movement of the parallel mechanism 1 according to the position of the assembly and the pre-input assembly features; the parallel mechanism 1 is used to adjust the horizontal and vertical positions and three attitude angles of the assembly, and its internal zero-stiffness mechanism 13 is used to unload the vertical gravity of the assembly, and the spherical air flotation and the plane air flotation are used to reduce the friction of the mechanism movement; the visual inspection system 3 detects the positional relationship between the assembly and the target in real time during the movement of the mechanism; when it is detected that the assembly has reached the expected position, the control system 4 controls the parallel mechanism 1 to stop moving, and then returns to the initial position, and the assembly is completed.

[0029] The active and compliant assembly mechanism of the present application highlights its active characteristics. The existing assembly mechanism is passively adjusted and needs to be passively adjusted through driving parts. The staff cannot interfere too much by themselves. However, the technology of the present application can complete the posture adjustment by the staff applying very little force based on the perception-assisted technology. This is the key technical content of the present application.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An active compliant assembly mechanism based on air flotation and zero stiffness, characterized in that: Including parallel mechanism, support platform and visual inspection system; The parallel mechanism comprises an upper platform, a base, an air float assembly, a zero stiffness mechanism, a plane air cushion and an electric cylinder assembly; The edges between the upper platform and the base are connected by an electric cylinder assembly, and the upper platform and the middle of the base are connected in sequence by an air float assembly, a zero stiffness mechanism and a plane air cushion; The electric cylinder assembly, air float assembly, zero stiffness mechanism and plane air cushion can work together to provide 3 rotational degrees of freedom and 3 translational degrees of freedom for the support platform; The visual inspection system is installed on the upper platform of the parallel mechanism through the support platform; The visual inspection system is used to determine the distance and position relationship between the assembly and the assembly target; The lower surface of the support platform is also provided with a control system for inputting information transmitted by the visual detection system and outputting a driving signal for controlling the movement of the electric cylinder, thereby achieving position and posture adjustment with six degrees of freedom.

2. The active compliant assembly mechanism based on air flotation and zero stiffness according to claim 1, characterized in that: The air flotation ball assembly comprises an air flotation ball body and an air flotation ball seat. The upper platform is connected to the air flotation ball body. An air film exists between the air flotation ball body and the air flotation ball seat, thereby providing the upper platform with three degrees of rotational freedom without friction.

3. The active compliant assembly mechanism based on air flotation and zero stiffness according to claim 1, characterized in that: The zero-stiffness mechanism is used to provide a constant force in the vertical direction, thereby accurately offsetting the gravity of the upper structure and providing the upper platform with a vertical translational degree of freedom.

4. The active compliant assembly mechanism based on air flotation and zero stiffness according to claim 2, characterized in that: The plane air cushion is arranged on the smooth contact surface of the base, and there is an air film between the contact surface of the plane air cushion and the base, so that the two can realize frictionless relative motion; The air flotation ball assembly and the plane air cushion can provide support for the upper platform and also achieve gas lubrication, thereby reducing friction.

5. The active compliant assembly mechanism based on air flotation and zero stiffness according to claim 1, characterized in that: The electric cylinder assembly includes 6 electric cylinder bodies, which are evenly arranged between the upper platform and the base, and the two ends of the electric cylinder bodies are respectively hinged to the upper platform and the base; The electric cylinder body contains a force sensor that can provide force feedback.

6. The active compliant assembly mechanism based on air flotation and zero stiffness according to claim 1, characterized in that: The electric cylinder assembly and the visual detection assembly are connected to a control system.

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