A variable diameter internal drive sleeve deployment method

Abstract

The present invention discloses a method for deploying a variable-diameter inner-driven sleeve, which belongs to the technical field of variable-structure space remote sensors. The method is based on a wheel drive component, a variable-diameter pre-tightening component capable of abutting the wheel drive component against the inner wall of the sleeve, and a control system for feeding back the wheel drive component and the abutment state. The method comprises the following steps: step S1, the variable-diameter pre-tightening component is fixedly connected to the lower part of the innermost or outermost sleeve, and the wheel drive component is installed on the variable-diameter pre-tightening component; step S2, the pre-tightening system ensures that the wheel drive component is in real-time contact with the inner wall of the sleeve to be deployed; step S3, the drive system controls the rotation of the wheel drive component to deploy the sleeve step by step, and stops after the sleeve is fully deployed. The method has the advantages of simplicity, reliability, scalability, compactness and high precision, and can be used in all occasions where a sleeve-type deployment mechanism is used, especially in the field of space remote sensing where deployment precision is required to be high.

Description

Technical Field

[0001] The present invention relates to the technical field of variable structure space remote sensors, and in particular to a variable diameter internal drive sleeve deployment method for completing the on-orbit deployment of a multi-stage sleeve and realizing the on-orbit reorganization of an ultra-large variable structure space remote sensor. Background Art

[0002] To overcome launch capacity limitations and enable the construction of larger-aperture space sensors in orbit, deployable space sensors have become a new development direction. The basic principle of this technology is to systematically fold the system to reduce its footprint before launch. Once in orbit, it automatically unfolds and reassembles, achieving imaging capabilities equivalent to the designed aperture. To achieve this, the deformation of deployable space sensors requires a deployment mechanism. Traditional deployment mechanisms include articulated trusses, thin-walled tubes, sleeves, coils, and inflatables.

[0003] The telescopic type has good stiffness and strength performance due to the large moment of inertia of the cylinder section and the certain length of overlap retained between each two-stage cylinder. By using carbon fiber materials with a small linear expansion coefficient and mechanical limit devices, high positioning accuracy can be achieved. It is particularly suitable for the field of variable structure space cameras that require high accuracy, stability and stiffness.

[0004] Depending on the method of sleeve deployment, it can be categorized as rope-driven, screw-driven, and thin-walled open-tube-driven. Rope-driven systems offer advantages such as good deployment synchronization, simple structure and principle, and lightweight drive components. However, in microgravity, the ropes present the risk of entanglement, resulting in low reliability. The elasticity of the ropes can cause oscillations during the deployment process, making system control difficult. Screw-driven systems offer significant advantages such as a simple principle, stable structure, high strength, and high deployment driving force. However, they require very high screw machining precision and nut assembly accuracy. Limited by screw manufacturing capacity, the sleeve cannot achieve a very long single-stage extension length, resulting in a relatively low deployment-folding ratio. Screw-driven systems are prone to bending and deformation, leading to mechanism jamming and low reliability. Thin-walled open-tube-driven systems offer a high axial driving force. However, their deployment and retraction mechanisms are complex, heavy, and inconvenient. Asymmetrical deformation of the thin-walled open-tube after deployment can cause axial rotation of the sleeve, squeezing the guide mechanism and causing deformation of the deployment mechanism. Furthermore, manufacturing thin-walled open-tube systems with long travels is difficult and costly. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a variable diameter internal drive sleeve deployment method.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention discloses a variable diameter internal drive sleeve deployment method, which is based on a wheel drive assembly, a variable diameter pre-tightening assembly capable of abutting the wheel drive assembly against the inner wall of the sleeve, and a control system for feeding back the abutment status of the wheel drive assembly;

[0008] The method comprises the following steps:

[0009] The method comprises the following steps:

[0010] Step S1: The variable diameter pre-tightening assembly is fixedly connected to the lower portion of the innermost or outermost sleeve, and the wheel drive assembly is installed on the variable diameter pre-tightening assembly;

[0011] Step S2: The pre-tightening system ensures that the wheel drive assembly is in real-time contact with the inner wall of the sleeve to be deployed;

[0012] Step S3: The drive system controls the wheel drive assembly to rotate, unfolds the sleeve step by step, and stops after the sleeve is fully unfolded.

[0013] Furthermore, the preload system control method includes the following steps:

[0014] Step S2.1: Detect the state parameters x1 to x2 of the variable diameter preload component. n , where n is the number of state parameters

[0015] Step S2.2: Calculate the contact force N=f(x1,...,x n );

[0016] Step S2.3: Determine whether the contact force N meets the requirement. If so, proceed to step S2.5; otherwise, proceed to step S2.4.

[0017] Step S2.4: Adjust the variable diameter preload assembly and go to step S2.1;

[0018] Step S2.5: End.

[0019] Furthermore, the driving system control method includes the following steps:

[0020] Step S3.1: Determine whether the sleeve is fully deployed. If it meets the requirements, stop the operation. If it does not meet the requirements, go to step S3.2;

[0021] Step S3.2: driving the wheel drive assembly to rotate at a constant speed to unfold the sleeve step by step.

[0022] Furthermore, the variable diameter preload assembly and the wheel drive assembly are built into the sleeve.

[0023] Furthermore, at least two sets of the wheel drive assemblies and the variable diameter preload assemblies are evenly distributed circumferentially around the axis of the sleeve.

[0024] Furthermore, during the entire process of sleeve deployment, the wheel drive assembly is in real-time contact with the inner wall of the sleeve.

[0025] In the above technical scheme, the present invention provides a variable diameter internal drive sleeve deployment method, which has beneficial effects. The method of the present invention is used to deploy the sleeve, which has a simple structure and will not cause obvious technical obstacles in design, manufacturing, assembly and use due to the increase in the extension length of the sleeve. The variable diameter pre-tightening component is embedded in the sleeve, with high integration and easy use; it has good scalability and no limit on the length of the single-stage sleeve, so there is no limit on the total extension length of the sleeve; it does not require a guide mechanism, has high reliability, a small sleeve diameter difference, and a large unfolding ratio; the present invention can be used in all occasions where a sleeve-type deployment mechanism is used, especially in the field of space remote sensing where deployment accuracy requirements are high. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0027] Figure 1 This is a schematic diagram of a fixed configuration of a variable diameter inner drive assembly in a variable diameter inner drive sleeve deployment method disclosed in the present invention;

[0028] Figure 2 This is a schematic diagram of a follower configuration of a variable diameter internal drive device in a variable diameter internal drive sleeve deployment method disclosed in the present invention;

[0029] Figure 3 This is a flow chart of a variable diameter internal drive sleeve deployment method disclosed in the present invention;

[0030] Figure 4 This is a simplified structural diagram of a variable diameter pre-tightening assembly and a wheel drive assembly based on a variable diameter internal drive sleeve deployment method disclosed in the present invention.

[0031] Description of reference numerals:

[0032] 1. Reducer preload assembly; 2. Wheel drive assembly; 3. Mounting base; 4. Outermost sleeve; 5. Secondary outer sleeve; 6. Secondary sleeve; 7. I sleeve; 8. Secondary inner sleeve; 9. Innermost sleeve; 10. Limit interlocking element; 11. Limit ring;

[0033] 101. Preload base; 102. First reduction motor; 103. Torque sensor; 104. First bevel gear; 105. Second bevel gear; 106. Preload support arm; 107. Angle sensor;

[0034] 201. Second reduction motor; 202. Drive wheel. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] See also Figure 1-3 As shown, a variable diameter internal drive sleeve deployment method is invented, which is based on a wheel drive assembly 2, a variable diameter preload assembly 1 capable of abutting the wheel drive assembly 2 against the inner wall of the sleeve, and a control system for feeding back the abutment state of the wheel drive assembly 2;

[0037] Among them, the variable diameter preload component 1 and the wheel drive component 2 are built into the sleeve;

[0038] The method comprises the following steps:

[0039] Step S1: The variable diameter pre-tightening assembly 1 is fixedly connected to the lower part of the innermost or outermost sleeve, and the wheel drive assembly 2 is installed on the variable diameter pre-tightening assembly 1; for details, see Figure 1 As shown, the variable diameter preload assembly 1 is fixedly connected to the lower part of the outermost sleeve through the mounting base 3, see Figure 2 As shown, the variable diameter preload assembly 1 is fixedly connected to the lower part of the innermost sleeve through the mounting base 3, and the wheel drive assembly 2 is mounted on the end of the variable diameter preload assembly 1;

[0040] Step S2: The pre-tightening system ensures that the wheel drive assembly 2 is in real-time contact with the inner wall of the sleeve to be deployed;

[0041] Step S3: The driving system controls the wheel drive assembly 2 to rotate, unfolds the sleeve step by step, and stops after the sleeve is fully unfolded.

[0042] Preferably, the preload system control method includes the following steps:

[0043] Step S2.1: Detect the state parameters x1 to x2 of the variable diameter preload component 1 n , where n is the number of state parameters

[0044] Step S2.2: Calculate the contact force N between the wheel drive assembly 2 and the inner wall of the sleeve based on the state parameters of the variable diameter preload assembly 1. n );

[0045] Step S2.3: Determine whether the contact force N meets the requirement. If so, proceed to step S2.5; otherwise, proceed to step S2.4.

[0046] Step S2.4: Adjust the variable diameter preload assembly 1 and go to step S2.1;

[0047] Step S2.5: End.

[0048] Preferably, the drive system control method includes the following steps:

[0049] Step S3.1: Determine whether the sleeve is fully deployed. If it meets the requirements, stop the action. If it does not meet the requirements, go to step S3.2:

[0050] Step S3.2: driving the wheel drive assembly 2 to rotate at a constant speed, and unfolding the sleeve step by step.

[0051] Preferably, at least two sets of wheel drive assemblies 2 and variable diameter preload assemblies 1 are evenly distributed circumferentially around the sleeve axis.

[0052] Preferably, the wheel drive assembly 2 is in real-time contact with the inner wall of the sleeve during the entire process of sleeve deployment.

[0053] In this method, the rotational motion of the wheel drive assembly 2 can be replaced by any motion form in the prior art that can provide an axial rotational driving force, and can be rolled against the inner wall of the sleeve to achieve the step-by-step deployment of the drive sleeve.

[0054] The variable diameter pre-tightening assembly 1 can be any mechanism in the prior art that can support the wheel drive assembly 2 and keep the wheel drive assembly 2 in real-time contact with the inner wall of the sleeve, and can provide a contact pre-tightening force;

[0055] Figure 4 This is a simplified structural diagram of the variable diameter preload assembly 1 and the wheel drive assembly based on the sleeve deployment method. This method is not limited to using this structure to deploy the sleeve. This method only uses this structure as an example;

[0056] The variable diameter pre-tightening component 1 in the structure;

[0057] The variable diameter preload assembly 1 includes a preload base 101, a first reduction motor 102, a torque sensor 103, a first bevel gear 104, a second bevel gear 105, a preload support arm 106, and an angle sensor 107;

[0058] The preload base 101 is fixedly connected to the first reduction motor 102, wherein one end of the torque sensor 103 is fixedly connected to the power output shaft of the first reduction motor 102, and the other end is fixedly connected to the first bevel gear 104. The second bevel gear 105 is mounted on the input shaft, and the first bevel gear 104 and the second bevel gear 105 are engaged to realize gear transmission. The input shaft is fixedly connected to the preload support arm 106, and the end of the input shaft away from the second bevel gear 105 is fixedly connected to the angle sensor 107. The housing of the angle sensor 107 is fixedly connected to the preload base 101, and the first bevel gear 104 and the second bevel gear 105 are both rotatably connected to the preload base;

[0059] The variable diameter preload assembly 1 is integrally fixed to the mounting base 3 via the preload base 101. When two sets of wheel drive assemblies 2 and variable diameter preload assemblies 1 are mounted on the mounting base 3, their distribution is symmetrical along the sleeve axis. When three or more sets of wheel drive assemblies 2 and variable diameter preload assemblies 1 are mounted on the mounting base 3, their distribution is evenly distributed along the sleeve axis, providing self-centering and offsetting the radial force acting on the sleeve.

[0060] In this structure, the wheel drive assembly 2;

[0061] The wheel drive assembly 2 includes a second reduction motor 201 and a drive wheel 202;

[0062] The second reduction motor 201 is fixedly connected to the end of the pre-tightening support arm 106, and the driving wheel 202 is fixedly connected to the power output shaft of the second reduction motor 201. During normal operation, the driving wheel 202 contacts the inner wall of the sleeve group and is driven by the second reduction motor 201 to rotate, thereby realizing the expansion of the sleeve;

[0063] like Figure 1 As shown;

[0064] Specific implementation method 1 of the variable diameter internal drive sleeve deployment method;

[0065] One end of the mounting base 3 is fixedly connected to the lower part of the outermost sleeve 4, and the other end thereof is provided with at least two (optimally 3) variable-diameter pre-tightening assemblies 1 evenly distributed circumferentially around the central axis of the sleeve. The variable-diameter pre-tightening assembly 1 can rotate around one end thereof under the action of a driving element, and a wheel drive assembly 2 is installed at the other end of the variable-diameter pre-tightening assembly 1, and the wheel drive assembly 2 can rotate under the action of a driving element. The angle α between the variable-diameter pre-tightening assembly 1 and the axis of the sleeve and the external torque M it bears can be fed back through corresponding sensors.

[0066] The sleeve assembly to be deployed consists of the outermost sleeve 4 (level 0), the secondary outer sleeve 5 (level 1), the secondary sleeve 6, the i-level sleeve 7, the secondary inner sleeve 8 (level n-1), and the innermost sleeve 9 (level n), which are connected in sequence. In the initial state, the secondary inner sleeve 8 and the i-level sleeve 7, and the i-level sleeve and the i-1-level sleeve (i is an integer greater than or equal to 1) are fixedly connected by the limiting interlocking member 10 on each sleeve level. Therefore, in the initial state, all sleeves except the innermost sleeve 9 can be regarded as a whole, and the innermost sleeve 9 and the secondary inner sleeve 8 can slide axially. The number of sleeves can be increased or decreased according to design requirements and is not limited to the 9-level sleeve in this embodiment.

[0067] When the control system receives the sleeve deployment command;

[0068] The control system starts to determine whether the wheel drive assembly 2 is reliably preloaded. If it is reliably preloaded, it jumps to the drive system control; if it is not reliably preloaded, it jumps to the preload system control.

[0069] The preload system is controlled as follows;

[0070] Step S2.1: Detect the state parameters α,M of the variable diameter preload component 2

[0071] Step S2.2: Calculate the contact force N = f(α, M) between the wheel drive assembly 2 and the inner wall of the sleeve based on the state parameters of the variable diameter preload assembly 2.

[0072] Step S2.3: Determine whether the contact force N meets the requirement. If so, proceed to step S2.5; otherwise, proceed to step S2.4.

[0073] Step S2.4: Adjust the reducer preload assembly and go to step S2.1

[0074] Step S2.5: Set the pre-tightening completion flag.

[0075] The drive system is controlled as follows:

[0076] Step S3.1: Determine whether the vehicle is fully deployed. If not, go to step S3.2. If fully deployed, the system stops.

[0077] Step S3.2: The wheel drive assembly 2 is driven to rotate at a constant speed to gradually deploy the sleeve. During the deployment process, the wheel drive assembly 2 is controlled in real time to maintain effective contact with the inner wall of the sleeve until the sleeve is fully deployed.

[0078] The working principle of the specific embodiment 1 is as follows:

[0079] After the control system receives the instruction to expand the sleeve, the variable diameter preload assembly 2 operates under the control of the system, so that the wheel drive assembly 2 abuts against the inner surface of the innermost sleeve 9. When the abutment force N meets the design requirements, it can provide sufficient friction force for the wheel drive assembly 2. When the wheel drive assembly 2 rotates, the friction force can be converted into an effective driving force F for expanding the sleeve. When the wheel drive assembly 2 receives the action command, it rotates, generating an effective axial driving force F at the contact point between the wheel drive assembly 2 and the inner surface of the sleeve. This force drives the innermost sleeve 9 to move axially and unfold. When the innermost sleeve 9 is fully unfolded, the innermost sleeve 9 and the second-inner sleeve 8 are limited by the corresponding mechanical limit ring 11. At this time, the limit interlocking member 10 on the innermost sleeve 9 is actuated, locking the innermost sleeve 9 and the second-inner sleeve 8 together and forming a whole, and unlocking it from the first-stage sleeve 7. In this way, the wheel drive assembly 2 drives the whole composed of the innermost sleeve 9 and the second-inner sleeve 8 to continue to unfold. This unfolding drive action is repeated on all sleeves until all sleeves are unfolded. When the sleeve is fully unfolded, the corresponding sensor is triggered and a signal feedback is given, ending the sleeve unfolding process.

[0080] During the process of gradual expansion of the sleeve, the inner surface of the sleeve will form a stepped discontinuous surface. When the wheel drive assembly 2 is undergoing a discontinuous surface transition, the problem can also be solved by using the cooperation between the preload system and the drive system. However, the formula for solving the abutment force is more complicated at this time, and the driving force of the wheel drive assembly 2 is no longer along the axial direction.

[0081] like Figure 2 As shown;

[0082] Specific implementation method 2 of the variable diameter internal drive sleeve deployment method;

[0083] One end of the mounting base 3 is fixedly connected to the innermost sleeve 9, and the other end thereof is provided with at least two (optimally 3) variable-diameter pre-tightening assemblies 1 evenly distributed circumferentially around the central axis of the sleeve. The variable-diameter pre-tightening assembly 1 can rotate around one end thereof under the action of a driving element, and a wheel drive assembly 2 is installed at the other end of the variable-diameter pre-tightening assembly 1, and the wheel drive assembly 2 can rotate under the action of a driving element. The angle α between the variable-diameter pre-tightening drive assembly and the axis of the sleeve and the external torque M it bears can be fed back through corresponding sensors.

[0084] The sleeve assembly to be deployed is composed of the outermost sleeve 4 (level 0), the secondary outer sleeve 5 (level 1), the secondary sleeve 6, the i-level sleeve 7, the secondary inner sleeve 8 (level n-1), and the innermost sleeve 9 (level n) which are connected in sequence. In the initial state, the innermost sleeve 9 and the secondary inner sleeve 8, the secondary inner sleeve 8 and the i-level sleeve 7, and the i-level sleeve and the i-1-level sleeve (i is an integer greater than or equal to 2) are fixedly connected by the limiting interlocking member 10 on each sleeve level. Therefore, in the initial state, all sleeves except the outermost sleeve 4 can be regarded as a whole, and the secondary outer sleeve 5 and the outermost sleeve 4 can slide axially. The number of sleeves can be increased or decreased according to design requirements and is not limited to the 9-level sleeve in this embodiment;

[0085] When the control system receives the sleeve deployment command;

[0086] The system starts to determine whether the wheel drive assembly 2 is reliably preloaded. If it is reliably preloaded, it jumps to the drive system control. If it is not reliably preloaded, it jumps to the preload system control.

[0087] The preload system is controlled as follows;

[0088] Step S2.1: Detect the state parameters α,M of the variable diameter preload component

[0089] Step S2.2: Calculate the contact force N = f(α, M) between the wheel drive assembly 2 and the inner wall of the sleeve based on the state parameters of the variable diameter preload assembly.

[0090] Step S2.3: Determine whether the contact force N meets the requirement. If so, proceed to step S2.5; otherwise, proceed to step S2.4.

[0091] Step S2.4: Adjust the variable diameter preload assembly and go to step S2.1;

[0092] Step S2.5: Set the pre-tightening completion flag.

[0093] The drive system is controlled as follows:

[0094] Step S3.1: Determine whether the vehicle is fully deployed. If not, go to step S3.2. If fully deployed, the system stops.

[0095] Step S3.2: The wheel drive assembly 2 is driven to rotate at a constant speed to gradually deploy the sleeve. During the deployment process, the wheel drive assembly 2 is controlled in real time to maintain effective contact with the inner wall of the sleeve until the sleeve is fully deployed.

[0096] The working principle of the second specific embodiment is as follows:

[0097] After the control system receives the instruction to expand the sleeve, the variable diameter preload assembly 2 operates under the control of the system, so that the wheel drive assembly 2 abuts against the inner surface of the outermost sleeve. When the abutment force N meets the design requirements, it can provide sufficient friction force for the wheel drive assembly 2. When the wheel drive assembly 2 rotates, this friction force can be converted into an effective driving force F for expanding the sleeve. When the wheel drive assembly 2 receives the action command, it rotates, generating an effective axial driving force F at the contact point between the wheel drive assembly 2 and the inner surface of the sleeve. This force drives the entire assembly, consisting of all sleeves except the outermost sleeve 4, to move axially, unfolding. When the secondary sleeve 5 is fully unfolded, it is restrained by the corresponding mechanical stop ring 11. At this time, the stop interlocking member 10 on the secondary sleeve 5 actuates, unlocking the secondary sleeve 5 from the secondary sleeve 6 and locking it with the outermost sleeve 4, forming a single unit. In this way, the wheel drive assembly 2 drives the entire assembly, consisting of all sleeves except the outermost sleeve 4 and the secondary sleeve 5, to continue unfolding. This unfolding driving action is repeated for all sleeves until all sleeves are fully unfolded. When the sleeve is fully unfolded, the corresponding sensor is triggered and a signal feedback is provided, ending the sleeve unfolding process.

[0098] During the process of gradual expansion of the sleeve, the inner surface of the sleeve will form a stepped discontinuous surface. When the wheel drive assembly 2 is undergoing a discontinuous surface transition, the problem can also be solved by using the cooperation between the preload system and the drive system. However, the formula for solving the abutment force is more complicated at this time, and the driving force of the wheel drive assembly 2 is no longer along the axial direction.

[0099] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A variable diameter internal drive sleeve deployment method, which is based on a wheel drive assembly, a variable diameter pre-tightening assembly capable of abutting the wheel drive assembly against the inner wall of the sleeve, and a control system for feedback of the abutment state of the wheel drive assembly, characterized in that ； The method comprises the following steps: Step S1: The variable diameter pre-tightening assembly is fixedly connected to the lower portion of the innermost or outermost sleeve, and the wheel drive assembly is installed on the variable diameter pre-tightening assembly; Step S2: The pre-tightening system ensures that the wheel drive assembly is in real-time contact with the inner wall of the sleeve to be deployed; When the abutment force N meets the design requirements, sufficient friction can be provided for the wheel drive assembly, and the friction can be converted into an effective driving force F for the sleeve to unfold when the wheel drive assembly rotates; Step S3: The drive system controls the wheel drive assembly to rotate, unfolds the sleeve step by step, and stops after the sleeve is fully unfolded.

2. A variable diameter internal drive sleeve deployment method according to claim 1, characterized in that; The preload system control method includes the following steps: Step S2.1: Detect the state parameters x1 to x2 of the variable diameter preload component. n , where n is the number of state parameters; Step S2.2: Calculate the contact force N between the wheel drive assembly and the inner wall of the sleeve based on the state parameters of the variable diameter preload assembly. n ); Step S2.3: Determine whether the contact force N meets the requirement. If so, proceed to step S2.5; otherwise, proceed to step S2.

4. Step S2.4: Adjust the variable diameter preload assembly and go to step S2.1; Step S2.5; end.

3. A variable diameter internal drive sleeve deployment method according to claim 1, It is characterized by: The drive system control method includes the following steps: Step S3.1: Determine whether the sleeve is fully deployed. If the requirement is met, stop the operation. If not, go to step S3.

2. Step S3.2: driving the wheel drive assembly to rotate at a constant speed, and unfolding the sleeve step by step.

4. A variable diameter internal drive sleeve deployment method according to claim 1, characterized in that ； The variable diameter pre-tightening assembly and the wheel drive assembly are built into the sleeve.

5. The variable diameter internal drive sleeve deployment method according to claim 1, characterized in that ； At least two sets of the wheel drive assemblies and the variable diameter preload assemblies are evenly distributed circumferentially around the sleeve axis.

Images