IT201900006076A1 - PROCESS FOR THE PRODUCTION OF CUSTOMIZED CUSTOMIZED INSOLES, WITH REMOTE ACQUISITION AND THREE-DIMENSIONAL PRINTING - Google Patents

Description

Description of the industrial invention entitled: PROCEDURE FOR THE PRODUCTION OF CUSTOMIZED CUSTOMIZED INSOLES, WITH REMOTE ACQUISITION AND THREE-DIMENSIONAL PRINTING;

STATE OF THE ART

The use of insoles, footwear and orthopedic aids is one of the most popular solutions in the rehabilitation and pain management fields. Many musculoskeletal diseases are in fact associated with postural problems of the lower limbs and, more specifically, of the feet.

The insoles therefore represent an optimal solution for the postural adaptation of the foot with the aim of making structural changes that extend up to the level of the spine and the cervical area. In addition, breech orthoses have undergone a significant evolution over the years in order to combine the corrective function with a function of reducing pain localized to the plantar arch. Many materials have been used over the years to obtain the maximum ratio between corrective effectiveness and the level of comfort and acceptability by the patient. In addition, the use of insoles is also widely used in sports, in order to improve performance and, in the context of daily life, in order to improve the level of comfort during normal work, home life or leisure activities.

The standard production chain of orthopedic insoles is, to date, cumbersome and complex. The typical production chain starts from the mold of the patient's foot which is usually carried out in plaster or in dedicated foam boxes. This mode represents a strong limit both from an accessibility point of view, as it is necessary to go in person to specialized facilities with professionals in the sector, and from the point of view of transporting the impression obtained to the production site. The use of disposable materials and the burden of transport therefore represent both a temporal and economic limit in the production chain. In recent years, different alternative technologies have been developed for the acquisition of plantar anatomy. Among the most common are optical scanners and sensorized instrumentation with sensing pins. If on the one hand these technologies guarantee a reduction in production waste, on the other hand they are now bulky and very expensive machinery. In addition, they require a high level of experience in order for the operator to use them correctly. The result of these acquisitions is a representation of the plantar anatomy that can be used as a working basis for the final design of the insole. However, in the majority of cases, these digital acquisitions are converted into physical models which are then used as casts for making the insole, leading to the production of additional disposable materials.

The second phase of the production chain consists in the actual creation of the insole. This process can be carried out with different methodologies. The most widespread is manufacturing production. In this case, expert operators manually create the prescribed insole model, starting from the cast obtained in the previous phase and following the indications of the clinician, in order to make the necessary changes for each individual case. However, this production method has limitations. First of all, the entire process requires a high production time (usually of the order of 2/3 weeks), furthermore, manual production is associated with the creation of waste material that is difficult to reuse. From a clinical point of view, this methodology prevents, or at least makes it difficult, the creation of identical insoles in case it is necessary to reproduce one of them.

An alternative technology is that of milling. This technique considerably reduces the timing compared to the previous one. However, this technique requires the use of highly technological machinery associated with high costs both for the purchase of the same and for maintenance. A further limitation of milling is the creation of a considerable amount of waste material as the final insole is obtained, by material removal, from a single block of material.

Another known technique, alternative to the previous ones, is thermoforming. This technique is more used in sports as it allows the creation of insoles in materials such as carbon fibers with high performance under load. The major limitation of this technology is the high cost and difficult accessibility of such machinery, which are often used only by an elite of manufacturers.

From the analysis of the current state of the art, therefore, the main limitations of current production techniques emerge, which can be summarized in the following points:

· Difficult accessibility

· Need for highly specialized personnel. · Long production times

· High costs

· Production of large quantities of non-reusable waste materials

· High use of disposable materials SUMMARY OF THE INVENTION

The innovative process according to the present invention aims to solve the problems listed above and substantially comprises four specific steps.

I. First phase: in this phase the customer will have to acquire and send a digital version of a video and / or a series of images of the foot (s). For this purpose, it will not be necessary to use any particular technology or plaster / foam rubber casts. The customer can use any device that allows the capture of video and / or images such as smartphones, tablets, cameras. Advantageously, according to the invention, a specific application can also be provided for the user, to guide and further facilitate him in the acquisition process indicated above. Together with the image dataset, the consumer can provide any information or needs (type of footwear used, particular conditions, etc.) useful in order to optimize and customize the final product.

II. Second phase: the second phase consists in the creation of a digital model of the foot (s) through the technique of reconstruction from images. This methodology guarantees the reconstruction of the plantar anatomy with high accuracy. More specifically, a photogrammetry-based procedure is used to reconstruct the model. This technique, widely used in architecture and cartography, has been specially adapted in order to obtain a highly accurate representation of the anatomies of the foot (s).

III. Third phase: the digital model of the plantar surface is imported into the CAD environment for the creation of the final model of the insole. This phase guarantees, on the one hand, a very high level of customization, and on the other hand, it allows the necessary changes to be made to make orthopedic insoles, directly on the virtual model, based on the instructions of the competent clinician. In the case of a non-orthopedic insole, the specific information provided by the individual user will be used to modify the model and obtain the maximum level of customization.

IV. Fourth phase: the last phase of the proposed procedure uses modern three-dimensional printing technologies to create the physical model of the customized orthopedic insole. This phase guarantees high accuracy and significantly reduces the amount of waste materials.

A better understanding of the invention will be obtained with the following detailed description and with reference to the attached drawings which illustrate, purely by way of example and not limiting, a preferred embodiment.

In the drawings:

Figure 1 shows a representative diagram of the acquisition protocol of the dataset relating to foot films / images;

Figure 2 shows some points of integration that can be identified on the digital model of the foot reconstructed on the basis of the acquired dataset;

Figure 3 is a flow chart showing the main steps of the process according to the present invention;

Figures 4 and 5 show reference lines represented on the digital model of the foot of fig. 2;

Figure 6 shows a digital model of the insole obtained according to the present invention;

Figure 7 shows a real insole, 3D printed starting from the digital model of fig. 6.

DESCRIPTION OF THE INVENTION

Step 1: The creation of the starting model is a crucial step for the production of customized insoles. Modern technology now makes the use of smartphones, tablets and cameras accessible. The proposed idea is based on the use of these technologies to increase the accessibility by the user to the purchase of a custom made to measure insole. Furthermore, the use of remote acquisitions guarantees a net lowering of production costs both for the elimination of the disposable materials currently used for the creation of the initial cast of the foot, and because it is based on commonly used technologies thus excluding the need for purchase of highly specific and expensive dedicated machinery. During this first phase, the user is instructed on the correct video / image acquisition procedure and can then remotely create the dataset necessary for the next phase (Figure 1). In this phase, respecting the techniques currently recommended for the creation of traditional casts, a series of guidelines will be provided to ensure the correct acquisition of the dataset. The protocol consists of a few simple recommendations:

· Avoid direct exposure to strong light sources to avoid the creation of shadows;

· Try to use an autofocus system to avoid creating out-of-focus images / videos;

· In case of creation of a photographic dataset and, therefore, not in video format, take a series of photos such that each is partially overlapping the previous one to ensure the correct reconstruction of the model;

· Avoid placing reflective surfaces in the acquisition volume;

· Maintain a constant distance of about 40/50 cm throughout the acquisition phase;

· In case of video recording, avoid abrupt and sudden movements trying to maintain a constant speed of movement during the recording;

· In the case of video recording, move around the subject's foot in a circle while maintaining the recommended distance;

· Take photos / videos from different angles with respect to the foot, in order to ensure a complete representation of the three-dimensional geometry;

· Take a photo with the foot placed on a standard size sheet (A4 format recommended) to obtain a reliable scale factor;

· Take a photo in medial perspective and with the foot under load in order to show the curvature of the arch under load.

Phase 1bis: provides for the user to send the acquired images to the competent technician for the subsequent phase of modeling and construction of the insole. The method of sending the dataset is not binding for the subsequent phases of the invention. However, original file sizes must be guaranteed to avoid loss of important details or accuracy. Where possible or necessary, in the case of insoles with specific or therapeutic characteristics, the user must provide all the necessary information in order to make the necessary changes to the insole. This information includes, but is not limited to, medical reports, baropodometric tests, specific requests, type of footwear used. Possible systems for data transmission include the use of email, a dedicated web platform, a mobile app.

Phase 2: consists of transforming the image dataset into a virtual model. This phase is based on modern image reconstruction techniques. The dataset sent by the user as indicated above is analyzed with dedicated algorithms based on photogrammetry techniques to reconstruct the acquisition volume. These operations can be performed with known software such as "3DF Zephyr" or through dedicated algorithms.

In particular, in the preferred embodiment described, the first step to be carried out provides for the selection of the frames necessary for the reconstruction on the basis of an LMS (Least Mean Square) algorithm which evaluates the similarity threshold of successive frames. The frames are then analyzed with computer vision algorithms of the SIFT type (Scale-invariant feature transform) or of the SURF type (Speeded Up Robust Features) in order to identify the position in the space of the camera with respect to the object and identify the characteristic points ( e.g. points on the edges of objects) in common in multiple images. The coordinates of the points in space are then calculated, which form a dense point cloud. Subsequently, through a software - preferably open-source - for the management and modification of point clouds, it is planned to transform the point clouds into mesh, polygonal entities.

At this point, the area of interest (foot) is cleaned of any surrounding disturbance volumes and the final model is exported in digital format. This phase guarantees a reduction in the reconstruction times compared to acquisitions from plaster or foam rubber casts, while guaranteeing high accuracy. Furthermore, the main advantage of using software for reconstruction from images is the ability to receive and process datasets from any geographical location, avoiding delays (and any damage) due to the time required for the transport of the physical casts.

Phase 3: consists in the design of the insole model in a CAD (Computer Aided Drafting) environment. Working with CAD software has the advantage of allowing the operator to have a high fidelity model based on real geometry. According to the invention, a specific modeling strategy was developed to optimize the creation of the insole. First, the 3D model is loaded and aligned with the global reference system of the CAD software. This positioning is necessary to ensure that the model is not altered from the anatomical position in the later stages of modeling. This third step also ensures that the foot model respects the anatomical geometries relevant to the creation of the insole. In particular, the support point of the heel, or the most distal part of the heel (as shown in Figure 2 point A) is positioned in such a way as to recreate the specific alignment of the individual with the talus joint. After this specific positioning operation, it is necessary to identify some anatomical reference points, which are the reference points used to create the construction lines and cutting planes. First it is necessary to mark the center of the heel (figure 2 point A) and then the first and fifth metatarsus (figure 2 points B and C, respectively), the midpoint along the joining is then calculated and finally a reference point on the arch that will be used to model the arch support (figure 2, point D).

Three construction lines are generated by interpolating the identified points and can be manually edited to better suit the anatomy. A line that passes along the metatarsal joints is used to define the end of the plantar arch, a longitudinal line that passes in the middle of the foot following the arch shape and a second longitudinal line like the previous one but lower to maintain the height of the center of the heel (Figures 4 and 5, lines A and B).

These lines are projected onto the footprint and used to generate the cutting planes (Figures 4 and 5, line B).

The original geometry is then cut from these planes and the slab is virtually extruded through CAD modeling operations to the thickness needed to provide optimal strength and flexibility.

The model obtained can be modified to make structural changes in case of pathologies and / or specific needs. To create forefoot support, a flat surface is shaped around the metatarsal line following the size of the shoe. The two parts are merged together through a Boolean union process. A support at the heel level is connected to the insole with another Boolean union in order to ensure a better housing in the shoe and a greater level of comfort and stability for the end user. The quality of the mesh of the final model is checked, corrected if necessary, and the model exported - for example - as a “* .stl” file.

The use of CAD technology offers the possibility to modify the insole in order to guarantee the highest therapeutic level (in the case of orthopedic insoles on the instructions of the competent clinician), the maximum performance (in the case of sports insoles) or the highest level of comfort (in the case of insoles for working / daily life) (example in Figure 6)

Phase 4: The model obtained in the previous modeling phase is used as input for the final manufacturing procedure. This process exploits the innovation and versatility of three-dimensional printing technology. The main advantage of 3D printing is the great variety of materials on the market. This feature guarantees the possibility of obtaining insoles suitable for every need, ranging from orthopedic insoles to insoles for sports and insoles for everyday life. Furthermore, the procedure according to the present invention guarantees the reduction of waste materials with respect to the previous production lines.

3D printing, in combination with the procedure described so far, guarantees a net reduction in both production times and costs (example in Figure 7).

In conclusion, it can be said that the present invention provides at least the following procedural peculiarities:

· Geometry acquisition procedure with creation of an image / video dataset starting from a standardized protocol that the customer can carry out from anywhere in the world;

· Reconstruction from images to obtain a customized geometry;

· Custom insole development procedure which involves identification of different specific points of the 3D anatomical model;

· Custom insole development procedure which includes three construction lines generated by the interpolation of the points identified in the previous claim;

· Production procedure of the customized insole through the use of additive manufacturing techniques and other 3D printing technologies.

Claims (14)

CLAIMS: 1. Method for the production of custom made to measure insoles for footwear, with remote acquisition and three-dimensional printing, characterized by the fact of including the following phases: - acquisition, by a client / user, of one or more videos and / or a series of images of each foot for which the insole is to be made, by means of a device that allows the capture of said videos and / or images in digital format, such as smartphones, tablets, cameras, etc .; - telematic sending of said videos and / or digital images acquired to an operator for their processing, together with specific information and / or therapeutic or use needs; - processing of the videos and / or digital images received, for the creation and export of a digital model of the plantar surface of the foot, through a technique of reconstruction from images; - import of the digital model of the plantar surface in a CAD environment and creation of a final digital model of the insole to be created; - three-dimensional print of the final digital model of the insole, for the actual creation of the personalized orthopedic insole, which can be inserted into a shoe. 2. Method according to the previous claim, characterized by the fact that said acquisition step of said films and / or digital images provides for providing the user with a protocol for the correct video / image acquisition procedure in order to create the dataset necessary for the subsequent phases; for this purpose the following video and / or image acquisition protocol is provided: · Avoid direct exposure to strong light sources to avoid the creation of shadows · Try to use an autofocus system to avoid creating out-of-focus images / videos In case of creation of a photographic dataset and, therefore, not in video format, take a series of photos such that each is partially overlapping the previous one to ensure the correct reconstruction of the digital model of the foot · Avoid placing reflective surfaces in the acquisition volume · Maintain a constant distance of about 40/50 cm throughout the acquisition phase · In the case of video recording, avoid abrupt and sudden movements by trying to maintain a constant moving speed during recording · In the case of video recording, move around the subject's foot in a circle while maintaining the recommended distance Take photos / videos from different angles with respect to the foot, in order to ensure a complete representation of the three-dimensional geometry · Take a photo with your foot placed on a standard size paper (A4 size recommended) to get a reliable scaling factor. · Take a photo in medial perspective and with the foot under load in order to show the curvature of the arch under load. 3. Method according to claim 1 or 2, characterized by the fact that said step of telematic sending of the acquired digital movies / images, or datasets, provides that the original size of the files is guaranteed in order to avoid the loss of important details or accuracy, and moreover that all the necessary information is provided in order to make the necessary changes to the insole according to specific needs or the desired therapeutic purposes; such information being able to include, for example, medical reports, baropodometric exams, indication of foot pathologies, type of footwear used, particular conditions of use, etc. Method according to one or more of the preceding claims, characterized in that said step of processing the received digital data, for the creation of a digital virtual model of the plantar surface of the foot, provides for analyzing said data relating to the digital movies / images acquired , or dataset, with algorithms based on photogrammetry techniques in order to reconstruct the acquisition volume, with known software such as "3DF Zephyr" or through specially developed dedicated algorithms; in which at the end of this modeling, the area of interest is cleared of any surrounding disturbance volumes and the final model is exported in digital format. 5. Method according to one or more of the preceding claims, characterized in that said step of importing the real digital model of the plantar surface in a CAD environment, provides for the design of the insole model in a CAD environment by means of a specific modeling strategy, which account of the information provided by the client / user together with the images / videos, to optimize the creation of the insole, in which - to ensure that the model is not altered with respect to the anatomical position in the subsequent phases of the modeling - the three-dimensional model is expected to be loaded and aligned with the global reference system of CAD software. 6. Method according to the previous claim, characterized by the fact that the support point of the calcaneus, that is the most distal part of the heel (point A) is positioned in such a way as to recreate the specific alignment of the single individual with the talus joint, after which some anatomical reference points are identified, which are the reference points that can be used to create construction lines and cutting planes. 7. Method according to the previous claim, characterized by the fact that after identifying the center of the heel (point A) and then the first and fifth metatarsal (points B and C, respectively), it is planned to calculate the midpoint along the joining and finally a reference point on the arch that will be used to model the arch support (point D). 8. Method according to the previous claim, characterized by the fact that after having identified said points (A, B, C, D), it is foreseen to generate three construction lines, by interpolating the identified points, which can be manually modified to better adapt them to the anatomy: a line that passes along the metatarsal joints is used to define the end of the plantar arch, a longitudinal line that passes in the middle of the foot following the arch shape and a second longitudinal line like the previous one but lower to maintain the height of the center of the heel (lines A and B); in which said lines are projected on the footprint and used to generate the cutting planes (B). Method according to the preceding claim, characterized in that the original geometry is cut from these planes and the insole is virtually extruded through CAD modeling operations to the thickness necessary to provide optimal strength and flexibility for the insole. 10. Method according to one or more of the preceding claims, characterized in that the digital model of the insole thus obtained can be modified to make structural changes in order to take into account pathologies and / or specific needs. Method according to one or more of the preceding claims, characterized in that to create the support of the forefoot, it envisages shaping a flat surface around the metatarsal line, following the dimensions of the shoe in which the insole is to be inserted; the two parts consisting of the digital model of the insole and said flat surface being then fused together to create a complete model of the insole through a Boolean union process, while a support at the heel level is resized to be suitable for the original shape of the shoe in which can be inserted and connected to the insole with another Boolean union, in order to provide a better housing in the shoe and a greater level of comfort and stability for the user. 12. Method according to one or more of the preceding claims, characterized by the fact that it involves the use of CAD technology to modify the digital model of the insole in order to ensure: the highest therapeutic level, the maximum sporting performance or the maximum level of comfort; for this purpose, the information received relating to the user's specific needs or therapeutic purposes is taken into account, including, for example, medical reports, baropodometric exams, indications of foot pathologies, etc. 13. Method according to one or more of the preceding claims, characterized by the fact that said three-dimensional printing step involves using a digital model of the insole obtained in the previous modeling step as input for the final production procedure by 3D printing, drastically reducing or eliminating the waste materials, as well as limiting both production times and costs. 14. Method according to claim 4, characterized in that the reconstruction of the acquisition volume, referred to in the processing step of the digital data received, for the creation of a digital virtual model of the plantar surface of the foot, provides: - the selection of the frames necessary for the reconstruction on the basis of an LMS (Least Mean Square) algorithm which evaluates the similarity threshold of successive frames; - the analysis of these frames with SIFT (Scale-invariant feature transform) or SURF (Speeded Up Robust Features) computer vision algorithms in order to identify the position of the camera in space with respect to the object and identify the points characteristic, e.g. points on the edges of objects, in common in several images; - the calculation of the coordinates of these points in space, which constitute at least one dense point cloud; - the transformation of these point clouds into meshes, polygonal entities, by means of a software for the management and modification of point clouds.