CN111000565A - Motion capture sensor device and manufacturing method thereof - Google Patents

Abstract

The invention discloses a motion capture sensor device and a manufacturing method thereof, wherein the motion capture sensor device comprises a first protective layer, a first conductive layer, a dielectric layer, a second conductive layer and a second protective layer which are sequentially arranged; the first conductive layer and the second conductive layer are partially overlapped and form a plurality of overlapping areas, and the overlapping areas form a plurality of capacitors and are used as stretching sensors; the first protective layer is attached to or worn on a measured body, and when the measured body deforms, the shape of the stretching sensor changes together; the first and second conductive layers each comprise a mixture of silicone and carbon black. The motion capture sensor device provided by the invention does not need sight, is low in price and can be suitable for acquiring the real-time motion of deformation of a dense and non-rigid surface.

Description

Motion capture sensor device and manufacturing method thereof

Technical Field

The invention relates to the technical field of motion capture, in particular to a motion capture sensor device and a manufacturing method thereof.

Background

Motion capture is an essential tool in many graphics applications, such as movies and games, sports, biomechanics, Virtual Reality (VR) and Augmented Reality (AR) character animation. Most commonly, motion capture systems are camera-based, or rely on body-worn markers. Vision-based methods can be very accurate without occlusion and good lighting conditions, and they can provide dense surface reconstruction in the case of multi-view or depth imaging. However, such systems rely on extensive infrastructure and are therefore primarily limited to laboratory and studio use, and furthermore, vision-based methods, often relying on multiple calibrated cameras installed in the environment, require line of sight, are unable to accurately capture motion in cases of severe occlusion or partial non-observability, and are not suitable for outdoor use. Other sensing means, such as inertial and magnetic sensors worn by the human body, or resistive and capacitive distance sensors, provide more mobility, but these methods are generally limited to capturing skeletal deformations, are not capable of capturing non-skeletal deformations, have limited capturing capabilities, and are also susceptible to environmental interference.

In view of the above problems, no effective solution has been proposed.

Disclosure of Invention

In order to solve the above-mentioned problems, it is an object of the present invention to provide a motion capture sensor device that can capture non-skeletal deformation without requiring a line of sight and can be used outdoors, and a method for manufacturing the same, so as to solve the problems that the conventional motion capture sensor device requires a line of sight, can capture skeletal deformation only, and is not suitable for outdoor use.

In a first aspect, an embodiment of the present invention provides a motion capture sensor apparatus, including:

the first protective layer, the first conducting layer, the dielectric layer, the second conducting layer and the second protective layer are arranged in sequence;

the first conductive layer and the second conductive layer are partially overlapped and form a plurality of overlapping areas, and the overlapping areas form a plurality of capacitors and are used as stretching sensors;

the first protective layer is attached to or worn on a measured body, and when the measured body deforms, the shape of the stretching sensor changes together;

the first and second conductive layers each comprise a mixture of silicone and carbon black.

Further, the first conducting layer and the second conducting layer both comprise a plurality of electrode strips which are arranged in a non-uniform grid mode, and the electrode strips of the first conducting layer and the electrode strips of the second conducting layer are partially overlapped to form a plurality of capacitors.

Furthermore, one side of the electrode strips is connected with a PCB board used for measuring the capacitance of the capacitor.

Further, the plurality of capacitors are laid out into one or more sensor arrays, and when laid out into a plurality of sensor arrays, reading can be performed in parallel.

Further, the silicone is kenter RTV4420 silicone.

Further, the measured body is a human body, and the first protective layer is worn on a wrist, an elbow or a finger of the human body.

In a second aspect, an embodiment of the present invention provides a method for manufacturing a motion capture sensor device as described in any one of the above, where the method for manufacturing includes:

step S1, casting a first protective layer;

step S2, casting a first conductive layer using a mixture of silicone and carbon black;

step S3, etching patterns on the cast first conductive layer;

step S4, casting a dielectric layer;

step S5, casting a second conductive layer using a mixture of silicone and carbon black;

step S6, etching patterns on the cast second conductive layer;

step S7, casting a second protective layer;

and step S8, cutting a required contour of the motion capture sensor device after layer-by-layer casting.

Further, before the step S3, the manufacturing method further includes:

the motion capture sensor device after casting the first conductive layer was cured in an oven at 100 ℃ for 20 minutes.

Advantageous effects

The motion capture sensor device provided by the invention does not need sight, is low in price and can be suitable for real-time acquisition of deformation of a dense non-rigid surface.

Compared with the vision-based method, our motion capture sensor device does not require installation of multiple calibration cameras in the environment, does not need to contend with visual clutter (self-occlusion) and difficult lighting conditions, can accurately capture deformations even under severe occlusion or partially unobservable conditions, and can be suitable for outdoor use.

Compared with other existing sensing modes, the motion capture sensor device can estimate deformation of a dense surface, is not limited to rigid deformation, can be used for non-skeleton three-dimensional deformation, such as expansion of muscles below clothes, is high in measurement accuracy and low in cost, and can capture motion deformation in real time.

Drawings

FIG. 1 is a schematic diagram of a motion capture sensor apparatus according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a motion capture sensor apparatus according to an embodiment of the present invention;

FIG. 3 is a pattern of a second conductive layer according to an embodiment of the present invention;

FIG. 4 is a pattern of a first conductive layer according to an embodiment of the present invention;

FIG. 5 is a schematic view of a stretch sensor formed according to the superposition of FIGS. 3 and 4;

FIG. 6 is a schematic layout of the stretch sensors of a motion capture sensor arrangement according to an embodiment of the present invention;

FIG. 7 is a schematic view of the motion capture sensor apparatus according to FIG. 6 worn on a human bicep;

FIG. 8 is a schematic view of a motion capture sensor apparatus according to an embodiment of the present invention worn on an elbow of a human being;

FIG. 9 is a diagram illustrating the effect of real-time reconstruction of a motion capture sensor device in a motion capture system, according to an embodiment of the present invention;

fig. 10 is a flow chart illustrating a method of manufacturing a motion capture sensor device according to an embodiment of the invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In an implementation of the present invention, there is provided a motion capture sensor device, as shown in fig. 1-2, comprising:

a first protective layer 11, a first conductive layer 12, a dielectric layer 13, a second conductive layer 14 and a second protective layer 15, which are sequentially provided;

the first conductive layer 12 and the second conductive layer 14 are partially overlapped and form a plurality of overlapping regions which form a plurality of capacitors and function as the tension sensor 16;

the first protective layer 11 is attached to or worn on the measured body, and when the measured body deforms, the shape of the stretching sensor 16 changes together;

first conductive layer 12 and second conductive layer 14 each comprise a mixture of silicone and carbon black.

The measured object can be, but is not limited to, a human body, an object or an animal body, and the first protective layer 11 can be worn on a wrist, an elbow or a finger of the human body.

Among them, the present invention is based on two observations discovered by the inventors: (1) it has recently become possible to produce soft, stretchable sensor arrays entirely from silicone (2) modern data-driven techniques are available to map the resulting sensor readings to posture, and are no longer relevant to bone transitions.

Further, the first conductive layer 12 and the second conductive layer 14 each include a plurality of electrode bars 17 arranged in a non-uniform grid, and the electrode bars 17 of the first conductive layer 12 and the second conductive layer 14 are partially overlapped to form a plurality of capacitors.

Fig. 1 shows a schematic diagram of a motion capture sensor device according to an embodiment of the invention, which is shown in fig. 2 and is composed of 5 layers, a first conductive layer 12 and a second conductive layer 14 each embedded in a pattern of electrode strips 17, which when overlapped together form a capacitor, which we refer to as a stretch sensor 16.

The stretch sensor 16 is composed of a first conductive layer 12 and a second conductive layer 14, each of which may have n and k individual electrode strips 17, respectively, as shown in fig. 3 and 4. We refer to the individual electrode strips 17 but they may have any shape. The two electrode strips 17 form a local capacitor from the overlapping parts of the different layers, which we call the sensor unit S. We arrange the electrode strips 17 in a non-uniform grid, as shown in fig. 5, with each pair of electrode strips 17 of the upper and lower layers crossing at most once, i.e. s sensor cells (s ≦ kn), as shown in fig. 3 showing the pattern of the various electrode strip patterns 17 of the second conductive layer 14, fig. 4 showing the pattern of the various electrode strip patterns 17 of the first conductive layer 12, and fig. 5 is a schematic view of the stretch sensor 16 formed after being overlaid according to fig. 3 and 4. This design allows routing all electrode strips 17 to the same side of the stretch sensor 16 for capacitance measurement by connection to the PCB 18, as shown in the dashed area in fig. 5 for connection to the PCB 18.

Wherein the stretch sensor 16 is flexible and stretchable, when attached or worn on the subject, the stretch sensor 16 senses its own deformation and estimates the local surface area change during the deformation, by integrating all capacitance readings, we can obtain the area change with sufficient granularity and accuracy to reconstruct the geometry of the object given a suitable geometric prior. Therefore, these dense region measurements, in combination with a deep learning based regressor, can obtain a three-dimensional position estimate and elastic deformation optimization of surface keypoints, thus obtaining a dense deformation reconstruction. The plurality of stretch sensors 16 form a sensor array that includes a mixture of silicone and carbon black that can be used to obtain dense local area variations. The sensor array is made by placing the electrode strips 17 in two conductive layers, separated by a dielectric layer 13, together forming a non-uniform capacitive grid. The first conductive layer 12 and the second conductive layer 14 can be designed to contain custom electrode patterns by etching using a standard laser cutter. This method avoids the production of a template or mold, making the interlayer alignment very direct and accurate.

In order to solve the problem of hysteresis of the existing resistive sensors, capacitive stretch sensors 16 are used, which are based on shape variability, any change in shape: such as width w, length l, or plate-to-plate distance d, all result in a change in capacitance, and the capacitance C (in farads) of the capacitor is expressed as follows:

wherein A is the overlapping area (square meter) of the two electrodes and epsilon_rIs the dielectric constant, ∈₀Is the electrical constant and d is the spacing between the plates (meters). Assume a rectangular plate capacitor, with l its length and w its width. Although originally derived for static plate capacitors, this relationship also applies to capacitors made of silicone rubber. In order to minimize the effect of capacitive coupling with other objects, the capacitor is usually shielded by the first protective layer 11 and the second protective layer 15 as insulating layers. Using equation (1) above, it is assumed that the Poisson's ratio of the width and thickness of the sensor is the same (d/d)⁰＝w/w⁰) The length l of the stretching capacitor and the length l of the static pose can be established⁰Ratio of (a) to the capacitor C of the stretching capacitor and the static pose capacitance C⁰By continuously measuring the capacitance and then converting it to a length measurement using the following expression:

assuming conservation of volume

And constant stretching of the entire sensor unit, the capacitance ratio before and after deformation can be expressed as:

thus, if we know the current capacitance C of the sensor unit and record its rest position area A⁰And static pose capacitance C⁰We can calculate the area change between the quiescent state and the current configuration as follows:

further, a plurality of capacitors are laid out into one or more sensor arrays, and when laid out into a plurality of sensor arrays, reading can be performed in parallel.

Where fig. 5 and 6 show two sensor layouts, the stretch sensor 16 of fig. 6 is a larger sensor (300 x 250 mm) with 144 sensor cells on both sides, the sensor layout consists of four identical sub-sensors, which can be read in parallel, the layout is hand designed, a non-uniform grid, all electrode strips 17 are routed to the same side of the sensor where they are connected to a connector PCB board. The layout may be in the form of a plane or a cylinder, fig. 7 is a schematic diagram of the motion capture sensor apparatus according to fig. 6 worn on a human biceps, and fig. 8 is a schematic diagram of a motion capture sensor apparatus according to an embodiment of the invention worn on an elbow of a human.

Further, the silicone is kenter RTV4420 silicone.

Wherein, the first protective layer 11, the second protective layer 15 and the dielectric layer 13 may be prepared by mixing a kent RTV4420 component a (weight ratio ═ 1.0) and toluene (1.0), and adding a kent RTV4420 (1.0) component B; the first conductive layer 12 and the second conductive layer 14 may be formed by mixing kent RTV4420 component a (1.0) and toluene (2.0) and then adding kent RTV4420 (1.0) component B. In a separate vessel, the beneficiary graphite Ensaco 250P conductive carbon black (0.2) was mixed with isopropanol (2.0) by slowly adding the isopropanol with stirring. The two compositions were then combined and mixed for about 3 minutes. The silicone kenter RTV4420 can be used to capture large deformations because of its strong tear properties.

The motion capture sensor device provided by embodiments of the present invention can be made as a wearable, such as a flexible wearable glove, or as a prototype of wearable wrist, elbow and biceps sensors, can be used to capture deformations without line of sight by forming capacitors measuring dense regional variations from overlapping conductive regions of the first conductive layer 12 and the second conductive layer 14, can be used for data-driven reconstruction, and the data sets obtained by the motion capture sensor device provided by embodiments of the present invention can be used to train a deep neural network based regressor for pose estimation.

In order to prove the real-time capability of the device, a real-time system is designed, and an effect graph of real-time reconstruction of the motion capture sensor device in the motion capture system is shown in fig. 9, so that the reconstruction precision is high.

The motion capture sensor device provided by the embodiment of the invention does not need sight, is low in price and can be suitable for real-time acquisition of dense non-rigid surface deformation.

Compared with the vision-based method, our motion capture sensor device does not require installation of multiple calibration cameras in the environment, does not need to contend with visual clutter (self-occlusion) and difficult lighting conditions, can accurately capture deformations even under severe occlusion or partially unobservable conditions, and can be suitable for outdoor use.

Compared with other existing sensing modes, the motion capture sensor device can estimate deformation of a dense surface, is not limited to rigid deformation, can be used for non-skeleton three-dimensional deformation, such as expansion of muscles below clothes, is high in measurement accuracy and low in cost, and can capture motion deformation in real time.

In an implementation of the present invention, there is further provided a method for manufacturing any one of the motion capture sensor devices described above, as shown in fig. 10, the method comprising the steps of:

step S1, casting the first protective layer 11;

step S2, casting the first conductive layer 12 using a mixture of silicone and carbon black;

step S3, etching a pattern on the cast first conductive layer 12;

step S4, casting the dielectric layer 13;

step S5, casting the second conductive layer 14 using a mixture of silicone and carbon black;

step S6, patterning the cast second conductive layer 14;

step S7, casting the second protective layer 15;

step S8, a desired contour is cut out of the layer-by-layer cast motion capture sensor device.

Specifically, as shown in fig. 10, the motion capture sensor device is composed of two conductive layers, i.e., a first conductive layer 12 and a second conductive layer 14, with a dielectric layer 13 therebetween, and is surrounded by a first protective layer 11 and a second protective layer 15. During the manufacturing process, the motion capture sensor device is placed on a flat glass plate to which the silicone elastomer adheres well, but the final motion capture sensor device is easily separated. Dispersing organic silicon by using a blade, and casting layer by layer; kapton tape (65 μm thick) passed over the edge of the glass plate. After each layer was cast, the motion capture sensor device was cured in an oven at 100 ℃ for 20 minutes. The first conductive layer (silicone mixed with carbon black) is cast directly onto the first protective layer 11 and, after curing, the desired pattern is etched with a laser cutter. The etch was done with a 100W zettack fast 360 laser cutter. Two rounds of etching were performed using the following settings: 20 power, 60 speed and 500 pulses/inch. This will cause the carbon black to evaporate, forming nonconductive areas between the traces, while the underlying silicone layer remains intact. The dust generated can be removed carefully with isopropyl alcohol without damaging the electrodes. The motion capture sensor device is completed by adding a dielectric layer 13, a second conductive layer 14 (also etched and cleaned) and finally a second protective layer 15. The entire process took approximately 30 seconds (1 h for mixing and casting, 1h for curing, 1h for laser etching) and produced a motion capture sensor device size of 200mm x 200 mm.

In the prior art, the different layers of a multilayer sensor have to be aligned manually. High precision, wrinkle-free layered calibration is a difficult task, and for large sensors such as our motion capture sensor devices, high alignment quality can be achieved by directly casting the layers onto each other and placing the glass substrate in a laser cutter, aligned with the physical plugs, prior to etching.

The thickness of the final motion capture sensor device is about 500 μm, the thickness of the first 12 and second 14 conductive layers is 45 μm, we use four layers of tape for the first 11 and second 15 protective layers and two layers of tape for the dielectric layer 13.

We can use connectors to connect the electrode strips 17 to the PCB board for measurement. During manufacture, the connectors may be covered with tape and the remaining layers then cast. The tape is removed to re-expose the connectors before curing the respective layers.

Finally, the motion capture sensor device is cut to the desired profile shape with a laser cutter. The resulting motion capture sensor device is then pulled off the glass plate and a silicone adhesive is optionally used to close the motion capture sensor device to form a cylinder to wrap around the wrist or elbow, the effect being shown in fig. 7 or 8.

It is challenging to produce a capacitive elastomeric stretch sensor 16 whose mechanical, electrical and thermal properties all depend on the type of material used and the shape of the conductive traces or electrodes. Another challenge is that silicones are hydrophobic and thus adhesion of non-silicones is very difficult. The prior art proposes a series of methods for preparing conductive trace patterns. Most methods rely on potentially expensive intermediate tool fabrication such as screen printing masks, dies or stencils. To avoid sticking problems, a special plasma chamber is usually required for selective pre-treatment of the substrate layer, however, our process opens up possibilities for digitally designing the electrode pattern and producing it with low tolerance errors by etching away the negative sensor pattern with a standard laser cutter. However, in contrast to the prior art, our manufacturing method does not require a plasma chamber or manual alignment and bonding of the different layers. It therefore allows the production of larger sensors, i.e. motion capture sensor devices, with high alignment quality. The manufacturing method of the invention hardly needs special hardware and can manufacture large-scale high-resolution multilayer sensor arrays.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein. The scope of the invention is defined by the appended claims.

Claims (8)

1. A motion capture sensor apparatus, the apparatus comprising:

the first protective layer, the first conducting layer, the dielectric layer, the second conducting layer and the second protective layer are arranged in sequence;

the first conductive layer and the second conductive layer are partially overlapped and form a plurality of overlapping areas, and the overlapping areas form a plurality of capacitors and are used as stretching sensors;

the first protective layer is attached to or worn on a measured body, and when the measured body deforms, the shape of the stretching sensor changes together;

the first and second conductive layers each comprise a mixture of silicone and carbon black.

2. The motion capture sensor apparatus of claim 1, wherein the first and second conductive layers each comprise a plurality of electrode strips arranged in a non-uniform grid, the electrode strips of the first and second conductive layers partially overlapping to form a plurality of capacitors.

3. The motion capture sensor apparatus of claim 2, wherein a PCB board for measuring the capacitance of the capacitor is connected to one side of the plurality of electrode bars.

4. The motion capture sensor apparatus of claim 1, wherein the plurality of capacitors are arranged in one or more sensor arrays that can be read in parallel when arranged in multiple sensor arrays.

5. The motion capture sensor apparatus of claim 1, wherein the silicone is kenter RTV4420 silicone.

6. The motion capture sensor apparatus of claim 1, wherein the subject is a human body and the first protective layer is worn on a wrist, elbow, or finger of the human body.

7. A method of manufacturing a motion capture sensor device, wherein the motion capture sensor device is the motion capture sensor device of any one of claims 1 to 6, the method comprising:

step S1, casting a first protective layer;

step S2, casting a first conductive layer using a mixture of silicone and carbon black;

step S3, etching patterns on the cast first conductive layer;

step S4, casting a dielectric layer;

step S5, casting a second conductive layer using a mixture of silicone and carbon black;

step S6, etching patterns on the cast second conductive layer;

step S7, casting a second protective layer;

and step S8, cutting a required contour of the motion capture sensor device after layer-by-layer casting.

8. A method for manufacturing a motion capture sensor device, wherein before the step S3, the method further comprises:

the motion capture sensor device after casting the first conductive layer was cured in an oven at 100 ℃ for 20 minutes.

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