Directional transmitter / sensor for enhanced electromagnetic tracking in display systems

Abstract

The invention relates to a directional transmitter / sensor for enhancing electromagnetic tracking in a display system. The handheld controller includes an electromagnetic transmitter configured to generate an electromagnetic field characterized by an electromagnetic field pattern; and a first electromagnetic reflector positioned adjacent to the electromagnetic emitter and configured to form a modified electromagnetic field pattern. The electromagnetic tracking system also includes a head-mounted augmented reality display including an electromagnetic sensor configured to sense a pattern of an electromagnetic field; and a second electromagnetic reflector adjacent an electromagnetic sensor configured to optimally sense an electromagnetic field pattern in the region of interest.

Description

[0001] This application is a divisional application of a patent application with an application date of September 5, 2019, application number 201980057553.1, and name "Directional transmitter / sensor for electromagnetic tracking in enhanced display systems".

[0002] Cross-reference of related applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 727,489, filed on September 5, 2018, entitled “DIRECTED EMITTER / SENSOR FOR ELECTROMAGNETIC TRACKING IN AUGMENTEDREALITY SYSTEMS,” the entire disclosure of which is incorporated herein by reference for all purposes. Background Art

[0004] Modern computing and display technologies have facilitated the development of systems for so-called "virtual reality" (VR) or "augmented reality" (AR) experiences, in which digitally reproduced images, or portions thereof, are presented to a user in a manner that appears or can be perceived as real. VR scenarios generally involve presenting digital or virtual image information that is opaque to other actual real-world visual input, and AR scenarios typically involve presenting digital or virtual image information as an enhancement to the visualization of the actual real world around the user.

[0005] Despite these advances in display technology, there remains a need in the art for improved methods and systems related to augmented reality systems, and particularly display systems. Summary of the invention

[0006] The present disclosure relates to virtual reality and / or augmented reality imaging and visualization systems. The present disclosure generally relates to methods and systems related to electromagnetic tracking in virtual reality and / or augmented reality systems. More specifically, embodiments of the present disclosure provide methods and systems for directing energy transmitted by a transmitter (also referred to as a sender) and / or received by a sensor (also referred to as a receiver) to improve the performance of a positioning process. In some embodiments, a shaped electromagnetic (EM) reflector is used to modify a transmission pattern generated using an EM transmitter / received pattern received by an EM sensor. In some embodiments, an unshaped EM pattern is susceptible to deformation, which may affect its ability to accurately determine position and orientation. In some embodiments, a shaped EM field can minimize deformation and can increase field strength. As a result, the field strength near the electromagnetic sensor is increased. Similarly, the receiving capability of the electromagnetic sensor in the direction of the electromagnetic transmitter is improved. These modifications can improve positioning information, improve power consumption efficiency, reduce EM deformation, and reduce the size of the electromagnetic transmitter and / or electromagnetic sensor. The present disclosure is applicable to various applications in computer vision and image display systems.

[0007] According to an embodiment of the present invention, an electromagnetic tracking system is provided. The electromagnetic tracking system includes a handheld controller, which includes: an electromagnetic transmitter configured to generate an electromagnetic field characterized by an electromagnetic field pattern; and a first electromagnetic reflector positioned adjacent to the electromagnetic transmitter and configured to form a modified electromagnetic field pattern. The electromagnetic tracking system also includes a head-mounted augmented reality display, which includes: an electromagnetic sensor configured to sense the modified electromagnetic field; and a second electromagnetic reflector adjacent to the electromagnetic sensor configured to optimally sense the modified electromagnetic field pattern in an area of ​​interest.

[0008] According to a particular embodiment of the present invention, a method of operating an electromagnetic tracking system is provided. The method includes generating an electromagnetic field using an electromagnetic transmitter; and reflecting the electromagnetic field using a first electromagnetic reflector to form a modified electromagnetic field pattern. The method also includes reflecting a portion of the modified electromagnetic field pattern using a second electromagnetic reflector; and sensing the reflected portion of the modified electromagnetic field pattern using an electromagnetic sensor adjacent to the second electromagnetic reflector.

[0009] Many advantages over conventional techniques are obtained through the present disclosure. For example, embodiments of the present disclosure provide methods and systems for increasing electromagnetic field strength in a predetermined manner. Thus, the system can achieve desired functions while reducing transmit power, reducing component size, reducing or avoiding EM deformation, etc. These and other embodiments of the present disclosure and their many advantages and features are described in more detail in conjunction with the following text and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A system diagram of an electromagnetic (EM) tracking system is schematically shown in accordance with some embodiments.

[0011] Figure 2 is a flow chart describing the operation of an electromagnetic tracking system according to some embodiments.

[0012] Figure 3 An electromagnetic tracking system in combination with an augmented reality (AR) system according to some embodiments is schematically illustrated.

[0013] Figure 4 is a flow chart describing the functionality of an electromagnetic tracking system in the context of an AR device, according to some embodiments.

[0014] Figure 5 is a plan view of an electromagnetic transmitter and corresponding electromagnetic field lines according to some embodiments.

[0015] Figure 6 is a plan view of an electromagnetic transmitter incorporating a double-sided reflector and corresponding electromagnetic field lines according to some embodiments.

[0016] Figure 7 is a plan view of an electromagnetic transmitter incorporating a segmented reflector and corresponding electromagnetic field lines according to some embodiments.

[0017] Figure 8 is a plan view of an electromagnetic transmitter incorporating a three-sided reflector and corresponding electromagnetic field lines according to some embodiments

[0018] Fig. 9 is a plan view of an electromagnetic transmitter incorporating a hemispherical reflector and corresponding electromagnetic field lines according to some embodiments.

[0019] Fig. 10A is a perspective view showing the integration of an electromagnetic transmitter incorporating a three-sided reflector with a handheld controller according to some embodiments.

[0020] Fig. 10B is a perspective view showing the integration of an electromagnetic sensor incorporating a three-sided reflector with a head-mounted device according to some embodiments.

[0021] Fig. 10C It is shown Fig. 10B A perspective view of an expanded view of the sensor housing is shown.

[0022] Fig.11 is a simplified flow chart illustrating a method of operating an electromagnetic tracking system incorporating an integrated reflector in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In an augmented reality (AR) system, the AR system may be designed to interact with a user. As an example, a user may be provided with a handheld controller, also referred to as a totem, which the user may utilize to interact with the AR system. Therefore, it is useful to have the ability to determine the position and orientation (e.g., 6 degrees of freedom (DOF) pose) of the totem relative to other elements of the AR system, including a head-mounted display system (also referred to as a head-mounted device or AR headset) worn by the user.

[0024] One method of achieving high-precision positioning may involve the use of electromagnetic fields (EM), such as those emitted by an electromagnetic field transmitter that is coupled to an electromagnetic field sensor strategically placed on the user's AR headset, belt pack, and / or other auxiliary devices (e.g., totems, tactile devices, gaming tools, etc.). An electromagnetic tracking system typically includes at least one electromagnetic field transmitter (generally referred to as a "transmitter") and at least one electromagnetic field sensor (generally referred to as a "sensor"). The transmitter generates an electromagnetic field with a known spatial (and / or temporal) distribution in the user environment of the AR headset. The sensor measures the electromagnetic field generated at the location of the sensor. Based on these measurements and knowledge of the distribution of the generated electromagnetic field, the posture (e.g., position and / or orientation) of the sensor relative to the transmitter can be determined. Therefore, the posture of the object to which the sensor and / or transmitter is attached can be determined. That is, the relative position of the sensor and the transmitter can be determined.

[0025] Reference now Figure 1 , which shows an example system diagram of an electromagnetic tracking system. In some embodiments, the electromagnetic tracking system includes one or more electromagnetic field transmitters 102 (generally referred to as "transmitters 102") configured to emit a known electromagnetic field. Figure 1 As shown, the transmitter 102 can be coupled to a power source 110 (eg, electrical current, battery, etc.) that provides power to the transmitter 102 .

[0026] In some embodiments, the transmitter 102 includes a number of coils that generate an electromagnetic field (e.g., at least three coils positioned perpendicular to each other to generate fields in the X, Y, and Z directions). The electromagnetic field is used to establish a coordinate space (e.g., an XYZ Cartesian coordinate space). This allows the system to map the position of the electromagnetic sensors 104a, 104b relative to the known electromagnetic field (e.g., (X, Y, Z) position) and determine the position and / or orientation of the electromagnetic sensors 104a, 104b. In some embodiments, the electromagnetic sensors 104a, 104b (generally referred to as "sensors" 104) can be attached to one or more real objects. The sensor 104 may include a coil in which a current is induced by an electromagnetic field (e.g., an electromagnetic field emitted by the transmitter 102). The sensor 104 may include coils or loops (e.g., at least three coils positioned perpendicular to each other) coupled together in a small structure such as a cube or other container, which are positioned / oriented to capture incoming electromagnetic flux from an electromagnetic field (e.g., the electromagnetic field emitted by the transmitter 102), and by comparing the currents induced through the coils, and knowing the positioning and orientation of the coils relative to each other, the relative position and orientation of the sensor 104 with respect to the transmitter 102 can be calculated.

[0027] One or more parameters related to the characteristics of the coil and inertial measurement unit ("IMU") components operably coupled to the sensor 104 may be measured to detect the position and / or orientation of the sensor 104 (and the object to which it is attached) relative to the coordinate system to which the transmitter 102 is coupled. In some embodiments, multiple sensors 104 may be used relative to the transmitter 102 to detect the position and orientation of each sensor 104 within the coordinate space. The electromagnetic tracking system may provide a position in three directions (e.g., X, Y, and Z directions) and may also provide two or three orientation angles. In some embodiments, the measurements of the IMU may be compared with the measurements of the coil to determine the position and orientation of the sensor 104. In some embodiments, electromagnetic (EM) data and IMU data and various other data sources (such as cameras, depth sensors, and other sensors) may be combined to determine the position and orientation. This information may be sent (e.g., via wireless communication, Bluetooth, etc.) to the controller 106. In some embodiments, the posture (or position and orientation) may be reported at a relatively high refresh rate in a conventional system. Conventionally, the electromagnetic field transmitter is coupled to a relatively stable and large object, such as a table, operating table, wall or ceiling, and one or more sensors are coupled to a smaller object, such as a medical device, a handheld game component, etc. Alternatively, as described below with reference to Figure 3As described, various features of an electromagnetic tracking system can be used to produce a configuration in which changes or variations in position and / or orientation between two objects moving in space relative to a more stable global coordinate system can be tracked; in other words, Figure 3 A configuration is shown in which changes in an electromagnetic tracking system can be used to track deltas (changes) in position and orientation between a head-mounted component and a handheld component, while the pose of the head relative to a global coordinate system (e.g., the user's local room environment) is otherwise determined, such as using an outward-facing capture camera that can be coupled to the head-mounted component of the system, using simultaneous localization and mapping ("SLAM") techniques.

[0028] The controller 106 can control the transmitter 102 and can also capture data from the sensor 104. It should be understood that the various components of the system can be coupled to each other by any electromechanical or wireless / Bluetooth means. The controller 106 can also include data about the known electromagnetic field and the coordinate space relative to the electromagnetic field. This information is then used to detect the position and orientation of the sensor 104 relative to the coordinate space corresponding to the known electromagnetic field.

[0029] One advantage of electromagnetic tracking systems is that they produce high-resolution and highly repeatable tracking results with minimal latency. Additionally, electromagnetic tracking systems do not have to rely on optical trackers and can easily track sensors / objects that are not within the user's line of sight.

[0030] It should be understood that the strength v of the electromagnetic field decreases as a cubic function of the distance r from the coil transmitter (e.g., transmitter 102). Therefore, an algorithm based on the distance from the transmitter 102 can be used. The controller 106 can be configured with such an algorithm to determine the position and orientation of the sensor 104 at different distances from the transmitter 102. Assuming that the strength of the electromagnetic field decreases rapidly when the sensor 104 moves away from the transmitter 102, the best results in terms of accuracy, efficiency, and low latency can be obtained at closer distances. In a typical electromagnetic tracking system, the transmitter is powered by an electric current (e.g., a plug-in power supply) and the sensor is located within a 20-foot radius of the transmitter. In many applications, including AR applications, a shorter radius between the sensor and the transmitter is more desirable.

[0031] Reference now Figure 2, briefly describing an example flow chart describing the operation of an electromagnetic tracking system according to some embodiments. At 202, a known electromagnetic field is emitted. In some embodiments, an electromagnetic field transmitter can generate an electromagnetic field. For example, each coil of the electromagnetic field transmitter can generate an electromagnetic field in one direction (e.g., X, Y, or Z). The electromagnetic field can be generated in an arbitrary waveform. In some embodiments, the electromagnetic field components along each axis can oscillate at a slightly different frequency than other electromagnetic field components along other directions. At 204, a coordinate space corresponding to the electromagnetic field can be selectively determined. For example, the controller can automatically determine the coordinate space around the transmitter and / or sensor based on the electromagnetic field. In some embodiments, the coordinate space is not determined at this stage of the method. At 206, a characteristic of a coil at a sensor (which can be attached to a known object) can be detected. For example, the current induced at the coil can be calculated. In some embodiments, the rotation or any other quantifiable characteristic of the coil can be tracked and measured. At 208, the characteristic can be used to detect the position or orientation of the sensor and / or a known object (e.g., an AR headset including a sensor) relative to the transmitter, and vice versa. For example, the controller 106 may look up a mapping table that relates the characteristics of the coils at the sensor to various positions or orientations. Based on these calculations, the position in coordinate space and the orientation of the sensor and / or transmitter may be determined.

[0032] In the context of an AR system, one or more components of the electromagnetic tracking system may need to be modified to facilitate accurate tracking of mobile components (e.g., transmitters and sensors). As described above, in many AR applications, it may be desirable to track the user's head posture and orientation. Accurately determining the user's head posture and orientation enables the AR system to display appropriate / relevant virtual content to the user. For example, a virtual scene may include a virtual monster hidden behind a real building. Depending on the posture and orientation of the user's head relative to the building, the view of the virtual monster may need to be modified to provide a realistic AR experience. Alternatively, the position and / or orientation of a totem, haptic device, or some other device that interacts with virtual content is very important for the user's interaction with the AR system. For example, in many gaming applications, an AR system can detect the position and orientation of a real object relative to virtual content. Alternatively, when a virtual interface is displayed, the position of a totem, a user's hand, a haptic device, or any other real object configured to interact with the AR system relative to the displayed virtual interface is known, so that the system understands commands, interactions, etc. Some positioning methods and other methods including optical tracking may encounter problems of high latency and low resolution, which makes it extremely challenging to render virtual content in many AR applications.

[0033] In some embodiments, Figure 1 and Figure 2The electromagnetic tracking system discussed can be adapted to an AR system to detect the position and orientation of one or more objects relative to the emitted electromagnetic field. Typical electromagnetic tracking systems usually have large, bulky electromagnetic transmitters (e.g., Figure 1 102 in ), which is problematic for head-mounted AR devices with totems, for example. However, in the context of AR systems, smaller electromagnetic transmitters (e.g., in the millimeter range) can be used to emit known electromagnetic fields.

[0034] Reference now Figure 3 , the electromagnetic tracking system can be incorporated into the AR system as shown, where the electromagnetic field transmitter 302 (generally referred to as "transmitter 302") is incorporated as part of a handheld controller 306 (generally referred to as "controller 306"). Controller 306 can move independently relative to the AR headset 301 (or belt bag 370). For example, controller 306 can be held in the hand of the user, or controller 306 can be mounted on the hand or arm of the user (for example, as a ring or bracelet or as part of a glove worn by the user). In some embodiments, controller 306 can be a totem, such as for use in a gaming scene (e.g., a multi-degree-of-freedom controller), or to provide a rich user experience in an AR environment, or to allow a user to interact with an AR system. In some embodiments, controller 306 can be a tactile device. In some embodiments, transmitter 302 can be incorporated as part of belt bag 370. Controller 306 may include a battery 310 or other power source for powering transmitter 302. It should be understood that the transmitter 302 may also include or be coupled to an IMU 350 component that is configured to help determine the position and / or orientation of the transmitter 302 relative to other components. This is particularly advantageous when both the transmitter 302 and the electromagnetic field sensor 304 (generally referred to as "sensor 304") are mobile. Figure 3 Placing the transmitter 302 in the controller 306 rather than the strap pack 370 as shown in the embodiment of the present invention helps ensure that the transmitter 302 does not compete for resources at the strap pack 370, but uses its own battery source on the controller 306. In some embodiments, the transmitter 302 can be provided on the AR headset 301, and the sensor 304 can be provided on the controller 306 or the strap pack 370. Therefore, embodiments of the present invention provide implementations in which the controller 306 is implemented as a handheld unit, while in other embodiments, the controller is implemented in the AR headset 301, but in other embodiments, the controller is implemented in an auxiliary unit (e.g., the strap pack 307). In addition, in addition to implementations in which the controller 306 is implemented in a single device, the functionality of the controller and accompanying physical components can also be distributed across multiple devices, such as the controller 306, the AR headset 301, and / or an auxiliary unit (e.g., the strap pack 307).

[0035] In some embodiments, the sensor 304 may be placed at one or more locations on the AR headset 301 along with other sensing devices such as one or more IMUs or additional electromagnetic flux capture coils 308. For example, Figure 3 As shown, sensors 304, 308 can be placed on one side or both sides of the AR headset 301. Since sensors 304, 308 can be designed to be quite small (and may not be so sensitive in some cases), multiple sensors 304, 308 can be included to improve efficiency and accuracy. In some embodiments, one or more sensors can also be placed on the belt bag 370 or any other part of the user's body. Sensors 304, 308 can wirelessly communicate with a computing device that determines the posture and orientation of sensors 304, 308 (and the AR headset 301 to which they are attached), for example, via Bluetooth. In some embodiments, the computing device can reside on the belt bag 370. In some embodiments, the computing device can reside on the AR headset 301 or the controller 306. In some embodiments, the computing device can further include a mapping database 330 (e.g., a mapping database, a cloud resource, a passable world model, a coordinate space, etc.) for detecting postures to determine the coordinates of real objects and / or virtual objects, and can even be connected to cloud resources and passable world models. In one embodiment, the controller 306 can control the timing of electromagnetic emission of the electromagnetic transmitter and sensing of the electromagnetic sensor so as to calculate the position and orientation of the electromagnetic transmitter and the electromagnetic sensor based on the field from the modified electromagnetic field pattern. In some embodiments, the position and orientation of the electromagnetic transmitter relative to the electromagnetic sensor is calculated. In other embodiments, the position and orientation of the electromagnetic sensor relative to the electromagnetic transmitter is calculated. In some embodiments, the position and orientation of the electromagnetic transmitter and the electromagnetic sensor are calculated simultaneously.

[0036] As mentioned above, some electromagnetic transmitters may be too large for AR devices. Therefore, the transmitter can be designed to be more compact using smaller components (e.g., coils) than traditional systems. However, given that the electromagnetic field strength decreases as a cubic function of the distance from the transmitter, it may be possible to use a smaller transmitter than the traditional system. Figure 1 The conventional system described in detail in has a shorter radius between the sensor 304 and the transmitter 302 (eg, approximately 3 to 3.5 feet) to reduce power consumption.

[0037] In some embodiments, in one or more embodiments, this aspect can be used to extend the life of the battery 310 that powers the controller 306 and the transmitter 302. In some embodiments, this aspect can be used to reduce the size of the coil that generates the electromagnetic field at the transmitter 302. However, to obtain the same electromagnetic field strength, the power may need to be increased. This allows the use of a compact transmitter 302 that fits compactly on the controller 306.

[0038] When using an electromagnetic tracking system for an AR device, some other changes may be made. Although this posture reporting rate is quite excellent, an AR system may require a more efficient posture reporting rate. To this end, IMU-based posture tracking can be used (in addition or alternatively). Advantageously, the IMU is kept as stable as possible to improve the efficiency of the posture detection process. The IMU can be designed to be able to remain stable for up to 50-100 milliseconds. It should be understood that some embodiments may utilize an external posture estimation module that can report posture updates at a rate of 10 to 20 Hz (for example, the IMU may drift over time). By keeping the IMU stable at a reasonable rate, the posture update rate can be significantly reduced to 10 to 20 Hz (compared to higher frequencies in traditional systems).

[0039] If the electromagnetic tracking system can run at, for example, a 10% duty circle (e.g., only pinging the ground truth once every 100 milliseconds), the AR system can save power. This means that the electromagnetic tracking system wakes up for 10 milliseconds out of every 100 milliseconds to generate a pose estimate. This can directly translate into power savings, which in turn affects the size, battery life, and cost of the AR device (e.g., AR headset 301 and / or controller 306).

[0040] In some embodiments, this can be accomplished by providing two controllers 306 (not shown) instead of Figure 3 Only one controller 306 is shown to strategically take advantage of the reduction in duty cycle. For example, a user is playing a game that requires two controllers 306, etc. Or, in a multi-user game, two users use their own controllers 306 to play the game. When two controllers 306 (e.g., two symmetrical controllers, one for each hand) are used instead of one, the controller 306 can operate with an offset duty cycle. The same concept can also be applied to controllers 306 used by two different users playing a multi-player game.

[0041] Reference now Figure 4, which describes an example flow chart describing an electromagnetic tracking system in the context of an AR device. At 402, a portable (e.g., handheld) controller (e.g., controller 306) transmits an electromagnetic field. For example, transmitter 302 transmits an electromagnetic field. At 404, an electromagnetic sensor (placed on a headset, belt pack, etc.) detects the electromagnetic field. For example, sensors 304, 308 detect the electromagnetic field. At 406, a pose (e.g., position or orientation) of the AR headset / belt pack is determined based on the characteristics of the coil / IMU at the sensor. For example, the AR headset 301 / belt pack 370 determines the pose of the AR headset 301 / belt pack 370 based on the characteristics of the sensor 304 and / or the IMU and the coil 308. At 408, the pose information is transmitted to a computing device. For example, the pose information is transmitted to a computing device in the AR headset 301 and / or the belt pack 370. At 410, a mapping database may be optionally queried to associate real world coordinates (e.g., determined for the headset / strap) with virtual world coordinates. For example, mapping database 330 may be queried to associate real world coordinates with virtual world coordinates. At 412, virtual content may be transmitted to an AR headset and displayed to a user (e.g., via a light field display as described herein). For example, virtual content may be transmitted to AR headset 301 and displayed to a user. It should be understood that the above flowchart is for illustrative purposes only and should not be construed as limiting.

[0042] Advantageously, one can use Figure 3 The AR system may use an electromagnetic tracking system similar to the electromagnetic tracking system outlined in 3D to implement gesture tracking (e.g., the position and orientation of the head, the position and orientation of totems and other controllers). This allows the AR system to project virtual content (based at least in part on the determined gestures) with greater accuracy and very low latency than optical tracking techniques. In addition, this allows the AR system to track user input devices (e.g., controller 306) with high accuracy, low power consumption (e.g., power consumption of battery 210), low latency, etc.

[0043] Figure 5 is a plan view of an electromagnetic transmitter and corresponding electromagnetic field lines according to some embodiments. Figure 5 As shown, electromagnetic wire 520 emitted by electromagnetic transmitter 510 (generally referred to as "transmitter 510") forms a closed loop that passes through the interior region of transmitter 510 along the x-direction, substantially parallel to the line connecting the poles created by transmitter 510. Figure 5 As shown, the electromagnetic field generated by transmitter 510 extends equally along both the positive and negative z-directions.

[0044] As mentioned above about Figure 3 As described, during use, a transmitter 510 (e.g., Figure 3The electromagnetic field created by the transmitter 302 in the sensor (e.g., Figure 3 The electromagnetic field emitted by the transmitter 510 extends away from the transmitter 510 in both the positive and negative z directions, so that the energy directed in the direction opposite to the direction from the transmitter 510 to the sensor is not utilized, thereby reducing the system efficiency.

[0045] In some embodiments, Figures 6 to 9 The graphs in can be based on finite element analysis of time-varying electromagnetic fields. In some embodiments, adding reflectors of various shapes and configurations at or near the coils of the transmitter and / or sensor can increase the strength of the electromagnetic wires from the transmitter and / or sensor in the region of interest (ROI). The ROI is where the most motion is active in an AR or VR system. Although the description is made with respect to the transmitter, similar reflectors can be applied to the sensor to enhance the reception capabilities of the sensor in the ROI. Figure 6 is a plan view of an electromagnetic transmitter incorporating a double-sided reflector and corresponding electromagnetic field lines according to some embodiments. Figure 6 In FIG. 1 , for clarity, only the electromagnetic field lines in the xz plane are shown, but those skilled in the art will appreciate that there will be a three-dimensional lobe pattern. Figure 8 More fully discussed, Figure 6 The design shown can be extended to three dimensions.

[0046] refer to Figure 6 , two reflective elements have been placed near the transmitter 510: a first reflective element 620 and a second reflective element 622, thereby providing an integrated electromagnetic reflector, also referred to as an integrated reflector. The transmitter 510 is oriented so that the electromagnetic field passing through the transmitter coil is aligned with the x-axis. The first reflective element 620 is oriented at a predetermined angle (e.g., a 135° angle) relative to the x-axis, and the second reflective element 622 is oriented at a predetermined angle (e.g., a 45° angle) relative to the x-axis. In other words, the first reflective element 620 is aligned with a diagonal line having a slope of -1 measured in the xz plane, and the second reflective element 622 is aligned with a diagonal line having a slope of +1 measured in the xz plane. As Figure 6 As shown, the first reflective element 620 and the second reflective element 622 are joined at a vertex 630 located at the midpoint of the emitter 510 .

[0047] The first reflective element 620 and the second reflective element 622 are made of a material having high conductivity at the operating frequency of the transmitter 510 (e.g., 27kHz to 40kHz, such as 35kHz). In some embodiments, a highly conductive metal plate (e.g., a 2mm thick copper plate) can be used to form the reflective elements 620, 622. In some embodiments, a substrate coated with a highly conductive material can be used to combine the mechanical properties of the substrate (e.g., plastic) with the electrical properties of the conductive material coated on the substrate. It is obvious to those skilled in the art that the materials used to make the first reflective element 620 and the second reflective element 622 can be appropriately applied to other reflective elements described herein. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0048] Electromagnetic field lines 610 form a single lobe oriented along the positive z-direction because the electromagnetic field established along the negative z-direction is reflected by first reflective element 620 and second reflective element 622. Because electromagnetic energy is present in the single lobe, an electromagnetic field sensor (e.g., sensor 304) positioned along the positive z-axis relative to transmitter 510 will detect a stronger electromagnetic field at a given distance from transmitter 510, thereby improving system performance.

[0049] Additionally, electromagnetic field lines 610 are characterized by a field with a higher intensity for a given lobe width. Figure 6 , the presence of reflective elements 620 and 622 causes the electromagnetic field lines 610 to compress, thereby producing a higher intensity field. The width of the electromagnetic field lines 610 characterized by half of the maximum field strength is defined as the full width half maximum of the electromagnetic field. Figure 6 As shown, for an electromagnetic field line 610 with a strength of half the maximum field strength, the width is equal to W. Therefore, Figure 6 The lobe pattern shown (which may be referred to as a modified electromagnetic field pattern) has a full width at half maximum of W. This can be compared to the electromagnetic field produced by the transmitter in the absence of the first reflective element 620 and the second reflective element 622. In the absence of the reflective elements 620 and 622, the electromagnetic field lines 610 will extend over a large area and be characterized by a full width at half maximum greater than W, which corresponds to a weaker field intensity in the ROI 640, and unwanted EM energy in the non-ROI region. Therefore, while the conventional electromagnetic field pattern produced by a conventional transmitter is characterized by an initial full width at half maximum, in some embodiments, utilizing reflective structures such as reflective elements 620 and 622 produces a modified electromagnetic field pattern characterized by a modified full width at half maximum that is less than the initial full width at half maximum. In other words, the electromagnetic field lines in the ROI 640 have a higher intensity field. Reference Figure 6, the presence of reflective elements 620 and 622 will result in an electromagnetic field that is in addition to the original electromagnetic field that would exist without reflective elements 620 and 622. In effect, this produces a modified field pattern that is much higher than the original field without reflective elements 620 and 622 in ROI 640. This can be compared to Figure 5 6. The electromagnetic field produced by the transmitter without the reflective elements 620, 622 is shown for comparison. In the absence of the reflective elements 620, 622, the electromagnetic field lines 610 will extend over a large area and the field strength in the ROI 640 will be significantly reduced. Therefore, Figure 5 The conventional electromagnetic field pattern produced by the conventional transmitter shown distributes its energy field not only in the ROI 640, but also in non-ROI areas, such as Figure 5 Utilizing reflective elements such as reflective elements 620 and 622 will produce a modified electromagnetic field pattern that is concentrated in ROI 640. In this modified pattern, the deformation caused by metal in the area with the least electromagnetic wires will be minimal. Thus, reflective elements 620 and 622 isolate the coils of the transmitter and the coils of the sensor from deformation caused by metal on the other side of reflective elements 620 and 622. Figure 6 ,as well as Figures 7 to 9 With these configurations shown, the controller 106 is able to calculate the position and orientation based on the modified field pattern.

[0050] Figure 7 7 is a plan view of an electromagnetic transmitter incorporating a segmented reflector and corresponding electromagnetic field lines according to some embodiments. The segmented reflector 720 is placed near one side of the transmitter 510. The segmented reflector 720 includes a first distal reflective element 722, a central reflective element 724, and a second distal reflective element 726. Because the elements of the segmented reflector 720 reflect the electromagnetic field established along the negative z-direction, the electromagnetic field lines 710 form a single lobe oriented along the positive z-direction. The dimensions (e.g., length) of the reflective elements 720, 724, 726, as well as the angle between the first distal reflective element 722 and the central reflective element 724, and the angle between the second distal reflective element 726 and the central reflective element 724 can be selected to control the distribution of the electromagnetic field lines 710.

[0051] In some embodiments, the length of the central reflective element 724 is equal to the length of the transmitter 510 in the x-direction, and the angles between the distal reflective elements 722, 726 and the central reflective element 724 are both 45°. The lengths of the distal reflective elements 722, 726 can be selected based on the length of the central reflective element 724. It will be apparent to those skilled in the art that an increase in the length of the distal reflective elements 722, 726 will result in less electromagnetic field in the area behind the distal reflective elements 722, 726 (opposite to the centerline of the electromagnetic field pattern). However, an increase in the length of the distal reflective elements 722, 726 will result in increased system weight and cost. In a similar manner, the angles between the central reflective element 724 and a pair of distal reflective elements 722, 726 can be appropriately changed depending on the specific application. Therefore, although Figure 7 45° equal angles are shown in FIG. 1 , but the embodiments are not limited to such implementations and configurations with other angles may also be utilized. In addition, the angles need not be equal and may be different. Those of ordinary skill in the art will recognize many variations, modifications and substitutions.

[0052] Figure 8 is a plan view of an electromagnetic transmitter incorporating a three-sided reflector and corresponding electromagnetic field lines according to some embodiments. Figure 8 In the figure, for clarity, only the electromagnetic field lines located in the xz plane are shown, but those skilled in the art will understand that there will be a three-dimensional lobe pattern with the center of the lobe along a direction orthogonal to the x-axis and extending away from the electromagnetic transmitter at an angle of 45° relative to the xz plane.

[0053] refer to Figure 8 , where three reflective elements are shown. A first reflective element 812 and a second reflective element 814 are positioned adjacent to the emitter 510. A third reflective element 816 located in the xz plane is shown by a dashed line. Figure 8 In the illustrated embodiment, the three reflective elements 812, 814, 816 are orthogonal to each other and form half of a cube structure, wherein the intersection of the three reflective elements forms the corner vertices of the cube. Figure 6 The orientation shown is at a 45° orientation. Thus, in this embodiment, the plate of the emitter 510 is oriented at a 45° orientation relative to the x-axis.

[0054] Since the first reflective element 620, the second reflective element 622, and the third reflective element 816 reflect the electromagnetic field established along the negative z-direction and the positive y-direction, the electromagnetic field lines 810 form a single lobe oriented outward from the plane of the figure along the positive z-direction and the negative y-direction. In some embodiments, the presence of the reflective elements 812, 814, 816 in the hemicube configuration results in an increase in efficiency of up to eight times and a reduction in power consumption of up to one-eighth. Alternatively, the size of the transmitter 510 can be reduced to achieve a given efficiency / power consumption. In addition, in some embodiments, the size of the transmitter 510 is reduced while achieving improved efficiency / power consumption performance. Those of ordinary skill in the art will recognize many variations, modifications, and alternatives.

[0055] Fig. 9 is a plan view of an electromagnetic transmitter incorporating a hemispherical reflector and corresponding electromagnetic field lines according to some embodiments. Fig. 9 , a portion of the hemispherical reflector 920 located in the xz plane is shown as an arc. It should be understood that the rotation of the illustrated arc about the z-axis will define the hemispherical shape of the hemispherical reflector. Since the hemispherical reflector 920 reflects the electromagnetic field established along the negative z-direction, the electromagnetic field lines 910 form a single lobe oriented along the positive z-direction.

[0056] Fig. 10A is a perspective view showing the integration of an electromagnetic transmitter incorporating a three-sided reflector with a handheld controller according to some embodiments. Fig. 10A , the handheld controller 1000 includes an electromagnetic transmitter 1010 (generally referred to as "transmitter 1010") integrated with a trihedral corner cube reflector 1020. In this example, the three sides of the reflector are located in the following planes: the first side 1022 is located in the xz plane, the second side 1024 is located in the xy plane, and the third side 1026 is located in the yz plane. The reflection of the electromagnetic field generated by the transmitter 1010 by the trihedral corner cube reflector 1020 causes the center of the three-dimensional lobe pattern generated by the transmitter 1010 to be aligned with the vector 1030, and the vector 1030 is aligned with the direction away from the intersection of the three reflector planes (in the direction of the main lines equidistant from the three axes of the trihedral corner cube reflector, where each axis corresponds to the intersection of two reflectors). As shown Fig. 10A As shown, vector 1030 starts from the origin of the xyz coordinate space and points along a line pointing to the point (1,1,1) in the xyz coordinate space, which corresponds to the center of the three-dimensional lobe pattern. When such a trihedral corner cube reflector is applied to a sensor, it will allow the sensor to sense most effectively along the main line pointing to the ROI.

[0057] In typical use, handheld controller 1000 is placed in front of the user with surface 1050 generally orthogonal to a line pointing to the user's head and the AR headset worn by the user. A line connecting surface 1050 and the user's head and orthogonal to surface 1050 is generally parallel to vector 1030. As a result, due to the increased directionality of the electromagnetic field generated by transmitter 1010, a stronger field is generated along vector 1030 and a stronger field is generated near the user's head and the AR headset worn by the user. Similarly, as described below with respect to Fig. 10B As described, the head mounted device may include sensors with corresponding trihedral corner cube reflectors (or other suitable integrated reflectors as described herein) that are configured such that maximum reception occurs in the ROI that is expected to include the transmitter, thereby providing improved system performance relative to embodiments that do not utilize reflective elements.

[0058] Fig. 10B is a perspective view showing the integration of an electromagnetic sensor incorporating a three-sided reflector with a head mounted device according to some embodiments. Fig. 10B As shown, the AR head-mounted device 301 includes a sensor housing 1075. In some embodiments, the sensor housing 1075 is installed under the right temple of the AR head-mounted device 301. Fig. 10C It is shown Fig. 10B 1075 is a perspective view of an expanded view of a sensor housing 1075 shown. Sensor housing 1075 includes an electromagnetic sensor 1070 (generally referred to as "sensor 1070") that is integrated with a trihedral corner cube reflector 1072. The trihedral corner cube reflector reflects the electromagnetic field received by sensor 1070, and such reflection causes the center of the three-dimensional lobe pattern received by sensor 1070 to be aligned with vector 1074, which is oriented in a direction away from the intersection of the three reflector planes (in the direction of the main lines equidistant from the three axes of the trihedral corner cube reflector, where each axis corresponds to the intersection of two reflectors). Fig. 10B As shown, vector 1074 starts from the origin of the xyz coordinate space and points along a line pointing to the point (1,1,1) in the xyz coordinate space, which corresponds to the center of the three-dimensional lobe pattern. It should be noted that for clarity, Fig. 10B The xyz coordinate space shown is different from Fig. 10A The coordinate space shown in Fig. 10B As shown, by applying a trihedral corner cube reflector 1072 to the sensor 1070, the sensor 1070 is allowed to sense most effectively along a main line pointing toward the emitter.

[0059] In typical use, due to Fig. 10AThe handheld controller 1000 is shown placed in front of and below the user's head, so the electromagnetic field received by the sensor housing 1075 from the transmitter will be enhanced by the presence of the trihedral cube reflector 1072. The location of the trihedral cube reflector 1072 next to the sensor 1070 results in an enhanced directionality of the electromagnetic field received by the sensor 1070. Therefore, the sensitivity of the sensor increases along the line connecting the handheld controller 1000 and the AR headset 301. In this way, the sensor 1070 has a higher sensitivity to the electromagnetic field generated near the handheld controller. Therefore, improved system performance is provided relative to embodiments that do not utilize reflective elements.

[0060] Fig.11 is a simplified flow chart illustrating a method of operating an electromagnetic tracking system incorporating an integrated reflector according to an embodiment of the present invention. The method 1100 wherein the electromagnetic tracking system includes one or more integrated electromagnetic reflectors includes generating an electromagnetic field using an electromagnetic transmitter (1100). The electromagnetic transmitter may be provided in a handheld controller as an element of the electromagnetic tracking system, the electromagnetic tracking system including the handheld controller, an auxiliary unit that may include the controller, and a head-mounted augmented reality display. The integrated electromagnetic reflector may be used with a transmitter and / or a sensor and may be a component of the present invention. Figures 6 to 9 Any integrated electromagnetic reflector shown.

[0061] The method also includes reflecting the electromagnetic field using a first electromagnetic reflector to form a modified electromagnetic field pattern (1112). The first electromagnetic reflector can be positioned adjacent to the electromagnetic transmitter. The first electromagnetic reflector can include reflective elements having various geometric properties, including two or more reflective plates that can be joined at a vertex. In other embodiments, three reflective plates are utilized and arranged to define the corner vertices of a cube. In alternative embodiments, the first electromagnetic reflector is formed as a single reflector element. As an example, the single reflector element can be about Figure 7 The segmented reflector discussed and shown, or about Fig. 9 A hemispherical reflector is discussed and illustrated.

[0062] The method also includes reflecting a portion of the modified electromagnetic field pattern using a second electromagnetic reflector (1114) and sensing the reflected portion of the modified electromagnetic field pattern using an electromagnetic sensor adjacent to the second electromagnetic reflector (1116). The method further includes controlling, using a controller, the timing of generating the electromagnetic field and sensing the reflected portion of the modified electromagnetic field, and digitally calculating the position and orientation of the electromagnetic transmitter and the electromagnetic sensor based on the modified electromagnetic field pattern.

[0063] It should be understood that Fig.11The specific steps shown provide a specific method of operating an electromagnetic transmitter incorporating an integrated reflector according to an embodiment of the present invention. According to alternative embodiments, other sequences of steps may also be performed. For example, alternative embodiments of the present invention may perform the steps outlined above in a different order. In addition, Fig.11 The various steps shown may include multiple sub-steps, which may be performed in various orders suitable for the various steps. In addition, additional steps may be added or deleted depending on the specific application. Those of ordinary skill in the art will recognize many variations, modifications, and substitutions.

[0064] It should also be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes thereof will be suggested to those skilled in the art and are included within the spirit and scope of the present application and the scope of the appended claims.

Claims

1. A head-mounted augmented reality display system, include: A handheld controller including a transmitter housing, comprising: a first electromagnetic reflector comprising three first reflective elements, the three first reflective elements forming first corner vertices of a first cube, wherein the first electromagnetic reflector defines a first coordinate space and the first corner vertices of the first cube are located at an origin of the first coordinate space; and an electromagnetic transmitter configured to generate an electromagnetic field, wherein the electromagnetic transmitter is positioned along a line pointing to point (1, 1, 1) in the first coordinate space; and Head mounted device, comprising: Right temple; left temple; and A sensor housing mounted on at least one of the right temple or the left temple, the sensor housing comprising: Electromagnetic sensors; and A second electromagnetic reflector includes three second reflective elements, wherein the three second reflective elements form second corner vertices of a second cube.

2. The head-mounted augmented reality display system according to claim 1, in, The first electromagnetic reflector generates a modified electromagnetic field having lobes along the line pointing to the point (1, 1, 1) in the first coordinate space.

3. A head-mounted augmented reality display system according to claim 2, wherein the electromagnetic field is characterized by an initial half-maximum full-width width, and the modified electromagnetic field is characterized by a modified half-maximum full-width library width that is smaller than the initial half-maximum full-width width.

4. The head-mounted augmented reality display system according to claim 2, in, The modified electromagnetic field is characterized by a higher field strength at the center of the lobe than the electromagnetic field.

5. The head mounted augmented reality display system of claim 2, further comprising a controller operable to: controlling the timing of electromagnetic emission and sensing; and Based on the modified electromagnetic field, the position and orientation of the electromagnetic transmitter and the electromagnetic sensor are digitally calculated.

6. The head-mounted augmented reality display system according to claim 5, further comprising an auxiliary unit including the controller.

7. The head mounted augmented reality display system according to claim 6, in, The auxiliary unit includes a belt pack.

8. The head-mounted augmented reality display system according to claim 6, in, The controller is distributed between the handheld controller, the head mounted device and the auxiliary unit.

9. The head-mounted augmented reality display system according to claim 1, in, The sensor housing is mounted on the right temple.

10. The head mounted augmented reality display system according to claim 1, in, The sensor housing is mounted on the left temple.

11. The head mounted augmented reality display system according to claim 1, in, The second electromagnetic reflector defines a second coordinate space, wherein the second corner vertex of the second cube is located at the origin of the second coordinate space. 12 . The head-mounted augmented reality display system according to claim 11 , wherein the three second reflective elements define a quadrant of the second coordinate space where the electromagnetic transmitter is located.

13. The head-mounted augmented reality display system according to claim 1, in, The three first reflecting elements include three reflecting plates, and the three second reflecting elements include three additional reflecting plates.

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