Patent Description:
Despite the progress made in these display technologies, there is a need in the art for improved methods, systems, and devices related to augmented reality systems, particularly, display systems.

The present invention relates generally to localization (position, orientation, and/or distance) of a peripheral device. More particularly, embodiments of the present invention provide systems, devices, and methods for localization of a handheld device with respect to a wearable device. Although portions of the present disclosure are described in reference to an augmented reality (AR) system, the disclosure is applicable to a variety of applications. Optional features are defined by the dependent claims.

In accordance with a first example, a method of performing localization of a handheld device with respect to a wearable device is provided. The method may include obtaining, by at least one sensor mounted to the handheld device, handheld data indicative of movement of the handheld device with respect to the world. In some example, obtaining the handheld data includes detecting, by an inertial measurement unit (IMU) mounted to the handheld device, linear accelerations and rotational velocities of the handheld device. In some examples, obtaining the handheld data includes capturing, by a handheld camera mounted to the handheld device, a world image containing one or more features surrounding the handheld device. The method may further include obtaining, by a wearable camera mounted to the wearable device, fiducial data indicative of movement of the handheld device with respect to the wearable device. In some examples, obtaining the fiducial data includes capturing, by the wearable camera, a fiducial image containing a number of light-emitting diodes (LEDs) affixed to the handheld device of a plurality of LEDs affixed to the handheld device.

The method may further include determining the number of LEDs contained in the fiducial image. The method may further include in response to determining that the number of LEDs is equal to or greater than three, updating the position and the orientation of the handheld device with respect to the wearable device based solely on the fiducial data in accordance with a first operating state. The method may further include in response to determining that the number of LEDs is equal to one or two, updating the position and the orientation of the handheld device with respect to the wearable device based on the fiducial data and the handheld data in accordance with a second operating state. The method may further include in response to determining that the number of LEDs is equal to zero, updating the position and the orientation of the handheld device with respect to the wearable device based solely on the handheld data in accordance with a third operating state.

In accordance with a second example, a method of performing localization of a handheld device with respect to a wearable device. The method may include obtaining, by at least one sensor mounted to the handheld device, handheld data indicative of movement of the handheld device with respect to the world. The method may also include obtaining, by an imaging device mounted to a first device, fiducial data indicative of movement of the handheld device with respect to the wearable device. In some examples, the first device is either the handheld device or the wearable device. In some examples, obtaining the fiducial data includes capturing, by the imaging device, a fiducial image containing a number of fiducials affixed to a second device different than the first device. In some examples, the second device is either the handheld device or the wearable device. The method may further include determining the number of fiducials contained in the fiducial image. The method may further include based on the number of fiducials contained in the fiducial image, updating a position and an orientation of the handheld device with respect to the wearable device based on the fiducial data and the handheld data in accordance with a first operating state or a second operating state.

In some examples, obtaining the handheld data includes detecting, by an IMU mounted to the handheld device, rotational movement of the handheld device. In some examples, the imaging device is mounted to the handheld device and a plurality of fiducials including the number of fiducials are affixed to the wearable device. In some examples, the imaging device is mounted to the wearable device and a plurality of fiducials including the number of fiducials are affixed to the handheld device. In some examples, the imaging device is mounted to the handheld device and a plurality of fiducials including the number of fiducials are affixed to the wearable device. In some examples, obtaining the handheld data includes capturing, by a second handheld imaging device mounted to the handheld device, a world image containing one or more features surrounding the handheld device. In some examples, the imaging device is mounted to the wearable device and a single fiducial including the number of fiducials is affixed to the handheld device. In such examples, obtaining the handheld data includes capturing, by a second handheld imaging device mounted to the handheld device, a world image containing one or more features surrounding the handheld device.

In some examples, the imaging device is mounted to the wearable device and a plurality of fiducials including the number of fiducials are affixed to the handheld device. In such examples, obtaining the handheld data includes capturing, by a second handheld imaging device mounted to the handheld device, a world image containing one or more features surrounding the handheld device. The method may further include in response to determining that the number of fiducials is equal to or greater than three, updating the position and the orientation of the handheld device with respect to the wearable device based on the fiducial data in accordance with a first operating state. The method may further include in response to determining that the number of fiducials is equal to one or two, updating the position and the orientation of the handheld device with respect to the wearable device based on the fiducial data and the handheld data in accordance with a second operating state. The method may further include in response to determining that the number of fiducials is equal to zero, updating the position and the orientation of the handheld device with respect to the wearable device based on the handheld data in accordance with a third operating state. In some examples, the position and the orientation of the handheld device with respect to the wearable device is updated based solely on the fiducial data in accordance with the first operating state. In some examples, the position and the orientation of the handheld device with respect to the wearable device is updated based solely on the handheld data in accordance with the third operating state.

In accordance with a third example, a system for performing localization of a handheld device with respect to a wearable device is provided. The system may include the wearable device. The system may also include the handheld device. The system may further include one or more processors communicatively coupled to the wearable device and the handheld device. In some examples, the one or more processors are configured to perform operations including obtaining, by at least one sensor mounted to the handheld device, handheld data indicative of movement of the handheld device with respect to the world. The operations may also include obtaining, by an imaging device mounted to a first device, fiducial data indicative of movement of the handheld device with respect to the wearable device. In some examples, the first device is either the handheld device or the wearable device. In some examples, obtaining the fiducial data includes capturing, by the imaging device, a fiducial image containing a number of fiducials affixed to a second device different than the first device. In some examples, the second device is either the handheld device or the wearable device. The operations may further include determining the number of fiducials contained in the fiducial image. The operations may further include based on the number of fiducials contained in the fiducial image, updating a position and an orientation of the handheld device with respect to the wearable device based on the fiducial data and the handheld data in accordance with a first operating state or a second operating state.

In some examples, obtaining the handheld data includes detecting, by an IMU mounted to the handheld device, rotational movement of the handheld device. In some examples, the imaging device is mounted to the handheld device and a plurality of fiducials including the number of fiducials are affixed to the wearable device. In some examples, the imaging device is mounted to the wearable device and a plurality of fiducials including the number of fiducials are affixed to the handheld device. In some examples, the imaging device is mounted to the handheld device and a plurality of fiducials including the number of fiducials are affixed to the wearable device. In such examples, obtaining the handheld data includes capturing, by a second handheld imaging device mounted to the handheld device, a world image containing one or more features surrounding the handheld device. In some examples, the imaging device is mounted to the wearable device and a single fiducial including the number of fiducials is affixed to the handheld device. In such examples, obtaining the handheld data includes capturing, by a second handheld imaging device mounted to the handheld device, a world image containing one or more features surrounding the handheld device. In some examples, the imaging device is mounted to the wearable device and a plurality of fiducials including the number of fiducials are affixed to the handheld device. In such examples, obtaining the handheld data includes capturing, by a second handheld imaging device mounted to the handheld device, a world image containing one or more features surrounding the handheld device.

In some examples, the operations further include in response to determining that the number of fiducials is equal to or greater than three, updating the position and the orientation of the handheld device with respect to the wearable device based on the fiducial data in accordance with a first operating state. In some examples, the operations further include in response to determining that the number of fiducials is equal to one or two, updating the position and the orientation of the handheld device with respect to the wearable device based on the fiducial data and the handheld data in accordance with a second operating state. In some examples, the operations further include in response to determining that the number of fiducials is equal to zero, updating the position and the orientation of the handheld device with respect to the wearable device based on the handheld data in accordance with a third operating state.

Numerous benefits are achieved by way of the present invention over conventional techniques. For example, embodiments of the present invention offer higher accuracy localization of a handheld device than conventional techniques, such as electromagnetic tracking systems which employ a series of magnetic coils. Embodiments of the present invention may also make use of hardware already being utilized by an AR system, such as the front-facing or side-facing world cameras equipped on the head set. Embodiments may extend beyond AR systems and into any application where localization of one device with respect to another device is important. Other benefits of the present invention will be readily apparent to those skilled in the art.

In conventional virtual reality (VR) or augmented reality (AR) systems, six degrees of freedom tracking of a peripheral device is achieved by incorporating a series of electromagnetic sensors and emitters that are strategically placed on the user's AR headset, belt pack, and/or other ancillary devices (e.g., totems, haptic devices, gaming instruments, etc.). Typically, electromagnetic tracking systems include at least one electromagnetic field emitter and at least one electromagnetic field sensor. Because the emitted electromagnetic fields have a known distribution, the detected fields may be analyzed to determine a position and/or orientation of the peripheral device. Although such systems offer a simple solution to the localization problem, there is a need for additional solutions that offer higher accuracy localization. Embodiments of the present invention can replace or supplement electromagnetic tracking systems.

Embodiments of the present invention provide a visual tracking system for performing high-accuracy localization of a handheld device (e.g., a totem) with respect to a wearable device (e.g., a head set). An imaging device is mounted to one of the devices and may capture an image of one or more fiducials affixed to the other device. An additional imaging device may be mounted to the handheld device for capturing various environmental markers. Based on the number of fiducials in the captured image, different data processing schemes may be implemented that utilize fiducial data (i.e., data based on the fiducial image having a local reference) and handheld data (data gathered from sensors mounted to the handheld device having a world reference) differently. Each data processing scheme, referred to herein as an operating state, may enable accurate estimation of the position and/or orientation of the handheld device with respect to the wearable device. The tracking system may inform the AR system of the estimated localization, and the AR system may use the localization information to generate virtual content that feels comfortable to the user.

<FIG> illustrates an AR scene as viewed through a wearable AR device according to an embodiment described herein. An AR scene <NUM> is depicted wherein a user of an AR technology sees a real-world park-like setting <NUM> featuring people, trees, buildings in the background, and a concrete platform <NUM>. In addition to these items, the user of the AR technology also perceives that he "sees" a robot statue <NUM> standing upon the real-world platform <NUM>, and a cartoon-like avatar character <NUM> flying by, which seems to be a personification of a bumble bee, even though these elements (character <NUM> and statue <NUM>) do not exist in the real world. Due to the extreme complexity of the human visual perception and nervous system, it is challenging to produce a VR or AR technology that facilitates a comfortable, natural-feeling, rich presentation of virtual image elements amongst other virtual or real-world imagery elements.

<FIG> illustrates various possible components of an AR system. In the illustrated embodiment, an AR system user <NUM> is depicted wearing a head mounted component <NUM> featuring a frame <NUM> structure coupled to a display system <NUM> positioned in front of the eyes of the user. A speaker <NUM> is coupled to frame <NUM> in the depicted configuration and is positioned adjacent the ear canal of the user (in one embodiment, another speaker, not shown, is positioned adjacent the other ear canal of the user to provide for stereo/shapeable sound control). Display <NUM> is operatively coupled (as indicated by <NUM>), such as by a wired lead or wireless connectivity, to a local processing and data module <NUM> which may be mounted in a variety of configurations, such as fixedly attached to frame <NUM>, fixedly attached to a helmet or hat, removably attached to the torso of user <NUM> in a backpack-style configuration, or removably attached to the hip of user <NUM> in a belt-coupling style configuration.

Local processing and data module <NUM> may comprise a power-efficient processor or controller, as well as digital memory, such as flash memory, both of which may be utilized to assist in the processing, caching, and storage of data a) captured from sensors which may be operatively coupled to frame <NUM>, such as image capture devices (such as cameras), microphones, inertial measurement units, accelerometers, compasses, GPS units, radio devices, and/or gyroscopes; and/or b) acquired and/or processed using remote processing module <NUM> and/or remote data repository <NUM>, possibly for passage to display <NUM> after such processing or retrieval.

Local processing and data module <NUM> may be operatively coupled (as indicated by <NUM>, <NUM>), such as via wired or wireless communication links, to remote processing module <NUM> and remote data repository <NUM> such that these remote modules <NUM>, <NUM> are operatively coupled to each other and available as resources to local processing and data module <NUM>. In one embodiment, remote processing module <NUM> may comprise one or more relatively powerful processors or controllers configured to analyze and process data and/or image information. In one embodiment, remote data repository <NUM> may comprise a relatively large-scale digital data storage facility, which may be available through the internet or other networking configuration in a "cloud" resource configuration. In one embodiment, all data is stored and all computation is performed in the local processing and data module, allowing fully autonomous use from any remote modules.

<FIG> illustrates an example of how a visual tracking system may be incorporated into an AR system having a wearable device <NUM> (e.g., a head set) and a handheld device <NUM> (e.g., a controller). In some embodiments, handheld device <NUM> may be a handheld controller that allows a user to provide an input to the AR system. For example, handheld device <NUM> may be a totem to be used in a gaming scenario. Handheld device <NUM> may be a haptic device and may include one or more haptic surfaces utilizing a variety of sensor types. During operation of the AR system, a user may hold handheld device <NUM> in his/her left or right hand by actively gripping handheld device <NUM> and/or by securing an attachment mechanism (e.g., a wraparound strap) to the user's hand.

Handheld device <NUM> may include one or more fiducials (referred to herein as handheld fiducials <NUM>) positioned along one or more exterior surfaces of handheld device <NUM> such that the fiducials may be within the field of view of an imaging device external to handheld device <NUM>. Handheld fiducials <NUM> may have a known relationship with respect to each other such that an imaging device may determine its position and/or orientation with respect to handheld device <NUM> by capturing an image of one or more of handheld fiducials <NUM>. Handheld fiducials <NUM> may be dynamic, static, electrically powered, unpowered, and may, in some embodiments, be distinguishable from each other. For example, a first fiducial may be a light-emitting diode (LED) having a first wavelength and a second fiducial may be an LED having a second wavelength. Alternatively or additionally, different fiducials may have different brightness and/or may pulsate at different frequencies (e.g., a first fiducial may pulsate at <NUM> and a second fiducial may pulsate at <NUM>).

Handheld device <NUM> may include one or more imaging devices (referred to herein as handheld imaging devices <NUM>) positioned in a manner such that wearable device <NUM> and/or some feature in the surroundings of handheld device <NUM> is within the field of view(s) of the imaging device(s) when handheld device <NUM> is being held by a user. For example, a front handheld imaging device 326A may be positioned such that its field of view is oriented away from the user towards one or more features in the surroundings of handheld device <NUM>, and a rear handheld imaging device 326B may be positioned such that its field of view is oriented towards wearable device <NUM>. Handheld imaging devices <NUM> may include one or more front-facing imaging devices and/or one or more rear-facing imaging devices to create a desired cumulative field of view. In some embodiments, handheld imaging devices <NUM> may be optical devices such as cameras and may capture still or moving images.

Handheld device <NUM> may include an inertial measurement unit (IMU) (referred to herein as handheld IMU <NUM>) that is rigidly secured within handheld device <NUM> such that rotational and linear movement of handheld device <NUM> is similarly experienced by handheld IMU <NUM>. In some instances, handheld IMU <NUM> may include one or more accelerometers (e.g., three), one or more gyroscopes (e.g., three), one or more magnetometers (e.g., three), and/or digital signal processing hardware and software to convert raw measurements into processed data. For example, handheld IMU <NUM> may include an accelerometer, a gyroscope, and a magnetometer for each of three axes. For each axis, handheld IMU <NUM> may output one or more of: linear position, linear velocity, linear acceleration, rotational position, rotational velocity, and/or rotational acceleration. Alternatively or additionally, handheld IMU <NUM> may output raw data from which any of the above-mentioned forms of processed data may be calculated.

Handheld device <NUM> may comprise a rechargeable and/or replaceable battery <NUM> or other power supply that powers handheld fiducials <NUM>, handheld imaging devices <NUM>, handheld IMU <NUM>, and any other components of handheld device <NUM>. Although not illustrated in <FIG>, handheld device <NUM> may include circuitry for enabling wireless communication with wearable device <NUM> and/or belt pack <NUM>. For example, upon detecting or capturing data using handheld imaging devices <NUM> and handheld IMU <NUM>, handheld device <NUM> may transmit raw or processed data to wearable device <NUM> and/or belt pack <NUM>.

Wearable device <NUM> may include one or more fiducials (referred to herein as wearable fiducials <NUM>) positioned along one or more exterior surfaces of wearable device <NUM> such that the fiducials may be within the field of view of rear handheld imaging device 326B. Wearable fiducials <NUM> may have a known relationship with respect to each other such that an imaging device may determine its position and/or orientation with respect to wearable device <NUM> by capturing an image of one or more of wearable fiducials <NUM>. Wearable fiducials <NUM> may be dynamic, static, electrically powered, unpowered, and may, in some embodiments, be distinguishable from each other. For example, a first fiducial may be an LED having a first wavelength and a second fiducial may be an LED having a second wavelength. Alternatively or additionally, different fiducials may have different brightness and/or may pulsate at different frequencies.

Wearable device <NUM> may include one or more imaging devices (referred to herein as wearable imaging device <NUM>) positioned in a manner such that handheld device <NUM> (specifically handheld fiducials <NUM>) is within the field of view(s) of the imaging device(s) when handheld device <NUM> is being held by a user. For example, one or more wearable imaging devices <NUM> may be positioned front-facing on wearable device <NUM> above, below, and/or to the side of an optical see-through component of wearable device <NUM>. In one embodiment, two wearable imaging devices <NUM> may be positioned on opposite sides of the optical see-through component of wearable device <NUM>. In some embodiments, wearable imaging devices <NUM> may be optical devices such as cameras and may capture still or moving images.

Wearable device <NUM> may include an IMU (referred to herein as wearable IMU <NUM>) that is rigidly secured within wearable device <NUM> such that rotational and linear movement of wearable device <NUM> is similarly experienced by wearable IMU <NUM>. In some instances, wearable IMU <NUM> may include one or more accelerometers (e.g., three), one or more gyroscopes (e.g., three), one or more magnetometers (e.g., three), and/or digital signal processing hardware and software to convert raw measurements into processed data. For example, wearable IMU <NUM> may include an accelerometer, a gyroscope, and a magnetometer for each of three axes. For each axis, wearable IMU <NUM> may output one or more of: linear position, linear velocity, linear acceleration, rotational position, rotational velocity, and/or rotational acceleration. Alternatively or additionally, wearable IMU <NUM> may output raw data from which any of the above-mentioned forms of processed data may be calculated.

In some embodiments, the AR system may include a belt pack <NUM>, which may include a computing apparatus (e.g., one or more processors and an associated memory) for performing a localization of handheld device <NUM> with respect to wearable device <NUM>. Alternatively or additionally, the computing apparatus may reside in wearable device <NUM> itself, or even handheld device <NUM>. The computing apparatus may receive (via a wired and/or wireless connection) raw or processed data from each of wearable IMU <NUM>, wearable imaging device <NUM>, handheld IMU <NUM>, and handheld imaging devices <NUM>, and may compute a geospatial position of handheld device <NUM> (with respect to the geospatial position of wearable device <NUM>) and an orientation of handheld device <NUM> (with respect to the orientation of wearable device <NUM>). The computing apparatus may in turn comprise a mapping database <NUM> (e.g., passable world model, coordinate space, etc.) to detect pose, to determine the coordinates of real objects and virtual objects, and may even connect to cloud resources and the passable world model, in one or more embodiments. In some embodiments, images captured using wearable imaging device <NUM> and/or handheld imaging devices <NUM> may be used to build a passable world model. For example, features may be detected in the captured images, and the collected data (for example sparse points) may be used for building the passable world model or environmental maps otherwise.

<FIG> illustrates a diagram of the localization task, as performed by the AR system, in which the position and the orientation of handheld device <NUM> are determined with respect to wearable device <NUM>. In the illustrated diagram, wearable device <NUM> has a geospatial position ("wearable position") defined as (XWP, YWP, ZWP) with respect to a world reference and an orientation ("wearable orientation") defined as (Xwo, Ywo, Zwo) with respect to a world reference. In some instances, the geospatial position of wearable device <NUM> is expressed in longitude, latitude, and elevation values and the orientation of wearable device <NUM> is expressed in pitch angle, yaw angle, and roll angle values.

As illustrated, handheld device <NUM> has a geospatial position ("handheld position") defined as (X'HP, Y'HP, Z'HP) with respect to the geospatial position of wearable device <NUM> (XWP, YWP, ZWP) and an orientation ("handheld orientation") defined as (X'HO, Y'HO, Z'HO) with respect to the orientation of wearable device <NUM> (Xwo, Ywo, Zwo). In some instances, the geospatial position of handheld device <NUM> is expressed in X, Y, and Z Cartesian values and the orientation of handheld device <NUM> is expressed in pitch angle, yaw angle, and roll angle values. As one specific example, when handheld device <NUM> is being held by a user, the geospatial position of handheld device <NUM> may be equal to (<NUM>, -<NUM>, <NUM>) and the orientation of handheld device <NUM> may be equal to (<NUM>°, -<NUM>°, <NUM>°).

<FIG> illustrates an example configuration of an AR system <NUM> in which wearable device <NUM> includes one or more wearable fiducials <NUM> and handheld device <NUM> includes one or more rear-facing handheld imaging devices <NUM> having a field of view that at least partially and at least temporarily includes wearable fiducials <NUM> while handheld device <NUM> is being held by a user in normal operation. AR system <NUM> may include additional sensors mounted to handheld device <NUM> such as handheld IMU <NUM>. One advantage of such a configuration may be that handheld device <NUM> has all the data needed to perform localization of itself with respect to wearable device <NUM>, thereby reducing the processing load on wearable device <NUM>. AR system <NUM> may include additional sensors mounted to wearable device <NUM> such as wearable IMU <NUM>.

<FIG> illustrates a method <NUM> of performing localization of handheld device <NUM> with respect to wearable device <NUM> using AR system <NUM>. One or more steps of method <NUM> may be omitted or may be performed in an order different than the illustrated embodiment, and one or more steps of method <NUM> may be performed at one or more processing apparatus located within wearable device <NUM>, handheld device <NUM>, and/or belt pack <NUM>.

At step <NUM>, an image ("fiducial image") is captured by handheld imaging device <NUM>. The fiducial image may contain a number of fiducials of wearable fiducials <NUM>. For example, if there are three wearable fiducials <NUM>, the fiducial image may be analyzed to determine that it contains zero, one, two, or three fiducials.

At step <NUM>, a position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated, for example, based on the fiducial image. For example, the fiducial image may be analyzed to determine the locations of any fiducials of wearable fiducials <NUM>, and the position and/or orientation may be determined based on the locations of the fiducial(s) within the fiducial image as well as the known physical relationship between wearable fiducials <NUM>. The position and/or orientation of handheld device <NUM> may be used to determine a pose of handheld device <NUM> with respect to wearable device <NUM>. The output of step <NUM> is referred to as fiducial data <NUM>.

At step <NUM>, data ("IMU data") indicative of at least rotational movement of handheld device <NUM> with respect to the world (and/or with respect to wearable device <NUM>) is detected by handheld IMU <NUM>. The IMU data may include rotational velocities or raw data from which rotational velocities may be calculated. In some embodiments, the IMU data is also indicative of linear movement of handheld device <NUM>, and may include linear accelerations or raw data from which linear accelerations may be calculated.

At step <NUM>, the position and/or orientation of handheld device <NUM> is calculated based on the IMU data. In some embodiments, the position and/or orientation of handheld device <NUM> with respect to the world is calculated (using previous known and/or estimated orientations with respect to the world) and/or, in some other embodiments, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated (using previous known and/or estimated orientations with respect to wearable device <NUM>).

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated based on fiducial data <NUM> and/or handheld data <NUM>. Fiducial data <NUM> may include the fiducial image and/or the position and/or orientation calculations based on the fiducial image performed in step <NUM>. Handheld data <NUM> may include the IMU data and/or the position and/or orientation calculations based on the IMU data performed in step <NUM>. The position and orientation calculation at step <NUM> may be performed in accordance with one of various operating states based on the number of fiducials found in the fiducial image. Each operating state may treat fiducial data <NUM> and handheld data <NUM> differently and may place greater emphasis on one type of data with respect to the other type of data. The operating states are described in further detail in reference to <FIG>.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is outputted, for example, to an external device and/or process for use in operating AR system <NUM>. For example, the position and/or orientation may be outputted to AR system <NUM> for generating and displaying virtual content.

<FIG> illustrates an example configuration of an AR system <NUM> in which wearable device <NUM> includes one or more wearable imaging devices <NUM> having a field of view that at least partially and at least temporarily includes handheld fiducials <NUM> while handheld device <NUM> is being held by a user in normal operation, and handheld device <NUM> includes one or more handheld fiducials <NUM>. AR system <NUM> may include additional sensors mounted to handheld device <NUM> such as handheld IMU <NUM>. One advantage of such a configuration may be the simplicity and low-power consumption of handheld device <NUM>. AR system <NUM> may include additional sensors mounted to wearable device <NUM> such as wearable IMU <NUM>.

At step <NUM>, an image ("fiducial image") is captured by wearable imaging device <NUM>. The fiducial image may contain a number of fiducials of handheld fiducials <NUM>. For example, if there are three handheld fiducials <NUM>, the fiducial image may be analyzed to determine that it contains zero, one, two, or three fiducials.

At step <NUM>, a position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated, for example, based on the fiducial image. For example, the fiducial image may be analyzed to determine the locations of any fiducials of handheld fiducials <NUM>, and the position and/or orientation may be determined based on the locations of the fiducial(s) within the fiducial image as well as the known physical relationship between handheld fiducials <NUM>. The position and/or orientation of handheld device <NUM> may be used to determine a pose of handheld device <NUM> with respect to wearable device <NUM>. The output of step <NUM> is referred to as fiducial data <NUM>.

At step <NUM>, data ("IMU data") indicative of at least rotational movement of handheld device <NUM> with respect to the world is detected by handheld IMU <NUM>. The IMU data may include rotational velocities or raw data from which rotational velocities may be calculated. In some embodiments, the IMU data is also indicative of linear movement of handheld device <NUM>, and may include linear accelerations or raw data from which linear accelerations may be calculated.

At step <NUM>, the position and/or orientation of handheld device <NUM> is calculated based on the IMU data. In some embodiments, the position and/or orientation of handheld device <NUM> with respect to the world is calculated (using previous known and/or estimated orientations with respect to the world) and/or, in some embodiments, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated (using previous known and/or estimated orientations with respect to wearable device <NUM>). The output of step <NUM> may be referred to as handheld data <NUM>.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated based on fiducial data <NUM> and/or handheld data <NUM>. Fiducial data <NUM> may include the fiducial image and/or the position and/or orientation calculations based on the fiducial image performed in step <NUM>. Handheld data <NUM> may include the IMU data and/or the position and/or orientation calculations based on the IMU data performed in step <NUM>. The position and/or orientation calculation at step <NUM> may be performed in accordance with one of various operating states based on the number of fiducials found in the fiducial image. Each operating state may treat fiducial data <NUM> and handheld data <NUM> differently and may place greater emphasis on one type of data with respect to the other type of data. The operating states are described in further detail in reference to <FIG>.

<FIG> illustrates an example configuration of an AR system <NUM> in which handheld device <NUM> includes front handheld imaging device 326A having a field of view that at least partially and at least temporarily includes one or more surrounding features <NUM> while handheld device <NUM> is being held by a user and rear handheld imaging device 326B having a field of view that at least partially and at least temporarily includes one or more wearable fiducials <NUM> while handheld device <NUM> is being held by a user in normal operation. In the example configuration, multiple wearable fiducials <NUM> are affixed to wearable device <NUM>. AR system <NUM> may include additional sensors mounted to handheld device <NUM> such as handheld IMU <NUM>. One advantage of such a configuration may be the increased accuracy provided by the multiple imaging devices. AR system <NUM> may include additional sensors mounted to wearable device <NUM> such as wearable IMU <NUM>.

At step <NUM>, an image ("fiducial image") is captured by rear handheld imaging device 326B. The fiducial image may contain a number of fiducials of wearable fiducials <NUM>. For example, if there are three wearable fiducials <NUM>, the fiducial image may be analyzed to determine that it contains zero, one, two, or three fiducials.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated based on, for example, the fiducial image. For example, the fiducial image may be analyzed to determine the locations of any fiducials of wearable fiducials <NUM>, and the position and/or orientation may be determined based on the locations of the fiducial(s) within the fiducial image as well as the known physical relationship between wearable fiducials <NUM>. The position and/or orientation of handheld device <NUM> may be used to determine a pose of handheld device <NUM> with respect to wearable device <NUM>. The output of step <NUM> is referred to as fiducial data <NUM>.

At step <NUM>, an image ("world image") is captured by front handheld imaging device 326A. The world image may contain surrounding features <NUM>.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to the world is calculated based on the world image. In some instances, the world image is compared to previous world images to estimate the movement of handheld device <NUM> using visual odometry techniques, which may include performing feature detection in each of the world images to establish correspondence between the world images. The movement vector of handheld device <NUM> that is most consistent with the movement of the detected features in the world images may then be calculated. The output of step <NUM> is referred to as handheld data <NUM>.

At step <NUM>, the position and/or orientation of handheld device <NUM> is calculated based on the IMU data. In some embodiments, the position and/or orientation of handheld device <NUM> with respect to the world is calculated (using previous known and/or estimated orientations with respect to the world) and/or, in some embodiments, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated (using previous known and/or estimated orientations with respect to wearable device <NUM>). The output of step <NUM> is referred to as handheld data <NUM>.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated based on fiducial data <NUM> and/or handheld data <NUM>. Fiducial data <NUM> may include the fiducial image and/or the position and/or orientation calculations based on the fiducial image performed in step <NUM>. Handheld data <NUM> may include the world image, the position and/or orientation calculations based on the world image performed in step <NUM>, the IMU data, and/or the position and orientation calculations based on the IMU data performed in step <NUM>. The position and/or orientation calculation at step <NUM> may be performed in accordance with one of various operating states based on the number of fiducials found in the fiducial image. Each operating state may treat fiducial data <NUM> and handheld data <NUM> differently and may place greater emphasis on one type of data with respect to the other type of data. The operating states are described in further detail in reference to <FIG>.

<FIG> illustrates an example configuration of an AR system 1100A in which wearable device <NUM> includes one or more wearable imaging devices <NUM> having a field of view that at least partially and at least temporarily includes handheld fiducials <NUM> while handheld device <NUM> is being held by a user in normal operations, and in which handheld device <NUM> includes one or more handheld imaging devices <NUM> having a field of view that at least partially and at least temporarily includes one or more surrounding features <NUM> while handheld device <NUM> is being held by a user in normal operation. In the example configuration illustrated in <FIG>, a single handheld fiducial <NUM> is affixed to handheld device <NUM>. AR system <NUM> may include additional sensors mounted to handheld device <NUM> such as handheld IMU <NUM>. Advantages of the configuration illustrated in <FIG> include the increased accuracy provided by the multiple imaging devices as well as the computational efficiency of calculating position and orientation while constrained by a single fiducial location. AR system 1100A may include additional sensors mounted to wearable device <NUM> such as wearable IMU <NUM>.

<FIG> illustrates an example configuration of an AR system 1100B in which wearable device <NUM> includes one or more wearable imaging devices <NUM> having a field of view that at least partially and at least temporarily includes handheld fiducials <NUM> while handheld device <NUM> is being held by a user in normal operation, and in which handheld device <NUM> includes one or more handheld imaging devices <NUM> having a field of view that at least partially and at least temporarily includes one or more surrounding features <NUM> while handheld device <NUM> is being held by a user in normal operation. In the example configuration illustrated in <FIG>, multiple handheld fiducials <NUM> are affixed to handheld device <NUM>. AR system 1100B may include additional sensors mounted to handheld device <NUM> such as handheld IMU <NUM>. Advantages of such a configuration include the increased accuracy provided by the multiple imaging devices as well as the increased robustness by combining fiducial-based tracking with visual odometry techniques. AR system 1100B may include additional sensors mounted to wearable device <NUM> such as a IMU.

<FIG> illustrates a method <NUM> of performing localization of handheld device <NUM> with respect to wearable device <NUM> using AR system 1100A of <FIG> or AR system 1100B of <FIG>. One or more steps of method <NUM> may be omitted or may be performed in an order different than the illustrated embodiment, and one or more steps of method <NUM> may be performed at one or more processing apparatus located within wearable device <NUM>, handheld device <NUM>, and/or belt pack <NUM>.

At step <NUM>, an image ("fiducial image") is captured by wearable imaging device <NUM>. The fiducial image may contain a number of handheld fiducials <NUM>. For example, with respect to <FIG>, if there is one handheld fiducial <NUM>, the fiducial image may be analyzed to determine that it contains zero or one fiducial. For example, with respect to <FIG>, if there are three handheld fiducials <NUM>, the fiducial image may be analyzed to determine that it contains zero, one, two, or three fiducials.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated, for example, based on the fiducial image. For example, with respect to <FIG>, the fiducial image may be analyzed to determine the location of the fiducial, and a constraint for the position and/or orientation may be determined based on the location of the fiducial within the fiducial image. For example, with respect to <FIG>, the fiducial image may be analyzed to determine the locations of any fiducials, and the position and/or orientation may be determined based on the locations of the fiducial(s) within the fiducial image as well as the known physical relationship between wearable fiducials <NUM>.

At step <NUM>, an image ("world image") is captured by handheld imaging device <NUM>. The world image may contain surrounding features <NUM>.

At step <NUM>, the position and/or orientation of handheld device <NUM> is calculated based on the IMU data. In some embodiments, the position and/or orientation of handheld device <NUM> with respect to the world is calculated (using previous known and/or estimated orientations with respect to the world) and/or, in some embodiments, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated (using known and/or estimated orientations with respect to wearable device <NUM>). The output of step <NUM> is referred to as handheld data <NUM>.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated based on fiducial data <NUM> and/or handheld data <NUM>. For example, with respect to <FIG>, fiducial data <NUM> may include the fiducial image and/or the constraint for the position and/or orientation calculation based on the fiducial image performed in step <NUM>. For example, with respect to <FIG>, fiducial data <NUM> may include the fiducial image and/or the position and/or orientation calculations based on the fiducial image performed in step <NUM>. Handheld data <NUM> may include the world image, the position and/or orientation calculations based on the world image performed in step <NUM>, the IMU data, and/or the position and/or orientation calculations based on the IMU data performed in step <NUM>. The position and/or orientation calculation at step <NUM> may be performed in accordance with one of various operating states based on the number of fiducials found in the fiducial image. Each operating state may treat fiducial data <NUM> and handheld data <NUM> differently and may place greater emphasis on one type of data with respect to the other type of data. The operating states are described in further detail in reference to <FIG>.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is outputted, for example, to an external device and/or process for use in operating AR systems <NUM>. For example, the position and/or orientation may be outputted to AR systems <NUM> for generating and displaying virtual content.

<FIG> illustrates a method <NUM> of performing localization of handheld device <NUM> with respect to wearable device <NUM> using any one of AR systems <NUM>, <NUM>, <NUM>, <NUM> or any combination thereof. One or more steps of method <NUM> may be omitted or may be performed in an order different than the illustrated embodiment, and one or more steps of method <NUM> may be performed at one or more processing apparatus located within wearable device <NUM>, handheld device <NUM>, and/or belt pack <NUM>.

At step <NUM>, data ("fiducial data") indicative of movement of handheld device <NUM> with respect to wearable device <NUM> is obtained using an imaging device. Performing step <NUM> may including performing one or both of steps <NUM>, <NUM>. At step <NUM>, an image ("fiducial image") containing a number of wearable fiducials <NUM> is captured by rear handheld imaging device 326B. At step <NUM>, an image ("fiducial image") containing a number of handheld fiducials <NUM> is captured by wearable imaging device <NUM>.

At step <NUM>, data ("handheld data") indicative of at least rotational movement of handheld device <NUM> with respect to the world is detected. Performing step <NUM> may include performing one or both of steps <NUM>, <NUM>.

At step <NUM>, an image ("world image") is captured by front handheld imaging device 326A containing surrounding features <NUM>. At step <NUM>, data ("IMU data") indicative of at least rotational movement of handheld device <NUM> with respect to the world is detected by handheld IMU <NUM>. The IMU data may include rotational velocities or raw data from which rotational velocities may be calculated. In some embodiments, the IMU data is also indicative of linear movement of handheld device <NUM>, and may include linear accelerations or raw data from which linear accelerations may be calculated.

At step <NUM>, the number of fiducials contained in the fiducial image is determined as well as the locations (e.g., pixel locations) of the observed fiducials.

At step <NUM>, the position and/or orientation of handheld device <NUM> with respect to wearable device <NUM> is calculated/estimated/updated in accordance with one of three operating states. An operating state is selected based on the number of fiducials that are observed in the fiducial image. In the illustrated embodiment, the first operating state ("State <NUM>") is selected when three or more fiducials are observed in the fiducial image, the second operating state ("State <NUM>") is selected when one or two fiducials are observed in the fiducial image, and the third operating state ("State <NUM>") is selected when zero fiducials are observed in the fiducial image. Switching between states may occur each time a new fiducial image is captured or at predetermined intervals. For example, step <NUM> may be performed at each camera frame based on one or both of the fiducial data (e.g., the fiducial image) and the handheld data (e.g., the world image and the IMU orientation). Step <NUM> may further incorporate previous position and/or orientation calculations to improve estimation accuracy.

In accordance with the first operating state ("State <NUM>"), the position and/or orientation may be calculated (in full six degrees of freedom) with high accuracy, for example, based solely on the fiducial data. When four or more fiducials are observed, the position can be completely solved for. When exactly three fiducials are observed, two possible solutions to the position exist, one of which can be discarded based on additional processing and/or comparisons to previously calculated positions. In some embodiments, the handheld data may be used to supplement and improve the calculation accuracy. In some embodiments, an extended Kalman filter may be employed to improve accuracy based on previous position and/or orientation calculations.

In accordance with the second operating state ("State <NUM>"), the position and/or orientation may be calculated, for example, using both the fiducial data and the handheld data. When two fiducials are observed, the fiducial data enables a constrained position and/or orientation to be calculated, and the handheld data may be used to complete the calculation under the constraint imposed by the fiducial data. In some embodiments, an extended Kalman filter may be employed to improve accuracy based on previous position and/or orientation calculations. Calculations performed under the second operating state may overall be less accurate than calculations performed under the first operating state.

In accordance with the third operating state ("State <NUM>"), the position and orientation may be calculated, for example, based solely on the handheld data (i.e., dead reckoning). In some embodiments, an extended Kalman filter may be employed to improve accuracy based on previous position and/or orientation calculations. Calculations performed under the third operating state may overall be less accurate than calculations performed under the first or second operating states.

At step <NUM>, IMU bias corrections are performed to increase the accuracy of the IMU data provided as inputs at step <NUM>. Because the IMU data may drift over time, periodic updates can recalibrate the IMU data. In some embodiments, bias updates are only provided when the first operating state is selected and high-accuracy bias updates can be provided. In some embodiments, bias updates are provided when either the first operating state or the second operating state is selected, as both states utilize fiducial data in their calculations. Bias updates can be provided at each camera frame or at predetermined intervals.

<FIG> illustrates a simplified computer system <NUM> according to some embodiments described herein. <FIG> provides a schematic illustration of one example of computer system <NUM> that can perform some or all of the steps of the methods provided by various embodiments. It should be noted that <FIG> is meant only to provide a generalized illustration of various components, any or all of which may be utilized as appropriate. <FIG>, therefore, broadly illustrates how individual system elements may be implemented in a relatively separated or relatively more integrated manner.

Computer system <NUM> is shown comprising hardware elements that can be electrically coupled via a bus <NUM>, or may otherwise be in communication, as appropriate. The hardware elements may include one or more processors <NUM>, including without limitation one or more general-purpose processors and/or one or more special-purpose processors such as digital signal processing chips, graphics acceleration processors, and/or the like; one or more input devices <NUM>, which can include without limitation a mouse, a keyboard, a camera, and/or the like; and one or more output devices <NUM>, which can include without limitation a display device, a printer, and/or the like.

Computer system <NUM> may further include and/or be in communication with one or more non-transitory storage devices <NUM>, which can comprise, without limitation, local and/or network accessible storage, and/or can include, without limitation, a disk drive, a drive array, an optical storage device, a solid-state storage device, such as a random access memory ("RAM"), and/or a read-only memory ("ROM"), which can be programmable, flash-updateable, and/or the like. Such storage devices may be configured to implement any appropriate data stores, including without limitation, various file systems, database structures, and/or the like.

Computer system <NUM> might also include a communications subsystem <NUM>, which can include without limitation a modem, a network card (wireless or wired), an infrared communication device, a wireless communication device, and/or a chipset such as a Bluetooth™ device, an <NUM> device, a WiFi device, a WiMax device, cellular communication facilities, etc., and/or the like. The communications subsystem <NUM> may include one or more input and/or output communication interfaces to permit data to be exchanged with a network such as the network described below to name one example, other computer systems, television, and/or any other devices described herein. Depending on the desired functionality and/or other implementation concerns, a portable electronic device or similar device may communicate image and/or other information via the communications subsystem <NUM>. In other embodiments, a portable electronic device, e.g. the first electronic device, may be incorporated into computer system <NUM>, e.g., an electronic device as an input device <NUM>. In some embodiments, computer system <NUM> will further comprise a working memory <NUM>, which can include a RAM or ROM device, as described above.

Computer system <NUM> also can include software elements, shown as being currently located within the working memory <NUM>, including an operating system <NUM>, device drivers, executable libraries, and/or other code, such as one or more application programs <NUM>, which may comprise computer programs provided by various embodiments, and/or may be designed to implement methods, and/or configure systems, provided by other embodiments, as described herein. Merely by way of example, one or more procedures described with respect to the methods discussed above, might be implemented as code and/or instructions executable by a computer and/or a processor within a computer; in an aspect, then, such code and/or instructions can be used to configure and/or adapt a general purpose computer or other device to perform one or more operations in accordance with the described methods.

A set of these instructions and/or code may be stored on a non-transitory computer-readable storage medium, such as the storage device(s) <NUM> described above. In some cases, the storage medium might be incorporated within a computer system, such as computer system <NUM>. In other embodiments, the storage medium might be separate from a computer system e.g., a removable medium, such as a compact disc, and/or provided in an installation package, such that the storage medium can be used to program, configure, and/or adapt a general purpose computer with the instructions/code stored thereon. These instructions might take the form of executable code, which is executable by computer system <NUM> and/or might take the form of source and/or installable code, which, upon compilation and/or installation on computer system <NUM> e.g., using any of a variety of generally available compilers, installation programs, compression/decompression utilities, etc., then takes the form of executable code.

For example, customized hardware might also be used, and/or particular elements might be implemented in hardware, software including portable software, such as applets, etc., or both.

As mentioned above, in one aspect, some embodiments may employ a computer system such as computer system <NUM> to perform methods in accordance with various embodiments of the technology. According to a set of embodiments, some or all of the procedures of such methods are performed by computer system <NUM> in response to processor <NUM> executing one or more sequences of one or more instructions, which might be incorporated into the operating system <NUM> and/or other code, such as an application program <NUM>, contained in the working memory <NUM>. Such instructions may be read into the working memory <NUM> from another computer-readable medium, such as one or more of the storage device(s) <NUM>. Merely by way of example, execution of the sequences of instructions contained in the working memory <NUM> might cause the processor(s) <NUM> to perform one or more procedures of the methods described herein. Additionally or alternatively, portions of the methods described herein may be executed through specialized hardware.

The terms "machine-readable medium" and "computer-readable medium," as used herein, refer to any medium that participates in providing data that causes a machine to operate in a specific fashion. In embodiments implemented using computer system <NUM>, various computer-readable media might be involved in providing instructions/code to processor(s) <NUM> for execution and/or might be used to store and/or carry such instructions/code. In many implementations, a computer-readable medium is a physical and/or tangible storage medium. Such a medium may take the form of a non-volatile media or volatile media. Non-volatile media include, for example, optical and/or magnetic disks, such as the storage device(s) <NUM>. Volatile media include, without limitation, dynamic memory, such as the working memory <NUM>.

Common forms of physical and/or tangible computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, punchcards, papertape, any other physical medium with patterns of holes, a RAM, a PROM, EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other medium from which a computer can read instructions and/or code.

Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to the processor(s) <NUM> for execution. Merely by way of example, the instructions may initially be carried on a magnetic disk and/or optical disc of a remote computer. A remote computer might load the instructions into its dynamic memory and send the instructions as signals over a transmission medium to be received and/or executed by computer system <NUM>.

Specific details are given in the description to provide a thorough understanding of exemplary configurations including implementations. However, configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of the configurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the scope of the disclosure.

Also, configurations may be described as a process which is depicted as a schematic flowchart or block diagram. Although each may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process may have additional steps not included in the figure. Furthermore, examples of the methods may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments to perform the necessary tasks may be stored in a non-transitory computer-readable medium such as a storage medium. Processors may perform the described tasks.

Having described several example configurations, various modifications, alternative constructions, and equivalents may be used without departing from the scope of the disclosure. For example, the above elements may be components of a larger system, wherein other rules may take precedence over or otherwise modify the application of the technology. Also, a number of steps may be undertaken before, during, or after the above elements are considered. Accordingly, the above description does not bind the scope of the claims.

Also, the words "comprise", "comprising", "contains", "containing", "include", "including", and "includes", when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or steps, but they do not preclude the presence or addition of one or more other features, integers, components, steps, acts, or groups.

Claim 1:
A method of performing localization of a handheld device (<NUM>) with respect to a wearable device (<NUM>), the method comprising:
capturing, by a handheld imaging device (<NUM>) mounted on the handheld device (<NUM>), a world image containing one or more features surrounding the handheld device (<NUM>);
capturing, by a wearable imaging device (<NUM>) mounted on the wearable device (<NUM>), a fiducial image containing a number of fiducials (<NUM>, <NUM>) affixed to the handheld device (<NUM>);
determining the number of fiducials (<NUM>, <NUM>) contained in the fiducial image;
selecting an operating state of a plurality of operating states based on the number of fiducials (<NUM>, <NUM>) contained in the fiducial image;
in response to selecting a first operating state, updating a position and an orientation of the handheld device (<NUM>) using solely the fiducial image; and
in response to selecting a second operating state, updating the position and the orientation of the handheld device (<NUM>) using the world image and the fiducial image.