Patent Publication Number: US-2020282320-A1

Title: Tracks with optical markers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/538,575, filed Jul. 28, 2017, which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     One or more embodiments described herein relate to a track system with optical markers designed to provide notifications to a vehicle navigating the track system. Other embodiments are also described herein. 
     BACKGROUND 
     Track systems and vehicles designed to navigate these track systems have been used for transportation and various industrial and consumer applications. Some of the applications that use miniature track systems, such as toy train systems, are based on interconnected assemblies of individual track pieces to serve either certain entertainment or educational purposes. While physical configurations of such track systems can be customized to user&#39;s preferences and objectives, these track systems lack the ability to provide an inexpensive and easily configurable approach to achieve a higher degree of interactivity between the track system and an associated vehicle. This interactivity could assist in providing the user with additional controls and customization of the vehicle&#39;s actions. 
     SUMMARY 
     A track system for a robotic vehicle according to some embodiments is described. The track system may comprise a set of track pieces that each include a set of track coupling components to couple the track pieces in the set of track pieces together to form a track for the robotic vehicle to traverse; and a set of optical markers that each include a first set of marker coupling components, wherein the set of track pieces include a second set of marker coupling components that are complementary to the first set of marker coupling components to couple the set of optical markers to the set of track pieces. 
     A track piece according to some embodiments for use in assembling a track for a robotic vehicle is described. The track piece may comprise one or more male elements that each form a protruding joint, wherein each male element in the one or more male elements includes a lip along an outer edge of a corresponding protruding joint; and one or more female elements that each form a recessed joint and are complementary with the protruding joints, wherein each female element in the one or more female elements includes a set of tabs along a corresponding recessed joint, and wherein the set of tabs are placed in an alternating sequence along a top edge and a bottom edge of the recessed joint such that tabs along the top edge are unaligned with tabs along the bottom edge. 
     The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the disclosure includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures use like reference numbers to refer to like elements. Although the following figures depict various exemplary embodiments, alternative embodiments are within the spirit and scope of the appended claims. In the figures: 
         FIG. 1  shows a track system with optical markers, including a vehicle with optical sensing capabilities navigating the track system, according to one example embodiment. 
         FIG. 2  shows a component diagram of the vehicle with optical sensing capabilities, according to one example embodiment. 
         FIG. 3A  shows an example of a top surface of a single color optical marker, according to one example embodiment. 
         FIG. 3B  shows an example of a top surface of a two-dimensional optical marker, according to one example embodiment. 
         FIG. 4  shows a method for operating the vehicle on the track system, according to one example embodiment. 
         FIG. 5A  shows a track piece with an evenly spaced array of side positioned marker slots, according to one example embodiment. 
         FIG. 5B  shows a track piece with centrally positioned marker slots, according to one example embodiment. 
         FIG. 5C  shows a track piece with a replaceable optical marker, according to one example embodiment. 
         FIG. 6  shows example cross-section views of a replaceable optical marker and a track piece, according to one example embodiment. 
         FIG. 7  shows a track piece with a permanent optical marker, according to one example embodiment. 
         FIG. 8  shows a junction track piece with a permanent optical marker applied before a junction, according to one example embodiment. 
         FIG. 9  shows a track piece with a non-permanent adhesive optical marker, according to one example embodiment. 
         FIG. 10  shows a track piece with a magnetic optical marker, according to one example embodiment. 
         FIG. 11A  shows an optical marker with a rectangular upper surface, according to one example embodiment. 
         FIG. 11B  shows an optical marker with a circular upper surface, according to one example embodiment. 
         FIG. 12  shows a combination/sequence of optical markers, according to one example embodiment. 
         FIG. 13A  shows a cross-section of a single-sided track piece with dual recessed rails, according to one example embodiment. 
         FIG. 13B  shows a cross-section of a dual-sided track piece with dual recessed rails, according to one example embodiment. 
         FIG. 13C  shows a cross-section of a single-sided track piece with dual protruding/embossed rails, according to one example embodiment. 
         FIG. 13D  shows a cross-section of a dual-sided track piece with dual protruding/embossed rails, according to one example embodiment. 
         FIG. 13E  shows a cross-section of a single-sided track piece with a single recessed rail, according to one example embodiment. 
         FIG. 14A  shows a cross-section of a dual-recessed rail based dual-sided track piece with dual cut-through marker slots, according to one example embodiment. 
         FIG. 14B  shows a cross-section of the dual-recessed rail based dual-sided track piece with dual cut-through marker slots with an optical marker, according to one example embodiment. 
         FIG. 15  shows a track piece with a vehicle in the presence of ambient light sources, according to one example embodiment. 
         FIG. 16  shows a track piece with a vehicle and an optical marker along the side of the outer ridge of the track piece, according to one example embodiment. 
         FIG. 17A  shows an overhead view of track pieces with male and female joints, according to one example embodiment. 
         FIG. 17B  shows a cross-section of track pieces with male and female joints, according to one example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the understanding of this description. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation. 
     References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
     In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. “Coupled” is used to indicate that two or more elements, which may or may not be in direct physical or electrical contact with each other, co-operate or interact with each other. “Connected” is used to indicate the establishment of communication between two or more elements that are coupled with each other or a direct physical connection. 
       FIG. 1  shows a track system  100  with optical markers  103 , according to one example embodiment. As shown, the track system  100  includes a track  101  and a set of optical markers  103 . The track  101  may be comprised or otherwise assembled from one or more interconnected track pieces  111 . The track pieces  111  may be in various forms or styles (e.g., straight, curved right, curved left, etc.). As will be described in greater detail below, the optical markers  103  are coupled to various positions along the track  101  such that a vehicle  105  with optical sensing capabilities may detect the optical markers  103  as the vehicle  105  approaches, traverses, passes over, or is otherwise proximate the optical markers  103 . The vehicle  105  may traverse the track  101  while powered by one or more motors or while being manually pushed by a user of the track system  100 . Upon detecting an optical marker  103 , the vehicle  105  may perform an action associated with the detected optical marker  103  or a sequence/combination of two or more optical markers  103 . The use of optical markers  103  with the track system  100  may provide additional interactivity with and/or additional control over the vehicle  105 . For example, this additional interactivity and control may extend to track navigation, gamified entertainment, and/or educational purposes. Various elements of the track system  100  will be described in greater detail below by way of example. 
     As noted above, the track system  100  may include or may be otherwise associated with a vehicle  105  with optical sensing capabilities.  FIG. 2  shows a component diagram of a vehicle  105  with optical sensing capabilities, according to one example embodiment. In the example embodiment shown in  FIG. 2 , the vehicle  105  may be any device that uses an electro-mechanical mechanism  205  and a set of optical sensors  203 , which allow the vehicle  105  to detect the optical markers  103  positioned along the track  101 . However, as noted above, in some embodiments, the vehicle  105  may not include an electro-mechanical mechanism  205 , but instead is propelled manually by a user of the track system  100  and/or the vehicle  105  (e.g., a user manually pushes, pulls, or otherwise moves the vehicle  105  along the track  101 ) or may be propelled by a force external to the vehicle  105 , the track  101 , and a user (e.g., a device separate from the vehicle  105 , a user, and the track  101  that pushes, pulls, or otherwise moves the vehicle  105  along the track  101 ). The electro-mechanical mechanism  205  may include one or more motors  207  that are coupled to wheels of the vehicle  105 . The motors  207  cause the wheels to turn and propel the vehicle  105  around/along the track  101 . As will be described in greater detail below, the wheels of the vehicle  105  may be complementary to a set of rails of the track  101  (in particular, complementary to rails of track pieces  111  of the track  101 ). The motors  207  may be controlled by one or more motor controllers (not shown), which control the speed of rotation of the motors  207  (e.g., rounds per minute). As used herein, the term engine may be used synonymously with the term motor and shall designate a machine that converts one form of energy into mechanical energy. For example, the motors  207  may be electrical motors/engines that convert electricity stored in a battery of the vehicle  105  into mechanical energy. The motors  207  power the movement of the vehicle  105  on/along the track  101  in a pre-programmed, remotely controlled, or autonomous fashion. As used herein, autonomous movement is an operating mode that does not involve human interaction or involves minimal human interaction. For example, a human user may turn on the vehicle  105  (e.g., toggle a power switch of the vehicle  105 ) and place the vehicle  105  on the track  101 . After being placed on the track  101 , the vehicle  105  may traverse various portions/areas of the track  101  according to an autonomous algorithm (e.g., the vehicle  105  may utilize inputs from the optical sensors  203  (e.g., sensor data) to determine a route along the track  101  and/or a set of actions to perform while moving along the track  101 ). 
     As shown in  FIG. 2 , the vehicle  105  may include a processor  201  and a memory unit  209 . The processor  201  and the memory unit  209  are used here to represent a suitable combination of programmable data processing and storage components that perform the operations needed to implement the various functions and operations of the vehicle  105 . For example, as will be described in greater detail below, the memory unit  209  may include an optical sensing unit  211  for autonomously controlling the vehicle  105  to traverse the track  101  according to optical markers  103  positioned along the track  101 . The processor  201  may be a special purpose processor such as an application-specific integrated circuit (ASIC), a general purpose microprocessor or a microcontroller, a field-programmable gate array (FPGA), a digital signal controller, or a set of hardware logic structures (e.g., filters, arithmetic logic units, and dedicated state machines), while the memory unit  209  may refer to any suitable combination of microelectronic, non-volatile random access memory and flash memory circuits, which may be internal or external to the processor  201 . In certain embodiments, an operating system may be stored in the memory unit  209  in addition to the optical sensing unit  211 . Application programs specific to the various functions of the vehicle  105  may be stored in the memory unit  209 , which are to be run or executed by the processor  201  to perform the various functions and operations of the vehicle  105 . For example, as noted above, an optical sensing unit  211  may be stored in the memory unit  209  and may be run/executed by the processor  201 . The optical sensing unit  211  may perform various functions/operations associated with the detection and classification of the optical markers  103  and triggering notifications to the processor  201  resulting in various actions performed by the vehicle  105 , as described in greater detail below. 
     As noted above, the vehicle  105  includes a set of optical sensors  203  for detecting optical markers  103 , including characteristics of the optical markers  103  (e.g., color, shape, shading, size, etc.). For example, in some embodiments, the set of optical sensors  203  may include one or more photoresistors and/or phototransistors. These photoresistor/phototransistor based optical sensors  203  may be particularly utilized for detecting and/or identifying colors of optical markers  103 . For example, these photoresistor/phototransistor based optical sensors  203  may detect the intensity of reflected light from the surface of optical markers  103 . As used herein, an optical marker  103  includes an upper surface, which includes an associated shape and/or color, and a lower connecting element for coupling with a portion of the track  101  (in particular, coupling with complementary elements of track pieces  111 ) according to the preferences of a user. An optical marker  103  with a lighter surface color reflects a higher intensity of light compared to another optical marker  103  with a darker surface color. Accordingly, the intensity level returned by an optical sensor  203  may be used for determining the surface color of an optical marker  103 . In some embodiments, an optical sensor  203  may include an internally or externally integrated light source (e.g., a light emitting diode (LED)) to provide a local illumination of the upper surface of an optical marker  103  even in dark ambient light conditions, such that the optical sensor  203  is able to detect reflected light from the upper surface of an optical marker  103 . In some embodiments, one or more photoresistor/phototransistor based optical sensors  203  may be an infrared (IR) photoresistor or phototransistor capable of detecting the intensity of infrared reflected light from an optical marker  103  illuminated by an IR LED integrated in or otherwise associated with an optical sensor  203 . 
     Based on reflected light data collected by a set of optical sensors  203  (sometimes referred to as sensor data or raw sensor data) and transmitted to the main processor  201 , the optical sensing unit  211  may classify the surface color of an optical marker  103 . For example, using a thresholding algorithm the optical sensing unit  211  may determine the surface color of an optical marker  103  (e.g., an intensity level between a first set of threshold values corresponds to a first color, an intensity level between a second set of threshold values corresponds to a second color, etc.). In some embodiments, the optical sensing unit  211  may include data processing and calibration routines to improve the robustness of color classification under different ambient lighting conditions. 
     Although described as photoresistor/phototransistor based optical sensors  203 , in some embodiments, the set of optical sensors  203  included in the vehicle  105  may include one or more digital color sensors, which includes multiple photodiode segments for red, green, blue, and clear channels and has the computational capacity to simultaneously integrate and output color sensor data to the processor  201  using a communication interface (e.g., a two-wire Inter-Integrated Circuit (I2C) serial bus). These digital color based optical sensors  203  enable the representation of the optical markers  103  using a finite number of different colors (e.g., red, green, blue, etc.). The number of reliably detectable colors by a vehicle  105  is dependent on the performance characteristics of the set of optical sensors  203  and the processor  201 , as well as the algorithmic sophistication of the optical sensing unit  211 .  FIG. 3A  shows an example of a top surface of single color optical marker  103  according to one example embodiment. Single color optical markers  103  may be represented using a single shape (e.g., a square, circle, etc.) of a single color (e.g., red, green, etc.). The example optical sensors  203  thus far described may be used for identifying/classifying the color of a single color optical marker  103 . 
     In some embodiments, the set of optical sensors  203  included in the vehicle  105  may include one or more low resolution digital cameras, which are each capable of capturing two-dimensional (2D) images in a form of a 2D matrix of data of light intensities in either grayscale (in the visible or infrared spectrum) or red-green-blue (RGB) color forms. Such low resolution digital camera based optical sensors  203  enable optical markers  103  to be represented in 2D patterns (e.g., a pattern that includes a set of shapes that each are represented with a color (e.g., black or white)). An example of such a 2D optical marker  103  is shown in  FIG. 3B . The complexity and detailed variance of such 2D patterns used as optical markers  103  is dependent on the performance characteristics of the low resolution digital camera based optical sensors  203 , the processor  201 , and the algorithmic sophistication of the optical sensing unit  211 . 
     Although not shown in  FIG. 2 , in some embodiments, the vehicle  105  may also include components to provide audio-visual feedback to a user of the track system  100  and/or a vehicle  105 . For example, the vehicle  105  may include a speaker for playing back sounds stored in the memory unit  209  in conjunction with various actions of the vehicle  105  (e.g., output a sound upon detecting an optical marker  103  or upon identifying a particular color of an optical marker  103 ). In another example, the vehicle  105  may include single or multi-color LEDs to provide visual feedback to the user of the track system  100  and/or the vehicle  105 , and/or perform light animations upon detecting an optical marker  103  or upon identifying a particular color of an optical marker  103 . 
     Additionally, although not shown in  FIG. 2 , the vehicle  105  may include an electro-magnet component to couple the vehicle  105  to other devices. For example, an electro-magnet component may be placed on the front and/or rear of the vehicle  105  to couple the vehicle  105  with other associated devices that are capable of traversing the track  101  (e.g., other devices that include wheels that complement with corresponding rails (either raised/protruding or recessed) of the track  101 ). For example, when the track system  100  is a toy train system, such associated devices may be wagons or cars with permanent magnet couplers to which the vehicle  105  can be coupled using the electro-magnet component. In some embodiments, the described electro-magnet component of the vehicle  105  may be an electro-permanent magnet. The electro-magnet component described herein may be capable of generating a magnetic field strong enough to counter the attracting field force generated by the permanent or electro-permanent magnet of an associated device to decouple the vehicle  105  from the associated device. In some embodiments, the electro-magnet component of the vehicle  105  may be controlled by the user using a wirelessly connected controller running a companion application (e.g., a telephone, a tablet, or another similar computing platform). In other embodiments, the electro-magnet component of the vehicle  105  may be controlled using optical markers  103  detected by the vehicle  105  on the track  101 . For example, in response to detecting a particular optical marker  103  (e.g., a green optical marker  103 ) or a particular sequence of optical markers  103  (e.g., a white optical marker  103  followed by a green optical marker  103 ), the electro-magnet component may generate a magnetic field strong enough to counter the attracting field force generated by a magnet of an associated device to decouple the vehicle  105  from the associated device. 
     Turning now to  FIG. 4 , a method  400  will be described for operating the vehicle  105  on the track system  100 , according to one example embodiment. Each operation of the method  400  may be performed by one or more of the vehicle  105 , the track system  100 , and a user. For example, as noted above, the track  101  may include one or more optical markers  103  coupled to corresponding track pieces  111  and the vehicle  105  may include an optical sensing unit  211  that (1) detects optical markers  103 , including characteristics of optical markers  103  and (2) causes the vehicle  105  to perform actions in response to detection/classification of optical markers  103 . In other embodiments, the operations/functions associated with the optical sensing unit  211  may be performed by devices external to the vehicle  105 . For example, a wirelessly connected device running a companion application that processes data captured in real-time by the optical sensors  203  may perform one or more operations (or partial operations) of the method  400 . As used herein, the term ‘real-time’ refers to a timeframe that is required to capture raw sensor data by an optical sensor  203  and transmit the raw sensor data to the external processing device such that the performance and functional requirements of the vehicle  105  are met. 
     Although shown and described in a particular order, in some embodiments the operations of the method  400  may be performed in a different order. For example, in some embodiments, two or more operations of the method  400  may be performed concurrently or in partially overlapping time periods. 
     Although the method  400  is described in relation to a single vehicle  105  navigating the track  101 , in other embodiments, the method  400  may be simultaneously performed (or at least performed in partially overlapping time periods) in relation to two or more separate vehicles  105  that are traversing the track  101 . 
     As shown in  FIG. 4 , the method  400  may commence at operation  401  with assembly of the track  101  using a set of track pieces  111 . The track pieces  111  may include a variety of shapes that vary movement of the vehicle  105 . For example, the set of track pieces  111  may include straight track pieces  111 , curved track pieces  111 , junction track pieces  111 , etc. Additionally, each track piece  111  may include interconnecting joints allowing a user to snap individual track pieces  111  together to form a track  101  of a desired shape and complexity at operation  401 .  FIG. 1  shows an example track  101  that may be generated at operation  401  using a set of track pieces  111 . 
     After assembling the track  101  at operation  401 , one or more optical markers  103  are placed by a user onto desired locations/positions of the track  101  at operation  403 . In some embodiments, individual optical markers  103  may be placed on the track  101 , while in other embodiments sequences of optical markers  103  may be placed on the track  101  (e.g., a group of optical markers  103  that are placed directly adjacent to each other on the track  101 ). 
     At operation  405 , the vehicle  105  is placed on the track  101  such that the vehicle  105  can begin traversing the track  101  to detect optical markers  103 . In particular, as described above, the vehicle  105  may include optical sensing abilities that allow the vehicle to detect optical markers  103  as the vehicle traverses the track  101 . 
     At operation  407 , the vehicle  105  continuously gathers and/or generates sensor data while traversing the track  101 . For example, using the electro-mechanical mechanism  205 , the vehicle  105  may traverse the track  101  to move over or otherwise proximate to a number of optical markers  103 . During this movement, the set of optical sensors  203  of the vehicle  105  may generate sensor data corresponding to optical markers  103  or other areas of the track  101 . 
     At operation  409 , the generated sensor data is continuously processed by the optical sensing unit  211  to determine when an optical marker  103  has been detected. When the optical sensing unit  211  determines at operation  409  that the sensor data does not correspond to an optical marker  103  (i.e., the optical sensing unit  211  determines that an optical marker  103  was not detected at operation  409 ), the method  400  may return to operation  407  to continue to generate sensor data while the vehicle  105  traverses the track  101 . In contrast, when the optical sensing unit  211  determines at operation  409  that the sensor data corresponds to an optical marker  103  (i.e., the optical sensing unit  211  determines that an optical marker  103  was detected at operation  409 ), the method  400  may move to operation  411 . 
     At operation  411 , the vehicle  105  may perform a set of actions associated with the detected optical marker  103 . In one embodiment, such actions may be stored in the memory unit  209  in a form of application programs or functions. In other embodiments, the application programs or functions representing various actions may be stored externally. For example, application programs or functions representing various actions may be stored within a device connected wirelessly to the vehicle  105  via an application programming interface (API). Each of the actions may be linked/mapped or otherwise associated with a set of optical markers  103  and/or a set of sequences of optical markers  103 . Examples of various actions triggered using the optical markers  103  (i.e., upon detection of a particular optical marker  103  at operation  409 ) and performed by the vehicle  105  may include 1) the vehicle  105  reversing direction (i.e., the vehicle  105  moving in the opposite direction along the track  101 ); 2) the vehicle  105  changing speed (e.g., the vehicle  105  accelerating to increase speed along the track  101  or decelerating to decrease speed along the track  101 ); 3) the vehicle  105  pausing movement along the track  101 ; 4) the vehicle  105  performing a special maneuver (e.g., the vehicle  105  stopping and performing a shaking maneuver by moving the vehicle  105  forwards and backwards by a prescribed distance (e.g., one centimeter) three times while playing back a sound effect); 5) the vehicle  105  changing an LED color or displaying an animation via a set of LEDs or another display component; 6) the vehicle  105  playing a sound; and 7) the vehicle  105  activating or deactivating an actuator or an electro-magnet component (e.g., activating or deactivating an electro-magnet component to decouple an associated device from the vehicle  105 ). 
     Following operation  411 , the method  400  may return to operation  407  to continue generating sensor data while the vehicle  105  is moving across or otherwise traversing the track  101 . The method  400  may therefore continue indefinitely until an end condition has been reached (e.g., the end of the track  101  is reached or the vehicle  105  is stopped by a user). 
     Depending on the mechanical design of the vehicle  105  and its applications, the track  101  may be made from different materials, use different track pieces  111  and corresponding rail types to guide the vehicle  105 , and utilize different track piece assembly methods. In embodiments in which the track system  100  is miniaturized (e.g., when the track system  100  is a toy train system), the track  101  may be made from injection molded plastic or wooden track pieces  111 . In embodiments that require a higher degree of reliability and longevity in comparison to toy applications (e.g., when the track system  100  is used for security and/or transportation/delivery applications), the track pieces  111  that form the track  101  may be made using metals (e.g., aluminum or stainless steel) or metal alloys. 
     In some embodiments, the track system  100  may contain a track  101  with elements designed for the placement of removable optical markers  103 . Namely, elements may be integrated into the track pieces  111  for removably coupling optical markers  103  to the track  101 . For example,  FIG. 5A  shows pairs of elongated slots  505 A directly adjacent to track rails  503  of a track piece  111 . In particular, each pair of elongated slots  503  are placed along inside edges of corresponding rails  503  of a track piece  111 . In comparison,  FIG. 5B  shows round slots  505 B located centrally between the rails  503  of a track piece  111 . In some embodiments, such slots  505 A and  505 B may be formed using a combination of one or more of extrusion, recessed, or cut-through shapes. As shown in  FIG. 5C , the slots  505 A provide a mechanical interface for coupling replaceable optical markers  103 A onto the track pieces  111  in a manner that cause these replaceable optical markers  103 A to stay in the desired position along the track  101  without easily shifting around or obstructing the movement of the vehicle  105 . However, the replaceable optical markers  103 A may be removed from the track  101 /track pieces  111  without tools (e.g., the replaceable optical markers  103 A include protrusions that fit within the slots  505 A to ensure minimal or no lateral movement of the replaceable optical markers  103 A along the track  101 /track pieces  111 , but allows for movement of the replaceable optical markers  103 A along an axis perpendicular to the track  101 /track pieces  111 ). 
       FIG. 6  shows example cross-section views of a replaceable optical marker  103 A and a track piece  111 , where both have complementary coupling features that allow easy replacement and or movement of the optical markers  103 A to different positions along the track piece  111  (e.g., the optical marker  103 A has a first set of marker coupling components and the track piece  111  has a second set of marker coupling components that are complementary to the first set of marker coupling components to couple the optical marker  103 A to the track piece  111 ). In particular, the optical marker  103 A includes recesses  601 A that fit within and are complementary to protrusions  603 A of the track piece  111 . The optical marker  103 A may also include protrusions  601 B that fit within and are complementary to recesses  603 B of the track piece  111 . In some embodiments, the optical marker  103 A may include protrusion  601 C that fits within or is otherwise complementary with the recess  603 C of the track piece  111 . For example, the recess  603 C may be the slot  505 B, which prevents movement of the optical marker  103 A in a direction parallel to the rails  503 . This coupling between the optical marker  103 A and the track piece  111  is helpful in the assembly of continuous optical marker  103  sequences, which are comprised of two or more directly adjacent optical markers  103 . As described above, through the use of one of more of the recesses  601 A,  603 B, and  603 C and the protrusions  603 A,  601 B, and  601 C, the optical marker  103 A may be coupled to the track  101  (in particular, coupled to track pieces  111  of the track  101 ). 
     In another embodiment shown in  FIG. 7 , a permanent optical marker  103 B may be added permanently to the track piece  111  using paint, adhesives, and/or another permanent application process. Permanent optical markers  103 B enable consistently repeatable actions in certain positions/areas of the track  101 . For example, as shown in  FIG. 8 , a permanent optical marker  103 B may be coupled to the track piece  111  in an area of the track piece  111  preceding a track junction  801 , where the rails  503  of the track split from one pair of rails  503  into two pairs of rails  503 . In this example, the permanent optical marker  103 B may notify the vehicle  105  of such a track junction  801  approaching ahead. 
       FIG. 9  shows another embodiment of an optical marker  103 C that is implemented using a decal, sticker, or another device with a non-permanent adhesive. In this embodiment, the sticker based optical marker  103 C may not be permanently affixed to the track piece  111  such that the optical marker  103 C may be moved from one position on the track piece  111  to another position on the track piece  111  without eliminating the adhesive properties of the sticker based optical marker  103 C. In this embodiment, optical markers  103  may be coupled to the track  101 /track pieces  111  without corresponding/complementary elements of the track  101 /track pieces  111 . 
       FIG. 10  shows yet another example embodiment of an optical marker  103 D that is implemented using a magnetic strip  1001  that is coupled to a track piece  111 . In this embodiment, one or both of the magnetic strip  1001  and the magnetic optical marker  103 D produce a magnetic field. In cases where only one of the magnetic strip  1001  and the magnetic optical marker  103 D produce a magnetic field (i.e., only one of the magnetic strip  1001  and the magnetic optical marker  103 D is or includes a magnet), the non-magnetic field producing element (i.e., the magnetic strip  1001  or the magnetic optical marker  103 D) includes a metal that is attracted to magnetic fields. 
     As noted above, in some embodiments, optical markers  103  may be of different shapes and sizes. For example, as shown in  FIGS. 11A and 11B , the optical marker  103 E is rectangular while the optical marker  103 F is circular. In particular, an upper surface of the optical marker  103 E is rectangular while the upper surface of the optical marker  103 F is circular. Although shown as rectangles and circles, optical markers  103  may be of any shape (e.g., hexagon, octagon, triangle, etc.) and are of sufficient size to allow detection/classification via sensor data generated by the optical sensors  103  while the corresponding vehicle is moving along a track  101 . 
     In some embodiments, a combination/sequence  1201  of optical markers  103  may be assembled to from a continuous sequence of two or more individual optical markers  103 , as shown in  FIG. 12 . A multi-piece combination/sequence  1201  of optical markers  103  may represent a trigger for an action of the vehicle  105  in a similar fashion as an individual optical marker  103  may serve as a trigger. Each optical marker  103  in a combination/sequence of optical markers  103  (e.g., the multi-piece combination/sequence  1201  of optical markers  103 ) may be represented by the same physical shapes or may include different shapes. For example, as shown in  FIG. 12 , the multi-piece combination/sequence  1201  of optical markers  103  includes both circle and square optical markers  103  that are positioned in a continuous manner such that a vehicle  105  is able to detect/classify the optical markers  103  as the vehicle  105  passes over or adjacent to each optical marker  103 . 
     Depending on application needs and performance requirements, the track  101  may utilize various rail types.  FIG. 13A  depicts a cross-section of a track piece  111 A with dual rails  503 A. As shown, the rails  503 A are recessed grooves along one side of the track piece  111 A. In this embodiment, the vehicle  105  is designed with complementary wheels. Namely, the wheels of the vehicle  105  are designed to fit within the recessed grooves of the rails  503 A for proper operation and compatibility. Although the rails  503 A are shown along a single side of the track piece  111 A, in some embodiments, rails  503  may be placed on both sides of a single track piece  111 . For example,  FIG. 13B  shows a dual-sided track piece  111 B with two sets of grooved rails  503 A, which are on opposing sides of the track piece  111 B, according to another embodiment. 
     Although shown with recessed rails  503 , in some embodiments, the rails  503  may be protruding/embossed on track pieces  111 . For example,  FIGS. 13C and 13D  show single and dual-sided track pieces  111 C and  101 D, respectively, with protruding/embossed rails  503 B. Further, although shown with pairs of rails  503 , in some embodiments, a track piece  111  may include a single rail  503 . For example,  FIG. 13E  shows a track piece  111 E with a single recessed rail  503 A (e.g., a mono-rail). In this example embodiment, the wheels of a vehicle  105  fit entirely within the recessed rail  503 A to travel along the track piece  111 E of a track  101 . Although shown as a single recessed rail  503 A, a single raised rail may also be used. 
       FIG. 14A  shows a cross-section, according to one embodiment, of a dual-recessed rail  503 A based dual-sided track piece  111 B with dual cut-through marker slots  505 A. In some embodiments, the track piece  111 B may be made from a plastic material such as acrylonitrile butadiene styrene (ABS) using an injection molded manufacturing process. Such a version of a track piece  111 B may be used in track systems  100  for toy train applications which involve custom track  101  assembly by the user. This configuration benefits from the versatility provided by a dual-sided track piece  111 B design. In some embodiments, the outer ridges  1401  and the inner ridges  1403  forming the grooved rails  503 A may have different heights. For example, the outer ridges  1401  may be made taller in comparison to the inner ridges  1403 , to reduce the chance of derailing when the vehicle  105  traverses a track  101  at higher speeds.  FIG. 14B  shows the optical marker  103 A with a first set of marker coupling components and the track piece  111 B with a second set of marker coupling components that are complementary to the first set of marker coupling components to couple the optical marker  103 A to the track piece  111 B. The first set of marker coupling components are on a bottom surface of the optical marker  103 A that is opposite a top surface of the optical marker  103 A. The top surface of the optical marker  103 A may be formed of any shape and may include/display a set of shapes and colors that are detectable/identifiable by the vehicle  105 . As shown in  FIG. 14B , the first set of coupling components includes a set of protruding elements. The set of protruding elements may include (1) a first protruding element located adjacent a first outside edge of a bottom surface of the optical marker  103 A, (2) a first protruding element located adjacent a second outside edge of the bottom surface of the optical marker  103 A, which is opposite the first outside edge, and (3) third and fourth protruding elements located between the first protruding element and the second protruding element on the bottom surface such that the first protruding element, the second protruding element, the third protruding element, and the fourth protruding element form a symmetric structure about an axis of the bottom surface. 
     In one embodiment shown in  FIG. 14B , the height of the inner ridges  1403  may be chosen such that when combined with a replaceable optical marker  103 A that is placed on top of such an inner ridge  1403 , the collective height of the inner ridge  1403  and the optical marker  103 A resting on the inner ridge  1403  is the same as the height of the outer ridge  1401 . Alternatively, if there is a height difference between the outer ridge  1401  and the combined height of the inner ridge  1403  and the portion of the optical marker  103 A resting on the inner ridge  1403 , such a height difference is less than the minimum clearance requirement of the vehicle  105 . In other embodiments, the outer ridges  1401  and the inner ridges  1403  may have the same height. In embodiments where the width of the track  101  is less than or equal to the width of the vehicle  105 , the heights of the outer ridges  1401  and the inner ridges  1403  may be limited by the bottom clearance of the vehicle  105  from the track  101 . The vehicle  105  with optical sensors  203  may have a clearance that is dependent on the width and length of the bottom of the vehicle  105 . In order to reduce the impact of ambient light on performance of the optical sensors  203 , the optical sensors  203  may be positioned away from the outer edges of the vehicle  105  such that these optical sensors  203  are within the shadow of the vehicle  105 . On the other hand, the minimum clearance of the vehicle  105  is large enough to not be obstructed by the joints of the track  101  and/or slopes of track pieces  111  that are ramps. For example, in vehicles  105  that have widths of approximately 40 millimeters (mm), the clearance between the bottom of the vehicle  105  and the track  105  may be set to be less than 5 mm. 
     In another example embodiment, the width of the track piece  111 B may be sufficiently wider than the width of the vehicle  105  such that the outer ridges  1401  always stay around the exterior of the vehicle  105  and would not be limited by the clearance height of the vehicle  105 . 
     The reliability of the optical marker  103  detection by the vehicle  105  traversing track systems  100  may be adversely affected by the presence of a strong ambient light.  FIG. 15  shows a track piece  111  with a vehicle  105  in the presence of ambient light sources  1501 . In certain configurations of the track piece  111  orientation in relation to the ambient light sources  1501 , such ambient light sources  1501  may be generating light that is reflected by the track piece  111  and an optical marker  103  in a manner that interferes with the ability of the sensor(s)  203  to reliably detect the optical marker  103 , including the color of the optical marker  103 . To reduce the effect of the ambient light sources  1501  on the detection of the optical marker  103 , in one embodiment, the outer ridges  1401  may be included in the track piece  111  to block light from ambient light sources  1501  that may interfere with the detection of the optical markers  103 . 
       FIG. 16  shows another embodiment of a track piece  111  with a vehicle  105 . However, in contrast to several other embodiments described herein, instead of using optical markers  103  that are placed within the recesses of rails  503  of a track piece  111 , the optical marker  103  shown in  FIG. 16  is placed along the side of the outer ridge  1401  of the track piece  111 . The vehicle  105  operating on such a track system  100  is designed such that an optical sensor  203  is positioned to detect the side-placed optical marker  103 . Such a side-placed optical marker  103  may function in a similar fashion as other embodiments described herein, including those embodiments in which the optical markers  103  are placed on the upwards facing surface of track pieces  111  (i.e., the side of the outer ridge  1401 ). Track systems  100  that incorporate side-placed optical markers  103  may provide advantages in comparison to other track systems  100  in terms of resistance to ambient light sources, since the placement of the optical markers  103  on the outer ridge  1401  provides a shield for optical sensors  203  from direct exposure to ambient light. 
     As discussed above, in some embodiments, tracks  101  are assembled from individual track pieces  111 . For example, toy train track systems allow the user to build custom tracks  101  from various different types of track pieces  111  (e.g., straights track pieces  111 , curved track pieces  111 , and split/junction track pieces  111 ). Split/junction track pieces  111  form a junction to either divide a single set of rails into multiple sets of rails or to merge multiples sets of rails into a single set of rails as shown in the example of  FIG. 8 . To streamline the assembly of tracks  101 , various joint designs are used to securely link track pieces  111  together. In one embodiment, shown in  FIGS. 17A and 17B , a set of plastic injection molded track pieces  111  may contain an extruded male/protruding joint  1701  and a complementary female/recessed joint  1703 , which each have circular shapes that interlock when a user snaps the joints  1701  and  1703  together. Although shown as the joints  1701  and  1703  having a circular shape, in other embodiments, the joints  1701  and  1703  may have different shapes (e.g., squares, rectangles, octagons, etc.). For example, in the case of a circular connector, the maximum width of the male joint  1701  (defined by the diameter of a circle/rounded area of the male joint  1701 ) is larger than the width of the opening at the front of the female joint  1703  to avoid the track pieces  111  from coming apart due to external forces parallel to the track pieces  111 . The tightness of the fit between the male joint  1701  and female joint  1703  may be chosen such that it is easy for a user to manually link and unlink corresponding track pieces  111  with minimal force. Such a force should not exceed the limits that may cause mechanical damage to the joints  1701  and  1703  based on the material type used to make the track  101 , yet the fit between the joints  1701  and  1703  is tight enough to maintain the rigidity of the assembled track pieces  111  and avoid an inadvertent disassembly of the track pieces  111  during normal operation of the vehicle  105  on the track  101 . When the joints  1701  and  1703  are snapped together, the corresponding track pieces  111  will not come apart without an external force directed to pull the track pieces  111  apart. In one embodiment, the female joint  1703  may also contain dual slits  1709  on either side of the circular opening of the joint  1703 . These slits  1709  provide flexibility for the female joint  1703 . This lower flexibility results in a reduced force and a reduced potential for mechanical damage during the interlocking process between the female joint  1703  of a track piece  111  and a male joint  1701  of another track piece  111 . 
     In some embodiments, the male joint  1701  may include a lip  1705  along an outer edge, while the opening of the female joint  1703  may have alternating knobs/tabs  1707  placed along a top edge and a bottom edge of the opening of the female joint  1703  (e.g., the knobs/tabs  1707 A are placed on a top edge of the opening of the female joint  1703  and the knobs/tabs  1707 B are placed on a bottom edge of the opening of the female joint  1703 ). Collectively, the lip  1705 , the knobs/tabs  1707 A along a top edge, and the knobs/tabs  1707 B along a bottom edge provide an additional locking mechanism when the track pieces  111  are snapped together along the joints  1701  and  1703 . Such a mechanism provides improved vertical alignment between track pieces  111  while maintaining a surface of a track  101  formed by the track pieces  111  continuously smooth and flat even if the track  101  is assembled on an uneven surface (e.g., assembled on a carpet). The alternating placement of the knobs/tabs  1707 A and  1707 B allow the core and the cavity of a plastic injection mold to form these elements in plastic and come apart without catching when ejecting from the mold. The quantity and size of the knobs/tabs  1707 A and  1707 B can be varied in terms of the lengths, heights, and extension from the opening of the female joint  1703  as long as the knobs/tabs  1707 A and the knobs/tabs  1707 B remain non-overlapping from a top-down/overhead perspective and the knobs/tabs  1707 A/ 1707 B can form a coupling joint with the lip  1705 . In particular, a set of knobs/tabs  1707 A are positioned along a top edge of the recessed female joint  1703  and a set of knobs/tabs  1707 B are positioned along a bottom edge of the recessed female joint  1703  such that knobs/tabs  1707 A along the top edge are unaligned with knobs/tabs  1707 B along the bottom edge. 
     The shape of the knobs/tabs  1707 A/ 1707 B can be varied, including, for example, rounded and rectangular shapes. The knobs/tabs  1707 A/ 1707 B are complementary to the shape of the lip  1705  to form a connection/joint. The tightness of such a connection/joint may be affected by the shape and the size of the knobs/tabs  1707 A/ 1707 B and the lip  1705  and is optimized to make the connection/joint assembly easy for the user, maintain the mechanical integrity of the knobs/tabs  1707 A/ 1707 B and the lip  1705  over the expected lifetime of the track  101 , and provide a sufficient joint strength to maintain the track  101  flat. 
     As shown above, several embodiments for a track system for a robotic vehicle are described herein. Similar or identical example embodiments are provided below. Example 1 provides an exemplary embodiment of a track system for a robotic vehicle, the track system comprising: a set of track pieces that each include a set of track coupling components to couple the track pieces in the set of track pieces together to form a track for the robotic vehicle to traverse; and a set of optical markers that each include a first set of marker coupling components, wherein the set of track pieces include a second set of marker coupling components that are complementary to the first set of marker coupling components to couple the set of optical markers to the set of track pieces. 
     Example 2 includes the substance of the exemplary track system of Example 1, wherein each optical marker in the set of optical markers includes a top surface that includes one or more of (1) a surface color and (2) a set of two-dimensional shapes on the top surface. 
     Example 3 includes the substance of the exemplary track system of Example 2, wherein the top surface of each optical marker is formed from a shape selected from a set of shapes. 
     Example 4 includes the substance of the exemplary track system of Example 2, wherein the first set of marker coupling components are on a bottom surface that is opposite the top surface. 
     Example 5 includes the substance of the exemplary track system of Example 4, wherein the first set of marker coupling components includes a set of protruding elements. 
     Example 6 includes the substance of the exemplary track system of Example 5, wherein (1) a first protruding element in the set of protruding elements is located adjacent a first outside edge of the bottom surface of the optical marker, (2) a first protruding element in the set of protruding elements is located adjacent a second outside edge of the bottom surface of the optical marker, which is opposite the first outside edge, and (3) third and fourth protruding elements in the set of protruding elements are located between the first protruding element and the second protruding element on the bottom surface such that the first protruding element, the second protruding element, the third protruding element, and the fourth protruding element form a symmetric structure about an axis of the bottom surface. 
     Example 7 includes the substance of the exemplary track system of Example 1, wherein the second set of marker coupling components includes a first set of slots through track pieces in the set of track pieces. 
     Example 8 includes the substance of the exemplary track system of Example 7, wherein each track piece in the set of track pieces includes a set of grooves or a set of rails for receiving wheels of the robotic vehicle. 
     Example 9 includes the substance of the exemplary track system of Example 8, wherein the set of grooves is a mono-groove system for receiving wheels of the robotic vehicle. 
     Example 10 includes the substance of the exemplary track system of Example 8, wherein the set of rails is a mono-rail system for receiving wheels of the robotic vehicle. 
     Example 11 includes the substance of the exemplary track system of Example 8, wherein the set of grooves is a dual-groove system for receiving wheels of the robotic vehicle. 
     Example 12 includes the substance of the exemplary track system of Example 8, wherein the set of rails is a dual-rail system for receiving wheels of the robotic vehicle. 
     Example 13 includes the substance of the exemplary track system of Example 11, wherein the first set of slots are placed between each groove in the set of grooves. 
     Example 14 includes the substance of the exemplary track system of Example 13, wherein a first slot in the first set of slots is adjacent a first groove in the set of grooves and a second slot in the first set of slots is adjacent a second groove in the set of grooves. 
     Example 15 includes the substance of the exemplary track system of Example 14, wherein the second set of marker coupling components includes a second set of slots through the track piece. 
     Example 16 provides an exemplary embodiment of a track piece for use in assembling a track for a robotic vehicle, the track piece comprising: one or more male elements that each form a protruding joint, wherein each male element in the one or more male elements includes a lip along an outer edge of a corresponding protruding joint; and one or more female elements that each form a recessed joint and are complementary with the protruding joints, wherein each female element in the one or more female elements includes a set of tabs along a corresponding recessed joint, and wherein the set of tabs are placed in an alternating sequence along a top edge and a bottom edge of the recessed joint such that tabs along the top edge are unaligned with tabs along the bottom edge. 
     Example 17 includes the substance of the exemplary track piece of Example 16, further comprising: a set of slits surrounding recessed joints of the one or more female elements. 
     Example 18 includes the substance of the exemplary track piece of Example 16, further comprising: a set of grooves or a set of rails for receiving wheels of the robotic vehicle. 
     Example 19 includes the substance of the exemplary track piece of Example 18, wherein the track piece is a junction track piece that splits a first set of grooves into a second set of grooves and a third set of grooves at a junction. 
     Example 20 includes the substance of the exemplary track piece of Example 18, wherein the track piece is a junction track piece that splits a first set of rails into a second set of rails and a third set of rails at a junction. 
     Some portions of the preceding detailed descriptions have been presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of operations leading to a desired result. The operations are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. The present disclosure can refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage systems. 
     The present disclosure also relates to an apparatus for performing the operations herein. This apparatus can be specially constructed for the intended purposes, or it can include a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program can be stored in a computer readable storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, and magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, or any type of media suitable for storing electronic instructions, each coupled to a computer system bus. 
     The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems can be used with programs in accordance with the teachings herein, or it can prove convenient to construct a more specialized apparatus to perform the method. The structure for a variety of these systems will appear as set forth in the description below. In addition, the present disclosure is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages can be used to implement the teachings of the disclosure as described herein. 
     The present disclosure can be provided as a computer program product, or software, that can include a machine-readable medium having stored thereon instructions, which can be used to program a computer system (or other electronic devices) to perform a process according to the present disclosure. A machine-readable medium includes any mechanism for storing information in a form readable by a machine (e.g., a computer). In some embodiments, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium such as a read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory components, etc. 
     In the foregoing specification, embodiments of the disclosure have been described with reference to specific example embodiments thereof. It will be evident that various modifications can be made thereto without departing from the broader spirit and scope of embodiments of the disclosure as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.