Patent Publication Number: US-2022214009-A1

Title: Pan tilt unit

Description:
CROSS REFERENCE TO OTHER APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/576,326 entitled PAN TILT UNIT filed Sep. 19, 2019 which is incorporated herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     Pan and tilt systems are often used for remote directional control of cameras and other position-sensitive sensors (e.g., radar or lidar). Typical pan and tilt systems suffer from limited pan rotation capability, often restricted by the cabling required to transmit data and power to the various attached payloads. To overcome rotation issues associated with cabling, some systems are designed to limit rotation to less than 360 degrees which results in a ‘dead zone’ region of sensor coverage. Other pan tilt systems can rotate more than 360 degrees (e.g., using a flex cable) but need to unwind at some point resulting in an undesirable communication delay or an undesirable delay from having to reset to an initial position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the invention are disclosed in the following detailed description and the accompanying drawings. 
         FIG. 1  is a block diagram illustrating perspective views of an embodiment of a pan tilt unit base assembly and support. 
         FIG. 2  is a block diagram illustrating perspective views of an embodiment of a data slip ring unit. 
         FIG. 3A  is a block diagram illustrating an embodiment of a power slip ring unit positioned above and around a pan tilt unit cylindrical support. 
         FIG. 3B  is a block diagram illustrating a cross-sectional view of an embodiment of a power slip ring unit positioned around a pan tilt unit cylindrical support. 
         FIG. 3C  is a block diagram illustrating side and cross-sectional views of an embodiment of lower (power) and upper (data) slip ring units positioned around a pan tilt unit cylindrical support. 
         FIG. 4  is a block diagram illustrating perspective and side views of an embodiment of a pan and tilt assembly positioned between lower and upper slip ring units and mounted on a pan tilt unit base assembly. 
         FIG. 5  is a block diagram illustrating exploded and perspective views of an embodiment of a pan motor mounted on a pan and tilt base support platform. 
         FIG. 6  is a block diagram illustrating exploded and perspective views of an embodiment of a tilt motor mounted on a pan and tilt assembly. 
         FIG. 7  is a block diagram illustrating perspective views of an embodiment of a pan tilt unit comprising a complete pan and tilt assembly. 
         FIG. 8  is a block diagram illustrating perspective and side views of an embodiment of a pan tilt unit with enclosure. 
         FIG. 9  is a block diagram illustrating an embodiment of an enclosed pan tilt unit with top-mounted computer and exemplary side-mounted payloads. 
         FIG. 10  is a block diagram illustrating an embodiment of a stacked pair of enclosed pan tilt units with side-mounted exemplary payloads. 
         FIG. 11  is a flow diagram illustrating an embodiment of a method for assembling a pan tilt unit. 
     
    
    
     DETAILED DESCRIPTION 
     The invention can be implemented in numerous ways, including as a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer readable storage medium; and/or a processor, such as a processor configured to execute instructions stored on and/or provided by a memory coupled to the processor. In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention. Unless stated otherwise, a component such as a processor or a memory described as being configured to perform a task may be implemented as a general component that is temporarily configured to perform the task at a given time or a specific component that is manufactured to perform the task. As used herein, the term ‘processor’ refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions. 
     A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured. 
     A pan tilt unit with no pan rotation limit is disclosed. The unit comprises a support, a slip ring, a rotating platform, and a tilting mechanism. The outer rotating portion of the slip ring is able to rotate about the support. The slip ring comprises connections between an inner static portion of the slip ring and the outer rotating portion of the slip ring. The rotating platform is coupled to the outer rotating portion of the slip ring. The tilting mechanism is coupled to the rotating platform. In various embodiments, coupled comprises one or more of the following: mechanically coupled (e.g., using screw(s), bolt(s), clip(s), clamp(s), etc.), adhesively coupled (e.g., using glue, epoxy, etc.), permanently affixed (e.g., using welding, brazing, soldering, etc.), or any other appropriate coupling. 
     One or more pan tilt units are a component(s) of a sensor tower or station (e.g., a fixed and/or mobile station) used to monitor and protect a surrounding area. In various embodiments, the sensor or tower station is used to monitor a border area, monitor against threat drones (e.g., for detection and interception of an incoming threat drone), or any other appropriate monitoring. In some embodiments, sensor payloads that require directional positioning (e.g., a camera, an audio sensor, a radar sensor, or a lidar sensor) are mounted on the one or more pan tilt units. Rapid and precise positioning of the sensor payload(s) without limitation is required to provide target acquisition and tracking so that the sensor tower can acquire sufficient and appropriate data for monitoring. This is especially important in the case of a counter drone system to allow rapid determination whether a detected object is a threat drone, and if determined to be a threat drone, provide precise and real-time tracking/intercept information. The top of the pan tilt unit is stationary to allow stacking or the placement of a unit with fixed orientation (e.g., a radio frequency antenna or optical communication link that needs a specific orientation for optimal functioning). 
     The disclosed pan tilt unit is an improvement over typical pan tilt units in that it is able to rapidly and precisely pan and tilt attached payloads (e.g., sensor payloads) without limitation in the number of panning rotations. The rotations of a pan tilt unit are typically restricted by the cabling required to transmit data and power to various attached payloads. For example, some pan tilt units are mechanically restricted to less than a 360-degree rotation (e.g., a 330-degree limit) which results in a ‘dead zone’ region of sensor coverage. Other pan tilt units can rotate more than 360 degrees (e.g., using a continuous flex cable) but need to unwind at some point resulting in an undesirable communication delay or undesirable motion to reset to an initial position. The disclosed pan tilt unit overcomes these limitations by use of slip rings that provide a wired mechanical connection without rotation limit. 
     A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure (e.g., a static inner portion of the slip ring to a rotating outer portion of the slip ring). A slip ring typically comprises a stationary graphite or metal contact (i.e., a brush) which rubs on the outside diameter of a rotating metal ring. As the metal ring turns, the electric current or signal is conducted through the stationary brush to the metal ring making the connection. In some embodiments, the brushes, as well as the unit&#39;s payload platform mounts, rotate around the central cylindrical support. In some embodiments, the slip ring is designed to be electrically ‘transparent’ to the transmission properties of the wiring or cable runs that pass through it (e.g., having identical or near-identical resistance, impedance, and capacitance values whether the slip ring is stationary or rotating). As used herein, a cable comprises an assembly of one or more wires running side by side or bundled and used to carry electric current. In some embodiments, the cable includes shielding to prevent crosstalk between wires of the cable and to shield the wires in the cable from electrical signals external to the cable. 
     In various embodiments, the support comprises a cylindrical support, a rigid hollow tube (e.g., an aluminum tube), a support with a non-cylindrical cross section (e.g., a square cross section, a rectangular cross section, an elliptical cross section, etc.), or any other appropriate support. Data and power to the various payloads are transmitted via cables that run from the bottom of the pan tilt unit (e.g., via a wiring harness through the cylindrical support and one or more slip rings) to the payloads at the sides and/or top. 
     In some embodiments, the pan tilt unit comprises two mounts on opposite sides of the cylindrical support (e.g., to mount sensor payloads useful to monitoring and protecting a surrounding area). In some embodiments, the two mounts are coupled to move together around a common tilt axis. In some embodiments, the pan tilt unit comprises more than two mounts. In some embodiments, the two or more mounts are independently controllable for tilt position. In various embodiments, a mount of the two or more mounts is coupled to one or more of the following payloads: a camera, an audio sensor, a radar sensor, a lidar sensor, a laser illuminator, or any other appropriate payload. In some embodiments, any tilt mount includes a slip ring so that tilt motion is not limited. 
     In some embodiments, pulley and belt assemblies are used to position the pan and tilt payload mounts. In some embodiments, the gear and belt assemblies are driven by electric motors (e.g., servo motors) via motor controllers (e.g., servo controllers). In various embodiments, other drive mechanisms are used to position the pan and/or tilt payload mounts including geared drives, worm drives, belt and pulley systems, or any other appropriate drive mechanisms. Power and control signals to the motor and motor controllers are transmitted via cables that run from the bottom or top of the pan tilt unit (e.g., via a wiring harness through the cylindrical support and one or more slip rings) to the pan and tilt motors coupled to rotating support platforms positioned around the pan tilt unit cylindrical support. 
     In some embodiments, the pan tilt unit comprises a stationary mount (e.g., a top platform is coupled to a top of the cylindrical support). A stationary platform is important for payloads that have orientation sensitivity—for example, payloads used in long-distance communication (e.g., directional antennas used in satellite communication). Traditional pan tilt units used for sensor systems also have an added challenge of calculating object positions due to various translations of attached sensor payloads (e.g., a camera). The disclosed pan tilt unit allows easier calculations to derive an object coordinate due to a known stationary coordinate; that is, calculating target position would be more difficult if the tilt axis didn&#39;t pass through the center of the rotation axis. In some embodiments, a computation unit is coupled to the top of the cylindrical support. 
     In various embodiments, the pan tilt unit receives positioning instructions from a network (e.g., a wired and/or wireless computer network), a local computer (e.g., mounted on top of the unit), and/or user interface that provides the unit with positioning instructions—for example, positioning instructions from a remote server or user, or during automatic mode (e.g., tracking, auto scanning, etc.). 
     In some embodiments, the pan tilt unit comprises an enclosure that seals the unit against weather and debris ingress (e.g., rain, snow, wind, dust, sand, etc.). In some embodiments, the pan tilt unit constituent components are chosen to withstand operation at extreme temperatures and relative humidity (RH) levels. 
     In various embodiments, the slip ring comprises a power slip ring, a data slip ring, a combined power and data slip ring, or any other appropriate slip ring. In some embodiments, a computer is mounted on the rotating platform of the PTU and then a data slip ring is not needed but a power slip ring is still necessary to allow infinite rotation. The static structural tube or support enables providing electrical connection (e.g., data and/or power) between the bottom and the top of the pan tilt unit—for example, between two pan tilt units, between a pan tilt unit and a static payload, between two static payloads (e.g., a mounting platform, a directional antennas, etc.). 
     In various embodiments, the support comprises a path or channel for passing wiring, tubing, and/or hoses, or any method of transmitting data, power, or fluid transfer through the PTU independently of the rotation and/or tilt axis, such that a system located at the bottom of the PTU is in direct communication with a system or systems located at the top of the PTU or systems located on a rotating platform of the PTU. 
       FIG. 1  is a block diagram illustrating perspective views of an embodiment of a pan tilt unit (PTU) base assembly and support. In the example shown in  FIG. 1 , the perspective view on the left illustrates PTU base assembly  100  comprising cylindrical support  102 , stationary mount  104 , PTU base collar  106 , and PTU base flange  108 . The perspective view in the middle illustrates cylindrical support  102  comprising support tube  110 , cylindrical support base  112 , interior through-hole  114 A, and side through-hole  116 A, and side through-hole  116 B. The perspective view on the right shows an upward-looking view of PTU base assembly  100  that illustrates interior through-hole  114 B that runs the length of cylindrical support  102  exiting at the top of cylindrical support  102  (as illustrated in the perspective view in the middle as interior through-hole  114 A). The perspective view on the right also illustrates that cylindrical support  102  is coupled to PTU base collar  106  via cylindrical support base  112 . PTU base collar  106  is coupled to PTU base flange  108  (e.g., via a threaded coupling). In some embodiments, PTU base collar  106  and PTU base flange  108  are machined from one piece of metal (e.g., aluminum). PTU base collar  106  is designed to house one or more slip rings and to couple to a pan belt gear (not shown) used for PTU rotation. PTU base flange  108  is used to couple the entire PTU to a sensor tower, station, or to another PTU (e.g., using through-holes in the flange). 
     In some embodiments, PTU base assembly  100  is made of aluminum or any other appropriate material to provide strength, rigidity, durability, and light weight (e.g., titanium). In various embodiments, cylindrical support  102  comprises a rigid hollow tube with an outer diameter of two inches, three inches, four inches, or any other appropriate outer diameter. The diameter and wall thickness of cylindrical support  102  is determined in part to provide sufficient mechanical strength to support the desired payloads and sufficient interior space to house the cables to the one or more payloads. Sufficient strength and interior space of the cylindrical support is a significant design factor when considering using the PTU in a multiple stacked configuration. In the example shown, cylindrical support  102  comprises multiple side through-holes (e.g., side through-hole  116 A and side through-hole  116 B) to allow cabling to pass from the interior to the exterior of cylindrical support  102 . In some embodiments, stationary mount  104  is used to couple a computation unit to the top of cylindrical support  102 . In some embodiments, interior through-hole  114 A and interior through-hole  114 B is used to allow cabling to enter the PTU to supply power and/or data to the computation unit, or any other appropriate device, mounted on stationary mount  104 . 
     In various embodiments, cylindrical support  102  does not have a round cross section—the support instead has a square, triangular, oval, or any other appropriate shaped cross section. For a non-round cross section, an adapter that mates the outer shape of the support with the inner shape of a slip ring is used to mount the slip ring to the support. 
       FIG. 2  is a block diagram illustrating perspective views of an embodiment of a data slip ring unit. In the example shown, the perspective view on the left illustrates data slip ring unit  200  comprising slip ring housing  202 , slip ring fixation collar  204 , input data cables  206 , and output data cables  208 . Slip ring fixation collar  204  is used to couple the data slip ring unit to the PTU cylindrical support (e.g., via set screws or any appropriate method of coupling) to prevent the inner portion of the slip ring unit from rotating. Slip ring housing  202  is free to rotate around slip ring fixation collar  204  such that input data cables  206  remain stationary while output data cables  208  rotate with slip ring housing  202 . In some embodiments, slip ring housing  202  and slip ring fixation collar  204  are made of aluminum (e.g. passivated aluminum) or any other appropriate material. 
     In various embodiments, slip ring housing  202  houses one or more individual connection paths each with a contactor (e.g., a contacting brush or copper rod) touching a rotating metal inner ring, sometimes referred to as waveguides, to make the connection path. Each of the individual connection paths, allows transmission of data and/or power to and/or from the various PTU payloads—for example, 1, 2, 3, 10, 20, 30, or any other appropriate number of connection paths as required to meet the PTU payload design criteria for data transmission. In some embodiments, the data connections comprise a plurality of shielded connections (e.g., Ethernet cables). In some embodiments, the data connections are used to transmit control signals to the PTU and its various payloads (e.g., toggle power on/off, control pan or tilt motor rotation, etc.). In some embodiments, the plurality of shielded connections comprise alternating signal and ground connections for the slip ring unit. In some embodiments, the data connections comprise 4, 8, 12, 16, or 24 data connections. 
     In some embodiments, separate slip ring units are used to supply power. In some embodiments, a power slip ring comprises one or more connection paths. In some embodiments, the power slip ring includes any number N of power connectors and a ground connector. In some embodiments, the power slip ring&#39;s outer housing is coupled to the rotating PTU platform, while the inner ring is fixed to the cylindrical support. In this configuration, one end of the slip ring is free to rotate with the payload mount, and one end is completely static and coupled to the support (e.g., the cylindrical support). 
     In some embodiments, power and data transmission is combined into a single slip ring unit. In various embodiments, any number N of data and/or power slip ring units, each comprising any number of connections, can be stacked one upon the other around the PTU cylindrical support to provide as many connections as desired. In various embodiments, the data slip ring unit is designed and tested for minimal signal crosstalk between the interior slip rings, and from one data slip ring unit to another (e.g., for multiple stacked slip ring units around one PTU cylindrical support). 
       FIG. 3A  is a block diagram illustrating an embodiment of a power slip ring unit positioned above and around a pan tilt unit cylindrical support. In some embodiments, PTU cylindrical support  302  is identical to cylindrical support  102  of  FIG. 1 . In the example shown in  FIG. 3A , the perspective view on the left illustrates power slip ring unit  300  in position to be lowered from above into position around PTU cylindrical support  302  (e.g., as shown in side view on the right). Once power slip ring unit  300  is at the desired vertical position, it is coupled to PTU cylindrical support  302  via a slip ring fixation collar (e.g., a fixation collar such as slip ring fixation collar  204  of  FIG. 2 ). In some embodiments, power slip ring unit  300  is coupled to PTU cylindrical support  302  using a thread, using glue, or any other appropriate fixation method. Power/ground input cable  304  is routed through hole  306  to pass down through the center of PTU cylindrical support  302 . In some embodiments, the lower positioned slip ring (e.g., power slip ring unit  300 ) is used to provide power to payloads mounted to a PTU via power/ground output cables  308 . 
       FIG. 3B  is a block diagram illustrating a cross-sectional view of an embodiment of a power slip ring unit positioned around a pan tilt unit cylindrical support. In some embodiments, power slip ring unit  320  of  FIG. 3B  comprises power slip ring unit  300  of  FIG. 3A . In some embodiments, cylindrical support  322  comprises cylindrical support  102  of  FIG. 1 . In some embodiments, power/ground input cable  324 A is routed up or down through the interior of cylindrical support  322  and exits a hole in the lower portion of cylindrical support  322  (e.g., via hole  306  of  FIG. 3A ). In some embodiments, power/ground cable  324 A connects to power slip ring unit  320  to provide power to various mounted payloads via power/ground cable  324 B. 
     In some embodiments, power/ground cable  326 A is threaded upward through the interior of cylindrical support  322 . In various embodiments, power/ground cable  326 A exits cylindrical support  322  via side through-hole  328  or via opening  330  at the top of cylindrical support  322 . In various embodiments, power/ground cable  324 A is electrically continuous with power/ground cable  324 B and power/ground cable  326 A is electrically continuous with power/ground cable  326 B. 
     In various embodiments, power slip ring unit  320  comprises a data slip ring (e.g., data slip ring unit  200  of  FIG. 2 ) or a combined single data/power slip ring. In some embodiments, power/ground cable  324 A, power/ground cable  324 B, power/ground cable  326 A, and power/ground cable  326 B comprise data cables (e.g., Ethernet cables) to allow the transmission of data in either direction. In some embodiments, power/ground cable  324 A, power/ground cable  324 B, power/ground cable  326 A, and power/ground cable  326 B comprise wiring for both power and data transmission in either direction. 
       FIG. 3C  is a block diagram illustrating side and cross-sectional views of an embodiment of lower (power) and upper (data) slip ring units positioned around a pan tilt unit cylindrical support. In some embodiments, lower slip ring unit  342  of  FIG. 3C  comprises power slip ring unit  300  of  FIG. 3A . In some embodiments, upper slip ring unit  340  of  FIG. 3C  comprises data slip ring unit  200  of  FIG. 2 . In some embodiments, cylindrical support  344  comprises cylindrical support  102  of  FIG. 1 . 
     In the example shown in  FIG. 3C , the side view on the left illustrates upper slip ring unit  340  and lower slip ring unit  342  fixed in position around cylindrical support  344 . In some embodiments, as illustrated in both left and right views of  FIG. 3C , upper slip ring unit  340  is mounted upside down compared to lower slip ring unit  342 . In some embodiments, as illustrated in the cross-sectional view on the right, cable  346 A passes through the interior of cylindrical support  344  and exits side-through hole  350  to connect with lower slip ring unit  342 . In some embodiments, cable  346 B of lower slip ring unit  342  is used connect to one or more PTU payloads (e.g., to transmit power and/or data) and is free to rotate without rotation limit. In some embodiments, cable  346 A is electrically continuous with cable  346 B. 
     In some embodiments, as illustrated in the cross-sectional view on the right, cable  348 A of upper slip ring unit  340  is available to connect to a top-mounted stationary PTU payload (e.g., a computation unit, a radar, etc.). In some embodiments, cable  348 A of upper slip ring unit  340  passes through cylindrical support  344  to connect to a PTU payload not mounted on cylindrical support  344 —for example, a PTU payload that is coupled to one of any number of stacked PTU&#39;s on top of cylindrical support  344 . 
     In some embodiments, cable  348 A passes through side hole  352  to the exterior of cylindrical support  344  and, via upper slip ring unit  340  and cable  348 B, is used to transmit data and/or power to a side-mounted PTU payload (e.g., a camera or any other appropriate sensor) that is free to rotate without limit. In some embodiments, cable  348 A is electrically continuous with cable  348 B. 
     In various embodiments, one or more of the cables interior to cylindrical support  344  (i.e., cable  348 A, cable  348 B, cable  348 C, and cable  348 D) connect to a common bus (e.g., a data bus, a ground bus, and/or a power bus). In some embodiments, the bus is contained within cylindrical support  344 . In various embodiments, the bus passes through cylindrical support  344  to one or more stacked PTU&#39;s or other static payloads on top of cylindrical support  344 . 
     In various embodiments, power sources (e.g., batteries, solar panels, grid power from AC wall plug, internal combustion generators, vehicles as generators, etc.) external to the PTU (e.g., mounted to a sensor tower, station, or any other appropriate external mounting surface) are used to supply power to any of the various PTU payloads. 
     In various embodiments, power sources mounted on any appropriate PTU mount (e.g., stationary top mount or rotational side mount), or comprising any of the mounted PTU payloads, are used to supply power to any of the various PTU payloads. 
       FIG. 4  is a block diagram illustrating perspective and side views of an embodiment of a pan and tilt assembly positioned between lower and upper slip ring units and mounted on a pan tilt unit base assembly. In some embodiments, upper slip ring unit  400  of  FIG. 4  comprises data slip ring unit  200  of  FIG. 2 . In some embodiments, lower slip ring unit  402  of  FIG. 4  comprises power slip ring unit  300  of  FIG. 3A . In some embodiments, stationary support cylinder  404  comprises cylindrical support  102  of  FIG. 1 . In some embodiments, PTU base collar  410  comprises PTU base collar  106  of  FIG. 1 . Note that in  FIG. 4  belts that are used for relative motion are not shown. 
     In the example shown, the lower side view in  FIG. 4  illustrates pan and tilt gear assembly  406  positioned between upper slip ring unit  400  and lower slip ring unit  402 . In some embodiments, pan and tilt assembly  406  is coupled to the top of lower slip ring unit  402  so that it is free to rotate without limit around stationary support cylinder  404 . In some embodiments, lower slip ring unit  402  is free to rotate relative to pan pulley  408 . Pan pulley  408  is fixed to PTU base collar  410  and an outer housing of a lower slip ring is free to rotate relative to it. 
     In some embodiments, as illustrated in the top left side perspective view of  FIG. 4 , pan pulley  408  is inserted into PTU base collar  410  such that lower slip ring unit  402  is interior to PTU base collar  410 . In some embodiments, pan pulley threaded fasteners  412  (as shown in the lower side view in  FIG. 4 ) are threaded into corresponding holes (not visible) in the top of PTU base collar  410  to keep pan pulley  408  from rotating (i.e., pan pulley  408  is coupled to PTU base collar  410 ). In some embodiments, pan belt gear  408  is used to provide a stationary mating surface for a drive belt (not shown) to provide rotation of pan and tilt assembly  406  about stationary support cylinder  404  via a pan motor (not shown). 
     In some embodiments, as illustrated in the lower side view in  FIG. 4 , pan and tilt gear assembly  406  comprises pan and tilt base  414 , tilt pulley  416 A, tilt pulley  416 B, tilt pulley support  418 A, tilt pulley support  418 B, tilt shaft  420 A, and tilt shaft  420 B. In some embodiments, pan and tilt base  414  is used to couple pan and tilt assembly  406  to the top of lower slip ring unit  402 . In various embodiments, tilt pulley  416 A, tilt pulley  416 B, tilt pulley support  418 A, tilt pulley support  418 B, tilt pulley shaft  420 A, and tilt pulley shaft  420 B are used to provide tilt rotation to various payloads (not shown). In various embodiments, tilt rotation to a payload is enabled by coupling tilt gear pulley  420 A or tilt gear pulley  420 B to the payload or payload mount (not shown). In various embodiments, a tilt motor (not shown) is used to provide rotation of tilt pulley  416 A and/or tilt pulley  416 B. In various embodiments, the tilt motor is coupled to tilt pulley  416 A and/or tilt pulley  416 B via a drive belt (not shown). In some embodiments, two payload mounts are coupled to move together around a common tilt axis. In some embodiments, the two or more mounts are independently controllable for tilt position by using more than one tilt motor. 
     In some embodiments, a payload is connected to a slip ring in the tilt axis, so that tilt as well as pan rotation are not limited. 
       FIG. 5  is a block diagram illustrating exploded and perspective views of an embodiment of a pan motor mounted on a pan and tilt base support platform. In some embodiments, cylindrical support  500 A, stationary mount  500 B, PTU base collar  500 C, and PTU base flange  500 D comprise PTU base assembly  100  of  FIG. 1 . In some embodiments, pan pulley  502  comprises pan pulley  408  of  FIG. 4 . In some embodiments, pan and tilt gear base  510  comprises pan and tilt gear base  414  of  FIG. 4 . 
     In the example shown, as illustrated in the right side perspective view of  FIG. 5 , pan motor  506  is coupled to pan and tilt gear base  510 . The left side perspective view of FIG.  5  illustrates an exploded view of pan motor  506 , pan drive pulley  504 , and coupling plate  508 . In some embodiments, coupling plate  508  is used to couple pan motor  506  to pan and tilt gear base  510 . In some embodiments, pan and tilt gear base  510  is coupled to the top of a lower slip ring unit (not shown) housed within PTU base collar  500 C. 
     In some embodiments, the drive shaft of pan motor  506  is coupled to pan drive gear  504 . In some embodiments, pan drive gear  504  is coupled to pan belt gear  502  via a drive belt (not shown). In some embodiments, pan motor  506  provides rotation of pan and tilt gear base  510  about cylindrical support  500 A via pan drive gear  504 , pan belt gear  502 , and the drive belt. In some embodiments, rotation of pan and tilt gear base  510  is measured using a rotary encoder (not shown). 
       FIG. 6  is a block diagram illustrating exploded and perspective views of an embodiment of a tilt motor mounted on a pan and tilt assembly. In some embodiments, cylindrical support  600 A, stationary mount  600 B, PTU base collar  600 C, and PTU base flange  600 D comprise PTU base assembly  100  of  FIG. 1 . In some embodiments, pan and tilt base  604  comprises pan and tilt base  414  of  FIG. 4 . In some embodiments, tilt pulley  606  comprises tilt pulley  416 B of  FIG. 4 . In some embodiments, tilt pulley  606  mounts to tilt bearing  610 A tilt pulley support  610 A comprises tilt pulley support  418 A of  FIG. 4 . In some embodiments, the tilt pulley mounted on tilt pulley support  610 A comprises tilt pulley  416 A of  FIG. 4 . In some embodiments, tilt pulley  606  is mounted to a tilt bearing (e.g., a crossed roller bearing) allowing a heavy payload to be mounted without needing a secondary support. 
     In the example shown, as illustrated in the upper perspective view of  FIG. 6 , tilt motor  602  is an exploded view of tilt motor  602  that is to be mounted on pan and tilt pulley base  604 . In some embodiments, tilt motor  602  is coupled to pan and tilt pulley base  604 . The lower perspective view of  FIG. 6  illustrating tilt motor  602  and tilt drive pulley  608  mounted on pan and tilt pulley base  604 . In some embodiments, tilt drive pulley  608  is coupled to the drive shaft of tilt motor  602  (e.g., as illustrated in the lower perspective view of  FIG. 6 ). In some embodiments, tilt drive pulley  608  is coupled to the tilt gear mounted on tilt pulley support  610 A (similar to tilt pulley  606  mounted on tilt pulley support  610 B) via a drive belt (not shown). In some embodiments, tilt motor  602  is used to provide rotation of the tilt pulley mounted on tilt pulley support  610 A. In some embodiments, tilt pulley  606  is coupled to the tilt gear mounted on tilt pulley support  610 A to move together around a common rotational axis. In various embodiments, tilt rotation to a payload is enabled by coupling tilt pulley  606  or the tilt pulley mounted on tilt pulley support  610 A to the payload or payload mount (not shown). 
       FIG. 7  is a block diagram illustrating perspective views of an embodiment of a pan tilt unit comprising a complete pan and tilt assembly. In some embodiments, PTU base assembly  700  comprises PTU base assembly  100  of  FIG. 1 . In some embodiments, pan and tilt pulley base  704  comprises pan and tilt pulley base  414  of  FIG. 4 . In some embodiments, pan motor  702  and pan drive pulley  712  comprise pan motor  506  and pan drive pulley  504  of  FIG. 5 . In some embodiments, pan belt pulley  714  comprises pan belt pulley  408  of  FIG. 4 . In some embodiments, tilt motor  706  and tilt drive pulley  708  comprise tilt motor  602  and tilt drive pulley  608  of  FIG. 6 . 
     In the example shown, as illustrated in the left perspective view of  FIG. 7 , pan motor  702  is coupled to pan and tilt pulley base  704 . As illustrated in the right perspective view of  FIG. 7 , tilt motor  706  is mounted on pan and tilt pulley base  704 . In some embodiments, tilt motor  706  is coupled to pan and tilt pulley base  704 . 
     In some embodiments, pan motor  702  is used to rotate pan and tilt pulley base  704  about the long axis of PTU base assembly  700  via pan drive pulley  712 . In some embodiments, pan drive pulley  712  is coupled to pan belt pulley  714  via a drive belt (not shown). 
     In some embodiments, tilt motor  706  is used to rotate tilt drive pulley  708 . In some embodiments, tilt drive pulley  708  is coupled to one of the two gears comprising tilt pulley coupler  710  (e.g., the gear immediately above tilt drive pulley  708 ). In some embodiments, tilt drive pulley  708  is coupled to tilt pulley coupler  710  via a drive belt (not shown). In some embodiments, tilt gear coupler  710  is coupled to the PTU tilt pulley (e.g., via drive belts) to provide tilt rotation to various payloads (not shown). 
     In some embodiments, tilt pulley coupler  710  comprises two gears on opposite ends of a split shaft (e.g., as illustrated in the right perspective view of  FIG. 7 ). In some embodiments, the split shaft is coupled together by shaft coupler  716 . In some embodiments, shaft coupler  716  comprises a clamp collar that holds the split shaft together by tightening clamping screws (e.g., allen screws). In various embodiments, shaft coupler  716  allows for independent tilt alignment of mounted payloads during assembly or during maintenance. In various embodiments, where independent tilt alignment of mounted payloads is not required, tilt pulley coupler  710  is a rigid single shaft or the split shafts are keyed wherein the shaft coupler comprises keyways that firmly grip the shaft&#39;s key(s) to eliminate slipping. In various embodiments, the shaft coupler does not comprise keyways instead the pulleys themselves have keyways pressed or set screwed. In various embodiments, the split shafts are not keyed and are instead set screwed, glued, press fit, sweat fit, or any other appropriate manner of coupling the split shafts. 
       FIG. 8  is a block diagram illustrating perspective and side views of an embodiment of a pan tilt unit with enclosure. In some embodiments, PTU base assembly  800  comprises PTU base assembly  100  of  FIG. 1 . In some embodiments, PTU base assembly  800  and PTU pan and tilt module  802  comprise the entire PTU assembly of  FIG. 7 . 
     In the example shown, as illustrated in the top left perspective view of  FIG. 7 , payload mount  804 A comprises tilt pulley shaft flange  806 A and payload mounting plate  806 B. In some embodiments, tilt pulley shaft flange  806 A is used to couple payload mounting plate  806 B to the tilt pulley shaft (e.g., via a tilt gear shaft similar to tilt pulley shaft  420 B of  FIG. 4 ). In some embodiments, payload mounting plate  806 B is coupled to one or more PTU side-mounted payloads (e.g., a camera or any other appropriate sensor). In some embodiments, payload mount  804 A and payload mount  804 B are used to provide tilt rotation to various payloads (not shown). In some embodiments, tilt rotation of the various payloads is measured using a non-contact tilt encoder (not shown). 
     In some embodiments, as shown in the lower perspective view of  FIG. 7 , enclosure profile  808  illustrates a protective perimeter to protect PTU pan and tilt module  802  against weather and debris ingress (e.g., rain, snow, wind, dust, sand, etc.). In some embodiments, as shown in the upper perspective views of  FIG. 7 , enclosure profile  808  comprises enclosure top  808 A and enclosure bottom  808 B. 
     In some embodiments, enclosure  808  comprises a box (e.g., aluminum or any other appropriate protective material). In some embodiments, as shown in the upper left exploded view of  FIG. 7 , enclosure top  808 A comprises multiple access ports (e.g., rectangular access ports) to allow for alignment, calibration, repair, and maintenance of PTU pan and tilt module  802 . In some embodiments, cover plates (e.g., metal cover plates) (not shown) are used to cover and seal (e.g., using gaskets) the access ports against weather ingress. 
     In some embodiments, enclosure top  808 A comprises openings for, and seals (e.g., shaft seals) around, payload mount  804 A, payload mount  804 B, and stationary mount  810 . In some embodiments, enclosure bottom  808 B comprises an opening for, and a seal (e.g., a collar seal) around, the base collar of PTU base assembly  800 . In some embodiments, a seal (e.g., a gasket) is used between enclosure top  808 A and enclosure bottom  808 B to protect against weather ingress. 
       FIG. 9  is a block diagram illustrating an embodiment of an enclosed pan tilt unit with top-mounted computer and exemplary side-mounted payloads. In some embodiments, PTU  900  comprises the entire pan tilt unit (with enclosure) of  FIG. 8 . In the example shown in  FIG. 9 , computer  902  is mounted to the top of PTU  900  (e.g., using stationary mount  904 ). In the example shown, the access ports of PTU  900  are sealed against weather ingress (e.g., using access port cover  906 ). In some embodiments, PTU base flange  908  is used to couple the PTU (e.g., PTU  900 ) with its mounted payloads (e.g., payload  910 A, payload  910 B, and payload  910 C) and computer (e.g., computer  902 ) to a sensor tower, station, or to another PTU (e.g., using through-holes in the PTU base flange). In various embodiments, PTU payloads are added to, mounted on, or otherwise coupled to, one or more payloads that are mounted to a PTU mounting plate—for example, as shown in  FIG. 9 , payload  910 C is coupled to payload  910 B which is mounted to the payload mounting plate of PTU  900 . In various embodiments, payload  910 A, payload  910 B, and/or payload  910 C are directly mounted to the payload mounting plates of PTU  900 . In various embodiments, payload  910 A, payload  910 B, and payload  910 C comprise payloads that require directional positioning (e.g., a camera, an audio sensor, a radar sensor, a lidar sensor, a laser, an illuminating device, etc.). 
     In various embodiments, payload  910 A, payload  910 B, and payload  910 C can tilt up or down. In some embodiments, a payload (e.g., payload  910 A or payload  910 B) is limited in its range of tilt (e.g., using a stop pin) to prevent it from over rotating—for example, to prevent a payload from causing damage to itself, another mounted payload, and/or any other interfering protuberance. In some embodiments, payload  910 A, payload  910 B, and payload  910 C tilt up and down about a common rotation axis. In some embodiments, payload  910 A and payload  910 B tilt independently (e.g., by using more than one tilt motor). 
       FIG. 10  is a block diagram illustrating an embodiment of a stacked pair of enclosed pan tilt units with side-mounted exemplary payloads. In some embodiments, PTU  1000  (with side-mounted payloads) comprises the pan tilt unit with side-mounted payloads of  FIG. 9  (without the top mounted computer). In the example shown, PTU  1002  is mounted to the stationary top mount of PTU  1000  (e.g., via a stationary mount similar to stationary mount  104  of  FIG. 1 ). In some embodiments, PTU  1002  is free to pan and tilt independently of PTU  1000  and PTU  1000  is free to pan and tilt independently of PTU  1002 . In various embodiments, PTU  1000  is mounted to a sensor tower, station, or to another PTU (e.g., via PTU base flange  1004 ). In some embodiments, another PTU, a computer, or any other appropriate payload is mounted to the top of PTU  1002  (e.g. via stationary top mount  1006 ). 
       FIG. 11  is a flow diagram illustrating an embodiment of a method for assembling a pan tilt unit. In the example shown, in  1100 , a cylindrical support is disposed. In some embodiments, the cylindrical support comprises a rigid hollow tube. In some embodiments, the rigid hollow tube comprises an aluminum tube. In some embodiments, the entire cylindrical support is made of aluminum or any other appropriate material to provide strength, rigidity, durability, and light weight (e.g., titanium). In some embodiments, the cylindrical support comprises through-holes to allow cabling to pass from the interior to the exterior of the cylindrical support. In some embodiments, a top platform is coupled to a top of the cylindrical support. In various embodiments, the top platform is used to couple the cylindrical support to another PTU cylindrical support, to a computation unit, or to any other appropriate payload. In some embodiments, the cylindrical support comprises a base flange used to couple the PTU to a sensor tower, station, or to another PTU. 
     In  1102 , data connections are disposed within a slip ring. In some embodiments, the data slip ring rotates with no rotation limit around the cylindrical support. In various embodiments, the slip ring houses one or more interior slip rings to allow transmission of data to or from the various PTU payloads. In some embodiments, the data connections comprise a plurality of shielded connections. In some embodiments, the plurality of shielded connections comprise alternating signal and ground connections for the slip ring unit. In some embodiments, the data connections comprise 4, 8, 12, 16, or 24 data connections. 
     In some embodiments, separate slip ring units are used to supply power. In some embodiments, a power slip ring comprises one or more connection paths. In some embodiments, the power slip ring includes any number N of power connectors and a ground connector. 
     In various embodiments, any number N of data and/or power slip ring units, each comprising any number of connection paths, can be stacked one upon the other around the PTU cylindrical support to provide as many connections as desired. 
     In  1104 , the data slip ring is disposed to rotate about the cylindrical support. In some embodiments, a slip ring fixation collar is used to fix the data slip ring to the cylindrical support to allow the data slip ring to rotate. In various embodiments, the data slip ring is affixed to the cylindrical support using glue, threaded hole, slot, quick release pin, retaining clip, cotter pin, or any other appropriate manner affixing. 
     In  1106 , a rotating platform is disposed. In some embodiments, the rotating platform comprises a pan and tilt gear base, a pan motor, a pan drive gear, a coupling plate, and a pan belt gear, wherein the pan drive gear is coupled to the pan belt gear via a drive belt. In some embodiments, the rotating platform&#39;s angular position, velocity, and acceleration are measured using a rotary encoder. 
     In  1108 , the rotating platform is coupled to the rotating portion of the data slip ring of  1104 . In some embodiments, the rotating platform is coupled to the top of the data slip ring. In some embodiments, the rotating platform is coupled to the rotating portion of a power slip ring (e.g., the top of the power slip ring). 
     In  1110 , a tilting mechanism is disposed. In some embodiments, the tilting mechanism comprises a tilt motor, a tilt drive gear, a tilt gear coupler, and a shaft coupler, wherein the tilt drive gear is coupled to the tilt gear coupler (e.g., via a drive belt or other drive mechanism) and the tilt gear coupler is coupled to the PTU tilt gears (e.g., via drive belts). In some embodiments, the tilting mechanism comprises two mounts on opposite sides of the cylindrical support. In some embodiments, the two mounts are coupled to move together around a common tilt axis. In various embodiments, a mount of the two mounts is coupled to one of the following: a camera, an audio sensor, a radar sensor, laser, spotlight, a lidar sensor, or any other appropriate payload. In some embodiments, the two mounts rotate independently of each other. 
     In  1112 , the tilting mechanism is coupled to the rotating platform. In some embodiments, the tilt mechanism&#39;s angular position, velocity, and acceleration are measured using a rotary encoder. In some embodiments, the assembled pan tilt unit is one of a plurality of pan tilt units. In some embodiments, the plurality of pan tilt units are stacked onto the cylindrical support