Patent Publication Number: US-2012037575-A1

Title: Motion control system

Description:
RELATED APPLICATIONS 
     This application claims benefit of priority to Provisional U.S. Application No. 61/363,968, filed Jul. 13, 2010; the aforementioned priority application being incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosed embodiments relate to motion control systems for equipment, and more particularly to motorized camera mounts. 
     BACKGROUND 
     Filmmaking often employs sophisticated motion control equipment to capture specialized video segments and/or still shots. Often included under the category of “special effects” equipment, the systems may involve electromechanical features to assist in orienting or moving a camera, light, boom (or other equipment) in a manner that&#39;s overly difficult to achieve manually. Successful special effects often rely on the flexibility and performance of motion control systems to achieve optimum results. 
     Conventional motion control systems employ generic dolly&#39;s or car mounts to capture images while in motion. Such constructions are often bulky, difficult to employ in remote locations and limited in camera orientation capability. 
     What is needed, and as of yet unavailable, is a lightweight motion control system that provides portability, stability, and precise control over motion control equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
         FIG. 1A  illustrates a partial side view of one embodiment of a track assembly in accordance with one embodiment; 
         FIG. 1B  illustrates a transverse cross-sectional view of the track assembly of  FIG. 1A ; 
         FIG. 1C  illustrates a perspective view of the track assembly of  FIG. 1A , in an upright orientation; 
         FIG. 2A  illustrates a perspective view of one embodiment of a trolley assembly; 
         FIG. 2B  illustrates a side view of the trolley assembly of  FIG. 2A ; 
         FIG. 2C  illustrates a front view of the trolley assembly of  FIG. 2A ; 
         FIG. 2D  illustrates a top plan view of the trolley assembly of  FIG. 2A ; 
         FIG. 3A  illustrates a transverse side view of a further embodiment of a track assembly with a trolley assembly in operation; 
         FIG. 3B  illustrates a partial inline side view of the track assembly of  FIG. 3A ; 
         FIG. 3C  illustrates an embodiment of tubing employed in the track assembly of  FIG. 3A ; 
         FIG. 3D  shows a perspective view of the track assembly similar to  FIG. 3A ; 
         FIG. 4A  illustrates an embodiment of a trolley assembly for use with the track assembly of  FIG. 3A ; 
         FIG. 4B  illustrates a side view of the trolley assembly of  FIG. 4A ; 
         FIG. 4C  illustrates a perspective view of the trolley assembly of  FIG. 4A  looking upwards from a lower orientation; and 
         FIG. 4D  illustrates a top plan view of the trolley assembly of  FIG. 4A . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of motion control apparatus and systems to provide improved special effects for filmmaking are disclosed. In one embodiment, a motion control system comprises a modular track assembly comprising a plurality of connectable segments. The track assembly is configured to direct a movable trolley assembly that employs a platform to mount filmmaking equipment. The trolley assembly includes a drive assembly that responds to remotely generated control signals to move the trolley assembly along the track assembly. 
     Referring now to  FIGS. 1A-1C , a portion or segment of a track assembly is shown, generally designated  100 , that employs a plurality of rails comprising metal tubular members  102   a - 102   c . The tubular members are disposed longitudinally in a spaced-apart parallel relationship to provide a transport path for a trolley assembly ( FIGS. 2A-2D ). The relative spacing between a first pair  102   a  and  102   b  of the rails generally conforms to a corresponding trolley wheel spacing, while the third member  102   c  is offset (both vertically and horizontally) to effect a triangular cross-sectional shape with respect to the other two rails. A series of regularly spaced-apart U-shaped brackets  104   a - 104   c  are welded transversely to the rails to provide a support function and maintain the members in their relative parallel positions during transport of a trolley assembly. While the triangular configuration works well to minimize weight and materials, other arrangements may be used, including one or more additional rails to, for example, effect a rectangular configuration. 
     To achieve various track configurations, each segment of the track assembly  100  may employ connectors (not shown) at the ends of each rail to engage corresponding mating connectors formed on other segments. The connectors generally include respective male plugs (not shown) for engaging complementally formed female sockets (not shown) in a friction fit or quick disconnect manner. In one embodiment, segments join one way to minimize any risks of improper assembly. Other embodiments may employ universal segments that may join together in any desired orientation. Additional rigging in the form of support pillars (not shown) may be employed to provide even further support for the track assembly. 
     Further referring to  FIGS. 1A-1C , the tubular members  102   a - 102   c  and brackets  104   a - 104 C are formed from aluminum or stainless steel to provide a lightweight but strong structure. Other materials may also be employed that provide sufficient strength, rigidity, and portability to enable mobile set-up and tear-down operations. As described in further detail below, the lightweight segmented nature of the track  100  enables film crews to setup and operate trolley assemblies (described below) in a variety of remote and local environments. 
     Referring now to  FIGS. 2A-2D , one embodiment of a trolley assembly is shown, generally designated  200 , for operating along the track assembly  100  described above and shown in  FIGS. 1A-1C . The trolley assembly  200  includes an equipment platform  210  that rests upon a movable frame assembly  220  that&#39;s powered by a drive assembly  240 . 
     The equipment platform  210  comprises an L-shaped metal bracket including an optional rectangularly-formed vertical panel  214  joined at one end to a flat horizontally disposed seat  216 . Respective elongated rectangular containers  218  and  219  are disposed on each side of the seat for housing power and control modules including a battery pack assembly and a wireless receiver assembly. The seat is adapted to mount equipment such as a movie camera, light, or the like, and may include one or more mounts, fasteners, or clamps to effect the mounting. 
     Further referring to  FIGS. 2A-2D , the movable frame assembly  220  supports the equipment platform  210  and includes a first set of wheels  222   a - 222   d  to engage the upper surface of a track assembly (such as that disclosed in  FIGS. 1A-1C ). The first set of wheels is arranged in respective in-line pairs that are spaced-apart from each other in a manner that corresponds to the rail spacing of the track assembly. Respective horizontally disposed retaining rods  224  and  226  couple to each axle of each wheel to maintain wheel alignment and stability for each inline pair. The retaining rods  224  and  226  provide the support surface for mounting the equipment platform  210 . 
     The frame assembly  220  further includes a pair of spaced-apart downwardly projecting vertical legs  228  and  230  that support a second set of wheels  232   a  and  232   b  coupled together by an axle  234 . The second set of wheels are disposed in vertical alignment with each of the inline pairs of wheels  222   a / 222   d  and  222   b / 222   c , and are offset vertically by a dimension sufficient for the second set of wheels to engage the bottom surface of the track tubular members  102   a  and  102   b  ( FIG. 1C ). The second set of wheels  232   a  and  232   b  provide additional adhesion to the track for applications where somewhat vertical or even inverted orientations may be employed that might otherwise tend to cause a derailing of the trolley assembly  200 . 
     To effect maximum adhesion to the track rails  102   a  and  102   b  ( FIG. 1C ), all of the wheels are formed of a durable rubber or polyurethane material to maximize traction along the track assembly rails. Additionally, since each tubular member has a curvature associated with its surface, the engagement surface of each wheel is formed with a corresponding U-shaped curvature to complement the tubular member surface. The second set of wheels  232   a  and  232   b  and the associated legs  228  and  230  may be adjustable and/or pivotable to enable sufficient clearance for initially installing the trolley assembly  200  on the track assembly  100 . 
     Further referring to  FIGS. 2A-2D , the drive assembly  240  includes an electric motor  242  that is coupled to the power and control modules. The motor includes a rotating shaft (not shown) that mounts a first pulley  244 . A belt  246  is looped over the first pulley and a second pulley (not shown) coupled to one of the wheels  222   d  to form a belt drive. The motor  242  responds to wireless control signals received by the wireless receiver assembly (not shown) to generate rotation of the shaft, and corresponding movement of the drive wheel  222   d . A corresponding remote control (not shown) manipulated by a user provides the wireless input to the radio receiver. In one embodiment, to provide optimal control over a heavily-laden trolley assembly  200 , a single wheel drive motor is employed. This provides optimal speed and torque in one direction. An exemplary motor runs on 36 volts DC, at a redline of 3000 RPMs, and draws 28.5 amps to dissipate 800 W. Other embodiments, such as those described below, employ multiple wireless channels, and may control the trolley bidirectionally and also control the velocity and acceleration of the trolley. 
     In operation, the track assembly  100  is first laid out by assembling sufficient segments into place such that the trolley assembly  200  may be guided in a manner that provides the desired motion control to effect, for example, an extreme filmmaking sequence. A key benefit of the system is enabling motion shots without exposing a live crewman to an extreme orientation or condition. Equipment such as a camera or light may then be mounted to the equipment platform  210  of the trolley assembly  200 . With the trolley assembly secured to the track assembly  100 , a user may manipulate the trolley forward while filming by actuating a switch or joystick on the remote control. Because of the belt-driven configuration of the trolley assembly  100 , significant torque and speed may be achieved, depending on the application. This is especially beneficial for effects sequences employing heavy equipment, where horizontal transport on the order of 250 pounds or vertical transport of 100 pounds of equipment is desired. 
       FIGS. 3A-3D  illustrate an alternate embodiment of a track assembly, generally designated  300 . The track assembly is similar to that shown in  FIGS. 1A-1C , including a plurality of tubular rail members  302   a - 302   c  disposed in a spaced-apart parallel relationship, with regularly spaced support brackets  304 . Respective segments may be formed with curvatures to, when assembled with a sufficient number of segments, form a completed track assembly taking on a circular configuration, as shown in  FIGS. 3A and 3D . A stage  306  may optionally straddle a portion of the track to allow for movement of a trolley assembly at various surrounding orientations. Moreover, the circular track assembly may be oriented completely vertically, or at any desired angle (with sufficient bracing from auxiliary rigging attachments). 
     Although the track assembly embodiments of  FIGS. 1A-1C  and  FIGS. 3A-3D  are separately described herein as straight and circular tracks, various track layouts may benefit from mixed assemblies of straight and curved segments. 
     Referring now to  FIGS. 4A-4D , a further embodiment of a trolley assembly, generally designated  400 , is illustrated that provides bi-directional motion control. The trolley assembly includes an equipment platform  410  and frame assembly  420  constructed similar to that described in  FIGS. 2A-2D . In one embodiment, a drive train assembly  430  is provided that employs an electric motor  435  responsive to a mufti-channel wireless radio (not shown). One of the channels provides for forward motion control, while another channel provides for reverse motion control. The bidirectional wireless control also enables near-instantaneous changes in direction, and speeds in the range of approximately 50 to 70 feet per second. An optional third channel may provide for speed control. The motor is a 48V DC motor that provides an output of 4 KW at a maximum speed of 2800 RPMs, and 13.6 Nm of torque. As in the prior embodiment, respective containers  418  and  419  disposed on each side of the equipment platform  410  house a power supply (in the form of a parallel array of batteries), and a wireless receiver control module. 
     To effect additional traction along a track assembly  300 , the drive train assembly  400  implements a worm gear drive that allows for the direct drive and synchronization of two wheels  422  and  424 . The worm gear drive includes a drive axle  432  that distally mounts a worm gear  434  for engaging a worm  436  formed on a common axle  433  joining the two wheels  422  and  424 . Rotation of the drive axle  432  thus results in a corresponding rotation in the wheel axle  433 , which translates to the two drive wheels to develop torque. 
     In a further embodiment, the electric motor may be replaced by a servo that incorporates built-in memory and control circuitry. One of the benefits realized by using a servo is the ability to carry out precise and repeatable trolley movements. Software resident on a general purpose computer may assist a user in programming the servo memory with a given sequence of desired servo movements, for subsequent execution in response to wireless control signals to carry out the sequence. In one embodiment, the software allows a user to operate the servo-driven trolley assembly  400  for a set duration (such as two minutes), record the sequencing of the servo controls, and provide a playback option so that the recorded sequence of movements can be repeated by the trolley assembly. The programmability provides for infinite repeatable exact programmable reference points, with an additional speed control feature. This is especially beneficial for applications involving heavy effects sequences, where the same camera can be controlled in a repetitive manner any number of times to capture the effect. Maximum speeds on the order of approximately 30 to 50 feet per second may be obtained. Moreover, the servo may be controlled at a high granularity such that fine-motion control over the trolley may be achievable. One embodiment provides a control granularity of approximately one wheel revolution per year. One example of a servo provides a maximum speed of 1500 RPM, with 990 oz-in of torque, at a peak power level of 515 Watts, and manufactured by Quicksilver (model QCI-34H-4-E-01). 
     Those skilled in the art will appreciate the many benefits and advantages afforded by the embodiments described herein. The portability and modularity of the track assembly allows for the use of the motion control system in a variety of filmmaking settings, both inside a studio setting and on-location outside of a studio setting. Moreover, by effecting a wireless control system for directing the trolley in one or more directions, extreme orientations for film sequences may be carried out in motion without exposing crewmen to the extreme conditions. Further, having a programmability aspect in some embodiments to achieve repeatability and precision simplifies the effects process for multiple sequences of similar shots. 
     While the invention has been described with reference to specific embodiments thereof, it will be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. For example, features or aspects of any of the embodiments may be applied, at least where practicable, in combination with any other of the embodiments or in place of counterpart features or aspects thereof. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.