Field of Invention

The invention belongs to the field of conveying and supporting systems suspended on ropes/cables, more specifically to the field of devices and systems suspended by ropes/cables, with which equipment such as a camera or a still camera can be moved in space.

Prior Art

Systems for moving a platform in space together with any useful load such as recording/photography equipment or measuring/control instruments or supervision systems by way of one or several ropes/cables are well known and widely used. Several technical variants of such systems are known. Some of them will be described in the continuation.

Patents US4625938A, US4710819A, WO8402199A1 and IT1197748B disclose a device and a system for moving equipment, such as a camera, in space, wherein all drive components (motors, drums) are arranged on/at fixed support points, via which individual cables are guided by way of pulleys from a device to winding drums.

Similar technical solutions are described in patents US2004124803A1, US2004206715A1, US2005024004A1, US2007152141A1 and WO2005013195A2. Said inventions solve a problem of positioning and moving the equipment, for instance a camera, in space in three dimensions. Equipment is suspended above a space via cables and pulleys arranged on fixed pillars. The system is controlled and driven by way of drums and drives arranged at the foot of fixed support points. Said inventions offer a technical solution, in which one or several so-called endless cables are used, which allow movement of a load in space by using a large number of pulleys and drums arranged on fixed support points with less power needed. All existing systems sharing the endless cable principle are characterized in that both ends of the cable are attached to the same element, in this case to a winding drum arranged on/at a fixed support point, and the whole mass of the load is thus carried by this drum.

Technical solutions to movement of equipment suspended on ropes/cables are disclosed in the following patents as well: US6873355B1, US2011204196A1, US2011204197A1, US2013050652A1, US2013051805A1, WO0177571A1 and CN103873848A. All the mentioned solutions share a common point: winding drums and their drives are arranged on/at fixed support elements and the cables are guided via pulleys arranged on fixed supports to a platform, on which equipment is arranged. In this way, each of the cables carries part of equipment mass. This is the reason why the drums and their drives are relatively large, more expensive and a setup of the entire system is more demanding.

Patent applications US5224426A, US2007056463A1, US2005087089A1 and WO2005042385A2 describe a system, in which movement of a useful load through a two- or three-dimensional space is provided for by variously arranged pulleys and by one or several driving devices arranged on/at fixed points. Said patents also make use of one of the variants of endless cable system, wherein all proposed solutions have systems for driving and controlling a useful load arranged on fixed support points.

Apart from the above-mentioned technical solutions there are also inventions disclosed in US2190093A and WO2004074064A1 which solve the problem of movement of a load or equipment in space by way of a platform that travels on two rails and on which a load or equipment is suspended via pulley arrangements. The drive of the drums for winding or unwinding the cables, with which the load that is suspended on the platform is managed, can be arranged either on a movable platform that travels on rails or on fixed points.

Technical solutions including double winding drums, with which a more rapid winding of ropes/cables or higher load capacity are achieved are known from other fields of use of winding drums and systems with pulley arrangements. Such systems are for instance described in EP0420721A1, DE 10006486 Al, GB432342A and WO2006105701A1.

Solution to the Technical Problem

The present invention offers a technical solution to moving a platform in space, wherein the presented solution is more compact, more lightweight, more simple and, most importantly, provides for a more rapid preparation and arrangement of the entire system on the location of use.

For moving the platform together with a useful load (e. g. a camera) in space the system of the invention makes use of cables, of at least one positioning and at least one winding drum. All drums and their drives are arranged on the platform. The present solution differs from known solutions, in which an endless cable is used in that the endless cable begins and ends on the same winding drum arranged on the platform. Positioning drums are only used to shorten or extend individual pairs of cables. The system will be described in more detail in the continuation by way of figures, in which :

Figure 1 shows a system for moving a platform of the Invention;

Figure 2 shows a side view of several possible positions of the platform in space;

Figure 3 shows a positioning drum;

Figure 4 shows a winding drum;

Figures 5 and 6 show an example of use of the system of the invention; Figure 7 shows a differential drum;

Figures 8 and 9 show two examples of how positions of attachment points are determ ined;

Figure 10 shows a side view of an example of a possible embodiment of the system for moving a platform of the invention;

Figure 11 shows an example of controlling the platform via control panel;

Figure 12 shows an example of a technical solution with two positioning and two winding drums;

Figure 13 shows a detail of the example of a technical solution with two positioning and two winding drums.

A system for moving a platform 1 together with a useful load, for instance a camera 22, in space by way of cables 7 consists of at least one positioning drum 4 with a positioning motor 9 and of at least one winding drum 5 with a winding motor 8. All drums 4, 5 with belonging motors 8, 9 are arranged on the platform 1.

A variant shown In Figure 1 represents a configuration, in which the system is suspended on four fixed supports 2, to which four pairs 15 of cables 7 are guided via three positioning drums 4 and one winding drum S. The platform 1 Is connected with mounting pulleys 3 by way of cables 7 guided via guides 6, said pulleys 3 being fastened on fixed supports 2 of carrier structures. In this a , movement of the platform 1 by means of the positioning drums 4 and of the winding drum 5 and their drives is achieved: of the winding motor 8 and positioning motors 9 arranged on the platform 1. The so-called endless cable is guided through positioning drums and this is a key difference from a ll hitherto known solutions, in which drums and their drives are arranged on fixed supports and provided with at least one cable for each drum. The present solution also differs from known solutions, in which an endless cable is used in that the endless cable in the proposed technical solution begins and ends on the same winding drum 5 arranged on the platform. The winding drum 5 is used to extend and shorten the total length of the cable, while the positioning drums 4 are used only to shorten or extend individual pairs 15 of the cables 7. The function of the winding drum 5 is only to carry the weight of the load, while the positioning drums 4 have a positioning function, i. e. the function of moving the load in space.

Such system configuration is very useful where distances of movement of the platform 1 in transversal and longitudinal directions, in directions X and Y, are much longer than a distance of movement of the platform 1 in height, in direction Z. A typical example is athletic stadiums. In such cases, angles oc2, β2 between a horizontal plane and a tilt of an individual cable 7 are relatively small in a majority of examples of movement of the platform 1 during normal operation and at the same time smaller than angles ocl, βΐ that occur while the platform is moved close to the ground. Consequently, a small angle oc2, β2 between each cable 7 and a horizontal plane means that during the movement of the platform 1 a small change in the total length of cable 7, which is controlled by the winding motor 8 or the winding drum 5, will be needed. This is the reason why such winding motor 8 can be by an order of magnitude smaller than winding motors of other comparable systems, in which a winding motor functioning as a load weight transferring means at the same time performs a positioning function. It needs to be additionally stressed that in such configuration the positioning motors 9 do not transfer load weight (or only insignificantly) but only overcome a difference in force between individual pairs 15 of cables 7. In this way, all used motors can be smaller than those in comparable systems nowadays known on the market by an order of magnitude.

The platform 1 is controlled by an electronic control unit 16 collecting data from one or several sensors 17 and controls electric motors, more precisely winding motors 8 and the positioning motor 9, on the basis of control algorithms. These are supplied by one or several batteries 19. The following components are arranged on the platform 1: an electronic control unit 16, sensors 17, electric motors 8, 9 and batteries 19. Additional sensors 20 may be arranged in space, wherewith the manner of control of the platform 1 is improved or adjusted.

The entire system is wirelessly controlled by means of a ground control station 43, through which an operator transmits commands on a desired speed of movement of the platform 1 in all three directions: forwards-backwards, left-right and up-down. Commands are transmitted through wireless connection 44 to the electronic control unit 16 arranged on the platform 1 which independently controls individual electric motors based on received input data on a desired movement of the platform (speed in all three directions) and based on data from the sensors 17 on the platform 1 or external sensors 20.

Drive systems, i. e. the positioning drum 4 and the positioning motor 9 as well as the winding drum 5 and the winding motor 8 control winding or unwinding of the cable as a function of a desired movement of the platform 1 in space. Each positioning drum 4 controls shortening or extending of the length of the cable 7 in individual pairs 15 or »ends« of the cable which are fastened to fixed supports 2 via pulley 3. The function of the winding drum 5 is to shorten or extend the total length of the cable 7 in the system depending on the current position of the platform 1.

Figure 2 represents a side view of several possible positions of the platform 1, namely a starting or calibration point 24, a selected central point 25 and two additional possible positions 26, 27 of the platform 1 during operation. While the platform 1 is moving, the total length of the cable 7 needs to be changed and this is performed by the winding drum 5. Due to the earlier mentioned small angles oc2, β2 formed by the cables 7 of the platform 1 with the horizontal plane, the total length of the cable 7 changes slowly or for a relatively small amount while the platform 1 is moving. Thus a less powerful, more lightweight and less expensive winding motor 8 can be used.

Figure 3 represents a positioning drum 4 consisting of two halves. One part of the positioning drum 4 is always a winding part 10 and another part is an unwinding part 11, depending on the direction of movement of the platform 1. The amount of a wound cable 28 on the positioning drums 4 does principally not change due to said construction of the positioning drum 4. In other words: winding or unwinding of the positioning drums 4 does not extend or shorten the total length of the cable 7 in the system.

Figure 4 represents a winding drum 5 that also consists of two halves 5a and 5b, wherein both halves are winding or unwinding, depending on the position and the desired movement of the platform 1. While the winding drum 5 rotates, both the total length of the cable 7 in the system and consequently also the amount of the wound cable 29 on the winding drum 5 change accordingly. When a narrow positioning drum 4 and a winding drum 5 are used, where the cable 28 and 29 is wound in several layers and the effective diameter of winding/unwinding changes as a function of rotation of the drum 4 and 5, a minimal change in the total length of the cable may occur due to rotation of the positioning drum 4 and the winding drums 5. These changes are automatically considered in control algorithms of the platform and compensated with adequate corrections of rotation of the positioning drums 4 and the winding drum 5. This technical solution is substantially different from other solutions known on the market, in which each winding drum positioned on/at fixed supports is responsible for winding or unwinding the cable, wherein each drum must also carry part of the own weight of the platform. According to the proposed technical solution of the invention, the positioning motors 9 must only transfer differences in forces among individual pairs 15 of cables which result from the desired movement of the platform 1 in space. In conjunction with a relatively slow rotation of the winding drum 5 the system of the invention allows a use of the motors 8, 9 which can use even less than one tenth of the power of the motors used in hitherto known systems. The motors 8, 9 can therefore be smaller which results in a lower mass of the platform 1 and in a better relative capacity of the system with respect to the available power of the motors.

The centralized design of the system (on the platform 1 there are arranged positioning drums 4 and winding drums 5 and the belonging motors 8, 9 as well as the electronic control unit 16 which controls and synchronizes all motors 8, 9 at the same time) makes the entire system extremely simple to conceive, produce, install and use.

The main advantage and therefore the essence of the invention lies in the design of the entire system, in which the endless cable has both ends of the cable 7 fastened on the same winding drum 5 positioned on the platform 1. It takes the advantage of small angles between the horizontal plane and an individual pair of cables. While the platform moves in space (such as athletic stadiums), small changes in the total length of the cable in the system are required, and consequently a less powerful electric motor can be used to drive the winding drum 5. Owing to the concept of the system with the endless cable the positioning motors 9 do not need to overcome the weight of the entire platform 1 but have only to provide for the necessary torque depending on the difference in forces between adjacent pairs of cables, for instance 31 and 32, which consequently allows use of smaller electric motors for driving the positioning drums 4.

The embodiment in Figures 5 and 6 represents an example of use of the system of the invention, wherein the system consists of three positioning drums 34, 35 and 36 and of one winding drum 37 which are connected to four fixed supports 2 via four pairs 30, 31, 32, 33 of cables 7. If the platform 1 moves exactly over the central point 25, the winding drum 37 does not rotate at that moment (no shortening/extending of the total length of the cable 7 is required). If the platform deviates from the central point 25 towards an edge of a space, for instance in direction X 12, the winding drum 37 only needs to correct the length of the cable 7 with respect to a desired height 14 or the needed total length of the cable 7. If the platform moves in direction X 12, the pair 30 and 31 of the cable needs to extend and the pair 32 and 33 of the cable needs to shorten. This means that the drums must rotate by the following rule: the drum 34 must rotate in a way to wind the cable from the pair 31 of cables and unwind the cable to the pair 30 of cables; the drum 35 must rotate in a way to wind the cable from the pair 32 of cables and to unwind the cable to the pair 31 of cables; the drum 36 must rotate in a way to wind the cable from the pair 33 of cables and unwind the cable to the pair 32 of cables.

In said example, while moving longitudinally (along axis X) the positioning drum 35 must rotate approximately twice as fast than the remaining two positioning drums 34 and 36. The problem can be solved in three ways: use a more powerful/faster motor for the positioning drum 35, limit the speed of movement in longitudinal direction (in direction of axis X), or use a differential winding drum instead of the winding drum, which differential winding drum resembles in its concept to an automobile differential. Since the first two options are technically not optimal, the third solution is suggested in the present invention, i. e. use of a differential winding drum.

Figure 7 represents an example of a differential winding drum 40 that replaces the winding drum 37. In the present example, both halves of the differential winding drum 40, the left half 38 and the right half 39, can simultaneously rotate in different directions. This is also true in the event when one of the halves stands still and the other one rotates in a desired direction. The left half 38 and the right half 39 of the drum are driven by the positioning motor 45 and the winding motor 46. Such solution from the above described example of a system with four drums and four pairs of cables provides for simultaneous positioning of the winding drum 37 on the endless cable and at the same time provides control over the total length of the cable by winding/unwinding the cable depending on the needed movement of the platform 1.

Speeds of rotation of the left half 38 and the right half 39 of the differential drum 40 depend on the ratio between the current speed of rotation of the positioning motor 45 and the winding motor 46 and on the gear ratio of gear transmissions 47 within the differential winding drum 40. The platform 1 can thus be moved at equal speed in both horizontal directions, X 12 and Y 13 by using four equally powerful positioning motors (three positioning motors 9 which drive the positioning drums 34, 35 and 36 and one positioning motor 45 in the differential winding drum 40). By using adequate gear ratios in the differential winding drum 40 it can be achieved that the winding motor 46 is the same as the positioning motor 45. This can even additionally contribute to simplification and price efficiency of the entire system. When the differential winding drum 40 is used for moving the platform 1 at equal speed in both horizontal directions X and Y, this is possible due to the fact that the differential winding drum 40 can take over an average of one half of the load of winding/unwinding of the positioning drum 35 due to its simultaneous positioning and winding function. In case of transversal movement in direction of axis X the positioning drum 35 should be on the average two-times faster (more powerful) than the remaining two positioning drums 34 and 36.

Instead of the differential winding drum 40 as described above a technical solution can be used, in which two endless cables 7 are used, each provided with one positioning drum 4 and one winding 5 drum, and arranged in a crosswise way as shown in Figure 12. In this case, both winding drums 5 can independently shorten or extend the total length of each individual cable 7, while two positioning drums 4 only shorten or extend each individual pair of cables depending on the required movement of the platform 1.

Based on the concept of the technical solution suggested in the present invention, such system can relatively easily be used to determine the starting position of attachment points or mounting pulleys 3 of the platform 1 when the system is installed and calibrated. Figures 8 and 9 show an example of how positions of attachment points and the position of the platform 1 are determined.

The method for determining the positions of attachment points can be automated and is carried our separately for each pair 30, 31, 32, 33 of cables. When the system is installed and calibrated the platform 1 is in a starting position 24 which needs not be located in the centre of the area of movement. The position of the attachment point for the pair 30 of the cable 7 is determined as follows: the mounting pulley 3 of the pair 30 of the cable 7 is fastened to the fixed support 2. When beginning to determine the starting position of the attachment point on a suitable fixed support 2, an algorithm is used to provide for an adequate and predetermined force in the pair 30 of the cable 7. The length of the cable 7 in the pair 30 of the cable is then read on the basis of data on positions of all four motors/drums. At the same time, output angles δ and γ of the cable 7, with which orientation and position of the platform 1 towards the fixed support is determined, are determined with respect to the set coordinate system of the platform 1. If needed, correction of the output angles δ and γ and of the length of the cable 7 is done due to slacking of the cable 7. The obtained data are used to calculate a relative position of the attachment point on the adequate fixed support 2 with respect to the platform 1. The described method is then repeated for all attachment points on adequate fixed supports 2 of the platform 1.