Abstract
The present invention relates to a driverless transport system (81), comprising a plurality of driverless transport devices (10) having a support structure (12) with an outer contour (14); an undercarriage (16) which is secured to the support structure (12) and has at least one first wheel (18) and a second wheel (20), wherein the first wheel (18) is mounted in the undercarriage (16) so as to rotate about a first axis of rotation (D1) and the second wheel (20) is mounted in the undercarriage (16) so as to rotate about a second axis of rotation (D1); a drive unit (22) by means of which the first wheel (18) and the second wheel (20) can be driven independently of each other; a control unit (94) for controlling or regulating the driverless transport devices (10); and a communication device (76) by means of which information can be exchanged between the control unit (94) and the driverless transport devices (10), wherein one of the driverless transport devices (10) is designed as a master (86) and the other driverless transport devices (10) are designed as slaves (88).
Claims
1. A driverless transport system (81), comprising a plurality of driverless transport devices (10) having a support structure (12) having an outer contour (14); an undercarriage (16) which is secured to the support structure (12) and has at least one first wheel (18) and a second wheel (20), wherein the first wheel (18) is mounted in the undercarriage (16) so as to rotate about a first axis of rotation (D1) and the second wheel (20) is mounted in the undercarriage (16) so as to rotate about a second axis of rotation (D1); a drive unit (22) by means of which the first wheel (18) and the second wheel (20) can be driven independently of each other; a control unit (94) for controlling or regulating the driverless transport devices (10), and a communication device (76) by means of which information can be exchanged between the control unit (94) and the driverless transport devices (10); wherein one of the driverless transport devices (10) is designed as a master (86) and the other driverless transport devices (10) are designed as slaves (88).
2. The driverless transport system (81) according to claim 1, characterized in that the master (86) has a master sensor unit (90) for detecting the environment of the master (86), and the master (86) transmits information relating to the environment of the master (86) to the control unit (94) and/or to the slaves (88).
3. The driverless transport system (81) according to claim 1, characterized in that each of the transport devices (10) has a sensor unit (66) for detecting the environment of the transport device (10), the sensor unit (66) being arranged in a sensor portion (68) delimited by the outer contour (14) and the first axis of rotation (D1) or the second axis of rotation (D2), and the sensor unit (66) is designed in such a way that it only detects the part of the environment on the side of the first axis of rotation (D1) or the second axis of rotation (D2) on which the sensor unit (66) is arranged, at least a first of the sensor units being oriented in a first direction and at least a second of the sensor units being oriented in a second direction.
4. The driverless transport system (81) according to claim 1, characterized in that one or more of the transport devices (10) have a force measuring device (56) by means of which the force acting on the support portion (39) can be determined.
5. The driverless transport system (81) according to claim 1, characterized in that the outer contour (14) of the support structure (12) is substantially rotationally symmetrical about a rotational axis (R) in the top view, and the support portion (39) and/or the first wheel (18) and the second wheel (20) are arranged within the outer contour (14) or are flush with the outer contour (14).
6. The driverless transport system (81) according to claim 1, characterized in that the transport device (10) has a sensor unit (66) for detecting the environment of the transport device (10), the sensor unit (66) being arranged in a sensor portion (68) delimited by the outer contour (14) and the first axis of rotation (D1) or the second axis of rotation (D2), and the sensor unit (66) is designed in such a way that it only detects the part of the environment on the side of the first axis of rotation (D1) or the second axis of rotation (D2) on which the sensor unit (66) is arranged.
7. The driverless transport system (81) according to claim 1, characterized in that the transport device (10) has a storage unit (70) for electrical energy which, in the top view, protrudes in portions beyond the outer contour (14) of the support structure (12), the storage unit (70) being movably secured to the support structure (12).
8. The driverless transport system (81) according to claim 7, characterized in that the storage unit (70) is secured to the support structure (12) so as to rotate about the rotational axis (R).
9. The driverless transport system (81) according to claim 7, characterized in that the storage unit (70) is arranged outside the sensor portion (68).
10. The driverless transport system (81) according to claim 7, characterized in that the storage unit (70) is detachably secured to the support structure (12).
11. The driverless transport system (81) according to claim 7, characterized in that all the wheels (18, 20) are arranged so as to rotate about a common axis of rotation (D) and the driverless transport device (10) has a self-stabilizing device (74).
12. The driverless transport device (10) according to claim 1, characterized in that the driverless transport device (10) comprises a lifting device (32) which interacts with the support structure (12) for lifting and lowering at least one support portion (39), which interacts with the objects in order to transport same.
13. A method for operating a driverless transport system (81) according to claim 1, comprising the following steps: defining one of the driverless transport devices (10) as a master (86) and the other driverless transport devices as slaves (88), positioning the master (86) such that the environment of the master (86) can be detected by means of the master sensor unit (90), and transmitting information relating to the environment of the master (86) to the control unit (94) and/or to the slaves (88) by means of the communication device (76), and/or the wireless network is available for all the slaves (88).
14. The method for operating a driverless transport system (81) according to claim 13, comprising the following steps: determining the force acting on the respective support portions (39) of the transport device (10) by means of the force measuring devices (56), transmitting the determined forces to the control unit (94) by means of the communication device (76), comparing the determined forces by means of the control unit (94), and lifting or lowering one or more of the support portions (39) by means of the lifting devices (32) on the basis of the comparison and at the instigation of the control unit (94).
15. The method for operating a driverless transport system (81) according to claim 13, comprising the following steps: transporting an object (38) by means of at least two transport devices (10), detecting the environment of at least one transport device (10) with respect to selectable properties by means of a sensor unit (66), and lifting or lowering the support portions (39) by means of the lifting devices (32) on the basis of the detected properties of the environment.
Description
[0088] Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawings, which show:
[0089] FIG. 1A is a perspective view of a first exemplary embodiment of a transport device according to the invention for transporting objects;
[0090] FIG. 1B is a basic and not-to-scale top view of the exemplary embodiment of the transport device shown in FIG. 1A;
[0091] FIG. 2 is a perspective view of a second exemplary embodiment of the transport device according to the invention;
[0092] FIG. 3A is an isolated and perspective exploded view of a lifting device of the transport device;
[0093] FIG. 3B is an isolated view of a force measuring device according to a first exemplary embodiment, which device is integrated into the lifting device;
[0094] FIG. 3C is an isolated view of a force measuring device according to a second exemplary embodiment, which device is integrated into the lifting device;
[0095] FIG. 4 is a basic view of a part of a support structure of the transport device according to the invention according to a third exemplary embodiment, in which a storage unit for electrical energy is movably secured to the support structure;
[0096] FIG. 5 is a top view of an object which is being transported by a transport system;
[0097] FIG. 6A is a side view of a third exemplary embodiment of the transport device according to the invention, which device has an expanding device;
[0098] FIG. 6B is a top view of the third exemplary embodiment of the transport device according to the invention shown in FIG. 6A;
[0099] FIG. 6C is a sectional view through the third exemplary embodiment of the transport device along the sectional plane A-A defined in FIG. 6B;
[0100] FIG. 6D is a sectional view through the third exemplary embodiment of the transport device along the sectional plane B-B defined in FIG. 6B;
[0101] FIG. 6E is an enlarged view of the detail Q marked in FIG. 6D;
[0102] FIG. 6F is an isolated view of an actuator of a decoupling unit;
[0103] FIG. 7A is a perspective view of a fourth exemplary embodiment of the transport device according to the invention, which device has an expanding device;
[0104] FIG. 7B shows the expanding device of the transport device according to the invention according to the fourth embodiment in an isolated top view, where the expanding device is in a first position;
[0105] FIG. 7C shows the expanding device shown in FIG. 7B in a second position by means of a bottom-view;
[0106] FIG. 8 shows a load area being loaded with a plurality of objects using a transport system; and
[0107] FIG. 9 shows a workshop in which a transport system is being used.
[0108] A first exemplary embodiment of a transport device 10.sub.1 according to the present invention is shown in FIGS. 1A and 1B. FIG. 1A is a perspective view of the transport device 10.sub.1 while FIG. 1B is a top view of the transport device 10.sub.1 shown in FIG. 1A, with FIG. 1B not being to scale and being only of a basic nature.
[0109] The transport device 10.sub.1 has a support structure 12 which, in the present exemplary embodiment, is formed by a housing 13 which has an outer contour 14. The outer contour 14 designates the outer surfaces and edges of the support structure 12 or the housing 13. Secured to the support structure 12 is an undercarriage 16 in which a first wheel 18 and a second wheel 20 are mounted so as to rotate about an axis of rotation D1 and a second axis of rotation D2. In the illustrated exemplary embodiment, the first axis of rotation D1 and the second axis of rotation D2 coincide, thus creating a common axis of rotation D.
[0110] The transport device 101 also comprises a drive unit 22 which is likewise secured to the support structure 12. In this case, the drive unit 22 has a first drive motor 24 and a second drive motor 26, the first drive motor 24 being arranged adjacent to the first wheel 18 and the second drive motor 26 being arranged adjacent to the second wheel 20. The first drive motor 24 is connected by means of a first transmission 28 to the first wheel 18 and the second drive motor 26 by means of a second transmission 30 to the second wheel 20, so that the rotational movement provided by the first drive motor 24 and the second drive motor 26 is directly transmitted to the first wheel 18 and the second wheel 20, respectively. The first drive motor 24 can be operated independently of the second drive motor 26, so that the first wheel 18 and the second wheel 20 can also be driven in different directions and at different speeds, as a result of which the transport device 10.sub.1 can be rotated.
[0111] In addition, the transport device 10.sub.1 comprises a lifting device 32, which is shown separately in FIG. 3A. The lifting device 32 is provided with a spindle nut 34 which can be rotated about a rotational axis R by means of a third drive motor 36. The rotational axis R extends perpendicularly to the common axis of rotation D and vertically when the device is being used as intended. The spindle nut 34 interacts with a non-rotatable spindle 37, which in turn is connected to a support portion 39, which, in the first embodiment of the transport device 10.sub.1, is designed in the manner of a ro-tary plate that can rotate with respect to the housing 13. If the spindle nut 34 is rotated about the rotational axis R by means of the third drive motor 36, the spindle 37 and the support portion 39 connected thereto are moved along the rotational axis R. In relation to the intended use of the transport device 10.sub.1, which is the case when the first wheel 18 and the second wheel 20 are rolling on a surface (not shown in FIGS. 1A and 1B), the support portion 39 is either lifted or lowered depending on the direction of rotation of the third drive motor 36. In order to transport an object 38, for example a pallet 40 (see FIG. 5), the transport device 10.sub.1 is moved into a cavity in the pallet 40 and then the lifting device 32 is activated in such a way that the support portion 39 is lifted up. The support portion 39 is consequently brought into contact with the pallet 40, which is consequently lifted up so that it is no longer in contact with the surface. The pallet 40 can then be brought to the desired location by means of the transport device 10.sub.1.
[0112] With reference to FIG. 3A, it can be seen that the support portion 39 of the lifting device 32 has a plate 42 and a studded mat 44 connected to the plate 42. The studded mat 44 can be glued to the plate 42, for example. The plate 42 is connected to the spindle 37 by means of a clamping sleeve 46. The clamping sleeve 46 also simultaneously secures a plate housing 48, which is open toward the plate 42, to the spindle 37. An O-ring 50 is placed in a circumferential groove in the clamping sleeve 46 and seals the clamping sleeve 46 with respect to the plate 42. A thrust roller bearing 52 is arranged in the plate housing 48, so that the support portion 39 can rotate relative to the plate housing 48 and the rest of the transport device 10.sub.1. A rubber ring 54 is arranged between the thrust roller bearing 52 and the plate 42. The rubber ring 54 allows tilting movements between the plate 42 and the thrust roller bearing 52, which are caused by the support portion 39 being unevenly loaded.
[0113] In addition, a force measuring device 56.sub.1 according to a first exemplary embodiment is arranged in the plate housing 48 and is shown separately in FIG. 3B. In the first exemplary embodiment, the force measuring device 56.sub.1 comprises a total of six capacitive force sensors 58, which can be divided into a first group 60 and a second group 62, each group having three force sensors 58. In relation to the intended use of the transport device 10.sub.1, the main surfaces of the force sensors 58 of the first group 60 lie in a horizontal plane while the main surfaces of the force sensors 58 of the second group 62 are oriented perpendicularly to the main surfaces of the force sensors 58 of the first group 60. The force sensors 58 of the first group 60 are in the shape of circle ring segments, while the force sensors of the second group 62 are in the shape of cylinder segments. The main surfaces of the force sensors 58 of the second group 62 lie in a vertical plane when the transport device 10.sub.1 is used as intended. Instead of the capacitive force sensors 58, resistive force sensors, strain gauges, or a printed electronics system can also be used.
[0114] FIG. 3C shows a second exemplary embodiment of the force measuring device 56.sub.2, which differs substantially from the force measuring device 56.sub.1 according to the first exemplary embodiment in that it has only three capacitive force sensors 58, which can be assigned to the first group 60.
[0115] In both cases, it is possible to measure forces acting horizontally and forces acting vertically. In addition—depending on how the force sensors 58 are mechanically mounted—tilting, rotating, and sliding movements can be measured.
[0116] In the first exemplary embodiment of the force measuring device 56.sub.1, the force sensors 58 of the first group 60 are used to determine vertically acting forces. The force sensors 58 of the second group 62 are used to determine horizontally acting forces. On the basis of the division of the force sensors 58 into the first group 60 and the second group 62, the different load cases can be distinguished from one another more precisely than is the case with the second exemplary embodiment of the force measuring device 56.sub.2. Since, in principle, the greater the number of force sensors 58, the better the various load cases can be described, the aim is to increase the number of force sensors 58. However, this increases the space requirement. Arranging the force sensors 58 of the first group 60 perpendicularly to the force sensors 58 of the second group 62 increases the accuracy with which the load cases can be described. In addition, the installation space required for this purpose is kept within reasonable limits.
[0117] The force sensors 58 interact with an evaluation unit 63 in such a way that the forces acting on the support portion 39 can be determined. In addition, the evaluation unit 63 can determine how the forces are distributed over the support portion 39. On the basis of the degrees of freedom predetermined by the mounting of the support portion 39 in the lifting device 32, certain load cases to be determined, for example tilting, can be specified. In addition, the loads that can be determined depend on the arrangement of the force sensors 58 relative to the support portion 39.
[0118] The information of the size and distribution of the forces acting on the support portion 39 can be used in various ways; these will be discussed in more detail below. At this point it need only be pointed out that overloading the transport device 101 can be prevented. If the force acting on the support portion 39 exceeds a specific amount, the lifting of the support portion 39 can be interrupted and a corresponding warning signal can be output by means of a signal generator 64 (see FIG. 1B). The warning signal can be output, for example, in optical and/or acoustic form.
[0119] With reference to FIGS. 1A and 1B, the transport device 101 has a sensor unit 66 by means of which the environment of the transport device 10.sub.1 can be detected. In particular, it is possible to determine obstacles as well as the nature of the surface on which the wheels are rolling. The sensor unit 66 can comprise cameras 67, ultrasonic sensors 69, laser-based sensors 71, or radar-based sensors or the like, by means of which the environment can be detected with sufficient accuracy even under different conditions. The sensor unit 66 is arranged in a sensor portion 68 which is delimited by the outer contour 14 and by the common axis of rotation D or by a plane extending through the common axis of rotation D and the rotational axis R. According to this definition, the transport device 10.sub.1 has two such sensor portions 68, but the sensor unit 66 is arranged in only one of said sensor portions 68. As a result of this arrangement, the sensor unit 66 can detect only the part of the environment that is located on the side of the common axis of rotation D or the plane extending therethrough on which the sensor unit 66 is arranged.
[0120] In addition, the transport device 10.sub.1 is equipped with a storage unit 70 for electrical energy so that the relevant components can be supplied with electrical energy.
[0121] As can be seen in particular from FIG. 1B, the outer contour 14 is rotationally symmetrical to the rotational axis R, at least in portions. In addition, in particular the support portion 39 and the first wheel 18 and the second wheel 20 are arranged within the outer contour 14. Therefore, no components protrude radially beyond the outer contour 14. This results in the effect that, when the transport device 10.sub.1 rotates on the spot, which can be brought about by correspondingly controlling the first wheel 18 and the second wheel 20, there are no eccentric portions that could bump into adjacent objects and impair the rotation, as long as the adjacent objects are at a distance corresponding at least to the radius of the outer contour 14 about the rotational axis R.
[0122] It can be seen from FIG. 1A that a bristle portion 72 is arranged at the lower edge of the housing 13, which portion consists of a plurality of bristles that are not explicitly visible here. As mentioned, the first wheel 18 and the second wheel 20 are arranged on a common axis of rotation D. Consequently, the transport device 101 can tilt about the common axis of rotation D such that the housing 13 rests on the surface on one side of the common axis of rotation D and, when the transport device 101 is moved, drags along the surface. This dragging is prevented by the bristle portion 72, which also has a stabilizing effect on the transport device 10.sub.1. Furthermore, the bristle portion 72 has the effect of a broom, so that at least relatively small particles are removed and cannot negatively affect the rolling of the wheels 18, 20 on the surface.
[0123] In order to stabilize the transport device 101 about the common axis of rotation D, one or more support wheels (not shown) can alternatively also be used.
[0124] In the illustrated exemplary embodiment, the transport device 101 is also equipped with a self-stabilizing device 74 (FIG. 1B), which can determine the inch-nation and the change in inclination of the transport device 101 about the common axis of rotation D and can counteract it. For example, the self-stabilizing device 74 can have a gyroscope or a tilt sensor. If the self-stabilizing device 74 determines that the inclination about the common axis of rotation D exceeds a critical level, the self-stabilizing device 74 can initiate countermeasures. The countermeasures can consist of, for example, targeted acceleration or deceleration of the first wheel 18 and/or of the second wheel 20. Alternatively, a counterbalancing shaft (not shown here) can be driven or weights (also not shown here) can be shifted. All measures serve to generate a torque which counteracts the inclination about the axis of rotation D within the transport device 10.sub.1 in order to reduce the inclination back to values below the critical level. It should be noted that the self-stabilizing device 74 can only be used if no objects are being transported by the transport device 10.sub.1.
[0125] In addition, the transport device 10.sub.1 is equipped with a communication device 76 by means of which the transport device 10.sub.1 can exchange information with other communication partners; these will be discussed in more detail below.
[0126] FIG. 2 shows a perspective representation of a second exemplary embodiment of the transport device 10.sub.2 according to the invention. The transport device 10.sub.2 according to the second exemplary embodiment is largely of the same construction as the transport device 10.sub.1 according to the first exemplary embodiment. In addition, the transport device 10.sub.2 has a carrying handle 78 which is rotatably secured to the support structure 12. Consequently, the transport device 10.sub.1 can be gripped by the carrying handle 78 and transported in the manner of a bucket.
[0127] FIG. 4 is a basic and perspective view of a part of a support structure 12 of the transport device 10.sub.3 according to the invention according to a third exemplary embodiment, in which the support structure 12 is designed as a housing 13. There are two circular-ring-shaped grooves 80 in one of the two curved outer surfaces AW of the housing 13, into which grooves a storage unit 70 for electrical energy can engage interlockingly and be detachably connected to the housing 13. In this exemplary embodiment, the storage unit 70 is therefore arranged in the manner of a backpack outside the housing 13 and forms an eccentric portion. The storage unit 70 can be moved inside the two grooves 80 and rotates about the rotational axis R. The transport device 10.sub.1 can therefore be moved on the spot within certain limits in spaces that are only marginally wider than the housing 13 at the two flat outer surfaces AP. Such spaces can be the cavities in pallets 40. During rotation, the storage unit 70 strikes the walls of the pallet 40 and rotates about the rotational axis R of the transport device 10.sub.1 along the grooves 80 due to the rotational movement of the transport device 10.sub.1. The storage unit 70 does not hinder the further rotation of the transport device 10.sub.1.
[0128] FIG. 5 is a top view of an object 38 which can be transported by means of a transport system 81 according to the present invention. In FIG. 5, the object 38 is designed as a pallet 40 on which objects (not shown in more detail) such as crates or the like can be placed. The illustrated pallet 40 has three crosspieces 82 onto which a total of five boards 84 are nailed. In each crosspiece 82 there are two recesses (not visible in FIG. 5), each of which aligns with the recesses in the adjacent crosspieces 82.
[0129] The transport system 81 comprises a total of seven transport devices 10, which are described in FIGS. 1A and 1B and are only shown in a basic way in FIG. 5. Six of the transport devices 10 are each moved into one of the respective recesses in the crosspieces 82. The lifting device 32 is then lifted up so that the pallet 40 can be removed from the surface and then transported to the desired location. As can also be seen from FIG. 5, a seventh transport device 10.sub.1 is not introduced into the recesses in the pallet 40. The seventh transport device 101 is configured as a so-called master 86, while the other six transport devices 10 are designed as slaves 88. The master 86 is used in particular to detect the environment, since it is positioned outside the pallet 40 and can therefore, in contrast to the slaves 88, better identify the environment. Using the communication device 76, the master 86 can transmit commands to the slaves 88, in particular with regard to obstacles.
[0130] The master 86 accompanies the slaves 88 until the pallet 40 has been transported to the desired location. The lifting device 32 is then activated accordingly such that the pallet 40 is placed back on the surface. The slaves 88 then move out of the pallet 40 and can be used to transport a further object. The seven transport devices 10 can be identical in terms of design. However, it is also possible to provide the master 86 with a particularly powerful master sensor unit 90 so that the environment can be detected over a particularly large area.
[0131] In the event that the transport devices 10 are of identical design, each of the transport devices 10 can be defined as a master 86 or a slave 88. The distinction is determined exclusively by means of the software. The transport devices 10 can therefore be used differently. As mentioned, the master 86 is used to detect the environment of the pallet 40 as extensively as possible. For this purpose, the sensor unit 66 requires an above-average amount of electrical energy. The possibility of also using one of the other transport devices 10 as the master 86 prevents the storage unit 70 of a transport device 10.sub.1 from emptying more quickly than that of the other transport devices 10. Additionally, all the transport devices 10 are evenly loaded, which prevents one or more of the transport devices 10 from wearing out faster and having to be ser-viced sooner than others. For transporting the further object 38, another of the transport devices 10 can be used as the master 86.
[0132] FIG. 6A is a side view showing a fourth exemplary embodiment of the proposed transport device 10.sub.4 and FIG. 6B is a top view thereof. FIGS. 6C to 6E are sectional views of a fourth exemplary embodiment of the proposed transport device 10.sub.4. The basic design of the transport device 10.sub.4 according to the fourth exemplary embodiment largely corresponds to that of the above-described exemplary embodiments, and therefore only the differences will be discussed below.
[0133] The transport device 10.sub.4 according to the fourth exemplary embodiment comprises an expanding device 98 which, in the fourth exemplary embodiment of the transport device 104, comprises two expanding arms 100 which can be adjusted between a first position and a second position by means of an adjusting unit 106. In FIG. 6B, the two expanding arms 100 are shown in a second position, in which the expanding arms 100 protrude beyond the outer contour 14 of the support structure 12. In the first position (not shown) the expanding arms 100 are located within the outer contour 14, such that, when the transport device 10.sub.4 rotates on the spot, there are no eccentric portions that bump into adjacent objects 38 and could therefore hinder the rotation. The expanding arms 100 are movably mounted in guideways 102, the guideways 102 being formed by grooves in the support portion 39. Starting from the center of the transport device 10.sub.4, the guideways 102 extend radially outward, such that the expanding arms 100 can be moved in a radial direction.
[0134] In order to move the expanding arms 100 between the first and the second position, the expanding device 98 comprises, in addition to the adjusting unit 106, a further drive unit 107 which will be described in more detail below, in particular with reference to FIGS. 6C to 6E. The adjusting unit 106 and the further drive unit 107 interact using a drive train 109. The drive train 109 extends eccentrically to the axis of rotation R and comprises a first gear 111 and a second gear 113, which mesh with one another, as can be seen in particular from FIG. 6A. The first gear 111 is connected to the support portion 39 for conjoint rotation. As a result, the rotational movement of the further drive unit 107 can be transmitted to the adjusting unit 106. By means of the rotational movement, the expanding arms 100 can be moved between the first position and the second position. The mechanisms used for this purpose will be discussed in more detail below.
[0135] As mentioned above, the spindle 37 is mounted in the support structure 12 for conjoint rotation. To be able to move the support portion 39 and consequently also the expanding device 98 relative to the housing 13, a corresponding bearing unit 119 is provided. To be able to determine the rotational position of the expanding device 98, for example in relation to the first axis of rotation D1 and/or the second axis of rotation D2, an angle sensor 121 is provided.
[0136] The drive train 109 contains a decoupling unit 115 with which the drive train 109 can optionally be opened and closed. The decoupling unit 115 has the following purpose: The expanding arms 100 are used to clamp the transport device 104 in the second position with the object 38 to be transported, in particular with a pallet 40 (see FIG. 5), in order to prevent uncontrolled slipping. However, it would then not be possible to easily rotate the transport device 104 in the clamped state, in particular for steering, since otherwise the resistances present in the drive train 109 and in the further drive unit 107 would have to be overcome.
[0137] The decoupling unit 115 comprises a cam disk 117, which is shown separately in FIG. 6F. The cam disk 117 is connected to an output shaft 124 of the further drive unit 107 for conjoint rotation but also in an axially displaceable manner. The lateral surface of the cam disk 117 has a groove 120 with a helical shape and a specific gradient. A pin 122 anchored in the support structure 12 protrudes into the groove 120 (FIG. 6E). If the cam disk 117 is rotated by the output shaft 124, the cam disk also carries out, in addition to the rotational movement, a translational movement in parallel with the rotational axis R. The translational movement of the cam disk 117 is transmitted to a coupling element 126 which is annular. To this end, the coupling element 126 comes into contact with the cam disk 117 via a first end face 128. On a second end face 130, the coupling element 126 has a first serration 132 which, depending on the position, can engage a corresponding second serration 134 of the second gear 113. In the operating state shown in FIG. 6E, the first serration 132 and the second serration 134 are not in engagement. If the first serration 132 and the second serration 134 are engaged, the rotational movement of the output shaft 124 of the further drive unit 107 is transmitted to the first gear 111, as a result of which the expanding arms 100 are moved. Depending on the direction of rotation of the output shaft 124, the coupling element 126 is moved from the cam disk 117 toward or away from the second gear 113. Accordingly, the first serration 132 and the second serration 134 can be brought into or out of engagement. In order to ensure the contact between the cam disk 117 and the coupling element 126, the coupling element 126 interacts with a return spring 136.
[0138] If, for example, the expanding arms 100 are moved from the second position into the first position, and the further drive unit 107 is rotated further in this direction after reaching the first position, this brings about a rotation of the support portion 39. In this way, the expanding device 98 and consequently the expanding arms 100 can be brought into any rotational position with respect to the support structure 12 or the housing 13. The rotational position can be determined with the angle sensor 121. This applies analogously when the expanding arms have reached the second position.
[0139] FIG. 7A is a perspective view of a fifth exemplary embodiment of the transport device 10.sub.5 according to the invention. The design of the transport device 10.sub.5 according to the fifth exemplary embodiment is largely similar to that of the fourth exemplary embodiment of the transport device 104, in particular with regard to the design of the drive train 109 and the adjusting unit 106.
[0140] The expanding device 98 comprises a total of six expanding arms 100, which are located in a first position in FIG. 7B and in a second position in FIG. 7C. In FIG. 7A, too, the expanding arms 100 are in the first position. It can be seen that the expanding arms 100 do not protrude beyond the outer contour 14 of the support structure 12 when the expanding arms 100 are in the first position. As is also the case in the fourth exemplary embodiment of the transport device 104, the expanding arms 100 are movably mounted in the guideways 102, the guideways 102 extending from grooves arranged in the support portion 39 such that the support portion 39 forms a corresponding number of circle segment elements 104 (see FIG. 7A). For reasons of presentation, the circle segment elements 104 are not shown in FIG. 7C.
[0141] Starting from the center of the transport device 10.sub.4, the guideways 102 extend radially outward such that the expanding arms 100 can likewise move in a radial direction, as can also be seen from a comparison of FIG. 7B and FIG. 7C. The adjusting unit 106 comprises one toggle unit 108 per expanding arm 100, which unit can be extended or compressed by rotating a synchronization unit 110, which in the illustrated exemplary embodiment comprises a link disk 112. By extending the toggle unit 108 the expanding arms 100 are moved radially outwardly into the second position and by compressing the toggle unit 108 are moved into the first position. Since the link disk 112 interacts with all the toggle units 108 in the same way, all the expanding arms 100 are moved simultaneously when the link disk 112 is rotated.
[0142] The expanding device 98 comprises a blocking device 138, by means of which the adjusting unit 106 can be blocked at least when the expanding arms 100 are in the second position. In the fifth exemplary embodiment of the transport device, the blocking device 138 is realized in the following way: The link disk 112 interacts with the toggle units 108 in such a way that the two legs of the toggle units 108 are moved beyond an angle of 180° in the second position and are consequently pressed over and rest against a stop 140 in the second position. As a result, the expanding arms 100 are blocked in the second position without a blocking force having to be applied. As a result, it is possible to hold the expanding arms 100 in the second position even when the drive train 109 is open. In this respect, the blocking device 138 is largely formed by the adjusting unit 106 itself, so that no additional elements have to be provided for this purpose. Alternatively, however, the blocking device 138 can comprise one or more movable bolts or the like, by means of which the adjusting unit 138 can be blocked.
[0143] In addition, a stop element 114 is connected to the radially outer end of each expanding arm 100. As can be seen in particular from FIGS. 7A and 7B, in the first position the stop elements 114 strike the two adjacent stop elements 114. In addition, the stop elements 114 also strike the circle segment elements 104. As a result, the first position of the expanding arms 100 is clearly determined.
[0144] A support element 116 is movably secured to each of the stop elements 114, the support elements 116 being preloaded by means of a spring 118.
[0145] As shown in particular in FIG. 5, a pallet 40 can be transported, for example, by a total of six transport devices 10. If transport devices 10.sub.4, 10.sub.5 are used according to the fourth or fifth exemplary embodiment, the devices are moved into a cavity in the pallet 40 until they are located in the region of the above-mentioned crosspiece 82. In this case the expanding device 98 is in the first position.
[0146] Once the transport device 104, 105 has reached the desired position within the cavity, the lifting device is first activated, which causes the pallet 40 to be lifted up. Subsequently, the expanding device 98 is activated so that the expanding arms 100 are moved from the first position into the second position. In this case, the support elements 116 come into contact with the side walls of the cavity in the pallet 40, as a result of which the transport device 10.sub.4, 10.sub.5 is frictionally connected to the pallet 40. In this case, the springs 118 are compressed so as to prevent shock loads. In addition, the support elements 116 can be floatingly mounted so that manufacturing inaccura-cies can be compensated for together with the springs 118. As a result, the transport device 104,105 is oriented in a defined manner relative to the pallet 40. Consequently, the pallet 40 can no longer shift with respect to the transport device 104, 105. The pallet 40 can now be moved to the desired destination by means of the transport device 105.
[0147] As mentioned, the transport device 10.sub.5 according to the fifth exemplary embodiment differs from the transport device 10.sub.4 according to the fourth exemplary embodiment in particular in terms of the number of expanding arms 100. Owing to the higher number of expanding arms 100, it is possible to dispense with the use of the angle sensor 121, since the expanding device 98 can orient itself in such a way that the expanding arms 100 extend largely in parallel with the surface of the object 38 that is to be clamped by the transport device 10.sub.4.
[0148] FIG. 8 shows a transport system 81, which has a total of six transport devices 10 distributed within a workshop 92. Various objects are stored in the workshop 92 that are to be transported by means of the transport system 81. The transport system 81 comprises a control unit 94, by means of which the transport devices 10 can be controlled or regulated. As already mentioned, the transport devices 10 are equipped with communication devices 76 (see FIG. 1B), which enable mutual exchange of information. Additionally, the control unit 94 is equipped with a communication device 76 of this kind, so that not only can the transport devices 10 exchange information with one another, but also information can be exchanged between the transport devices 10 and the control unit 94. The control unit 94 can, for example, define tasks that are to be carried out by the transport devices 10. These tasks may consist of, for example, transporting the various objects 38 from one location to the destination location. As mentioned, the transport devices 10 are located within a workshop 92. The control unit 94 can be arranged outside the workshop 92, but an arrangement within the workshop 92 is also possible. To exchange information, the communication device 76 uses a wireless network, for example a WLAN or Bluetooth. Depending on the design and size of the objects, however, it is not always guaranteed that the WLAN is sufficiently available within the entire workshop 92. However, the functionality of the transport system depends on a sufficiently available WLAN. In order to stabilize the WLAN network, some or all of the transport devices 10 can be operated in the manner of a repeater or a relay station, so as to ensure that the WLAN is also available in the corners of the workshop 92 or behind or below the objects. As described in connection with FIG. 5, one or more of the transport devices 10 can be operated as a master 86. As also mentioned, the master 86 is used primarily to detect the environment around the object 38 to be transported, but the master 86 can also be positioned in such a way that the WLAN network is available at least for the slaves 88 assigned thereto.
[0149] FIG. 9 shows a load area 96, for example that of a truck, which is loaded with the transport system 81 according to the invention. Due to the fact that the force acting on the support portion 39 of at least one transport device 10 according to one of the above-described exemplary embodiments can be determined by means of the force measuring device 56, this information can also be used to load the load area 96 of the truck as evenly as possible. In the example shown in FIG. 9, the load area 96 is to be loaded with a total of six pallets 40, which are to have the same weight; however, the transport system 81 cannot initially assume this. Firstly, the transport system 81 places a total of three pallets 40 side by side in a first row and registers the exact positions and the weight of the respective pallets 40 on the load area 96. Subsequently, the transport device 10.sub.1 transports a fourth pallet 40 into a second row and finally a fifth and a sixth pallet 40 into a third row. After the sixth and final pallet 40 has also been transported to the load area 96, the transport system 81 receives information that no further pallets 40 are to be loaded onto the load area 96. The transport system 81 determines that the load area 96 is loaded unevenly. The transport system 81 changes the position of the fourth load area 96 in such a way that the load area 96 is now evenly loaded. The position of the fourth load area 96 is changed as indicated by the arrow.
[0150] As mentioned, the transport devices 10 each have a signal generator 64 (see FIG. 1B). The signal generator 64 can output a warning signal when the pallets 40 are so heavy that the maximum load of the transport devices 10 in question is exceeded. The exceeding of the maximum load can be detected by means of the force measuring device 56.
[0151] Furthermore, it can be seen from FIG. 9 that the sensor units 66 of the transport devices 10 are oriented in opposite directions. One of the transport devices 10 detects the environment on one side of the pallet 40, while the other of the transport devices 10 detects the environment on the other side of the pallet 40.
LIST OF REFERENCE SIGNS
[0152] 10 Transport device [0153] 10.sub.1-10.sub.5 Transport device [0154] 12 Support structure [0155] 13 Housing [0156] 14 Outer contour [0157] 16 Undercarriage [0158] 18 First wheel [0159] 20 Second wheel [0160] 22 Drive unit [0161] 24 First drive motor [0162] 26 Second drive motor [0163] 28 First transmission [0164] 30 Second transmission [0165] 32 Lifting device [0166] 34 Spindle nut [0167] 36 Third drive motor [0168] 37 Spindle [0169] 38 Object [0170] 39 Support portion [0171] 40 Pallet [0172] 42 Plate [0173] 44 Studded mat [0174] 46 Clamping sleeve [0175] 48 Plate housing [0176] 50 O-ring [0177] 52 Thrust roller bearing [0178] 54 Rubber ring [0179] 56 Force measuring device [0180] 58 Force sensors [0181] 60 First group [0182] 62 Second group [0183] 63 Evaluation unit [0184] 64 Signal generator [0185] 66 Sensor unit [0186] 67 Camera [0187] 68 Sensor portion [0188] 69 Ultrasonic sensor [0189] 70 Storage unit [0190] 71 Laser-based sensor [0191] 72 Bristle portion [0192] 74 Self-stabilizing device [0193] 76 Communication device [0194] 78 Carrying handle [0195] 80 Groove [0196] 81 Transport system [0197] 82 Crosspiece [0198] 84 Board [0199] 86 Master [0200] 88 Slave [0201] 90 Master sensor unit [0202] 92 Workshop [0203] 94 Control unit [0204] 96 Load area [0205] 98 Expanding device [0206] 100 Expanding arm [0207] 102 Guideway [0208] 104 Circle segment element [0209] 106 Adjusting unit [0210] 107 Further drive unit [0211] 108 Toggle unit [0212] 109 Drive train [0213] 110 Synchronization unit [0214] 111 First gear [0215] 112 Link disk [0216] 113 Second gear [0217] 114 Stop element [0218] 115 Decoupling unit [0219] 116 Support element [0220] 117 Cam disk [0221] 118 Spring [0222] 119 Bearing unit [0223] 120 Groove [0224] 121 Angle sensor [0225] 122 Pin [0226] 124 Output shaft [0227] 126 Coupling element [0228] 128 First end face [0229] 130 Second end face [0230] 132 First serration [0231] 134 Second serration [0232] 136 Return spring [0233] 138 Blocking device [0234] 140 Stop [0235] AP Flat outer surface [0236] AW Curved outer surface [0237] D Common axis of rotation [0238] D1 First axis of rotation [0239] D2 Second axis of rotation [0240] R Rotational axis
