Positioning device having a joint drive

Abstract

The present invention relates to a positioning device having a base (1) and a movable element (3) which is connected to the base (1) via a joint (4). In order to provide a compact positioning device with low complexity, the joint (4) is connected to a drive (10) which is designed to move the joint (4) relative to the base (1).

Description

[0001] Positioning device with articulated drive

[0002] The present invention relates to a positioning device with an articulated drive. In particular, the present invention relates to a positioning device in the configuration of a 6-axis parallel kinematic system or a hexapod.

[0003] Hexapods are parallel kinematic structures in which a base plate is connected to a movable platform via six legs. Hexapods are implemented in two fundamentally different concepts:

[0004] 1. Hexapods with variable-length legs and a fixed foot point, i.e. with legs that are variable in length and are connected to the base at a defined foot point.

[0005] 2. Hexapods with constant leg length and a moving foot point, i.e. with legs that are constant in length and a foot point that can be moved relative to the base to which the leg is mounted.

[0006] Hexapods according to the first concept, i.e., with adjustable-length legs and a fixed foot point, are by far the most widely used concept of hexapod structures. In this concept, the leg length is actively adjusted using an actuator, allowing the pose of the hexapod platform to be adjusted. In the second concept, the leg length is constant, and a targeted foot point movement changes the angle of the leg, which in turn adjusts the pose of the hexapod platform. The foot point can be moved linearly, along a circular path, or along any arbitrary path in space.

[0007] Due to the integration of the drive into the variable-length actuator, the structure according to the first concept is either relatively tall or requires a high, cost-intensive level of integration to ensure compactness. Furthermore, oscillating movements in the structure according to the first concept can only be realized through stop and start cycles, which places a load on the machine components used and requires a corresponding power input. While the structure according to the second concept can be realized with a very compact height of the passive structure, it requires space either in the height or width of the active structure. To further understand the disadvantages resulting from the known solutions, the typical kinematics of a hexapod structure according to the first concept are discussed below.

[0008] Fig. 1 schematically illustrates the arrangement of the joints on a length-variable leg 3 of a hexapod with base 1 and movable platform 2. As mentioned at the beginning, a hexapod comprises six legs, each of which connects the base 1 to the movable platform 2. For reasons of clarity, however, the illustration in Fig. 1 is limited to one leg 3. In order to realize six degrees of freedom for the movable platform 2, according to Grübler's equation, each of the six individual legs 3 must be equipped with joints 4, 5, 6, and 7, which have the degrees of freedom bj and for which the following applies: b4 + bs + be + b7 = 6.

[0009] The degrees of freedom are conventionally divided as follows and realized in various existing variants: In all known variants, the active drive is implemented in the joint with the shear degree of freedom. Motorizing the leg and detecting the sensor position requires, on the one hand, the integration of a motor and sensor, and, on the other hand, a cable connection that moves along with the overall system during movement and can impact the overall system's performance due to the restoring forces. Furthermore, the moving cable must be considered in the design with regard to service life / failure or particle generation. The motor and sensor, in turn, require installation space within the moving structure, which, on the one hand, affects the overall size, on the other hand, requires an increased depth of integration or leads to collision issues within the structure.

[0010] Against the background outlined above, the object of the present invention is to provide an improved positioning device which is characterized above all by a compact design with low complexity.

[0011] This object is achieved by a positioning device according to claim 1. The positioning device according to the invention comprises a base and a movable element (leg) connected to the base via a joint. According to the invention, the joint is connected to a drive configured to move the joint relative to the base.

[0012] According to the invention, the movable element (leg) is moved by driving the joint or a joint axis of the joint, whereby the joint connects the movable element (leg) to the base. The position of the hexapod platform (movable platform) is thus adjusted, for example, via the rotation of the joint angle (instead of changing the leg length or shifting the foot point) and calculated using the kinematic relationships of the hexapod structure. The movement or rotation of the joint can be recorded absolutely or incrementally.

[0013] By connecting the drive to the joint, which is connected to the base, the drive, sensors, and cables can be relocated to the part of the overall system that is not moving in space, thus resolving the aforementioned issues. This prevents cable movement, thus eliminating restoring forces and preventing particle generation. Furthermore, a lower integration depth is possible, allowing for a more compact moving structure, which also simplifies the design with regard to potential collisions.

[0014] Preferred embodiments are the subject of the dependent claims. It can be advantageous if the drive is configured to drive a rotational axis of the joint, which is preferably connected to the base. The drive can be connected to the axis directly or indirectly via structurally suitable transmission elements, such as a chain, belt, or gear. This allows the drive to be relocated to a position favorable for design integration. The rotational axis of the joint, which is connected to the base, corresponds to an outer rotational axis of the joint.

[0015] It may be useful if the joint is a cardan joint, of which a first axis of rotation (= outer axis of rotation) is connected to the base and a second axis of rotation (= inner axis of rotation) and possibly third axis of rotation (= inner axis of rotation) is / are connected to the movable element, wherein the first, second and possibly third axes of rotation are preferably each perpendicular to one another or have an offset from one another.

[0016] It can be convenient to mount the actuator on the base. Because the actuator is mounted on the stationary base, it is not part of the moving structure. Consequently, there are no inertial forces created by the mass / weight of the actuator that would need to be considered when designing the positioning device.

[0017] It can be useful if the axis of rotation of the joint to be driven by the drive is aligned parallel, perpendicular or obliquely to an extension plane of the base. If the axis of rotation of the joint to be driven is aligned parallel or inclined at a slight angle to the extension plane of the base, the drive is arranged laterally, facing inwards or outwards. To further reduce the width of the overall system, it is recommended that the axis of rotation of the joint to be driven be aligned perpendicular to the extension plane of the base. With this design, the system can be kept particularly compact and slim, since the drive, sensors, cabling, etc. can be arranged underneath the mechanical structure. Furthermore, if the axis of rotation of the joint "penetrates" the base, it can also be used with a continuous drive.This allows an oscillating movement of the moving platform to be realized without the actuators having to go through braking and acceleration cycles (or stop and start cycles), but can remain in a continuous movement in one direction (with only minor braking and acceleration effects and correspondingly low energy input).

[0018] It can be advantageous if the movable element comprises a first section and a second section, and the two sections are connected to one another via a joint, preferably a rotary and linear joint. It can prove useful if the positioning device comprises a base plate and a movable platform that are connected to one another by the movable element, with the base plate and / or the movable platform acting as the base. This means that the joint to be driven can be arranged either on the base plate or on the movable platform, or on the base plate and on the movable platform, which expands the design freedom and functionality of the positioning device.

[0019] A further aspect of the present invention relates to a positioning device comprising a base, a movable platform and a plurality of movable elements, each of which is connected to the base and the movable platform via joints, wherein at least one of the joints is connected to a drive which is configured to move the joint relative to the base or to the movable platform.

[0020] It may also prove useful if at least one cable for transmitting power or signals to or from the drive runs within the base or is fixed to the base, preferably without an exposed cable section between the base and the drive. This avoids exposed cables, which in particular reduces the likelihood of damage to the cables and makes the positioning device even more compact.

[0021] It may be advantageous if at least one line for transmitting power or signals runs toward or away from the base, with the at least one line branching within the base or at the base to each drive. The positioning device can be easily connected to a control device via the at least one line leading toward or away from the base, with the branches of the at least one line within the base or at the base to each drive further promoting the compact design of the device.

[0022] It may also be advantageous if the positioning device has a device for acquiring and processing measurement or operating data relevant to the state of the positioning device. This device is designed to continuously acquire and process the measurement or operating data during operation of the positioning device and optionally link them together so that an image of the state of the positioning device can be derived therefrom. From this image of the state of the positioning device, any necessary actions, such as replacing parts or elements of the positioning device, for example due to wear, can be identified. Brief description of the figures

[0023] Fig. 1 schematically illustrates the arrangement of the joints on a length-adjustable leg of a hexapod.

[0024] Fig. 2 schematically illustrates the arrangement of the joints in connection with a drive on a length-adjustable leg of a hexapod.

[0025] Detailed description of the preferred embodiments

[0026] An embodiment of the positioning device according to the invention is described with reference to Fig. 2. Fig. 2 is largely identical to Fig. 1, but additionally shows the arrangement of a drive 10 on the base 1. Furthermore, the leg 3 in the embodiment according to Fig.

[0027] 2 can be a leg of variable length or a leg of constant length.

[0028] According to the invention, it is provided that the joint 4, which connects the movable element (leg)

[0029] 3 with the base 1, is connected to the drive 10. The drive 10 is designed to move the joint 4 relative to the base 1. Preferably, the drive 10 acts on an axis of rotation of the joint 4, which is connected to the base 1. The drive 10 consequently causes a rotation of the joint 4 relative to the base 1. In a preferred embodiment, the joint 4 is formed by a cardan joint, in which the axis of rotation connected to the drive 10 is the outer axis of the cardan joint, which is connected to the base 1. The inner axis of the cardan joint is connected to the movable element 3.

[0030] The drive 10 can be suitably mounted on the base 1 to either be connected directly to the (outer) rotational axis of the joint 4 or to be connected to the (outer) rotational axis of the joint 4 via a transmission element, such as a belt, a band, or a chain. A line 11 or a cable for power or signal transmission to / from the drive 10 runs along the base 1 and is fixed to the base 1, or runs through the base 1 without being exposed between the base 1 and the drive 10.

[0031] The invention is particularly applicable to a hexapod with six movable elements (legs) 3, each of these movable elements 3 being equipped with a joint 4 connected to the base 1, each of which can be moved relative to the base 1 by a drive 10. List of reference symbols

[0032] 1 base

[0033] 2 Movable platform

[0034] 3 Movable element (leg)

[0035] 4 joint

[0036] 5 joint

[0037] 6 joint

[0038] 7 joint

[0039] 10 Drive

[0040] 11 Cable for power or signal transmission

Claims

Claims 1. Positioning device with a base (1) and a movable element (3) which is connected to the base (1) via a joint (4), characterized in that the joint (4) is connected to a drive (10) which is designed to move the joint (4) relative to the base (1).

2. Positioning device according to claim 1, characterized in that the drive (10) is arranged to drive a rotation axis of the joint (4), which is preferably connected to the base (1).

3. Positioning device according to claim 1 or 2, characterized in that the joint (4) is a cardan joint or universal joint, of which a first axis of rotation is connected to the base (1) and a second and optionally third axis of rotation is / are connected to the movable element (3), wherein the first, second and optionally third axes of rotation are preferably each perpendicular to one another or have an offset to one another.

4. Positioning device according to one of the preceding claims, characterized in that the drive (10) is mounted on the base (1).

5. Positioning device according to claim 2, characterized in that the axis of rotation of the joint (4) to be driven by the drive (10) is aligned parallel, perpendicular or obliquely to a plane of extension of the base (1).

6. Positioning device according to one of the preceding claims, characterized in that the movable element (3) comprises a first section and a second section which are connected to one another via a joint (6), preferably a rotary and linear joint.

7. Positioning device according to one of the preceding claims, characterized in that the positioning device comprises a base plate (1) and a movable platform (2) which are connected to one another by the movable element (3), the base plate (1) and / or the movable platform (2) acting as a base.

8. Positioning device with a base (1), a movable platform (2) and several movable elements (3), which are each connected to the base (1) and the movable platform (2) via joints (4, 5), characterized in that at least one of the joints (4, 5) is connected to a drive (10) which is designed to move the joint (4, 5) relative to the base (1) or to the movable platform (2).

9. Positioning device according to one of the preceding claims, characterized in that at least one line (11) for transmitting current or signals to or from the drive (10) runs within the base (1) or is fixed to the base (1), preferably without an exposed line section between the base (1) and the drive (10).

10. Positioning device according to claim 8, characterized in that at least one line (11) for transmitting current or signals runs towards or away from the base (1), wherein the at least one line (11) branches within the base (1) or at the base (1) to each drive (10).

11. Positioning device according to one of the preceding claims, characterized in that it has a device for recording and processing measurement or operating data relevant to the state of the positioning device, which device is designed to record and process the measurement or operating data during the operation of the positioning device and optionally to link them together so that an image of the state of the positioning device can be derived therefrom.

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