articulated arm robot

Abstract

According to the invention, the articulated robot arm (20) has several robot segments (22) connected to each other by a joint, which are driven by electric drive units (62), each of which has an electric motor (68). At least one drive unit (62) has a redundant braking device (60) with two brakes (64A, B), each designed to exert a braking force without current. To increase reliability, the two brakes (64A, B) are based on different operating principles, so that the respective braking force of the two brakes (64A, B) is exerted by different operating principles.

Description

[0001] The invention relates to an articulated arm robot with a plurality of robot members which are each connected to one another via a joint and are driven by electric motors, wherein at least one motor is assigned a redundant braking device which has two brakes which are each designed to exert a currentless braking force.

[0002] Such an articulated arm robot can be found, for example, in EP 2 024 145 B1.

[0003] An articulated-arm robot generally has several robot links, each connected to one another by a joint. The various robot links form a link chain and are connected to one another via the joints, allowing each robot link to perform a rotational movement relative to its neighboring robot link. The respective rotational movement is controlled by an electric motor, which may be located directly in the joint. For example, a motor shaft runs parallel to a joint axis.

[0004] Especially with articulated arm robots that come into contact with or in close proximity to people, especially with medical robots that work on patients, for example, it is important to have highly precise positioning and reliable, trouble-free operation of the robot and its movements in order to prevent any danger to people.

[0005] It is known to design various systems and devices of the robot redundantly, so that if one system fails, the other continues to function.

[0006] The aforementioned EP 2 024 145 B1 provides several redundant systems, in particular a redundant braking system. In this system, two different braking devices are arranged on an electric motor, which can be used to decelerate the movement of a respective robot limb. The two brakes are each designed as magnetic brakes, which exert a currentless braking force.

[0007] In this context, de-energized braking force means that the brake is active when de-energized, and a braking force can be exerted. This ensures that movements are decelerated in the event of a power failure. This is achieved in the known braking device by using a permanent magnet, which generates the braking force. The effect of the permanent magnet, and thus the braking force, is compensated and canceled or controlled during operation by an electromagnet.

[0008] Based on this, the invention is based on the object of providing an articulated arm robot, in particular for medical applications, which has a high functional reliability.

[0009] According to the invention, the object is achieved by an articulated arm robot having several robot links each connected to one another via a joint, which are driven by electric drive units each having an electric motor, wherein at least one and preferably all drive units each have a redundant braking device with two brakes. Each brake is designed to exert a power-off braking force, i.e. the braking force exerted in the event of a brake application acts without the need for an electrical supply. In order to ensure a high level of functional safety, the two brakes are based on different operating principles, so that the respective braking force is exerted by different operating principles..

[0010] This means that the forces required to generate the braking force are generated through various physical means. The different operating principles are based, for example, on the application of a magnetic force, a pneumatic force, a hydraulic force, or a mechanical spring force.

[0011] Each brake regularly has two braking partners, namely in particular a movable and a fixed braking partner, whereby the braking force or a braking torque is suitably transferred from the fixed braking partner to the other braking partner.

[0012] Typically, the two braking partners are mechanically pressed against each other to generate the braking force, so that the braking effect is generated by friction between the two braking partners. This pressing force, which generates the braking force, is generated in particular by one of the above-mentioned operating principles.

[0013] By using different operating principles, the risk of simultaneous failure of both brakes is reduced and the functional reliability of the respective drive unit and thus of the corresponding robot link of the articulated arm robot is increased.

[0014] The drive units for driving the individual robot limbs are usually designed as rotary drives for performing a rotary movement. Additionally, at least one of the drive units is also designed for a translational drive, or an additional drive unit for a translational drive is arranged, so that a robot limb can also be moved translationally, for example, like a telescope or along a (linear) guide.

[0015] In a preferred embodiment, one brake is a spring-actuated brake, meaning the braking force is generated by a spring force. The two brake partners are pressed against each other by spring force.

[0016] In a preferred further development, the other brake is a magnetic brake, in which the braking force is generated by magnetic force

[0017] In a preferred embodiment, a permanent magnet is used for this purpose. Similar to a spring-actuated brake, one brake partner is pressed against the other by the magnetic force.

[0018] The operating principles of the two currentless brakes permanently exert a force on the braking partners, which leads to the braking effect. In order to control the braking effect during normal operation, in a preferred embodiment each brake is assigned an electromagnet, via which the braking force of the respective brake can be controlled and via which the respective brake can be transferred to an open position. An electrically controlled magnetic force is therefore generated via the electromagnet, which acts on one of the braking partners at a time. The electrically controlled force counteracts the permanent and currentless force. This electromagnet therefore allows the braking force to be dosed and, in particular, the braking effect can be completely canceled.

[0019] In a preferred embodiment, the brakes are attached to a shaft of the drive unit. The braking force therefore acts on the shaft of the drive unit.

[0020] Preferably, at least one of the brakes, and preferably both brakes, each has a brake disc that is movable along the shaft and interacts with a stationary brake disc that is firmly connected to the shaft. The movable brake disc and the stationary brake disc are the two braking partners of a respective brake. The currentless force acts on the movable brake disc in the direction of the stationary brake disc. The effect of the previously described electromagnet is in the opposite direction, so that the movable brake disc is pulled away from the stationary brake disc by the electromagnet when it is activated. The movable brake discs are mounted, for example, on the motor shaft or otherwise displaceably.

[0021] The stationary brake disc is mechanically firmly connected to the shaft, for example via a mounting flange or a welded joint. However, the stationary brake disc is preferably a monolithic section of at least part of the shaft.

[0022] In a preferred embodiment, the stationary brake disc is arranged between the two movable brake discs. The stationary brake disc therefore forms a common brake disc for both brakes.

[0023] Preferably, the shaft of the drive unit is designed as a hollow shaft, at least in the region of the brakes. This provides, in particular, an additional internal cavity which can be used. In a preferred embodiment, the shaft is designed as a hollow shaft only in the region of the brakes. In this case, the hollow shaft is connected in a rotationally fixed manner, for example via a flange connection or a welded connection, to at least one further section of the shaft, which in particular is not designed as a hollow shaft. Alternatively, the entire shaft of the drive unit is designed as a hollow shaft.

[0024] In a practical embodiment, electrical wires are routed through the hollow shaft and connected to the electromagnet. These electrical wires serve to control the electromagnet.

[0025] In addition, the hollow shaft also offers the possibility of integrating additional functions, such as the arrangement or design of sensors, cooling elements, etc.

[0026] The drive unit has an output shaft, which controls the positioning movements of the respective robot limb. In addition to the electric motor, the drive unit typically also has a gearbox connected downstream of the motor.

[0027] Different positioning options are available for the two brakes: According to a preferred embodiment, the two brakes are arranged together on one side of the motor. For example, on the input side, i.e., opposite the output shaft and, in particular, also opposite the transmission. Alternatively, the two brakes are arranged together on the output side, i.e., downstream of the motor, preferably positioned between the motor and the transmission.

[0028] As an alternative to being positioned together on one side of the motor, the two brakes are arranged spaced apart on opposite sides of a component of the drive unit. Specifically, they are positioned on opposite sides of the motor or, alternatively, on opposite sides of the gearbox. Preferably, one of the brakes is positioned on the input side of the motor and the other brake is positioned on the output side of the motor, specifically between the motor and gearbox.

[0029] In a preferred embodiment, two redundant position sensors are assigned to each brake to detect the current position of the respective brake. This redundancy ensures reliable detection. Preferably, the two position sensors are designed differently. This ensures a high level of reliability. For example, the two position sensors are based on different (physical) operating principles and / or are connected in opposite directions, so that one sensor is normally closed and the other is normally open.

[0030] An embodiment of the invention is explained in more detail below with reference to the figures, which show, in simplified representations: Fig. 1 a simplified side view of an articulated arm robot, Fig. 2 perspective sectional view through a braking device, Fig. 3 a simplified side view of a drive unit and Fig. 4, Fig. 5 alternative variants of an articulated arm robot.

[0031] In Fig. 1 and in the Fig. 4 and Fig. 5 shows an articulated-arm robot 20, which is used in particular as a medical robot for medical applications. The articulated-arm robot 20 is a multi-axis robot with several robot limbs 22, each of which is connected to one another via joints 24.

[0032] In the exemplary embodiment, the articulated arm robot 20 has, for example, a base 26 on which a base is arranged as a first robot link 22 and can rotate about a vertical axis of rotation via a first joint 24. On this base, a rocker arm, as a second robot link 22, is pivotable about a horizontal axis about a second joint 24. At the end, a robot arm, as a further robot link 22, is mounted on the rocker arm so as to be rotatable about a third joint 24. Finally, a robot hand, as a further robot link 22, is mounted on the robot arm so as to be rotatable about a further joint 24. At its front end, this hand has a rotatable fastening flange which is used to attach a tool. In the case of a medical robot, this can be, for example, a medical instrument or a patient bed.

[0033] During operation, the individual robot links 22 are adjusted relative to one another about the respective joints 24. For this purpose, each joint is assigned an individual electric drive unit to execute the adjustment movement. The articulated-arm robot 20 is generally controlled via a control unit not shown in detail here.

[0034] In addition to or as an alternative to a rotational adjustment about a rotational axis, at least one robot member 22 can also be adjusted translationally. This is achieved in particular with an additional translational drive unit or with a combined drive unit that is designed to perform both a rotational movement and a translational movement. Fig. 5 shows a variant in which a robot link 22 (right half of the image) can be moved translationally, for example along a guide.

[0035] For safety reasons, the movement sequence of such articulated-arm robots 20 is monitored. A high level of functional reliability must be ensured, particularly for articulated-arm robots 20 that work near people or even on patients, as is the case with medical robots.

[0036] With regard to the desired high functional reliability of the articulated arm robot 20, a redundant braking device 60 is designed as part of a drive unit 62, as described below in connection with the Fig. 2 and Fig. 3. The adjustment movement of a respective robot link 22 is carried out via a respective drive unit 62. The drive unit 62 is arranged, in particular, directly in a joint 24.

[0037] The redundant braking device 60 has two brakes 64A, 64B, each designed to exert a braking force without current. The two brakes 64A, 64B and the generation of the braking force are based on different operating principles.

[0038] In the illustrated embodiment, the drive unit 62 has an electric motor 68 on a common shaft 66 and a gear 70 connected downstream of the electric motor on an output side. A portion of the shaft 66, designated as the output shaft 71, drives the robot member 22 and is connected to it via a suitable, for example, flexible, shaft connection.

[0039] In the exemplary embodiment, the braking device 60 is arranged on a section of the shaft 66 formed on the input side and thus opposite the output side.

[0040] Alternatively, according to a preferred variant, the braking device is arranged between the motor 68 and the transmission 70.

[0041] In the exemplary embodiment, the shaft 66 has a section designed as a hollow shaft 72, to which the braking device 60 is attached. The hollow shaft 72 is connected to the remaining shaft 66 in a suitable manner, for example via flanges.

[0042] In the center of the hollow shaft 72, it has a stationary brake disc 74 firmly connected to it. Positioned on either side of this is a movable brake disc 76A, 76B, each mounted so as to be displaceable in the longitudinal direction of the hollow shaft 72.

[0043] Each of these movable brake discs 76A, 76B is assigned an electromagnet 78A, 78B.

[0044] A currentless force acts on each of the movable brake discs 76A, 76B, directed toward the stationary brake disc 74. For one movable brake disc 76A, this force is exerted by means of a spring element 80. For the other movable brake disc 76B, this force is exerted by means of a permanent magnet 82. This permanent magnet is, for example, embedded in the movable brake disc 76B or forms a carrier on which a brake pad is arranged.

[0045] The two electromagnets 78A, 78B are used to control the braking force, which can generate a counterforce to the spring force or the force of the permanent magnet.

[0046] The two electromagnets 78A, 78B are controlled via electrical lines 84. The electrical lines 84 run within a cavity of the hollow shaft 72 to the electromagnets 78A, 78B.

[0047] Furthermore, position sensors 86A, B are preferably arranged, which detect the respective position of the movable brake disc 76A, 76B in relation to the stationary brake disc 74. Depending on these position sensors 86, the electromagnets 78A, 78B, for example, are controlled.

[0048] Preferably, two position sensors 86A, 86B are assigned to each movable brake disc 76A, 76B. These are preferably not only redundant but also differently configured. Specifically, the position sensors 86A, 86B monitor an air gap between the movable brake disc 76A, 76B and the stationary brake disc 74. The two redundant position sensors 86A, 86B, each assigned to a brake 64A, 64B, are preferably configured to rotate in opposite directions, so that one sensor is normally closed and the other sensor is normally open. List of reference symbols 20 articulated arm robots 22 robot limbs 24 joint 26 bases 60 braking device 62 drive unit 64A, B Brake 66 Wave 68 engine 70 gearboxes 71 Output shaft 72 hollow shaft 74 stationary brake disc 76A, B movable brake disc 78A, B Electromagnet 80 spring element 82 permanent magnet 84 Line 86A, B Position sensors QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 024 145 B1 [0002, 0006]

Claims

[1] Articulated arm robot (20) with a plurality of robot members (22) connected to one another via a joint, which are driven by electric drive units (62), each having an electric motor (68), wherein at least one drive unit (62) has a redundant braking device (60) with two brakes (64A, B), each designed to exert a currentless braking force, characterized by that the two brakes (64A, B) are based on different operating principles, so that the respective braking force of the two brakes (64A, B) is exerted by different operating principles. [2] Articulated arm robot (20) according to the preceding claim, characterized by that one brake (64A) is a spring-operated brake (64A) in which the braking force is exerted by spring force. [3] Articulated arm robot (20) according to one of the preceding claims, characterized bythat the other brake (64B) is a magnetic brake in which the braking force is exerted by magnetic force. [4] Articulated arm robot (20) according to the preceding claim, characterized by that the braking force is generated by a permanent magnet (82). [5] Articulated arm robot (20) according to one of the preceding claims, characterized by that each brake (64A, B) is assigned an electromagnet (78A, 78B) via which the braking force of the respective brake (64) can be controlled and via which the respective brake can be transferred into an open position. [6] Articulated arm robot (20) according to one of the preceding claims, characterized by that the brakes (64A, B) are attached to a shaft (66) of the drive unit (62). [7] Articulated arm robot (20) according to the preceding claim, characterized bythat at least one and preferably both brakes (64A, B) each have a brake disc movable along the shaft (66), wherein the brake disc interacts with a stationary brake disc firmly connected to the shaft (66). [8] Articulated arm robot (20) according to the preceding claim, characterized by that the stationary brake disc is arranged between the two movable brake discs. [9] Articulated arm robot (20) according to one of claims 6 to 8, characterized by that the shaft (66) is designed as a hollow shaft (72) at least in the region of the brakes (64A, B). [10] Articulated arm robot (20) according to the preceding claim, characterized by that the respective electromagnet (78A, 78B) is connected to electrical lines which are supplied via the hollow shaft (72). [11] Articulated arm robot (20) according to one of the preceding claims, characterized bythat the two brakes (64A, B) are arranged on one side of the motor (68). [12] Articulated arm robot (20) according to one of the preceding claims, characterized by that each brake (64A, B) is assigned two redundant position sensors (86A, 86B) for detecting the current position of the respective brake (64A, B). [13] Articulated arm robot (20) according to the preceding claim, characterized by that the two position sensors (86) are designed differently.

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