WO2021219199A1 - Dispositif d'entraînement, bras rototique et procédé de mesure de couple - Google Patents

Dispositif d'entraînement, bras rototique et procédé de mesure de couple Download PDF

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Publication number
WO2021219199A1
WO2021219199A1 PCT/EP2020/061728 EP2020061728W WO2021219199A1 WO 2021219199 A1 WO2021219199 A1 WO 2021219199A1 EP 2020061728 W EP2020061728 W EP 2020061728W WO 2021219199 A1 WO2021219199 A1 WO 2021219199A1
Authority
WO
WIPO (PCT)
Prior art keywords
drive device
drive
torque
outer ring
hub
Prior art date
Application number
PCT/EP2020/061728
Other languages
German (de)
English (en)
Inventor
Georg Bachmaier
Christian Bachmann
Dominik Bergmann
Gerit Ebelsberger
Matthias Gerlich
Christian Mose
Thomas Vontz
Wolfgang Zöls
Original Assignee
Rethink Robotics Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rethink Robotics Gmbh filed Critical Rethink Robotics Gmbh
Priority to PCT/EP2020/061728 priority Critical patent/WO2021219199A1/fr
Publication of WO2021219199A1 publication Critical patent/WO2021219199A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/14—Rotary-transmission dynamometers wherein the torque-transmitting element is other than a torsionally-flexible shaft
    • G01L3/1407—Rotary-transmission dynamometers wherein the torque-transmitting element is other than a torsionally-flexible shaft involving springs
    • G01L3/1428—Rotary-transmission dynamometers wherein the torque-transmitting element is other than a torsionally-flexible shaft involving springs using electrical transducers
    • G01L3/1457—Rotary-transmission dynamometers wherein the torque-transmitting element is other than a torsionally-flexible shaft involving springs using electrical transducers involving resistance strain gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
    • G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
    • G01L1/2206—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
    • G01L1/2231—Special supports with preselected places to mount the resistance strain gauges; Mounting of supports the supports being disc- or ring-shaped, adapted for measuring a force along a single direction

Definitions

  • the present invention relates to a drive device which has a drive motor with a drive shaft which is rotatable with respect to a central axis.
  • the invention also relates to a robot arm with such a drive device and a method for measuring a torque within a drive device.
  • Various drive devices are known from the prior art, in which a drive shaft is moved in rotation by a drive motor. In this way, a corresponding output body can be set into a rotary movement either directly or by means of a gear connected in between.
  • Such rotary drives are used, for example, in numerous industrial applications, but also in the field of electromobility or for many other applications.
  • the drive motor is often an electric motor.
  • the swivel joints of a robot arm are usually moved by a typically highly integrated rotary drive.
  • measuring devices are required in order to be able to characterize the system status as well as possible.
  • collaborative robots which work together with people in industrial processes, it is particularly important to record the current system status as precisely as possible other drive device) acting torque.
  • the object of the invention is therefore to provide a drive device which overcomes the disadvantages mentioned.
  • a drive device is to be made available which enables the precise measurement of a torque that is decisive for the respective application with a design that is as compact as possible.
  • Another object is to specify a robot arm with such a drive device and a method for measuring a torque within a drive device.
  • the drive device comprises a drive motor with a drive shaft which is rotatable with respect to a central axis of rotation.
  • the drive device further comprises a base holder and a measuring device for measuring a torque acting within the drive device.
  • the measuring device comprises a spoke wheel with a hub, a radially outer ring and a plurality of spokes which connect the hub and the outer ring to one another and the deformation of which can be used to measure the torque. Either the hub or the ring on the outside is firmly connected to the base holder.
  • the basic holder is used to connect the drive device to an external mechanical mass.
  • the mechanical mass is understood to be the mechanical reference point for the respective drive application.
  • this can be a base of a robot joint or another industrial drive, the chassis of a vehicle or another mechanical reference point.
  • the base holder serves as an internal mechanical reference point for the drive device, relative to which an output element rotates.
  • the drive motor can in particular be an electric motor. This can in particular include a rotor and a stator.
  • the measuring device for measuring the torque is integrated into the drive device and, in contrast to this, is not coupled to it as an external attachment.
  • one of the two essential reference elements of the measuring device namely either the hub or the outer ring of the spoked wheel, is firmly connected to the base holder.
  • the central element of the measuring device for measuring the torque is the spoked wheel, which is arranged in particular coaxially around the central axis A.
  • the Spei chenrad is designed to transmit a torque acting within the drive device, this torque being transmitted between the inner hub and the outer ring. So there is a transfer of torque across the spokes.
  • the deformation of one or more spokes is measured.
  • at least some of the spokes are each provided with one or more sensors, by means of which a deformation of the respective spoke can be detected.
  • Such a deformation can in particular include an expansion or a compression in a partial area of the spoke.
  • the hub or the outer ring of the spoke wheel is firmly connected to the base holder.
  • the spoked wheel is therefore in relation to the one described above mechanical mass seen in the fixed part of the drive device attached. This enables a stationary measurement of the torque.
  • the at least one sensor for deforming the associated spoke can be connected to an associated readout or evaluation unit via a fixed electrical connection (and not via a slip ring or another wireless connection). A transmission of the sensor signal from a rotating system to a stationary system is therefore advantageously not required.
  • the element of the spoked wheel that is firmly connected to the base holder can particularly preferably be the internal hub.
  • the hub is in particular directly connected to the basic holder - that is, directly and not via an additional intermediate part.
  • the hub is then directly connected to the base holder on its own inner radius (and not on the outer radius, mediated by the spokes).
  • the outer ring of the spoked wheel could also be firmly and directly connected to the base holder.
  • the embodiment according to the invention advantageously enables a particularly compact integration of the measuring device for torque measurement in the internal structure of the drive device.
  • This inner support torque can in particular be a support torque of a transmission optionally present within the drive device.
  • a torque can be measured within the drive device, in which both the motor torque and the output torque (that is to say the load torque) of the drive device are included.
  • Such an internal support torque is an important parameter, especially for applications in the field of robotics.
  • the compact integration of a torque measuring device into the drive device is advantageous in order to achieve the smallest possible installation space overall.
  • the robot arm according to the invention comprises one or more robotic joints, at least one of which has a drive device according to the invention.
  • the advantages of such a robot arm result analogously to the advantages of the drive device according to the invention described above.
  • the method according to the invention is used to measure a torque within a drive device according to the invention. This measurement takes place by means of the integrated measuring device described, the torque being determined from a measurement signal which is influenced by a deformation of one or more spokes of the spoked wheel. Such a deformation can in particular be an expansion and / or compression of the corresponding spoke.
  • a deformation can in particular be an expansion and / or compression of the corresponding spoke.
  • the drive device can comprise a drive housing which jointly encloses at least the drive motor and the spoked wheel.
  • the drive housing With this drive housing, the drive device is encapsulated from the external environment.
  • the fact that the spoked wheel as part of the measuring device for the torque is also located inside the housing makes it clear that this measuring device is in particular not implemented as an external attachment, but actually within the drive device. tion is integrated.
  • the drive housing can advantageously also enclose the additional optional elements, which are described below. These are in particular a transmission, a brake, at least a section of an output shaft and / or at least a section of the base holder.
  • an optionally present disk element of the base holder is advantageously also arranged within the drive housing.
  • an optionally present radially outer coupling element or base element of the basic holder can preferably be located outside or at least in the edge region of the drive housing.
  • a part of the base holder together with the hous se form the outer encapsulation and / or merge with respect to the outer contour into the other parts of the housing, so that part of the base holder can also be viewed as part of the housing.
  • the base holder can have a disk element which is oriented perpendicular to the central axis.
  • This disc element can in particular be firmly connected to the hub of the spoked wheel.
  • This disk element then forms a kind of inner wall which is in particular arranged in a circular and coaxial manner around the central axis.
  • It can advantageously be an annular disk element in which a recess is formed in the area of the central axis A through which further elements can be guided in the axial direction.
  • the base holder can have a radially outer coupling element which is provided for connection to an outer mechanical mass - that is to say in particular a base. This connection can be realized, for example, by a flange.
  • the drive device additionally has a gear, wherein the gear can comprise a fixed element, a drive element and an output element.
  • the driving force is Element connected in particular to transmit torque to the drive shaft of the drive motor.
  • the fixed element is verbun before geous with the outer ring of the spoked wheel.
  • the integration of a transmission in the drive device is useful when an increase or decrease in speed is to be achieved between the drive shaft of the motor and an additional output body that is optionally available.
  • the torque on the output side is also changed.
  • the general principle of internal torques can, however, in principle also be used with a direct drive - that is, a drive device that does not include such a transmission.
  • the fixed element of the optionally available transmission is used to connect it to the mechanical mass of the drive device.
  • a transmission support torque can be measured particularly easily and at the same time with a compact design of the measuring device.
  • the sum of the transmission support torque, output torque and motor torque results in a total of zero. From this consideration it also follows that not only the engine torque but also the output torque (as the load torque of the output) is included in the measured gear support torque.
  • This type of integrated torque measurement enables a real load condition of the drive device to be determined. For example, when using such a drive device in a robot arm, a load condition can be determined in which effects are taken into account by the intrinsic mass of the robot arm and also its external loads.
  • the transmission of the drive device can for example be a harmony drive transmission before geous.
  • the fixed element can then be formed by a circular spline of the harmonic drive transmission.
  • the drive element can by a wave generator and the output element can be formed by a flex spline of this gear.
  • Such a Harmonie Drive transmission in particular enables the implementation of a drive device with a relatively high gear ratio. With such a gear, the speed between drive and output can be reduced by a factor of about 100, for example.
  • other configurations of the transmission are also possible, for example as a planetary transmission.
  • the drive device in addition to a disk element of the base holder and a gear, also has an output body which is rotatably mounted by means of a radial bearing.
  • the output body can comprise an output shaft via which the output torque is diverted. It is particularly preferred here if the disk element of the base holder is arranged axially between the transmission and the radial bearing of the output body. This axial sequence, in which the disk element is embedded between the other elements, enables a particularly compact integration of the measuring device for the (internal) torque measurement. A transmission support torque is then measured, which is carried through the spoked wheel between the fixed element of the transmission and the disk element of the base holder.
  • the radial bearing of the output body is advantageously a roller bearing, in particular a roller bearing and particularly advantageously a crossed roller bearing.
  • the output body can in particular be designed as a hollow shaft, in which case further elements can then be passed through the interior of the hollow shaft, for example one or more electrical connection lines.
  • the hub of the spoke wheel is configured in a ring-shaped manner and has a recess in the area of the central axis.
  • the hub is then a radially inner ring.
  • electrical connection lines and / or a drive body can be passed through.
  • an output shaft connected to the output element of the transmission can in this way be passed through the torque measuring device to the side of the drive device axially opposite the motor - that is, to the output side.
  • the disk element of the base holder also advantageously has such a central recess so that cables and / or output bodies can be guided through both the spoke wheel and through the base holder.
  • the gear and the spoked wheel are nested in one another in such a way that they axially overlap at least in an axial partial area.
  • This also enables a particularly compact integration of the transmission and the measuring device for the torque.
  • the spoked wheel in the area of the outer ring has a jump that surrounds the transmission at least partially ra dial.
  • This projection can in particular extend over the entire outer ring, but alternatively also only over a radial part thereof. In the first-mentioned case, the entire outer ring is axially longer in the direction of the gearbox than the hub, so that this projection surrounds at least part of the gearbox in an annular manner.
  • An optionally available perforated ring of the outer ring (which is provided for the fixed torque-transmitting connection with the fixed element of the transmission by means of screws and / or bolts) can then extend in particular in the axial direction through this sleeve-like projection.
  • the disk element of the basic holder also has an axial projection in the direction of the gearbox in its radially outer area, so that the- this axial projection surrounds the spoke wheel and / or the gear radially.
  • This projection of the disk element particularly advantageously surrounds both a substantial part of the spoke wheel and an axial partial area of the transmission in the manner of a sleeve. Overall, this also allows a particularly compact integration of the transmission with the measuring device (including the torque support of the transmission).
  • a fixed part of the drive motor is mechanically firmly connected to the Grundhal ter.
  • the stator of an electric motor can be additionally supported against the base holder.
  • the fixed element of the transmission and the stator of the electric motor are then supported against the base holder as a common mechanical mass.
  • a brake can be arranged in the axial direction between the motor and the transmission.
  • This brake can be arranged around the drive shaft so that the rotation of the drive shaft can be braked or stopped with it.
  • Such a brake makes it possible to stop the movement caused by the drive device, in particular in the event of a malfunction.
  • This is particularly advantageous, for example, when using such a drive device in a robotic joint.
  • Such safety mechanisms are particularly relevant for robot arms, which work as collaborative robots with human workers. Further advantageous embodiments with regard to the brake and also with regard to the drive device in general are described in the application filed by the same applicant on the same filing date with the title "Drive device for a robotic joint", which should therefore be included in the content of the present application.
  • fixed, torque-transmitting connections are required between the outer ring or the hub and each necessary neighboring elements.
  • the disk element of the base holder can be firmly connected to the hub of the spoked wheel.
  • the outer ring of the spoked wheel can be firmly connected to the fixed element of the transmission.
  • These fixed torque-transmitting connections can each be implemented by a form-fitting connection.
  • the connection can be implemented by means of matching perforated rings and screws or bolts guided therein.
  • it can also be realized by a fitting polygonal connection or toothing of the elements to be connected to one another. Such a polygonal connection or toothing is particularly useful in the area of the hub, since here torque transmission must take place on a comparatively small radius.
  • the transition between the spokes and the outer ring lies on a first radius which is at least 70% of the outer radius of the drive device, particularly advantageously even at least 75% or even 80% and more.
  • the transition described can either lie on the same radius as the inner radius of the outer ring or it can be offset with respect to this radi al.
  • the transition area can be offset radially outwards in order to achieve an increased radial length for the torque-transmitting spokes. In the area described for the radius of the transition point, a particularly sensitive torque measurement is achieved because the torque with the spoked wheel is transmitted between two radially far apart points.
  • the transition between the spokes and the hub lies on a second radius which is at most 55% and in particular only at most 45% of the outer diameter.
  • the underlying measuring principle and the general structure of the measuring device can be very easily scaled to different absolute radii.
  • at least some of the Spei surfaces can be provided with one or more strain gauges (DMS).
  • DMS strain gauges
  • Such strain gauges can, for example, only be arranged on one of the spokes or also on several spokes.
  • the respective strain gauges can be designed either as single strips or as multiple strips (eg with several meander-shaped conductor structures and several electrical connection pairs).
  • the design as a double strain gauge is particularly advantageous in order to enable the signal to be averaged for two closely adjacent positions in a simple manner.
  • the electrical connections of the respective strain gauges for reading out the signals can be interconnected with an electrical bridge circuit.
  • the signals from a total of eight pairs of electrical connections i.e. eight individual strain gauges or four double strain gauges
  • the change in length of the spokes can also be determined in other ways, for example via a magnetostrictive measurement or via a measurement using fiber optics.
  • strain gauges are used for the measurement, then these can advantageously be arranged on an azimuthal boundary surface of the associated spoke.
  • the respective spoke can particularly advantageously have such opposing strain gauges on both azimuthal sides.
  • the azimuthal arrangement allows the strain gauges to be easily aligned along the main direction of the spoke, because an inclined installation position that is true to the angle is not required.
  • the main direction of the individual strain gauges thus runs in particular in the radial direction. In this way, an unambiguous measurement can take place with regard to a clearly defined one-axis load condition - namely the measurement a local radial change in length along the spoke.
  • the azimuthal arrangement in contrast to an axial, end-face arrangement) of the strain gauge enables the direction of rotation to be determined. Depending on the direction of rotation, a given azimuthal side of a spoke is either compressed or stretched.
  • Such a drive device can in particular be a drive device for a robotic joint in a robot arm.
  • a drive device for a robotic joint in a robot arm there are also numerous other advantageous applications into consideration, for example other industrial drives and / or drives in automated guided vehicles and in other electric vehicles.
  • the compact integration of a torque measurement directly into the drive is advantageous.
  • the present robotic joints can be equipped with a drive device according to the invention.
  • the measurement of the internal torques in several (especially all) such joints enables the measurement of a real load condition of the entire robot arm, including the effects caused by the weight and the external loads on the arm.
  • the measurement signal can be an electrical signal measured by means of one or more strain gauges.
  • it can be a deformation-dependent measurement of the electrical resistance of one or more strain gauges.
  • Figure 1 shows a schematic longitudinal section of a drive device according to a first example of the invention
  • Figure 2 shows a longitudinal section for partial elements of a second embodiment
  • Figure 3 shows a longitudinal section for a subset of the sectionele elements of Figure 2
  • Figure 4 shows a perspective view of a spoked wheel
  • Figure 5 shows a schematic cross section of the spoked wheel of Figure 4
  • Figure 6 shows a schematic longitudinal section of the spoked wheel of Figures 4 and 5
  • Figure 7 shows an exemplary load condition of such a spoked wheel
  • Figure 8 shows a plan view of a double strain gauge
  • FIG. 9 shows a schematic representation of a bridge circuit for reading out four such double strain gauges.
  • Figure 10 shows a schematic perspective illustration of a robot arm. Identical or functionally identical elements are provided with the same reference symbols in the figures.
  • a drive device 1 is shown according to a first example of the invention. Shown is a schematic longitudinal section along the central axis A.
  • the drive device 1 comprises a drive housing 3, which encloses a drive motor 5, a gear 50, a measuring device 30 for measuring an internal torque and other, partly optional components. It is therefore a highly integrated drive device, which is also extremely compact in the example.
  • the torque generated by the drive motor 5 is diverted via a drive shaft 7 and transmitted to a drive element 52 of the transmission 50.
  • the drive device 1 has an axial end a1 on the engine side and an axial end a2 on the output side.
  • the gear 50 also includes an output element 53 and a fixed element 51 as essential components.
  • the gear 50 is designed as a harmony drive gear, the drive element 52 being the wave generator, the Output element 53 forms the flex spline and the fixed element 51 forms the circular spline of this gear.
  • the flex spline here comprises a bushing-like shaped sub-element 53a, which is connected to an output body 40 to transmit torque. From this drive body 40 is shown here schematically as a rotationally symmetrical output shaft.
  • the dashed line shown on the right can either stand for a rotating, radi al extended part of the output body or for a stationary housing part - depending on the radial size of the rotating element on the output side a2.
  • the drive device 1 further comprises a base holder 20, which is designed in particular for connection to an external mechanical mass.
  • This basic holder 20 forms So a kind of mechanical reference body of the drive device 1, against which the other elements are supported.
  • the drive motor 5 is mechanically supported against a base 21 of this base holder via a support element 9, which is only shown extremely schematically here.
  • This base 21 lies in a radially outer region of the entire drive device 1 and is designed for connection to external elements, for example via a flange.
  • the drive device 1 comprises a measuring device for measuring a torque acting within the drive device.
  • a spoked wheel 31 forms an essential part of this measuring device.
  • This spoked wheel 31 is designed to transmit a torque between a radially inner and a radially outer area, as will become even clearer in connection with FIGS.
  • the torque transmitted by the spoked wheel is the size that is measured by the measuring device. In the present example, it is a support torque of the gear 50 against the base holder 20.
  • the radially outer area of the spoked wheel 31 is connected to the fixed element 51 of the gear 50 in a fixed and torque-transmitting manner.
  • This fixed connection Ver is conveyed for example via an outer perforated ring 38.
  • the radially inner region of the Spei chenrads 31 is firmly and torque-transmitting with the Grundhal ter 20 connected.
  • This fixed connection is conveyed via an inner perforated ring 39, for example.
  • it can also be conveyed by other types of connection, in particular via a toothing not shown in detail here.
  • the base holder in this example has a disk element 22 which is oriented perpendicular to the central axis A.
  • This disk element 22 lies in particular parallel to the main plane of the spoke wheel 31.
  • the spoke wheel 31 can be arranged essentially concentrically around the central axis A.
  • the disk element 22 enables a compact implementation of a fixed, torque-transmitting connection between the base holder 20 and the inner area of the spoke wheel 31.
  • the disk element 22 has an axially inner recess 23 through which the output shaft 40 is guided.
  • the spoked wheel has a similar internal recess 35, so that the output shaft 40 can extend both through the spoke wheel 31 and through the disk element 22 through from the gear 50 to the output-side end a2 of the drive device.
  • the disk element 22 has a projection 22a which extends in the axial direction towards the end a1 on the motor side.
  • the axial area a22 of the disk element is enlarged and the base holder 20 at least partially encloses the spoke wheel 31 in the manner of a sleeve.
  • the spoke wheel 31 also has an axial projection 32a, so that the axial area a31 of the spoke wheel is enlarged and at least encloses the bushing 53a of the output element of the transmission like a sleeve.
  • the area a31 thus at least partially overlaps the axial area a50 of the transmission. This results in a very compact and mechanically stable overall arrangement.
  • FIG 2 is a schematic longitudinal section for Operaelemen te a drive device 1 according to a second example of the invention is shown.
  • the drive device (also with regard to the elements not shown) is constructed in a manner similar to the drive device in FIG 50, through the spoke wheel 31 and through the disk element 22 of the base holder to the output-side end a2.
  • This embodiment causes the advantage that further elements can be passed through the inner recess 41 of the hollow shaft 40, for example an electrical connection line 42.
  • the output shaft 40 is rotatably supported here by means of a radial bearing 43 against the external fixed parts of the drive device, not shown here.
  • the Radi allager can be, for example, a crossed roller bearing. A similar radial bearing can also be provided for mounting the central output shaft in the example of FIG.
  • the disk element 22 of the base holder 20 should be arranged axially between the gear 50 and the bearing 43 of the output shaft 40.
  • the radial bearing 43 can generally advantageously lie on a comparatively large radius, that is to say in particular also further out than is indicated schematically in FIG.
  • the drive element 52 is omitted from the transmission 50 for the sake of clarity.
  • the axial Operabe rich, in the gear 50 and spoke wheel 31 axially overlap pen, is denoted by a3.
  • the area of the outer ring of the spoke wheel is denoted by 32, the area of the (here annular) hub by 33 and the radial area of the spokes by 34.
  • the output shaft can generally also extend all the way to the motor-side end al of the drive device, that is to say in particular also through the transmission and even through the drive motor.
  • the output shaft can either be hollow or solid.
  • a Hin implementation of the output shaft all the way to the engine-side axial end al enables an angle measurement and / or rotational speed measurement for the movement of the output to be carried out on this page in a relatively simple manner, in particular with an axially outer sensor. Due to the comparatively small twist of the spoked wheel 31 during the measurement of the torque, such an angle or speed measurement is advantageously only influenced insignificantly.
  • the drive shaft 7 shown in FIG. 1 is designed as a hollow shaft. Then the drive shaft 40 can for example be coaxial within the drive shaft 7 ge leads.
  • FIG. 3 shows a longitudinal section through the drive device according to the example of FIG. 2, the view being limited to the base holder 20 and the spoke wheel 31.
  • the connection of these two elements is brought about by the inner perforated ring 39 and / or a toothing not shown here or another form-fitting connection.
  • the axial sub-area in which the axial projection 22a of the disk element 22 closes the spoke wheel 31 in a sleeve-like manner is denoted here by a4.
  • the inner cavity of the spoke wheel, which is formed by the axial projection 32a of the outer ring, is denoted by 32b.
  • at least a part of the gear 50 is inserted into this inner cavity 32b - in particular the bushing 53a of the flex spline.
  • FIGS. 4 to 7 various individual views of a spoked wheel 31 are shown, as can be used in particular in the exemplary embodiments of FIGS. 1 to 3.
  • This spoke wheel 31 comprises an outer ring 32, a hub 33, which is configured in the form of a ring here, and four Spei surfaces 34, which each extend in the radial direction between the two ring-shaped elements 32 and 33.
  • the torque is measured via one or more sensors 36, which are attached to at least part of the spokes 34 and are designed to measure a deformation (in particular an expansion or compression) of the respective spoke.
  • sensors can be arranged either on an azimuthal boundary surface 34a and / or on an axial boundary surface 34b of the respective spoke.
  • the sensors are on the azimuthal boundary surfaces 34a arranged by two spokes. This has the advantage that by determining that side of a spoke that is stretched or compressed, a determination of the sign of the torque is made possible in a direct and simple manner.
  • FIG. 5 an embodiment of a spoke wheel 31 is shown, in which the two vertically aligned spokes are each equipped with such sensors on the left and right.
  • the sensors are strain gauges (strain gauges), which enable a simple, extremely sensitive and precise measurement of changes in length in the sub-per mil range by changing a resistance.
  • strain gauges strain gauges
  • FIG. 7 an exemplary load condition of such a spoked wheel 31 is shown in a schematic cross section.
  • a load condition is shown by an internal torque M of the drive device, the outer ring 32 being rotated clockwise in relation to the inner hub 33.
  • the surface 34c is stretched and the surface 34d is compressed.
  • the measurement of a torque M via such a spoked wheel is particularly sensitive if the torque is transmitted by means of the spokes over the greatest possible radial distance.
  • the first radius rl at which the transition between the spokes 34 and the outer ring 32 lies, is as large as possible. Accordingly, it is also advantageous if the second radius r2, at which the transition between the spokes and the hub 33 lies, is as small as possible.
  • the outer radius of the drive device is denoted here by ra, the radi al external housing 3 is only indicated here.
  • the outer radius ra of the drive device should be understood to mean the outer radius of a circular cylindrical part of the housing (in which the additional dimension of an optionally present lateral base 21 is not taken into account).
  • the first radius rl can, for example, generally lie in a range between 70% and 90%.
  • the second radius r2 can, for example, generally lie in a range between 25% and 55% of ra.
  • a strain gauge 60 as it can be used, for example, as one of the sensors Dia to D2b, is shown in a schematic plan view.
  • the strain gauge 60 is designed as a double strain gauge and comprises two single strain gauges 60a and 60b.
  • a conductor element is routed in a meandering manner, the main direction of each such individual strain gauge corresponding to the radial direction of the respective associated spoke.
  • a total of four electrical connections 61 are available for measuring the change in resistance in such a double strain gauge.
  • FIG. 9 shows a schematic representation of a bridge circuit 70 which is designed for reading out a total of four such double DMS (for example as in the arrangement in FIG. 5).
  • the two associated single strain gauges are integrated into this bridge circuit via their two electrical connections. So includes the Double DMS Dia, for example, the two single DMS Dia 'and Dia''.
  • the total of eight available individual strain gauges Dia 'to D2b'' are connected to one another via a double full bridge, so that the signals averaged by means of the circuit are transmitted via the six outer connections ol to o4 and a subsequent amplifier and output, not shown here seelektronik can be read out.
  • FIG. 10 shows a schematic perspective illustration of a robot arm 80 according to a further exemplary embodiment of the invention.
  • the robot arm has seven Robotikge joints J1 to J7, which each allow a rotation about an associated axis of rotation A1 to A7. So it is a robotic arm with seven degrees of rotational freedom.
  • the "innermost" joint J1 is connected to a base 81, which serves as a superordinate mechanical measuring device.
  • the "outermost” joint J7 can, for example, carry a tool holder.
  • Each of the individual joints J1 to J7 has a local mechanical mass for the respective rotary movement, which is given by the base of the respective joint.
  • the base of the third joint J7 is denoted here by 21.
  • the robotics joints J1 to J7 is provided with a drive device according to the invention.
  • a drive device according to the invention.
  • the base 21 represents the local mechanical mass of this joint J3. This is the base of a basic holder, as was previously described in connection with FIGS.
  • the remaining components not visible here, such as the drive motor, drive shaft, transmission, measuring device and output shaft are arranged.
  • the motor-side end is denoted by a1 and the output-side end is denoted by a2.
  • An end cap 82 is located at the end a1 on the motor side.
  • the output shaft (rotatable with respect to the local mechanical mass 21) merges into the base of the next robotic joint J4.
  • the disk element provided to support the internal torque measured by the measuring device is identified here by the dashed line 22.
  • An internal gear support torque is thus measured within the robotic joint J3, into which not only the motor torque but also the load due to the weight of the robot arm parts located further outside is included.
  • Such a torque measurement (in particular in several joints) enables the determination of an exact load state of the robot arm. This is particularly advantageous when it is used in a collaborative work environment.

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Abstract

L'invention concerne un dispositif d'entraînement (1) comprenant – un moteur d'entraînement (5) doté d'un arbre d'entraînement (7) qui est rotatif par rapport à un axe de rotation central (A), - un support de base (20) – ainsi qu'un système de mesure (30) destiné à la mesure d'un couple (M) agissant à l'intérieur du dispositif d'entraînement, - le dispositif de mesure (30) présentant une roue à rayons (31) pourvue de – un moyeu (33), - un anneau externe (32) radial – et une pluralité de rayons (34) qui relient le moyeu (33) à l'anneau externe (32), et dont la déformation permet de mesurer le couple (M), - soit le moyeu (33), soit l'anneau externe (32) étant relié à demeure avec le support de base (20). L'invention concerne également un bras robotisé (80) équipé d'un tel dispositif d'entraînement (1) ainsi qu'un procédé de mesure d'un couple (M) à l'intérieur d'un tel dispositif d'entraînement (1).
PCT/EP2020/061728 2020-04-28 2020-04-28 Dispositif d'entraînement, bras rototique et procédé de mesure de couple WO2021219199A1 (fr)

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PCT/EP2020/061728 WO2021219199A1 (fr) 2020-04-28 2020-04-28 Dispositif d'entraînement, bras rototique et procédé de mesure de couple

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10317304A1 (de) * 2002-04-12 2003-12-11 Deutsch Zentr Luft & Raumfahrt Verfahren und Einrichtung zum Bestimmen eines Abtriebsdrehmoments eines Elektromotors

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10317304A1 (de) * 2002-04-12 2003-12-11 Deutsch Zentr Luft & Raumfahrt Verfahren und Einrichtung zum Bestimmen eines Abtriebsdrehmoments eines Elektromotors

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