Strain wave gears with integrated encoder

Abstract

The present invention is entitled "Strain wave gear with encoder integration". The present invention relates to a strain wave gear, comprising: a gear element, the gear element comprising a circular element with an internally toothed gear, and the gear element comprising a flexible element with a flexible externally toothed gear arranged in the circular element; a wave generator, the wave generator being rotatably arranged in the flexible element and configured to flex the externally toothed gear in a radial direction to partially mesh the internally toothed gear and the externally toothed gear; a support element, the support element comprising a bearing input support element and a bearing output support element rotatably coupled to the bearing input support element, elements of the support element being respectively fixed to elements of the gear element; and an encoder arrangement, the encoder arrangement comprising an encoder track and an encoder reader, a portion of the encoder arrangement being fastened between elements of the support element and elements of the gear element.

Description

Technical Field

[0001] The invention relates to a strain wave gear, for example for a robot joint, and a method for assembling a strain wave gear. The invention further relates to a robot arm having a strain wave gear and the use of an element of a strain wave gear. Background Art

[0002] In the field of robotics, where a robot arm comprises a number of robot joints connecting different parts of the robot arm, and where the joint motors are configured to move the parts relative to each other, it is known to use strain wave gears as a transmission system between the joint motors and the movable parts, because strain wave gears transmit larger forces without generating backlash.

[0003] Strain wave gears are used in a variety of applications such as CNC machines, robotics, satellites, solar tracking, etc. They are very precise and have little backlash, so they are often the first choice in applications that require high output precision and accuracy. In these applications, a feedback system is often used, such as an electronic encoder connected to the control electronics that runs the electric motor that drives the input side of the strain wave gear.

[0004] Encoders typically rely on an encoder track and an encoder reader that is able to read the relative orientation of the track. By attaching the reader and track on the input and output ends respectively, it is possible to monitor the rotation of the gear.

[0005] In conventional strain wave gears, encoders for strain wave gears are typically attached outside / near the gear or in a housing / cabinet that houses the strain wave gear. Unfortunately, in conventional solutions, the attachment of the encoder track and reader is not as accurate and precise as required for strain wave gears. For example, strain on the track can slightly deviate it from the desired position. In addition, conventional attachment and adjustment of the track or reader as one or more separate steps results in increased assembly time.

[0006] WO 2019 / 096923 A2 provides a strain wave gear comprising an outer ring and an inner ring rotatably arranged in the outer ring. The inner ring comprises an internal gear, and a flexible key tooth is arranged in the inner ring and comprises a flexible component, the flexible component comprising an external gear. A wave generator is rotatable relative to the flexible key tooth, and is configured to cause the flexible component to bend radially so that the external gear is partially engaged with the internal gear, thereby causing the inner ring to rotate relative to the outer ring. A portion of the inner ring extends out of the outer ring and comprises an outwardly protruding output flange. An encoder reader may be provided on the outer ring, and an encoder track may be provided on the inner ring. A robot joint comprising the strain wave gear is also disclosed.

[0007] US 5,906,142 discloses a wave gear drive having a first end plate and a second end plate arranged to rotate relative to each other using a cross roller bearing positioned between the plates. The inner race of the cross roller bearing is integrally formed with the internal gear on the circumferential inner surface. The inner race is fixed directly to the first end plate, and the outer race of the cross roller bearing is fastened to the second end plate in such a way that the circular protrusion of the flexible external gear is retained between the outer race and the second end plate. The internal teeth are positioned approximately radially inward of the raceway of the cross roller bearing. Therefore, the wave gear drive is small and compact, and the rigidity is increased.

[0008] US 5,775,178 discloses a wave gear device having a circular key tooth, a flexible key tooth arranged inside the circular key tooth, and a wave generator arranged inside the flexible key tooth for radially deflecting the flexible key tooth so that the external teeth formed on the flexible key tooth partially engage with the internal gear teeth formed on the circular key tooth, and moving the engagement position in the circumferential direction to cause relative rotation according to the difference in the number of teeth of the internal gear teeth and the external gear teeth between the circular key tooth and the flexible key tooth. The circular key tooth has an annular rigid tooth portion having internal gear teeth formed along its inner circumference, a fastening portion rigidly fixed to one of a device housing and a support member rotatably supported in the device housing, and a connecting portion connecting the rigid tooth portion and the fastening portion. Compared with the rigid tooth portion, the connecting portion has lower rigidity in at least one of the direction of the axis of the device and the direction perpendicular to the axis.

[0009] US 8,991,282 discloses a wave gear unit having an input shaft positioned along a central axis by a first input bearing and a second input bearing. The first unit end plate on the first input bearing side is a composite member in which a bearing receiving member of an iron-based material is integrated with an end plate main body member of a lightweight material. The second unit end plate on the second input bearing side is formed integrally with a rigid internal gear, and is a composite member in which the second member of a lightweight material is integrated with the first member of a lightweight material. The first member has an end plate main body portion of the second unit end plate and a gear main body portion of the rigid internal gear, while the second member has a bearing receiving portion of the second unit end plate and a tooth forming portion of the rigid internal gear. Summary of the invention

[0010] An object of the present invention is to solve the above mentioned limitations with respect to the prior art or other problems with existing strain wave gears for robot arms. In particular, an object of the present invention is to provide a strain wave gear with a more accurate encoder arrangement compared to existing solutions.

[0011] The present invention relates to a strain wave gear, comprising:

[0012] a gear element, wherein the gear element comprises a circular element having an internally toothed gear, and wherein the gear element comprises a flexible element having a flexible externally toothed gear arranged in the circular element;

[0013] a wave generator rotatably disposed in the flexible element and configured to flex the external gear in a radial direction so as to partially mesh the internal gear and the external gear;

[0014] a support element, wherein the support element includes a bearing input support element and a bearing output support element rotatably coupled to the bearing input support element, wherein elements of the support element are respectively fixed to elements of the gear element; and

[0015] An encoder arrangement comprising an encoder track and an encoder reader, wherein a portion of the encoder arrangement is fastened between an element of the support element and an element of the gear element.

[0016] The gear elements and the support elements are usually manufactured according to precise and accurate standards to allow for well-functioning strain wave gears. For example, specific dimensions of these elements, such as specific lengths or diameters, usually have to be within narrow tolerances. By fastening a portion of the encoder arrangement between the support element and the gear element, the precision and accuracy of the gear element and / or the support element can be inherited to the encoder arrangement, which is advantageous. For example, the encoder track can be fastened between a circular element and a bearing output support element, which in turn are attached to each other. Thus, the encoder track can capture at least a portion of the precision and / or accuracy of the circular element and / or the bearing output support element.

[0017] Furthermore, by fastening a portion of the encoder arrangement between two elements, the fastened portion of the encoder arrangement is advantageously maintained in a planar arrangement. In other words, the risk of the encoder arrangement twisting, swaying or rocking from its intended position can be reduced, which is advantageous.

[0018] Furthermore, by fastening a portion of the encoder arrangement between two elements, the assembly process of the strain wave gear may become more efficient, which is advantageous. For example, a separate device for attaching a portion of the encoder arrangement may not be required.

[0019] Furthermore, since positioning of the encoder arrangement may be improved and wobble effects may be reduced, the invention may allow the distance between the encoder reader and the encoder track to be reduced, which is advantageous since this may increase the accuracy and precision of the measurements provided by the encoder arrangement.

[0020] Furthermore, integrating a portion of the encoder arrangement between two elements of the strain wave gear may allow for a more compact strain wave gear, which is advantageous.

[0021] Furthermore, integration of the encoder arrangement between the elements may allow at least a portion of the encoder arrangement to be positioned closer to the gear element. Hence, measurements of the encoder arrangement may allow a more accurate representation of the relative orientation of the gear element, which is advantageous.

[0022] Furthermore, by utilizing elements of a strain wave gear to secure a portion of the encoder track, fewer parts may be required for assembly, which is advantageous.

[0023] Furthermore, by securing a portion of the encoder arrangement between elements of the strain wave gear, it is possible to utilize a larger encoder track without the track undesirably becoming disengaged, which is advantageous. Furthermore, a larger encoder track may also have a better position resolution, which improves the accuracy of the encoder arrangement, which is advantageous.

[0024] Furthermore, the risk of parts of the encoder arrangement coming loose during operation may be reduced, which is advantageous.

[0025] The encoder reader, the encoder track, or both can be fastened between the elements in this manner to possibly ensure improved accuracy and precision, and possibly reduce the effects of wobbling. Typically, the encoder track is circular, and can therefore be fastened more directly. The encoder reader can, for example, be located on a printed circuit board (PCB), which in turn may or may not be circular. In an embodiment in which a portion of the encoder reader and the PCB are fastened between two elements, the elements can, for example, be manufactured with a groove for receiving the PCB, wherein the groove has an extension that matches the extension of the PCB, for example, it may not extend all the way around the center axis of the strain wave gear. In an embodiment in which a portion of the encoder track is fastened between two elements, the elements can similarly be manufactured with a groove for receiving the encoder track. Here, since the encoder track extends all the way around the center axis, the groove can typically extend all the way around the center axis of the strain wave gear.

[0026] A portion of the encoder arrangement is fastened between an element of the support element and an element of the gear element, for example, it can also be understood that the component is clamped between these elements, fixed between them or attached between these elements. Typically, the elements between which the encoder arrangement is fastened can be fixed to each other, for example, by fastening members. Such fastening components can, for example, include threads, screws, clamps, press fits, glue, welding, etc. Therefore, a portion of the encoder arrangement can be fastened between two elements because the two elements are fastened to each other by fastening components. However, it should be noted that the present invention is not limited to a specific fastening member or having such a fastening member. In addition, the present invention is not limited to any specific method of fastening a portion of the encoder arrangement. The fastening component can also be understood as one or more fasteners.

[0027] The fastening of the encoder reader and / or encoder track may generally result in the encoder reader and / or encoder track being approximately flat in one or more planes perpendicular to the central axis of the strain wave gear. Thus, the encoder track may generally be arranged rotationally symmetrically with respect to the central axis. The central axis may, for example, be the axis about which the wave generator rotates to drive the gear. The central axis may, for example, be the axis about which the bearing input support element and the bearing output support element are rotationally coupled. The central axis may, for example, be the axis about which the gear element is arranged.

[0028] The encoder arrangement may also include various extensions, flanges, protruding parts, etc. For example, for fastening or attachment. For example, the encoder track may have radially inward or radially outward extensions, and elements of the bearing support and the gear element are clamped to fasten the encoder track.

[0029] Generally speaking, strain wave gears may also be referred to as strain wave gears or harmonic gears. The wave generator may generally have an elliptical shape, arranged to slightly deform the flexible element to partially engage the inside and outside of other gears. The flexible element generally has slightly fewer gear teeth than the circular element, but in principle, the ratio of the number of gear teeth of the two elements is not limited to a specific ratio, and in various embodiments, the ratio may be greater or less than 1. When the wave generator rotates, one or more meshing positions of the gears move in the circumferential direction, thereby rotating the gear elements relative to each other. Similarly, the bearing input support element and the bearing output support element may be caused to rotate relative to each other.

[0030] The encoder arrangement can ensure tracking of the relative orientation between the gear elements, or equivalently, the relative orientation between the bearing input support element and the bearing output support element. As the wave generator rotates to drive the gear, the encoder track can rotate relative to the encoder reader, and the encoder reader can then read / measure the movement of the track and provide an output accordingly.

[0031] A gear element may be understood as an element, component, body or assembly having a gear for transmitting a rotational motion from the input end to the output end of the strain wave gear. A flexible element may also be understood as a flexible spline. A circular element or a part of a circular element may also be understood as a circular spline.

[0032] Support elements include bearing input support elements and bearing output support elements. These may generally support an internal bearing or a race of an internal bearing. More generally, support elements may be understood as elements, components, bodies or assemblies used to support the transfer of rotational motion, such as through bearings, spacers, housings and input / output elements, from the input end to the output end of the gear. The input and output elements may be, for example, flanges, shafts or discs. Support elements may generally be arranged partially or completely around the central axis of the strain wave gear, but are not limited to any particular geometry.

[0033] According to an embodiment of the present invention, elements of the support element are respectively fixed to elements of the gear element. This can also be understood as individual / individual elements of the support element are respectively fixed to individual / individual elements of the gear element. For example, a first element of the support element is fixed to a first element of the gear element, and a second element of the support element is fixed to a second element of the gear element. For example, when the bearing output support element is fixed to the flexible element, the bearing input support element is fixed to the circular element, or when the bearing input support element is fixed to the flexible element, the bearing output support element is fixed to the circular element.

[0034] A bearing input support element may be fixed to an input end of the strain wave gear, and a bearing output support element may be fixed to an output end of the strain wave gear.

[0035] In some embodiments of the present invention, the bearing input support element and the bearing output support element may be an outer bearing support element and an inner bearing support element, respectively, or vice versa.

[0036] In one embodiment of the invention, the externally toothed gear and the internally toothed gear mesh in a meshing position, wherein rotation of the wave generator moves the meshing position in a circumferential direction to cause a relative rotation between the circular element and the flexible element.

[0037] In some embodiments of the present invention, the external gear and the internal gear mesh at multiple meshing positions that move when the wave generator rotates, for example, two meshing positions or more than two meshing positions.

[0038] In one embodiment of the invention, the input shaft is configured to rotate said wave generator inside said flexible element.

[0039] The input shaft may advantageously be utilized to facilitate the transfer of rotation, for example from a drive motor.

[0040] In one embodiment of the invention, said input shaft is rotatably supported by said circular element via at least one shaft bearing.

[0041] In an embodiment of the invention, said input shaft is rotatably supported by said bearing input support element via at least one shaft bearing.

[0042] In one embodiment of the invention, the input shaft is rotatably supported by the end plate element via at least one shaft bearing.

[0043] It is advantageous to have one or more shaft bearings to ensure a stable transmission of the rotation.

[0044] An end plate can be understood as an element located at one end of the strain wave gear for enclosing the strain wave gear. It can, for example, support bearings, washers, have screw holes, and, for example, also be used to attach other elements to the strain wave gear.

[0045] In one embodiment of the invention, the end plate is an element of the support element, wherein a part of the encoder arrangement is fastened between the end plate and an element of the gear element.

[0046] In one embodiment of the invention, a portion of the encoder arrangement is fastened with a spacing element between an element of the support element and an element of the gear element.

[0047] In one embodiment of the invention, one or more spacer elements between elements of the support element and elements of the gear element may advantageously allow for greater flexibility as to how the support element and the gear element are arranged relative to each other.

[0048] In an embodiment of the invention, a portion of the encoder arrangement is clamped between an element of the support element and an element of the gear element.

[0049] In an embodiment of the invention, a part of the encoder arrangement is fixed between an element of the support element and an element of the gear element.

[0050] In an embodiment of the invention, a part of the encoder arrangement is attached between an element of the support element and an element of the gear element.

[0051] It is advantageous that clamping, fixing or attaching a part of the encoder arrangement between an element of the support element and an element of the gear element may improve the stability of the fastened encoder arrangement. The part may for example be an encoder track or an encoder reader.

[0052] In an embodiment of the invention, a portion of the encoder arrangement is in direct contact with an element of the support element.

[0053] In an embodiment of the invention, a portion of the encoder arrangement is in direct contact with an element of the gear element.

[0054] In an embodiment of the invention, a portion of the encoder arrangement is in direct contact with elements of the support element and elements of the gear element.

[0055] It is advantageous that the precision and accuracy of the support element and / or gear element can be more effectively transferred to a portion of the encoder arrangement by direct contact. The direct contact can be made with an element that secures the encoder arrangement. In various embodiments, the encoder track is in direct contact. In various embodiments, the encoder reader is in direct contact. In other embodiments, one or more portions of the encoder arrangement are not in direct contact with elements of the support element and / or elements of the gear element.

[0056] In one embodiment of the invention, said flexible element is fixed to said bearing output support element.

[0057] In one embodiment of the invention, said flexible element is fixed to said bearing input support element.

[0058] In one embodiment of the invention, said circular element is fixed to said bearing output support element.

[0059] In one embodiment of the invention, said circular element is fixed to said bearing input support element.

[0060] In one embodiment of the invention, the encoder track is fixed to the bearing output support element and the encoder reader is fixed to the bearing input support element.

[0061] In one embodiment of the invention, the encoder track is fixed to the bearing input support element and the encoder reader is fixed to the bearing output support element.

[0062] The encoder track and the encoder reader being fixed to the respective support element may be understood in such a way that the encoder track and the encoder reader follow the relative rotational movement of the element to which they are fixed. Thus, the encoder reader and the encoder track do not have to be in direct contact with the support element to which they are fixed.

[0063] In an embodiment of the invention, said encoder arrangement measures the relative rotation between said circular element and said flexible element.

[0064] In an embodiment of the invention, the encoder arrangement measures the relative rotation between the bearing input support element and the bearing output support element.

[0065] Measuring the relative rotation allows for improved control, which is advantageous.

[0066] In an embodiment of the invention, the encoder arrangement is located inside the strain wave gear.

[0067] By locating the encoder arrangement inside the strain wave gear, it can be protected from damage from external sources, which is an advantage.

[0068] In one embodiment of the invention, the encoder track is fastened between the circular element and the bearing input support element.

[0069] In one embodiment of the invention, the encoder track is fastened between the circular element and the bearing output support element.

[0070] By fastening the encoder track between the circular element and the bearing output support element, the invention can advantageously be implemented in existing strain wave gear designs with minimal changes to these designs. More generally, it is advantageous to arrange a portion of the encoder arrangement between two elements that are fixed to each other according to existing designs.

[0071] In one embodiment of the invention, the encoder track is fastened between the flexible element and the bearing input support element.

[0072] In one embodiment of the invention, the encoder track is fastened between the flexible element and the bearing output support element.

[0073] In one embodiment of the invention, said encoder reader is fastened between said circular element and said bearing input support element.

[0074] In one embodiment of the invention, said encoder reader is fastened between said circular element and said bearing output support element.

[0075] In one embodiment of the invention, said encoder reader is fastened between said flexible element and said bearing input support element.

[0076] In one embodiment of the invention, said encoder reader is fastened between said flexible element and said bearing output support element.

[0077] In one embodiment of the invention, the encoder reader is arranged on the bearing output support element.

[0078] In one embodiment of the invention, the encoder arrangement is an optical encoder arrangement.

[0079] In one embodiment of the invention, the encoder arrangement is a magnetic encoder arrangement.

[0080] In one embodiment of the invention, the encoder arrangement is an inductive encoder arrangement.

[0081] In an embodiment of the invention, the encoder arrangement has a reading distance of less than 1 mm, such as less than 0.5 mm, for example less than 0.2 mm, such as 0.15 mm.

[0082] Since the invention allows a more defined positioning of the encoder arrangement, the reading distance may be shortened, which is advantageous.The reading distance may be understood as the distance from the encoder track to the encoder reader or encoder reader head.

[0083] In one embodiment of the invention the encoder track diameter is at least 25 mm, such as at least 40 mm, such as at least 60 mm, such as at least 80 mm, such as at least 100 mm.

[0084] The diameter may for example be the inner or outer diameter of the encoder track.An encoder arrangement according to the invention may allow for larger diameters, and generally having a larger diameter is advantageous as it may allow for an improved rotational resolution of the encoder arrangement.

[0085] In one embodiment of the invention, the bearing output support element is fixed to the flexible element and the bearing input support element is fixed to the circular element.

[0086] In one embodiment of the invention, the bearing input support element is fixed to the flexible element and the bearing output support element is fixed to the circular element.

[0087] In an embodiment of the invention, the bearing input support element is configured to support a bearing input race.

[0088] In an embodiment of the invention, the bearing output support element is configured to support a bearing output race.

[0089] In one embodiment of the invention, the bearing input support element comprises a bearing input race.

[0090] In one embodiment of the invention, the outer bearing support element comprises a bearing output race.

[0091] In an embodiment of the invention, the bearing input support element and the bearing output support element are configured to support an internal bearing.

[0092] The bearing input and output support elements may generally include a race for an internal bearing or a support race for an internal bearing. The internal bearing may rotatably couple the bearing input support element and the bearing output support element, and thus may support relative rotation between the circular element and the flexible element, thereby supporting the transmission of the rotation of the strain wave gear.

[0093] In one embodiment of the invention, the internal bearing is a crossed roller bearing.

[0094] Crossed roller bearings can also be understood as crossed roller bearings. In such bearings, the rolling elements of the bearing can be generally cylindrical, wherein the axis of rotation of the rolling elements alternates between different directions. The rolling elements can be separated from each other by spacer retainers.

[0095] Crossed roller bearings can handle complex loads from any direction, which is advantageous.

[0096] In an alternative embodiment, the internal bearing is a ball bearing.Generally speaking, any bearing of embodiments of the present invention can be any type of bearing, such as a ball bearing, a cross roller bearing, a cylindrical roller bearing, a spherical roller bearing, a gear bearing, and the like.

[0097] In one embodiment of the invention, the material of the support element is different from the material of the gear element.

[0098] In one embodiment of the invention, the hardness of the support element is different from the hardness of the gear element.

[0099] By having gear elements and support elements, such as bearing input and output support elements, of different materials, it is advantageous, for example, to optimize the support element for supporting the bearing while optimizing the gear element for facilitating torque transfer. For example, the support element has a first material and the gear element has a second material, wherein the first material and the second material are different materials. Similarly, the support element may have a first hardness and the gear element may have a second hardness, wherein the first hardness and the second hardness are different. The materials may, for example, be two steel alloys, each having a different hardness.

[0100] Fastening a part of the encoder arrangement between elements of different materials is particularly advantageous, since these elements may then have been manufactured as separate elements. Thus, it is advantageous that minimal additional effort is required to implement the invention.

[0101] In one embodiment of the invention, elements of the support element and elements of the gear element are mechanically fixed to each other by fastening means to fasten a part of the encoder arrangement.

[0102] For example, the encoder track may be fastened between the circular element and the bearing output support element, and the two elements are mechanically fixed to each other by a fastening member, thereby fastening the encoder track.

[0103] In one embodiment of the invention a portion of the encoder arrangement is strained between an element of the support element and an element of the gear element by a force of at least 1 Newton, for example at least 3 Newtons, for example at least 10 Newtons, for example at least 25 Newtons such as 40 Newtons.

[0104] By having elements of the support element and elements of the gear element exert pressure on a part of the encoder arrangement, such as an encoder track, the fastening of this part is improved, which is advantageous. This pressure / force / stress can be applied, for example, by screwing elements of the support element onto elements of the gear element, thereby exerting pressure on a part of the encoder arrangement located between these elements.

[0105] In an embodiment of the invention a portion of the encoder arrangement is strained between an element of the support element and an element of the gear element with a force of less than 1000 Newtons, such as less than 300 Newtons, for example less than 100 Newtons, such as 60 Newtons.

[0106] By limiting the strain on a portion of the encoder arrangement, undesired deformation and damage may be avoided, which is advantageous.

[0107] The force may be measured, for example, by a force meter / gauge configured to measure the force between the associated support element and the associated gear element.

[0108] In an embodiment of the invention, the strain wave gear comprises an output flange.

[0109] The output flange may facilitate the mechanical output of the strain wave gear. Having different output flanges may help increase flexibility, which is advantageous.

[0110] In one embodiment of the invention, the output flange is manufactured as a separate element.

[0111] In an embodiment of the invention, the output flange is an element of the support element, wherein a part of the encoder arrangement is fastened between the output flange and an element of the gear element.

[0112] Thus, the output flange may, for example, fasten an encoder rail, or may fasten an encoder reader.

[0113] In one embodiment of the invention, the output flange and the circular element are manufactured as a single component.

[0114] In one embodiment of the invention, the output flange and the flexible element are manufactured as a single component.

[0115] In one embodiment of the invention, the output flange and the bearing output support element are manufactured as a single component.

[0116] Manufacturing the output flange and the further element as a single component simplifies the assembly of the strain wave gear, which is advantageous. Furthermore, it is advantageously possible to ensure that the center axis of the strain wave gear is accurately and precisely transferred to the output end of the strain wave gear.

[0117] In one embodiment of the invention, the output flange is a convex output flange.

[0118] The convex output flange makes it possible to increase the diameter of the contact surface, whereby a better, more reliable and more stable contact can be obtained between the strain wave gear and the object driven by the strain wave gear, which is advantageous.

[0119] For example, in one embodiment, the output flange is a convex output flange, which can be provided as one of the convex output flanges of the strain wave gear disclosed in WO2019 / 096923, which is incorporated herein by reference.

[0120] Furthermore, the convex output flange may be provided with mechanical elements ensuring a better connection between the strain wave gear and the connected object, such as connecting teeth, connecting flanges, indicating elements (e.g. matching surface structures) ensuring a correct orientation of the connected object relative to the strain wave gear.

[0121] For example, in one embodiment, the convex output flange can be provided as one of the part flanges of the releasable joint assembly disclosed in WO2018 / 130447, which is incorporated herein by reference.

[0122] In an embodiment of the invention, the strain wave gear comprises an input flange.

[0123] The input flange may facilitate the mechanical output of the strain wave gear.Having different input flanges may help increase flexibility, which is advantageous.

[0124] In an embodiment of the invention, the input flange is an element of the support element, wherein a part of the encoder arrangement is fastened between the input flange and an element of the gear element.

[0125] In one embodiment of the invention, the strain wave gear includes an inner housing having lubrication for movable components such as the inner bearing and the external gear meshing with the internal gear portion.

[0126] In one embodiment of the invention, the strain wave gear comprises a gasket for isolating lubrication in the inner housing.

[0127] In an embodiment of the invention, said encoder arrangement is located within said inner housing.

[0128] In one embodiment of the invention, said encoder arrangement is located outside said inner housing.

[0129] If the encoder arrangement is located within the inner housing, the wiring may be passed through the gasket. Embodiments of the invention may have more than one gasket.

[0130] The lubricant may be, for example, grease or oil.

[0131] The electronics may be coated with a suitable coating to ensure that it does not release any chemical agents into the grease / oil inside the gear. The encoder reading principle may be specifically chosen for situations where grease / oil may be present, such as magnetic vs. optical.

[0132] In one embodiment of the present invention, the strain wave gear is integrated in a robot joint of a robot arm, wherein the robot joint comprises a joint motor arranged in a robot joint housing, wherein the robot joint motor has a motor shaft configured to rotate the wave generator.

[0133] A robot joint can be connected to another robot joint, for example via an output flange.

[0134] In one embodiment of the present invention, the robot joint is mounted in a robot arm comprising a plurality of robot joints mechanically connecting a robot base to a robot tool flange, wherein at least one robot joint of the plurality of robot joints is the robot joint.

[0135] In one embodiment of the present invention, the robotic arm is part of a robotic system, the robotic system further comprising a robotic controller configured to control movement of the plurality of robotic joints, thereby controlling movement of the robotic tool flange.

[0136] One aspect of the invention relates to a robot system comprising a robot arm and a robot controller, wherein the robot arm comprises a plurality of robot joints mechanically connecting a robot base to a robot tool flange, wherein the robot controller is configured to control movement of the plurality of robot joints, thereby controlling movement of the robot tool flange, wherein at least one robot joint of the plurality of robot joints comprises a strain wave gear, the strain wave gear comprising:

[0137] a gear element, wherein the gear element comprises a circular element having an internally toothed gear, and wherein the gear element comprises a flexible element having a flexible externally toothed gear arranged in the circular element;

[0138] a wave generator rotatably disposed in the flexible element and configured to flex the external gear in a radial direction so that the internal gear and the external gear are partially meshed;

[0139] a support element, wherein the support element includes a bearing input support element and a bearing output support element rotatably coupled to the bearing input support element, wherein elements of the support element are respectively fixed to elements of the gear element; and

[0140] An encoder arrangement comprising an encoder track and an encoder reader, wherein a portion of the encoder arrangement is fastened between an element of the support element and an element of the gear element.

[0141] A robot joint and a robot arm according to the invention may have the same advantages as the strain wave gear according to the invention. The strain wave gear according to the invention is in principle not limited to any particular use, but is particularly suitable for high-precision tasks such as required for the operation of a robot arm, which is advantageous because the more well-defined positioning of the encoder arrangement may increase the accuracy and / or precision of the operation of the robot arm. Furthermore, the manufacturing costs of the robot joint and the robot arm may be reduced by providing them with the strain wave gear according to the invention, since the robot joint and the robot arm may be assembled more easily and more quickly.

[0142] In one embodiment of the invention, said strain wave gear of the robotic system is a strain wave gear according to the invention.

[0143] One aspect of the present invention relates to a method for assembling a strain wave gear, the method comprising the following steps:

[0144] Arranging a flexible externally toothed gear of a flexible element on a circular element having an internally toothed gear, wherein the flexible element and the circular element constitute a gear element;

[0145] providing an encoder arrangement comprising an encoder track and an encoder reader; and

[0146] A separate support element is secured to a corresponding element of the gear element to secure a portion of the encoder arrangement between elements of the support element and elements of the gear element, wherein the support element comprises a bearing input support element and a bearing output support element.

[0147] One aspect of the present invention relates to a method for assembling a strain wave gear, the method comprising the following steps:

[0148] Arranging a flexible externally toothed gear of a flexible element on a circular element having an internally toothed gear, wherein the flexible element and the circular element constitute a gear element;

[0149] providing a support element, wherein the support element comprises a bearing input support element and a bearing output support element; and

[0150] A portion of an encoder arrangement between elements of the support element and elements on the gear element is provided by fixing individual elements of the support element to corresponding elements of the gear element, wherein the encoder arrangement comprises an encoder track and an encoder reader.

[0151] The method for assembling a strain wave gear according to the invention may have any of the same advantages as the strain wave gear according to the invention, in that such a strain wave gear is allowed to be manufactured. In particular, the assembly process may be simplified, in that a separate device for attaching a part of the encoder arrangement may not be required, which is advantageous.

[0152] In an embodiment of the invention the step of providing a portion of the encoder arrangement comprises the step of arranging the portion of the encoder arrangement at an element of the support element before fixing the individual elements of the support element to the corresponding elements of the gear element.

[0153] In an embodiment of the invention the step of providing a portion of the encoder arrangement comprises the step of arranging the portion of the encoder arrangement at an element of the gear element before fixing a separate element of the support element to a corresponding element of the gear element.

[0154] In one embodiment of the invention, the strain wave gear of the method is a strain wave gear according to the invention.

[0155] In one embodiment of the present invention, the method further comprises the step of inserting a wave generator into the flexible element in a radial direction to partially flex the internally toothed gear and the externally toothed gear.

[0156] In an embodiment of the invention, said fixing said separate support element to said corresponding element of said gear element comprises fastening a part of said encoder arrangement by attaching an element of said support element to an element of said gear element using fastening means.

[0157] In an embodiment of the invention, the support element comprises an output flange, wherein a part of the encoder arrangement is fastened by attaching the output flange to an element of the gear element.

[0158] One aspect of the invention relates to securing a portion of an encoder arrangement in a strain wave gear using a support element and a gear element.

[0159] The use of support elements and gear elements to fasten a portion of an encoder arrangement in a strain wave gear may have any of the advantages of the strain wave gear according to the invention. The support element for fastening may, for example, be a support element of a strain wave gear as described in the present disclosure. The gear element for fastening may, for example, be a gear element of a strain wave gear as described in the present disclosure. The encoder arrangement to which a portion is fastened may, for example, be an encoder arrangement of a strain wave gear as described in the present disclosure. According to the invention, support elements and gear elements may therefore be used to fasten an encoder reader. And according to the invention, support elements and gear elements may be used to fasten an encoder track.

[0160] In an embodiment of the invention, the strain wave gear wherein the support element and the gear element are used for fastening a part of an encoder arrangement is a strain wave gear according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0161] Figure 1 shows a simplified cross-sectional view of one embodiment of the present invention;

[0162] Figure 2 shows a simplified cross-sectional view of another embodiment of the present invention;

[0163] 3 to 5 show simplified cross-sectional views of components of other embodiments of the present invention;

[0164] FIG6 shows a flow chart related to the assembly according to the present invention;

[0165] Figures 7 to 9 Simplified cross-sectional views showing components of other embodiments of the present invention;

[0166] Fig.10 shows a simplified perspective cutaway view of one embodiment of the present invention; and

[0167] Fig.11 A robotic system according to one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0168] Figure 1A simplified cross-sectional view of one embodiment of the present invention is shown. The strain wave gear 101 comprises gear elements 102 , 104 , a wave generator 106 , support elements 107 , 108 , and encoder arrangements 109 , 110 .

[0169] The strain wave gear 101 is generally rotationally symmetric around the central axis of the strain wave gear 101. However, some components of the gear, such as the encoder reader 110, may not extend all the way around the central axis, but may be located only on one side of the strain wave gear. In addition, the wave generator 106 in the strain wave gear 101 is generally not completely circularly symmetric and may be, for example, elliptical.

[0170] The gear element comprises a circular element 102 having an internally toothed gear 103 and a flexible element 104 having a flexible externally toothed gear 105. The flexible element 104 is partially arranged inside the circular element 102. The circular element may generally have an annular body. The inner wall of the flexible element 104 is formed as a relatively thin hollow cylinder, resulting in significant flexibility. The externally toothed gear 104 is located at the bottom of the inner wall of the flexible element 104. The flexible element further comprises an annular diaphragm connecting the inner wall with an annular protrusion 125 located at its outer periphery.

[0171] The wave generator 106 is arranged inside the flexible element 104 to bend it. That is, the wave generator 106 deforms the shape of the flexible element 104. The wave generator 106 may, for example, have an elliptical shape, which is then transferred to a portion of the flexible element 104, namely the portion where the external gear 105 is located. This flexure or deformation of the flexible element 104 causes the external gear 105 of the flexible element 104 to partially mesh with the internal gear 103 of the circular element 102. The rotational orientation of the wave generator 106 is not fixed to the rotational orientation of the flexible element 104. That is, when the wave generator 106 rotates, the flexible element 104 does not rotate at the same angular velocity. Instead, when the wave generator 106 rotates, the position where the gears 103, 105 are meshed rotates in the circumferential direction, which in turn causes a relative rotation between the circular element 102 and the flexible element 104. The flexible element 104 has slightly fewer gear teeth than the circular element 102 , which in turn may determine the reduction ratio of the strain wave gear.

[0172] The support elements 107, 108 include a bearing input support element 107 and a bearing output support element 108. The two are rotationally connected by an internal bearing 111. In addition, the bearing input support element 107 is fixed to the flexible element 104, and the bearing output support element 108 is fixed to the circular element 102. Therefore, the bearing input and output support elements 107, 108 support relative rotation between the circular element 102 and the flexible element 104. Other embodiments of the present invention may have additional support elements. The bearing input support element 107 is connected to the flexible element 104 via an annular protrusion 125 of the flexible element 104. For example, they can be connected via fasteners such as screws, rivets, nails, ratchet / snap mechanisms, adhesives, welding, etc.

[0173] In this embodiment, the bearing input and output support elements 107, 108 each support a different race for the internal bearing 111. In other embodiments, these support elements 107, 108 may be made of, for example, an integrated race for the internal bearing 111. In other embodiments, more than one internal bearing may be provided.

[0174] Typically, when the strain wave gear 101 is installed, the bearing input support element 107 is fixed to a motor configured to rotate the wave generator 106 through the shaft of the motor. The bearing output support element 108 can then be mechanically coupled or fixed to the output end, such as to rotate a tool or to rotate a connection with an adjacent robot joint. The rotation of the motor shaft can then be transmitted via the strain wave gear 101 with high torque capacity, coaxial input and output, high gear reduction and minimal backlash.

[0175] The encoder arrangement 109, 110 comprises an encoder reader 110 and an encoder track 109. In this embodiment, the encoder arrangement is a magnetic encoder arrangement. That is, the encoder track 109 has an alternating magnetic pattern encoded in one or more annular patterns around its periphery. The encoder reader 110 is capable of measuring / reading the pattern to determine an absolute or incremental measurement of the relative orientation between the encoder reader 110 and the encoder track 109. It should be understood that the encoder reader and encoder track may alternatively or additionally be provided as optical or inductive encoders.

[0176] In this particular embodiment, an encoder track 109 is fastened between the circular element 102 and the bearing output support element 108. An encoder reader 110 is attached to the bearing input support element 107. Relative rotation between the bearing input support element 107 and the bearing output support element 108 (and similarly between the flexible element 104 and the circular element 102) will therefore also result in relative rotation between the encoder reader 110 and the encoder track 109. Thus, the encoder arrangements 109, 110 are able to track relative rotations.

[0177] In this embodiment, the bearing output support element 108 has an internal thread (not shown) and the circular element 102 has a matching external thread (not shown). The bearing output support element 108 and the circular element 102 are assembled by screwing the two components together via their matching threads. Before assembling these components, the encoder track 109 is placed between the two components so that assembling the bearing output support element 108 and the circular element 102 results in the tightening of the encoder track 109. In this embodiment, the encoder reader 110 is attached by a screw (not shown) that clamps the encoder reader 110 to the bearing input support element 107.

[0178] When the strain wave gear is installed in an application, the encoder reader can output its readings to a controller, such as a robot controller, via a communicative coupling. The communicative coupling is typically wired so that the encoder reader does not require power, but it can alternatively be connected wirelessly. The controller can control the input (and therefore the output) of the strain wave gear 101 based on the measurements from the encoder arrangement 109, 110.

[0179] Figure 2 A simplified cross-sectional view of another embodiment of the present invention is shown. In this illustration, a central axis 117 of the strain wave gear 101 is indicated. The input and output of the strain wave gear rotate coaxially about this central axis 117.

[0180] The concepts of strain wave gears introduced above are applicable to Figure 2 1. The strain wave gear 101 shown in FIG. 1 is similar to the strain wave gear 101 shown in FIG. 1, but the individual components are connected in a different manner.

[0181] In this embodiment, the bearing input support element 107 is fixed to the circular element 102, and the bearing output support element 108 is fixed to the flexible element 104. The encoder track 109 is fastened between the bearing output support element 108 and the flexible element 104, which can be connected by glue, screws, welding or other fastening components. The encoder reader 110 is attached to the bearing input support element 107.

[0182] and Figure 1 Compared to the embodiment shown, the gear elements 102 , 104 are therefore connected differently to the support elements 107 , 108 , however, a part of the encoder arrangement 109 , 110 is still fastened between elements of the support elements 107 , 108 and elements of the gear elements 102 , 104 .

[0183] Figure 3 shows a simplified cross-sectional view of a portion of another embodiment of the invention. In this particular illustration, the portion of the strain wave gear 101 to the right of the central axis 117 has been omitted.

[0184] Several concepts of the strain wave gear introduced above are applicable to the strain wave gear 101 shown in FIG. 3 , but here the support element further includes an output flange 112 .

[0185] The output flange 112 facilitates the rotational output of the strain wave gear 101. For example, a tool may be connected to the output flange 112, or the output flange may be connected to an adjacent robot joint in a robot arm.

[0186] The encoder track 109 is fastened between the output flange 112 and an element of the gear elements 102, 104, namely the circular element 102. In other embodiments, the encoder track can be fastened between the output flange and the flexible element. In other embodiments, the encoder reader can be fastened between the output flange and the circular element, or between the output flange and the flexible element.

[0187] Figure 4 shows a simplified cross-sectional view of a portion of another embodiment of the invention. In this particular illustration, the portion of the strain wave gear 101 to the right of the central axis 117 has been omitted.

[0188] Several of the concepts of strain wave gears introduced above are applicable to the strain wave gear 101 shown in Figure 4. However, in this embodiment, both the encoder reader 110 and the encoder track 109 are secured between elements of the strain wave gear.

[0189] The encoder track 109 is fastened between the flexible element 104 and the bearing output support element 108, while the encoder reader 110 is fastened between the circular element 102 and the bearing input support element 107. In other embodiments of the invention, only the encoder reader 110 is fastened between the elements.

[0190] The encoder reader 110 is secured via an encoder reader PCB 113. Generally speaking, in addition to the encoder reader head, the encoder reader 110 may also include an encoder reader PCB 113 that defines the points where measurements of the encoder track 109 are performed. The encoder reader PCB 113 may hold the circuitry required for driving and measuring with the encoder reader head.

[0191] The embodiment further shows that at least a portion of the encoder arrangement can be located in an internal housing 114. In this and other embodiments, the internal housing 114 has lubrication for movable parts, such as internal bearings 111 and external gears 103 and internal gears 105. The extent of the internal housing 114 can generally be limited by one or more washers to limit the lubrication. Wiring for electronics, such as wiring for encoder reader 110 and its encoder reader PCB 113, can be guided through appropriate openings in such washers.

[0192] Figure 5 shows a simplified cross-sectional view of a portion of another embodiment of the invention. In this particular illustration, the portion of the strain wave gear 101 to the right of the central axis 117 has been omitted.

[0193] Several concepts of strain wave gears introduced above are applicable to the strain wave gear 101 shown in FIG5 . In addition, the strain wave gear 101 includes a spacing element 115 , and the encoder reader 110 is fixed to the bearing output support element 108 .

[0194] More specifically, the encoder reader 110 is fastened between the bearing output support element 108 and the flexible element 104. However, the encoder reader PCB 113 of the encoder reader is not in direct contact with the output support element 108, but only with the flexible element 104 and one of the spacer elements 115. The spacer element 115 may be included, for example, to ensure the correct spacing between the other elements of the strain wave gear 101. They may be fastened using any fastening means mentioned in the present disclosure.

[0195] In this embodiment, the bearing output support element 108 and the bearing input support element 107 each include a race for an internal bearing 111, which is a crossed roller bearing 116 capable of handling large loads from any direction.

[0196] Since the encoder reader 110 is fixed to the output portion of the strain wave gear 101, the wiring of the encoder reader does not necessarily point from the input portion to the reader without restricting the rotational coupling between the input and output or implementing a more complex wiring scheme. If the strain wave gear is installed in a robot arm, this can be solved, for example, by connecting the wiring of the encoder reader 110 to the adjacent robot joint attached to the output end of the strain wave gear 101.

[0197] Figure 6 shows a flow chart related to an assembly according to the invention. That is, the flow chart relates to a method of assembling a strain wave gear.

[0198] In a first step S1 of the method, a flexible externally toothed gear of a flexible element is arranged in a circular element with an internally toothed gear, wherein the flexible element and the circular element constitute a gear element.

[0199] In the next step S2 of the method, support elements are provided. The support elements include a bearing input support element and a bearing output support element.

[0200] In a next step S3 of the method, a part of an encoder arrangement is provided between elements of a support element and elements of the gear element by fixing individual elements of the support element to corresponding elements of the gear element.The encoder arrangement comprises an encoder track and an encoder reader.

[0201] The fixing of the individual support elements to the respective elements of the gear element may be understood, for example, as fixing the bearing input support element to the circular element and fixing the bearing output support element to the flexible element. Alternatively, it may be understood as fixing the bearing input support element to the flexible element and fixing the bearing output support element to the circular element. This may also include fixing the output flange to the element of the gear element.

[0202] The method of the invention may thus, for example, allow the assembly of a strain wave gear according to the invention.

[0203] It is noted that the sequence of steps of the method is not limited to the above examples. For example, before arranging the external gear in the circular element, one or more of the individual support elements may be fixed to the respective gear element. Furthermore, the method is not limited to these specific method steps, but may, for example, include the step of inserting a wave generator.

[0204] Figure 7 A simplified cross-sectional view of another embodiment of the present invention is shown.

[0205] The concepts of strain wave gears introduced above are applicable to Figure 7 1. The strain wave gear 101 shown in FIG. 1 is shown in FIG. 1 , but some optional details are illustrated here.

[0206] The input shaft 118 is configured to rotate the wave generator 106 relative to the flexible spline. In such embodiments with an input shaft 118, the wave generator 106 may be provided, for example, as an elliptical rigid cam, an elliptical wave bearing. The input shaft may be driven, for example, by a motor, whereby the strain wave gear forms a transmission system between the motor and the output side of the strain wave gear.

[0207] In addition, this embodiment has an output flange 112, which is manufactured / processed as a single component together with the circular element 102. In addition, the output flange 112 is an outwardly convex output flange. It extends outwardly relative to the circular element 102 and the bearing output support element 108. It extends radially outward to at least partially radially overlap with the bearing input support element 107.

[0208] Additionally, in this and other embodiments, the support element serves as a housing for the strain wave gear 101. In this particular embodiment, the bearing input support element 107 serves as the housing.

[0209] Figure 8 and Fig. 9 Simplified cross-sectional views of other embodiments of the present invention are shown.

[0210] Several concepts of strain wave gearing introduced above also apply to these embodiments. Figure 7 Compared to the embodiments shown in , these embodiments have other ways of fastening the circular element 102 to the bearing output support element 108. Figure 7 In the embodiment, these elements are fastened to each other via external threads on the circular element 102 and matching internal threads on the bearing output support element 108. Figure 8 In the embodiment, the circular element 102 is fastened to the bearing output support element 108 by welding. Fig. 9 , the circular element 102 is fastened to the circular element 102 using a screw 121. Therefore, the circular element 102 and the bearing output support element 108 include matching screw holes 120 with internal threads. By inserting the screw 121 into the screw hole 120, the encoder track is fastened between the circular element 102 and the bearing output support element 108. With such a fastening component, it is also possible to adjust the strain of the encoder track, for example, by tightening the screw 121 to the screw hole 120 more or less.

[0211] Fig.10 A simplified perspective cutaway view of one embodiment of the present invention is shown. Several concepts of strain wave gearing introduced above also apply to this embodiment.

[0212] The bearing input support element 107 and the bearing output support element 108 are each formed as an annular body and are rotatably coupled by an internal bearing 111, which is a cross roller bearing 116. The races of the bearing 111 are integrally formed in the two support elements 107, 108. The bearing output support element 108 is fixed to the circular element 102, and the bearing input support element 107 is fixed to the flexible element 104. The flexible element 104 includes an external gear 105, which is arranged inside the circular element 102 including the internal gear 103. The flexible element 104 is deformed by the wave generator 106, which in turn can be rotated by the input shaft. This deformation causes the external gear 105 to partially mesh with the internal gear 103. The input shaft 118 is configured to rotate the wave generator 106 relative to the flexible element 104, and the wave generator 106 is configured to flex the flexible cylindrical body of the flexible element in the radial direction when rotating to move the position where the external gear 105 is partially meshed with the internal gear 103. In the illustrated embodiment, the wave generator 106 is configured as an elliptical wave generator as is known in the field of strain wave gears. The number of teeth of the internal gear and the external gear is different, and the rotation of the wave generator moves the meshing position of the gears in the circumferential direction, thereby rotating the inner ring relative to the outer ring. The input shaft 118 can be driven, for example, by a motor, whereby the strain wave gear forms a transmission system between the motor and the output side of the strain wave gear.

[0213] The input shaft 118 is hollow, allowing wires to be routed to adjacent robot joints or other electronics when installed in a robot arm.

[0214] A portion of the circular element 102 extends out of the bearing input support element 107 and includes an outwardly convex output flange 112. The output flange 112 extends outwardly relative to the circular element 102 towards the outer ring.

[0215] The input shaft 118 extends through the flexible element 104 and is rotatably supported by the circular element 102 via n-axis bearings 119. The circular element 102 and the input shaft 118 each include a flange configured to support the bearings 119. This ensures that the input shaft 1111 is arranged at the correct position inside the strain wave gear.

[0216] The encoder arrangement comprises an encoder arrangement flange 124 to which the encoder track 109 is attached. The encoder arrangement flange 124 is fastened between the circular element 102 and the bearing output support element 108. The encoder arrangement further comprises an encoder reader 110, which in turn comprises an encoder reader PCB 113. The encoder reader PCB 113 has screw holes that allow attachment to the bearing input support element 107 via screws.

[0217] The strain wave gear 101 further comprises an end plate 123 which is arranged on the input side of the strain wave gear 101 above the annular protrusion 125 of the flexible element. The end plate 123 comprises an opening allowing the input shaft 118 to pass therethrough. The input shaft is rotatably supported by the end plate via bearings 119. The end plate has screw holes for attachment. Optionally, the flexible element 104 can be fixed to the bearing input support element 107 via matching screw holes and screws.

[0218] Alternatively, the second end plate may be disposed on the output side of the strain wave gear at the end surface of the circular element 102 , and may include an opening allowing the input shaft 123 and the protruding output flange 112 to pass therethrough.

[0219] Embodiments also include gaskets / seals 122 in the inner housing 114. Optionally, embodiments of the present invention may include additional gaskets, for example in the openings between the bearing input support element 107, the bearing output support element 108, and the encoder arrangement flange 124. Such gaskets prevent leakage of lubrication provided inside the inner bearing 1107. The seals may be provided as any type of seal known in strain wave gearing.

[0220] Fig.11A robotic system 1101 is shown according to one embodiment of the present invention. The robotic system 1101 comprises a robotic arm 1100 comprising a plurality of robotic joints 1102a, 1102b, 1102c, 1102d, 1102e, 1102f connecting a robot base 1105 and a robot tool flange 1104. The base joint 1102a is configured to rotate the robot arm about a base axis 1105a (shown as a short dashed line), as indicated by rotation arrow 1106a; the shoulder joint 1102b is configured to rotate the robot arm about a shoulder axis 1105b (shown as a cross indicating the axis), as indicated by rotation arrow 1106b; the elbow joint 1102c is configured to rotate the robot arm about an elbow axis 1105c (shown as a cross indicating the axis), as indicated by rotation arrow 1106c, the first wrist joint 1102d is configured to rotate the robot arm about a first wrist axis 1105d (shown as a cross indicating the axis), as indicated by rotation arrow 1106d, and the second wrist joint 1102e is configured to rotate the robot arm about a second wrist axis 1105e (shown as a short dashed line), as indicated by rotation arrow 1106e. The robot joint 1102f is a tool joint comprising a robot tool flange 1104 that is capable of rotating about a tool axis 1105f (shown in dashed lines) as indicated by rotation arrows 1106f. Thus, the robot arm shown is a six-axis robot arm with six degrees of freedom, having six rotational robot joints, however, it should be noted that the present invention may be provided in a robot arm comprising fewer or more robot joints as well as other types of robot joints, such as prismatic robot joints that provide translation, e.g. linear translation, of parts of the robot arm.

[0221] The robot tool flange reference point (also referred to as TCP) 1107 is indicated at the robot tool flange and defines the origin of the tool flange coordinate system, which defines three coordinate axes x 凸缘 ,y 凸缘 、z 凸缘 In the illustrated embodiment, the origin of the robot tool flange coordinate system has been arranged on the tool flange axis 1105f, with one axis (z 凸缘 ) is parallel to the tool flange axis, and the other axis x 凸缘 ,y 凸缘 Parallel to the outer surface of the robot tool flange 1104. In addition, the reference point 1108 is parallel to the outer surface of the robot tool flange 1104. 基准 ,y 基准 、z 基准 In the illustrated embodiment, the origin of the robot base coordinate system has been arranged on the base axis 1105a, one of which (z 基座 ) is parallel to the base axis 1105a, and the other axis x基座 ,y 基座 Parallel to the bottom surface of the robot base. The direction of gravity 1109 relative to the robot arm is also indicated by an arrow, and it should be understood that the robot arm can be arranged in any position and orientation relative to gravity, limited only by the operational degrees of freedom of the robot joints.

[0222] The robotic system 1101 includes at least one robotic controller 1110 configured to control the robotic arm 1100 and may be provided as a computer including an interface device 1111, enabling a user to control and program the robotic arm. The controller 1110 may be provided as Fig.11 The interface device may be provided as an external device as shown, as a device integrated into the robot arm, or as a combination thereof. The interface device may be provided, for example, as a teach pendant known in the field of industrial robots, which may communicate with the controller 1110 via a wired or wireless communication protocol. The interface device may, for example, include a display 1112 and a plurality of input devices 1113, such as buttons, sliders, touch pads, joysticks, trackballs, gesture recognition devices, keyboards, etc. The display may be provided as a touch screen that acts as both a display and an input device. The interface device may also be provided as an external device configured to communicate with the robot controller 1110, such as a smart phone, a table, a PC, a laptop, etc.

[0223] The robot tool flange 1104 includes a force-torque sensor 1114 (sometimes simply referred to as a force sensor) integrated into the robot tool flange 1104. The force-torque sensor 1114 provides a tool flange force signal that indicates the force-torque provided at the robot tool flange. In the illustrated embodiment, the force-torque sensor is integrated into the robot tool flange and is configured to indicate the force and torque applied to the robot tool flange relative to the robot tool flange reference point 1107. The force sensor 1114 provides a force signal that indicates the force provided at the tool flange. In the illustrated embodiment, the force sensor is integrated into the robot tool flange and is configured to indicate the force-torque applied to the robot tool flange relative to the reference point 1107 and the tool flange coordinate system. However, the force-torque sensor may indicate the force-torque applied to the robot tool flange relative to any point that may be connected to the robot tool flange coordinate system. In one embodiment, the force-torque sensor is provided as a six-axis force-torque sensor configured to indicate forces along three perpendicular axes and torques around three perpendicular axes. For example, the force-torque sensor may be provided as any force-torque sensor capable of indicating forces and torques relative to a reference point, such as any force-torque sensor disclosed in WO2014 / 110682A1, US4763531, US2015204742. However, it should be understood that the force sensor associated with the present invention does not necessarily need to be able to sense the torque applied to the tool sensor. It should be noted that the force-torque sensor may be provided as an external device arranged on the flange of the robot tool or omitted.

[0224] The acceleration sensor 1115 is arranged at the robot tool joint 1102f and is configured to sense the acceleration of the robot tool joint 1102f and / or the acceleration of the robot tool flange 1104. The acceleration sensor 1115 provides an acceleration signal indicating the acceleration of the robot tool joint 1102f and / or the acceleration of the robot tool flange 1104. In the illustrated embodiment, the acceleration sensor is integrated into the robot tool joint and is configured to indicate the acceleration of the robot tool joint in the robot tool coordinate system. However, the acceleration sensor may indicate the acceleration of the robot tool joint relative to any point that may be connected to the robot tool flange coordinate system. The acceleration sensor may be provided as any accelerometer capable of indicating the acceleration of an object. The acceleration sensor may, for example, be provided as an IMU (inertial measurement unit) capable of indicating both the linear acceleration and the rotational acceleration of an object. It should be noted that the acceleration sensor may be provided as an external device arranged on the robot tool flange or omitted.

[0225] Each robot joint includes a robot joint body and an output flange that can rotate or translate relative to the robot joint body, and the output flange is directly or via an arm portion known in the art connected to an adjacent robot joint. The robot joint includes a joint motor, which is configured to rotate or translate the output flange relative to the robot joint body, for example, via a transmission device or directly connected to a motor shaft. The robot joint body can be (for example) formed as a joint housing, and the joint motor can be arranged in the joint housing, and the output flange can extend out of the joint housing. In addition, the robot joint includes at least one joint sensor that provides a sensor signal, and the sensor signal indicates at least one of the following parameters: the angular position and / or linear position of the output flange, the angular position and / or linear position of the motor shaft of the joint motor, the motor current of the joint motor, or the external force and / or torque that attempts to rotate the output flange or the motor shaft. For example, the angular position of the output flange can be indicated by an output encoder such as an optical encoder, a magnetic encoder, which can indicate the angular position of the output flange relative to the robot joint. Similarly, the angular position of the joint motor shaft may be provided by an input encoder such as an optical encoder, a magnetic encoder, which may indicate the angular position of the motor shaft relative to the robot joint. It should be noted that both an output encoder indicating the angular position of the output flange and an input encoder indicating the angular position of the motor shaft may be provided, which in an embodiment where a transmission device is provided enables the relationship between the input side and the output side of the transmission device to be determined. The joint sensor may also be provided as a current sensor indicating the current through the joint motor, and thus the joint sensor is used to obtain the torque provided by the motor. For example, in combination with a multi-phase motor, multiple current sensors may be provided to obtain the current through each phase of the multi-phase motor. It should also be noted that some robot joints may include multiple output flanges that can be rotated and / or translated by the joint actuator, for example, one of the robot joints may include a first output flange that rotates / translates a first portion of the robot arm relative to the robot joint; and a second output flange that rotates / translates a second portion of the robot arm relative to the robot joint.

[0226] The robotic controller 1110 is configured to control the motion of the robotic arm and the robotic joints by controlling the motor torque provided to the joint motors based on a dynamic model of the robotic arm, the gravity work direction 1109 and the joint sensor signals.

[0227] One or more of the robotic joints 1102a to 1102f include a strain wave gear according to the strain wave gear of the present invention. As a result, the robotic arm 1100 may potentially operate more accurately and / or precisely.

[0228] In summary, it is now clear that the present invention relates to a strain wave gear, a robot arm with a strain wave gear, a method for assembling a strain wave gear, and a method for fixing a part of an encoder arrangement in a strain wave gear using certain elements. By utilizing typical components of a typical strain wave gear, it is possible to obtain a more well-defined positioning of a part of an encoder arrangement or of the entire encoder arrangement. Furthermore, it is possible to reduce undesired wobbling of parts of the encoder arrangement. Furthermore, since standard components can be utilized, the assembly of the strain wave gear can be simplified compared to conventional solutions.

[0229] The present invention has been illustrated above with reference to specific examples of strain wave gears, methods and systems for purposes of illustration and not limitation. Details of specific methods and system structures have been provided for the purpose of understanding the embodiments of the present invention, it being understood that the embodiments disclosed in the different figures and corresponding descriptions may be combined in any manner. It should be noted that detailed descriptions of well-known systems, devices, circuits and methods have been omitted so as not to obscure the description of the present invention with unnecessary detail. It should be understood that the present invention is not limited to the specific examples described above and that a person skilled in the art may also implement the present invention in other embodiments without these specific details. In particular, it is clear that the inventive concept of fastening a portion of an encoder track between two elements of a strain wave gear may be implemented using many different methods illustrated in the above description. Therefore, the present invention may be designed and changed in a variety of variations within the scope of the invention as specified in the claims.

[0230] BRIEF DESCRIPTION OF THE DRAWINGS REFERENCE

[0231]

[0232]

Claims

1. A strain wave gear, comprising: A gear element, the gear element comprising: a circular element comprising an internally toothed gear, and a flexible element comprising a flexible externally toothed gear disposed adjacent to the circular element; a wave generator rotatably disposed in the flexible element and configured to flex the external gear in a radial direction so that the internal gear and the external gear are partially meshed; A support element, the support element comprising: a bearing input support element configured to be connected to a motor to drive the wave generator, and a bearing output support element rotatably coupled to the bearing input support element, the bearing output support element being configured to be connected to an output end, wherein an element of the support element is coupled to an element of the gear element; and An encoder arrangement, the encoder arrangement comprising: encoder tracks, and Encoder reader; wherein the encoder track is connected between the circular element and the bearing output support element; and Therein, the encoder track is directly connected to both the circular element and the bearing output support element.

2. The strain wave gear of claim 1, wherein the encoder reader is connected to the bearing input support element. 3 . The strain wave gear of claim 1 , wherein the bearing input support element and the bearing output support element are configured to support an internal bearing.

4. A robot system, comprising: a robotic arm including a plurality of robotic joints mechanically connecting a robotic base to a robotic tool flange; as well as A robotic controller configured to control movement of the plurality of robotic joints and thereby control movement of the robotic tool flange, at least one robotic joint of the plurality of robotic joints comprising the strain wave gear according to claim 1.

5. A method for assembling a strain wave gear according to claim 1, the method comprising: arranging the flexible externally toothed gear of the flexible element within the circular element; as well as The encoder track is disposed between the circular element and the bearing output support element.

6. The method according to claim 5, further comprising: The encoder track is arranged between the bearing output support element and the circular element before assembling the bearing output support element and the circular element.

7. A strain wave gear comprising: A gear element, the gear element comprising: a circular element comprising an internally toothed gear, and a flexible element comprising a flexible externally toothed gear disposed adjacent to the circular element; a wave generator rotatably disposed in the flexible element and configured to flex the external gear in a radial direction so that the internal gear and the external gear are partially meshed; A support element, the support element comprising: a bearing input support element configured to be connected to a motor to drive the wave generator, and a bearing output support element rotatably coupled to the bearing input support element, the bearing output support element being configured to be connected to an output end, wherein an element of the support element is coupled to an element of the gear element; and An encoder arrangement, the encoder arrangement comprising: encoder tracks, and Encoder reader; wherein the encoder track is connected between the circular element and the bearing output support element; and wherein the bearing input support element is directly connected to the flexible element, and wherein the bearing output support element is directly connected to the circular element.

8. The strain wave gear according to claim 7, wherein: The encoder reader is directly connected to the bearing input support element.

9. The strain wave gear of claim 8, further comprising an output flange.

10. The strain wave gear according to claim 9, wherein: The output flange is connected to the circular element.

11. A strain wave gear comprising: A gear element, the gear element comprising: a circular element comprising an internally toothed gear, and a flexible element comprising a flexible externally toothed gear disposed adjacent to the circular element; a wave generator rotatably disposed in the flexible element and configured to flex the external gear in a radial direction so that the internal gear and the external gear are partially meshed; A support element, the support element comprising: a bearing input support element configured to be connected to a motor to drive the wave generator, and a bearing output support element rotatably coupled to the bearing input support element, the bearing output support element being configured to be connected to an output end, wherein an element of the support element is coupled to an element of the gear element; and An encoder arrangement, the encoder arrangement comprising: encoder tracks, and Encoder reader; wherein the encoder track is connected between the circular element and the bearing output support element; and Wherein, the strain wave gear further comprises a fastening device to directly connect the encoder track to both the circular element and the bearing output support element.

12. A strain wave gear comprising: A gear element, the gear element comprising: a circular element comprising an internally toothed gear, and a flexible element comprising a flexible externally toothed gear disposed adjacent to the circular element; a wave generator rotatably disposed in the flexible element and configured to flex the external gear in a radial direction so that the internal gear and the external gear are partially meshed; A support element, the support element comprising: a bearing input support element configured to be connected to a motor to drive the wave generator, and a bearing output support element rotatably coupled to the bearing input support element, the bearing output support element being configured to be connected to an output end, wherein an element of the support element is coupled to an element of the gear element; and An encoder arrangement, the encoder arrangement comprising: encoder tracks, and Encoder reader; wherein the encoder track is connected between the circular element and the bearing output support element; Wherein, the strain wave gear further comprises an output flange; and Therein, the output flange is connected to the encoder track and directly to the circular element.

13. The strain wave gear according to claim 12, wherein: The bearing output support member is configured to be connected to the output end to rotate one of a tool or a robot joint.

14. The strain wave gear according to claim 12, wherein: The encoder reader comprises an encoder printed circuit board PCB.

15. The strain wave gear according to claim 12, wherein: The bearing input support element is connected to the flexible element, and wherein the bearing output support element is connected to the circular element.

16. The strain wave gear according to claim 15, wherein: The bearing output support element is indirectly connected to the flexible element, and wherein the bearing input support element is indirectly connected to the circular element.

17. The strain wave gear according to claim 12, wherein: The bearing input support element and the bearing output support element are configured to support an internal bearing.

18. A method for assembling a strain wave gear according to claim 12, the method comprising: The flexible externally toothed gear of the flexible element is arranged within the circular element.

19. The method according to claim 18, further comprising: The encoder track is arranged between the bearing output support element and the circular element before assembling the bearing output support element and the circular element.

20. A robot system comprising: a robotic arm comprising a plurality of robotic joints connecting a robotic base to a robotic tool flange; as well as A robotic controller configured to control the movement of the plurality of robotic joints and thereby the movement of the robotic tool flange, at least one robotic joint of the plurality of robotic joints comprising the strain wave gear according to claim 12.

Images