Actuator systems and actuators

Abstract

To provide an actuator system and actuator capable of suppressing lead errors. [Solution] The actuator system comprises a multi-degree-of-freedom link mechanism driven by a plurality of actuators, and at least one of the plurality of actuators has a motor, a slide member that moves back and forth in the axial direction from which the rotation axis of the motor extends by the rotational force of the motor, a guide portion that supports the slide member so that it can move back and forth in the axial direction, and a holding portion that holds the position of the guide portion relative to the motor, the guide portion has a held portion that contacts the holding portion, and at least one of the holding portion and the held portion is subjected to a high-friction force treatment that increases the frictional force generated between the held portion and the holding portion.

Description

[[Technical Field]]

[0001] The present invention relates to actuator systems and actuators. [[Background Art]]

[0002] Conventionally, there are robots having multiple degrees of freedom by being provided with parallel link mechanisms connected in series (for example, Patent Document 1). Robots provided with parallel link mechanisms are superior in accuracy and strength and further have the advantages of being capable of reduction in size and weight compared with robots provided with general serial link mechanisms. As an actuator for driving a robot provided with a parallel link mechanism, there is an actuator driven by a ball screw. A ball screw-driven actuator includes, for example, a screw shaft, a nut through which the screw shaft is inserted, and a motor that rotates the nut.

[0003] When a hollow motor is used for a ball screw-driven actuator, reduction in size of the actuator can be achieved by accommodating the screw shaft inside the hollow motor. Further, a ball screw-driven actuator can achieve positioning with high accuracy by converting rotational driving force from the motor via the nut into axial thrust of the screw shaft. [[Prior Art Documents]] [[Patent Documents]]

[0004] [[Patent Document 1]] Japanese Patent No. 7088440 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0005] However, in an actuator system where actuators are connected in series, the tip working point of the end effector, located at the tip of the actuator system, is positioned far from each actuator. Therefore, if assembly errors occur between the components constituting the actuators, the lead error is amplified as it approaches the tip of the actuator system, potentially significantly degrading the operational accuracy of the end effector. Lead error refers to the error in the distance (lead) that the screw shaft and nut advance axially relative to each other when the screw shaft rotates once relative to the nut. If a lead error occurs in each of the actuators constituting the actuator system, it will significantly affect the operational accuracy of the end effector of the actuator system.

[0006] Based on the above circumstances, the present invention aims to provide an actuator system and actuator capable of suppressing lead errors. [Means for solving the problem]

[0007] To solve the above problems, this invention proposes the following means. The actuator system of the present invention comprises a multi-degree-of-freedom link mechanism driven by a plurality of actuators, wherein at least one of the plurality of actuators includes a motor, a slide member that moves back and forth in the axial direction from which the rotation axis of the motor extends by the rotational force of the motor, a guide portion that supports the slide member so as to be able to move back and forth in the axial direction, and a holding portion that holds the position of the guide portion relative to the motor, wherein the guide portion has a held portion that contacts the holding portion, and at least one of the holding portion and the held portion is subjected to a high-friction force treatment that increases the frictional force generated between the held portion and the holding portion.

[0008] The actuator of the present invention comprises a motor, a slide member that moves back and forth in the axial direction from which the rotation shaft of the motor extends by the rotational force of the motor, a guide portion that supports the slide member so that it can move back and forth in the axial direction, and a holding portion that holds the position of the guide portion relative to the motor, wherein the guide portion has a held portion that contacts the holding portion, and at least one of the holding portion and the held portion is subjected to a high-friction force treatment that increases the frictional force generated between the held portion and the holding portion. [Effects of the Invention]

[0009] According to the actuator system and actuator of the present invention, it is possible to provide an actuator system and actuator capable of suppressing lead errors. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the actuator system according to this embodiment. [Figure 2] This is a perspective view showing the actuator according to this embodiment. [Figure 3] A side view showing the actuator. [Figure 4] This is a front view showing the actuator. [Figure 5] A planar vector showing the actuator. [Figure 6] This is a cross-sectional view along the line VI-VI in Figure 4. [Figure 7] This is a perspective view showing some of the components of the actuator. [Figure 8] This is a side view showing the actuator system. [Figure 9] A planar vector showing the actuator. [Figure 10] This is a side view showing the actuator system. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an actuator system 1000 according to the present embodiment.

[0012] [Actuator system 1000] The actuator system 1000 includes a parallel link mechanism (link mechanism) 100 and an end effector 200. The actuator system 1000 is an actuator system that moves and tilts the end effector 200 by driving the parallel link mechanism 100, and controls the position and posture of the end effector 200. The end effector 200 includes a working point P that serves as a working point when the actuator system 1000 performs a predetermined work on an object.

[0013] In the present embodiment, as shown in FIG. 1, with respect to the X-axis, Y-axis, and Z-axis that are orthogonal to each other, the X-axis is defined as the horizontal front-rear direction (X-axis direction), the Y-axis is defined as the horizontal left-right direction (Y-axis direction), and the Z-axis is defined as the vertical up-down direction (Z-axis direction).

[0014] [Parallel link mechanism (link mechanism) 100] The parallel link mechanism 100 includes an arm portion 110 and a link portion 120. The arm portion 110 includes two actuators 1 and a connecting plate 111 that connects the two actuators 1.

[0015] [Actuator 1] FIG. 2 is a perspective view showing the actuator 1 according to the present embodiment. FIG. 3 is a side view showing the actuator 1. FIG. 4 is a front view showing the actuator 1. FIG. 5 is a plan view showing the actuator 1. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. FIG. 7 is a perspective view showing some of the component parts of the actuator 1.

[0016] The actuator 1, as shown in FIGS. 2 to 6, includes a drive unit 10, a screw shaft 20, a slide member 30, and a support portion 40. Note that in FIG. 6, the slide member 30 and the support portion 40 are omitted.

[0017] The drive unit 10, as shown in FIGS. 6 and 7, includes a motor 11, a housing 12, a nut 13, a first bearing (bearing) 14, a second bearing (bearing) 15, a third bearing (bearing) 16, an elastic member 17, and a restricting portion 18. Note that in FIG. 7, the housing 12 and the elastic member 17 are omitted.

[0018] The motor 11, as shown in FIG. 6, includes a stator 11a and a rotor 11b. The motor 11 is, for example, a stepping motor. When the motor 11 is driven, the rotor 11b rotates relative to the stator 11a in the circumferential direction Ma (see FIG. 2) about the rotation axis M as the rotation center.

[0019] In the present embodiment, as shown in FIGS. 2 to 7, the direction in which the rotation axis M extends is defined as "axial direction A", one side in the axial direction A is defined as "distal end side A1", and the other side is defined as "proximal end side A2" in the axial direction A. Further, two directions orthogonal to the axial direction A and orthogonal to each other are defined as "first direction B" and "second direction C".

[0020] The stator 11a and the rotor 11b have a cylindrical shape with the rotation axis M as the central axis. The stator 11a and the rotor 11b do not need to be strictly cylindrical. The rotor 11b passes through the internal space surrounded by the inner circumferential surface of the stator 11a in the axial direction A.

[0021] The housing 12 is a member that accommodates the motor 11, the nut 13, the first bearing 14, the second bearing 15, the third bearing 16, the elastic member 17 and the restricting portion 18, and mainly forms the outer surface of the drive unit 10. The housing 12 includes a first housing 12a, a second housing 12b, and a third housing 12c.

[0022] The first housing 12a has a closed-bottom rectangular tube shape with an opening at the tip side A1. The first housing 12a does not need to be strictly rectangular in shape. An opening is provided at the bottom of the base side A2 of the first housing 12a, penetrating the bottom of the first housing 12a in the axial direction A. The opening at the bottom of the first housing 12a is located on the rotation axis M.

[0023] The stator 11a is fixed inside the first housing 12a. A portion of the base end A2 of the rotor 11b is inserted axially through an opening provided in the bottom of the first housing 12a. That is, the end of the base end A2 of the rotor 11b is exposed outside the first housing 12a.

[0024] The second housing 12b is provided at the tip side A1 of the first housing 12a. The second housing 12b has a rectangular tube shape with openings at the tip side A1 and the base side A2. The second housing 12b does not need to be strictly rectangular in shape. The base side A2 of the second housing 12b is connected to the tip side A1 of the first housing 12a. The internal space of the first housing 12a and the internal space of the second housing 12b are in communication through the opening at the tip side A1 of the first housing 12a and the opening at the base side A2 of the second housing 12b.

[0025] The third housing 12c is a cover member that covers a portion of the opening A1 at the tip of the second housing 12b from the tip A1. The third housing 12c is provided with an opening that penetrates the third housing 12c in the axial direction A. The opening of the third housing 12c is located on the rotation axis M. A screw shaft 20, which will be described later, is inserted through the opening of the third housing 12c in the axial direction A.

[0026] As shown in Figure 6, the nut 13 comprises a first nut portion 13a and a second nut portion 13b. The nut 13 is fixed to the tip end A1 of the rotor 11b. When the rotor 11b rotates in the circumferential direction Ma, the nut 13 rotates together with the rotor 11b in the circumferential direction Ma.

[0027] The first nut portion 13a is positioned in the internal space of the rotor 11b at the tip A1 end of the rotor 11b. The first nut portion 13a has a cylindrical shape with the rotation axis M as its central axis. The first nut portion 13a does not need to be strictly cylindrical.

[0028] The second nut portion 13b is connected to the tip side A1 of the first nut portion 13a. The second nut portion 13b has a cylindrical shape with the rotation axis M as its central axis. The second nut portion 13b does not need to be strictly cylindrical. In the nut 13 of this embodiment, the first nut portion 13a and the second nut portion 13b are formed integrally.

[0029] The outer diameter of the second nut portion 13b is larger than the outer diameter of the first nut portion 13a and the outer diameter of the rotor 11b through which the first nut portion 13a is inserted. The inner diameter of the second nut portion 13b is slightly larger than the inner diameter of the first nut portion 13a. The internal space of the first nut portion 13a and the internal space of the second nut portion 13b are in communication in the axial direction A.

[0030] The first bearing 14 is a bearing comprising a first outer ring 14a, a first ball 14b, and a first inner ring 14c. In this embodiment, the first bearing 14 is a rolling bearing in which the first ball 14b is rotatably arranged between the first outer ring 14a and the first inner ring 14c. The first bearing 14 is located inside the first housing 12a.

[0031] The first outer ring 14a is in contact with the inner circumferential surface of the first housing 12a. The rotor 11b is inserted through the shaft hole of the first inner ring 14c in the axial direction A. The shaft hole of the first inner ring 14c refers to an opening through which the rotation axis M passes in the cylindrical first inner ring 14c with the rotation axis M as its central axis. The first bearing 14 supports the rotor 11b so that it can rotate in the circumferential direction Ma relative to the housing 12.

[0032] A first protrusion 12d, provided within the first housing 12a, is positioned at the base end A2 of the first outer ring 14a. The first outer ring 14a and the first protrusion 12d are in contact in the axial direction A. That is, the movement of the first outer ring 14a toward the base end A2 relative to the first housing 12a is restricted by the first protrusion 12d.

[0033] The second bearing 15 is a bearing comprising a second outer ring 15a, a second ball 15b, and a second inner ring 15c. In this embodiment, the second bearing 15 is a rolling bearing in which the second ball 15b is rotatably arranged between the second outer ring 15a and the second inner ring 15c. The second bearing 15 is located inside the housing 12. In this embodiment, as shown in Figure 6, the second bearing 15 is arranged across the internal space of the first housing 12a and the internal space of the second housing 12b in the axial direction A.

[0034] The second outer ring 15a is in contact with the inner circumferential surface of the first housing 12a and the inner circumferential surface of the second housing 12b. The rotor 11b is inserted through the shaft hole of the second inner ring 15c in the axial direction A. The shaft hole of the second inner ring 15c refers to an opening through which the rotation axis M passes in the cylindrical shape of the second inner ring 15c, which has the rotation axis M as its central axis. The second bearing 15 supports the rotor 11b so that it can rotate in the circumferential direction Ma relative to the housing 12.

[0035] A second protrusion 12e, provided within the first housing 12a, is positioned at the base end A2 of the second outer ring 15a. The second outer ring 15a and the second protrusion 12e are in contact in the axial direction A. That is, the movement of the second outer ring 15a toward the base end A2 relative to the first housing 12a is restricted by the second protrusion 12e.

[0036] A first projection 11c is positioned at the base end A2 of the second inner ring 15c, projecting outward (away from the rotation axis M) from the outer circumferential surface of the rotor 11b. The second inner ring 15c and the first projection 11c are in contact in the axial direction A. In other words, the movement of the second inner ring 15c toward the base end A2 relative to the rotor 11b is restricted by the first projection 11c.

[0037] The third bearing 16 is a bearing comprising a third outer ring 16a, a third ball 16b, and a third inner ring 16c. In this embodiment, the third bearing 16 is a rolling bearing in which the third ball 16b is rotatably arranged between the third outer ring 16a and the third inner ring 16c. The third bearing 16 is located within the second housing 12b. Furthermore, as shown in Figures 6 and 7, the third bearing 16 is located at the tip side A1 of the second bearing 15.

[0038] The third outer ring 16a is in contact with the inner circumferential surface of the second housing 12b. The rotor 11b is inserted through the shaft hole of the third inner ring 16c in the axial direction A. The shaft hole of the third inner ring 16c refers to an opening through which the rotation axis M passes in the cylindrical shape of the third inner ring 16c, which has the rotation axis M as its central axis. The third bearing 16 supports the rotor 11b so that it can rotate in the circumferential direction Ma relative to the housing 12.

[0039] A third protrusion 12f, located within the second housing 12b, is positioned at the tip A1 of the third outer ring 16a. The third outer ring 16a and the third protrusion 12f are in contact in the axial direction A. That is, the movement of the third outer ring 16a toward the tip A1 relative to the second housing 12b is restricted by the third protrusion 12f.

[0040] The elastic member 17 is provided on the tip side A1 of the first bearing 14 and is a member that can expand and contract in the axial direction A. The elastic member 17 is, for example, a compression coil spring having an internal space through which the rotor 11b is inserted in the axial direction A.

[0041] A second projection 11d is positioned at the tip A1 of the elastic member 17, projecting outward from the outer circumferential surface of the rotor 11b. The elastic member 17 is positioned between the first inner ring 14c and the second projection 11d in the axial direction A.

[0042] The restricting portion 18 has a cylindrical shape with the rotation axis M as its central axis. The restricting portion 18 does not need to be strictly cylindrical. The rotor 11b is inserted through the internal space of the restricting portion 18 in the axial direction A. The restricting portion 18 is positioned between the third inner ring 16c and the second nut portion 13b in the axial direction A.

[0043] The restricting portion 18 is fixed to the rotor 11b. Alternatively, the restricting portion 18 may be fixed to the second nut portion 13b and then to the rotor 11b via the second nut portion 13b. The third inner ring 16c and the restricting portion 18 are in contact in the axial direction A. That is, the movement of the third inner ring 16c toward the tip side A1 relative to the rotor 11b is restricted by the restricting portion 18.

[0044] In this way, the rotor 11b is supported by bearings 14, 15, and 16 so as to be rotatable in the circumferential direction Ma relative to the housing 12. Furthermore, when the motor 11 is driven and the rotor 11b rotates in the circumferential direction Ma, the nut 13 and regulating part 18 fixed to the rotor 11b also rotate together with the rotor 11b in the circumferential direction Ma.

[0045] As shown in Figures 6 and 7, the screw shaft 20 is a member that extends in the axial direction A, and is inserted through the rotor 11b, the nut 13, and the opening of the third housing 12c in the axial direction A. A helical groove shape is formed on the inner circumferential surface of the nut 13, with the rotation axis M as the central axis. Multiple balls (not shown) are provided to roll in the groove shape formed on the inner circumferential surface of the nut 13.

[0046] A helical groove shape is formed on the outer surface of the screw shaft 20, with the rotation axis M as the central axis. Multiple balls provided in the groove shape of the nut 13 are fitted so as to be able to roll against the groove shape of the screw shaft 20, which is inserted into the internal space of the nut 13.

[0047] Because the groove shape of the nut 13 and the groove shape of the screw shaft 20 are fitted together via multiple balls, when the nut 13 rotates in the circumferential direction Ma, the nut 13 and the screw shaft 20 move relative to each other in the axial direction A.

[0048] The rotor 11b, to which the nut 13 is fixed, is supported by bearings 14, 15, and 16 so as to be rotatable in the circumferential direction Ma relative to the housing 12, and is positioned so as to be substantially immovable in the axial direction A relative to the housing 12. As the rotor 11b rotates in the circumferential direction Ma, the screw shaft 20 moves in the axial direction A relative to the nut 13 which rotates with the rotor 11b. In other words, when the motor 11 is driven and the rotor 11b rotates in the circumferential direction Ma, the screw shaft 20 moves back and forth in the axial direction A relative to the housing 12.

[0049] As shown in Figures 2 to 5, the slide member 30 comprises a first slide member 31, a second slide member 32, and a supported portion (guide rail) 33. The first slide member 31 is a member that extends in the first direction B and is connected to the tip side A1 of the screw shaft 20.

[0050] The second slide member 32 is a member that extends in the axial direction A and is connected to one end of the first slide member 31 in the first direction B. As shown in Figures 2 to 4, the second slide member 32 is positioned alongside the housing 12 in the first direction B. In the slide member 30 of this embodiment, the first slide member 31 and the second slide member 32 are formed integrally.

[0051] The slide member 30 is mainly formed by a first slide member 31 extending in the first direction B and a second slide member 32 extending in the axial direction A, and as shown in Figure 3, it has an L-shape when viewed from the second direction C. The slide member 30 does not need to be strictly L-shaped.

[0052] The supported portion 33 is a member extending in the axial direction A, and as shown in Figures 4 and 5, it is connected to both sides of the second slide member 32 in the second direction C. The slide member 30 moves back and forth in the axial direction A together with the screw shaft 20 when the screw shaft 20 moves back and forth in the axial direction A.

[0053] As shown in Figure 2, the support portion 40 comprises a fixing member 41, a pair of guide portions 42, and a cover member 43. In the first direction B, the support portion 40 is positioned on the side of the housing 12 where the second slide member 32 is positioned.

[0054] The fixing member 41 is a plate-shaped member extending in the axial direction A and the second direction C, and is fixed to the outer surface of the housing 12. In the first direction B, the fixing member 41 is positioned between the housing 12 and the second sliding member 32.

[0055] The pair of guide portions 42 are connected to the surface of the fixing member 41 on the side of the second slide member 32. The pair of guide portions 42 are plate-shaped members extending in the axial direction A and the first direction B, and are provided facing each other in the second direction C. The second slide member 32 is positioned between the pair of guide portions 42 in the second direction C.

[0056] The cover member 43 is a plate-shaped member extending in the axial direction A and the second direction C, and is provided opposite the fixing member 41 in the first direction B. A pair of guide portions 42 are sandwiched between the fixing member 41 and the cover member 43 in the first direction B.

[0057] The dimensions of the fixing member 41 and the cover member 43 in the axial direction A and the second direction C are approximately the same. The dimension of the guide portion 42 in the axial direction A is approximately the same as the dimension of the fixing member 41 and the cover member 43 in the axial direction A. The pair of guide portions 42 are positioned at both ends of the fixing member 41 and the cover member 43 in the second direction C, respectively.

[0058] As shown in Figure 4, the support portion 40 is rectangular when viewed from the axial direction A, formed by a pair of guide portions 42 that form both sides in the second direction C, and a fixing member 41 and a cover member 43 that form both sides in the first direction B.

[0059] The support portion 40 is surrounded by a fixing member 41, a pair of guide portions 42, and a cover member 43, and has a space (insertion space 40s) that opens to the tip side A1 and the base side A2. In the slide member 30, the second slide member 32 and the supported portion 33 are arranged by inserting the insertion space 40s formed in the support portion 40 in the axial direction A.

[0060] As shown in Figures 4 and 5, a linear guide 42a is connected to the surface of the guide portion 42 on the insertion space 40s side. In this embodiment, as shown in Figure 5, each pair of guide portions 42 is provided with two linear guides 42a arranged side by side in the axial direction A. Note that the cover member 43 is omitted in Figure 5.

[0061] The slide member 30 is supported so as to be able to move back and forth in the axial direction A by linear guides 42a provided on each of a pair of guide portions 42 facing the second direction C. As shown in Figure 4, a groove into which the supported portion 33 can be fitted is formed on the insertion space 40s side of the linear guide 42a. The slide member 30 is supported by the linear guide 42a with the supported portion 33 fitted into the groove of the linear guide 42a.

[0062] Multiple balls (not shown) are arranged inside the linear guide 42a so as to be able to roll. When the slide member 30 moves back and forth in the axial direction A, the linear guide 42a supports the supported portion 33 so that the slide member 30 can move back and forth smoothly in the axial direction A by the rolling of the multiple balls inside.

[0063] The actuator 1 is driven by the motor 11, which causes the nut 13 to rotate in the circumferential direction Ma, and the screw shaft 20 and the slide member 30 connected to the screw shaft 20 to move back and forth in the axial direction A. The slide member 30 is supported by a linear guide 42a provided on the guide portion 42, which allows it to move back and forth precisely in a predetermined direction (in this case, the axial direction A).

[0064] The support portion 40 maintains the position of the slide member 30 relative to the motor 11 in a predetermined position by supporting the supported portion 33 with the linear guide 42a. For example, if the support portion 40 is assembled with the fixed member 41 and the guide portion 42 in a position where the linear guide 42a is misaligned from its predetermined position, it may become difficult for the linear guide 42a to guide the slide member 30 in the predetermined direction.

[0065] In this embodiment, the slide member 30 moves back and forth in a direction parallel to the rotation axis M of the motor 11. The support portion 40 guides the slide member 30 in a direction parallel to the rotation axis M of the motor 11 by holding the slide member 30 in a predetermined position relative to the motor 11.

[0066] For example, the fixing member 41, guide member 42, and cover member 43 that constitute the support portion 40 are mainly made of aluminum. By using aluminum as the material for the support portion 40, the actuator 1 can be made lighter.

[0067] The position of the guide portion 42 relative to the motor 11 is fixed by fastening the guide portion 42 to the fixing member 41 with a screw member SC (see Figures 2 and 3). Furthermore, the position of the guide portion 42 relative to the motor 11 can be stably maintained by sandwiching and fixing the guide portion 42 between the fixing member 41 and the cover member 43.

[0068] In this embodiment, the cover member 43 and the guide portion 42 are fastened together by a screw member SC. Specifically, the guide portion 42 and the cover member 43 are fixed to the fixing member 41 by screwing the screw member SC, which is inserted in the first direction B through an opening (not shown) that penetrates the cover member 43 in the first direction B, and an opening 42h (see Figure 5) that penetrates the guide portion 42 in the first direction B, into the fixing member 41.

[0069] Here, the member that holds the position of the guide portion 42 relative to the motor 11 is referred to as the "holding portion 44". As shown in Figure 4, in this embodiment, the holding portion 44 includes a first holding portion 44a which is part of the fixing member 41 that contacts the guide portion 42, and a second holding portion 44b which is part of the cover member 43 that contacts the guide portion 42.

[0070] The guide portion 42 is held in a predetermined position by being sandwiched in the first direction B between the first holding portion 44a and the second holding portion 44b, and further fastened to the fixing member 41 together with the cover member 43 by a screw member SC.

[0071] Here, the portion of the guide portion 42 that comes into contact with the holding portion 44 is referred to as the "held portion 42s". The guide portion 42 is held in a predetermined position by the holding portion 44 with the held portion 42s in contact with the holding portion 44.

[0072] For example, when assembling the guide portion 42 to the fixing member 41, or when an external force is applied to the guide portion 42 after the guide portion 42 and the cover member 43 have been fastened to the fixing member 41, the position of the guide portion 42 relative to the fixing member 41 may shift from its predetermined position. In particular, when the support portion 40 is formed from aluminum, which has lower rigidity compared to iron or stainless steel, the external force may cause the components of the support portion 40 (for example, the guide portion 42) to undergo elastic deformation, which may cause the guide portion 42 to shift position.

[0073] If the guide portion 42 is misaligned, a load may be placed on the screw shaft 20 and the nut 13, and a lead error may occur due to the movement direction of the screw shaft 20 and the slide member 30 deviating from the predetermined direction. The lead error refers to the error in the distance (lead) that the screw shaft 20 and the nut 13 move relative to each other in the axial direction A when the screw shaft 20 rotates once relative to the nut 13.

[0074] The distance that the screw shaft 20 and the nut 13 move relative to each other in the axial direction A can be set to a desired distance by, for example, adjusting the pitch of the groove shape provided on the inner surface of the nut 13 or the outer surface of the screw shaft 20. Lead errors may occur, which could cause the distance that the screw shaft 20 moves when the nut 13 is rotated by a predetermined angle to differ from the preset distance.

[0075] In this case, for example, it becomes difficult to properly control the position of the work point P of the actuator system 1000 driven by actuator 1, and there is a risk that the working accuracy of the actuator system 1000 will decrease. In particular, in an actuator system 1000 that drives multiple actuators 1 connected in series, there is a risk that the positional accuracy of the work point P will decrease significantly due to the lead errors of each of the multiple actuators 1.

[0076] In this embodiment, the holding portion 44 that maintains the position of the guide portion 42 relative to the motor 11 and the held portion 42s of the guide portion 42 that contacts the holding portion 44 are subjected to a high-friction force treatment that increases the frictional force generated between the held portion 42s and the holding portion 44.

[0077] By increasing the frictional force between the held portion 42s and the holding portion 44 through high-friction force treatment, even when an external force is applied to the support portion 40 when assembling the guide portion 42 to the fixing member 41, transporting the actuator 1 after assembly, or driving the actuator 1, the frictional force generated between the held portion 42s of the guide portion 42 and the holding portion 44 that holds the guide portion 42 can suppress displacement of the guide portion 42. As a result, the position of the guide portion 42 relative to the motor 11 can be sufficiently maintained during assembly of the actuator 1 and during long-term use after assembly, and lead errors can be suppressed.

[0078] Examples of high-friction treatments applied to the retained portion 42s and the retaining portion 44 include blast treatment, coating treatment using a high-friction coating agent, texture processing, and diamond coating using diamond particles. In this embodiment, diamond coating refers to a coating treatment that improves the surface roughness of the object to be treated (here, the retained portion 42s and the retaining portion 44).

[0079] Furthermore, the high-friction force treatment only needs to be applied to at least one of the holding portion 44 and the held portion 42s. Even if the high-friction force treatment is applied to only one of the holding portion 44 and the held portion 42s, the frictional force generated between the holding portion 44 and the held portion 42s can be increased, thereby suppressing the occurrence of lead errors in the actuator 1.

[0080] Furthermore, it is preferable that the first holding portion 44a of the holding portion 44 is subjected to a high-friction treatment. By subjecting at least one of the first holding portion 44a provided on the fixing member 41 fixed to the housing 12 and the held portion 42s that comes into contact with the first holding portion 44a to a high-friction treatment, the misalignment of the guide portion 42 relative to the motor 11 can be effectively suppressed.

[0081] In addition, the high-friction force treatment on the fixing member 41 and the cover member 43 may be applied only to the first holding portion 44a and the second holding portion 44b that come into contact with the held portion 42s of the guide portion 42, or it may be applied to the entire surface of the fixing member 41 and the cover member 43 on the guide portion 42 side.

[0082] As described above, the guide portion 42 and the cover member 43 are fastened together to the fixing member 41 by a screw member SC. In this embodiment, the fixing member 41 is provided with a screw insert 41a (see Figure 3). The screw insert 41a is embedded in the fixing member 41 and forms a groove shape that screws into the screw member SC.

[0083] The screw insert is made of a material such as stainless steel, which has higher strength than aluminum. By screwing the screw member SC into the screw insert 41a provided on the fixing member 41, the fastening force of the screw member SC can be improved compared to when the screw member SC is directly screwed into the fixing member 41.

[0084] This allows the guide portion 42 and the cover portion 43 to be firmly fastened to the fixing member 41 by the screw member SC, more effectively suppressing displacement of the guide portion 42 due to external forces, and further reducing the lead error of the actuator 1.

[0085] As shown in Figure 1, the arm portion 110 of the actuator system 1000 includes a first arm portion 110a and a second arm portion 110b. Furthermore, in the actuator system 1000, the actuator 1 includes a first actuator 1a and a second actuator 1b provided on the first arm portion 110a, and a third actuator 1c and a fourth actuator 1d provided on the second arm portion 110b.

[0086] The connecting plate 111 includes a first connecting plate 111a that connects the first actuator 1a and the second actuator 1b, and a second connecting plate 111b that connects the third actuator 1c and the fourth actuator 1d.

[0087] As shown in Figures 1 and 8, the first actuator 1a and the second actuator 1b of the first arm 110a are provided with their rotation axes M (rotation axis M1, rotation axis M2) parallel to the Y axis. Rotation axis M1 is the rotation axis of the motor 11 of the first actuator 1a. Rotation axis M2 is the rotation axis of the motor 11 of the second actuator 1b.

[0088] As shown in Figures 1 and 10, the third actuator 1c and fourth actuator 1d of the second arm 110b are provided with their rotation axes M (rotation axis M3, rotation axis M4) parallel to the X-axis. Rotation axis M3 is the rotation axis of the motor 11 of the third actuator 1c. Rotation axis M4 is the rotation axis of the motor 11 of the fourth actuator 1d.

[0089] [Link section 120] As shown in Figure 1, the link portion 120 of the actuator system 1000 includes a first link portion 120a that connects the first arm portion 110a and the second arm portion 110b, and a second link portion 120b that connects the second arm portion 110b and the end effector 200.

[0090] The link section 120 (first link section 120a and second link section 120b) comprises a base end link member 121 and a tip end link member 122.

[0091] The base-side link member 121 is connected to the tip side A1 of the first slide member 31 of the actuator 1 provided on the arm portion 110. The tip-side link member 122 is rotatably mounted relative to the base-side link member 121 with the link axis L as the center of rotation.

[0092] Next, the detailed configuration of the first arm portion 110a and the first link portion 120a will be described. As described above, the first arm portion 110a comprises a first actuator 1a, a second actuator 1b, and a first connecting plate 111a.

[0093] The rotation axis M1 of the first actuator 1a and the rotation axis M2 of the second actuator 1b extend parallel to the Y axis. As shown in Figure 1, in this embodiment, the first actuator 1a is positioned above the second actuator 1b in the Z-axis direction.

[0094] The first connecting plate 111a is a plate-shaped member extending in the Y-axis and Z-axis directions, and connects the first actuator 1a and the second actuator 1b. Specifically, the first connecting plate 111a is connected to the housing 12 of the first actuator 1a and the second actuator 1b on the side opposite to the side where the support portion 40 is provided.

[0095] As shown in Figure 8, a base-side link member 121 is connected to the slide member 30 of the first actuator 1a and the slide member 30 of the second actuator 1b, respectively.

[0096] A tip-side link member 122 is connected to a base-side link member 121 connected to the first actuator 1a so as to be rotatable around a link axis L1 extending in the X-axis direction. A tip-side link member 122 is connected to a base-side link member 121 connected to the second actuator 1b so as to be rotatable around a link axis L2 extending in the X-axis direction.

[0097] Specifically, the slide members 30 of the first actuator 1a and the second actuator 1b are connected to a base-side link member 121 and a tip-side link member 122 that is rotatably mounted relative to the base-side link member 121 with the link axis L(L1, L2) as the center of rotation. The tip-side link members 122 connected to the first actuator 1a and the second actuator 1b are connected to the second arm portion 110b.

[0098] Next, the detailed configuration of the second arm portion 110b and the second link portion 120b will be described. As described above, the second arm portion 110b comprises a third actuator 1c, a fourth actuator 1d, and a second connecting plate 111b.

[0099] The rotation axis M3 of the third actuator 1c and the rotation axis M4 of the fourth actuator 1d extend parallel to the X-axis. As shown in Figure 1, in this embodiment, the third actuator 1c is positioned above the fourth actuator 1d in the Z-axis direction.

[0100] The second connecting plate 111b connects the third actuator 1c and the fourth actuator 1d. In the actuator system 1000 taking the reference posture shown in Figures 1, 8, 9, and 10, the second connecting plate 111b is a plate-shaped member extending in the X-axis and Z-axis directions. The second connecting plate 111b is connected to the housing 12 of the third actuator 1c and the fourth actuator 1d on the side opposite to the side where the support portion 40 is provided.

[0101] As shown in Figure 8, on the second connecting plate 111b, the tip-side link member 122 of the first link portion 120a is connected to the side opposite to the side to which the third actuator 1c and the fourth actuator 1d are connected.

[0102] As shown in Figures 1 and 10, a base-side link member 121 is connected to the slide member 30 of the third actuator 1c and the slide member 30 of the fourth actuator 1d, respectively.

[0103] A tip-side link member 122 is connected to a base-side link member 121 that is connected to the third actuator 1c, so as to be rotatable about the link shaft L3 as the center of rotation. A tip-side link member 122 is connected to a base-side link member 121 that is connected to the fourth actuator 1d, so as to be rotatable about the link shaft L4 as the center of rotation.

[0104] Link axes L3 and L4 extend in directions perpendicular to the rotation axes M3 and M4. In the actuator system 1000 taking the reference posture shown in Figures 1, 8, 9, and 10, link axes L3 and L4 extend in the Y-axis direction.

[0105] The slide members 30 of the third actuator 1c and the fourth actuator 1d are connected to a base-side link member 121 and a tip-side link member 122 that is rotatably mounted relative to the base-side link member 121 with the link axis L (L3, L4) as the center of rotation. The tip-side link members 122 connected to the third actuator 1c and the fourth actuator 1d are connected to the end effector 200.

[0106] [End Effector 200] The end effector 200 comprises a working section 210, a drive section 220, a screw shaft 230, a sliding member 240, and a third connecting plate 250.

[0107] The working section 210 is a component in the actuator system 1000 that has a working point P for performing a predetermined operation, and is, for example, a surgical instrument for ophthalmic surgery. In this embodiment, the working section 210 includes a needle member 211 that acts on the object on which the end effector 200 performs the operation. In this embodiment, the working point P of the actuator system 1000 is the tip of the needle member 211.

[0108] Furthermore, the work unit 210 is not limited to surgical instruments for ophthalmic surgery, but may also be other medical devices, or instruments used for manufacturing or inspecting industrial products, etc.

[0109] The drive unit 220 comprises a motor (not shown), a housing 221 that houses the motor, and a nut 222 provided inside the housing 221. The motor housed in the drive unit 220 is capable of rotating the nut 222 around the rotation axis M5. In the actuator system 1000 that takes a reference position, the rotation axis M5 is an axis extending in the Z-axis direction.

[0110] The screw shaft 230 is mounted on the rotating shaft M5, with a nut 222 inserted through it. The drive unit 220 and the screw shaft 230 constitute a ball screw-driven actuator that can move the screw shaft 230 forward and backward in the direction in which the rotating shaft M5 extends by driving a motor housed in the housing 221 of the drive unit 220. The drive unit 220 has a configuration similar to, for example, the drive unit 10 in actuator 1, and holds the screw shaft 230, which corresponds to the screw shaft 20 of actuator 1, so that it can move forward and backward.

[0111] The slide member 240 is connected to the tip of the screw shaft 230 and is provided to move back and forth together with the screw shaft 230. The working part 210 is connected to the slide member 240. That is, when the drive unit 220 is driven, the screw shaft 230, the slide member 240 and the working part 210 move back and forth in the direction in which the rotation shaft M5 extends.

[0112] The third connecting plate 250 is a member that connects the second link portion 120b and the drive portion 220. When the drive portion 220 is driven, the screw shaft 230, the sliding member 240, and the working portion 210 move back and forth in the direction in which the rotation shaft M5 extends relative to the third connecting plate 250 and the drive portion 220.

[0113] Next, the operation of the actuator system 1000 will be described. The first arm 110a can move and tilt the second arm 110b and the end effector 200 by driving the first actuator 1a and the second actuator 1b.

[0114] Specifically, the first arm 110a can move the second arm 110b and the end effector 200 in the Y-axis direction. In addition, the first arm 110a can tilt the second arm 110b and the end effector 200 around the X-axis.

[0115] The first arm 110a moves the slide members 30 of the first actuator 1a and the second actuator 1b in the Y-axis direction, thereby moving the second arm 110b, which is connected to the slide members 30 of the first actuator 1a and the second actuator 1b via the first link 120a, in the Y-axis direction. At this time, the end effector 200, which is connected to the second arm 110b via the second link 120b, moves in the Y-axis direction together with the second arm 110b.

[0116] Furthermore, the first arm 110a tilts the second arm 110b around the X-axis by moving the sliding members 30 of the first actuator 1a and the second actuator 1b forward and backward by different amounts of movement. At this time, the tip-side link member 122 of the first link portion 120a rotates with respect to the base-side link member 121 with respect to the link axis L(L1, L2) as the center of rotation.

[0117] The second arm 110b can move and tilt the end effector 200 by driving the third actuator 1c and the fourth actuator 1d. Specifically, the second arm 110b can move the end effector 200 in the X-axis direction. In addition, the second arm 110b can tilt the end effector 200 around the Y-axis.

[0118] The second arm 110b moves the slide members 30 of the third actuator 1c and the fourth actuator 1d forward and backward in the X-axis direction, thereby moving the end effector 200, which is connected to the slide members 30 of the third actuator 1c and the fourth actuator 1d via the second link 120b, forward and backward in the X-axis direction.

[0119] Furthermore, the second arm 110b tilts the end effector 200 around the Y axis by moving the sliding members 30 of the third actuator 1c and the fourth actuator 1d forward and backward by different amounts of movement from each other. At this time, the tip-side link member 122 of the second link section 120b rotates with respect to the base-side link member 121 with the link axis L (L3, L4) as the center of rotation.

[0120] In this way, the actuator system 1000 can move the end effector 200 in the X-axis and Y-axis directions, and tilt it around the X-axis and Y-axis directions, by driving the actuators 1 (first actuator 1a, second actuator 1b, third actuator 1c, and fourth actuator 1d) provided in the first arm 110a and the second arm 110b. The parallel link mechanism 100 that can move and tilt the end effector 200 is a link mechanism with multiple degrees of freedom.

[0121] Furthermore, as described above, the end effector 200 can move the work section 210 forward and backward in the direction in which the rotation axis M5 extends by driving the drive unit 220. Specifically, the end effector 200 can change the position of the work section 210 in the Z-axis direction by driving the drive unit 220.

[0122] Thus, the actuator system 1000 is a 5-axis robot having 5 degrees of freedom in the X-axis direction, Y-axis direction, Z-axis direction, and around the X-axis and Y-axis. The actuator system 1000 moves the needle member 211 with its 5 degrees of freedom and controls the position and orientation of the needle member 211 relative to the object.

[0123] Because the actuator system 1000 controls the position and orientation of the end effector 200 by a parallel link mechanism 100, it offers superior precision and strength compared to robots equipped with a typical serial link mechanism, and also enables miniaturization and weight reduction.

[0124] The parallel link mechanism 100 controls the position and orientation of the end effector 200 by driving the actuators 1 provided in the first arm 110a and the second arm 110b, which are connected by the first link 120a.

[0125] In other words, the actuator system 1000 controls the position and orientation of the end effector 200 using a parallel link mechanism 100 in which multiple actuators 1 are arranged in series.

[0126] Ball screw-driven actuators, which consist of a nut and a screw shaft, can experience lead errors due to relative misalignment of their components. When controlling the position and orientation of an end effector using an actuator that experiences lead errors, the accuracy of the control of the end effector's position and orientation decreases due to the occurrence of lead errors. In particular, in actuator systems with actuators arranged in series, if lead errors occur in any of the actuators, the lead errors of each actuator accumulate and significantly affect the operational accuracy of the end effector.

[0127] As described above, the actuator 1 of this embodiment suppresses misalignment of the guide portion 42 with respect to the motor 11 and prevents lead errors by increasing the frictional force generated between the held portion 42s and the holding portion 44 through high-friction force processing.

[0128] Therefore, even when the position and orientation of the end effector 200 are controlled by a plurality of actuators 1 arranged in series, the actuator system 1000 of this embodiment can suppress a decrease in the operational accuracy of the end effector 200 due to lead errors of the actuators 1.

[0129] This makes it possible to realize an actuator system 1000 that can be used for tasks requiring high precision, such as ophthalmic surgery. Because the actuator system 1000 can control the position and orientation of the end effector 200 with high precision, it can achieve high operational accuracy even when controlling the position and orientation of the working point P of the needle member 211 within a small range of motion, such as when performing ophthalmic surgery on one eye.

[0130] Furthermore, since it is not necessary to excessively ensure the rigidity of the components of the actuator 1 (for example, the guide portion 42) to prevent misalignment of the guide portion 42, lightweight materials such as aluminum can be used for the guide portion 42, thereby achieving a lighter actuator system 1000.

[0131] The actuator system 1000 of this embodiment includes a multi-degree-of-freedom link mechanism 100 driven by a plurality of actuators 1. The actuator 1 includes a motor 11, a slide member 30 that moves back and forth in the axial direction A from which the rotation axis M of the motor 11 extends by the rotational force of the motor 11, a guide portion 42 that supports the slide member 30 so that it can move back and forth in the axial direction A, and a holding portion 44 that holds the position of the guide portion 42 relative to the motor 11. The guide portion 42 has a held portion 42s that contacts the holding portion 44. At least one of the holding portion 44 and the held portion 42s is subjected to a high-friction force treatment that increases the frictional force generated between the held portion 42s and the holding portion 44.

[0132] With the actuator system 1000 and actuator 1 configured in this way, it is possible to provide an actuator system 1000 and actuator 1 that can suppress lead errors. This makes it possible to provide an actuator system 1000 with improved operational accuracy of the end effector 200.

[0133] Furthermore, in at least one of the multiple actuators 1 provided by the actuator system 1000, high-friction force treatment is applied to at least one of the holding portion 44 and the held portion 42s. By suppressing the lead error of at least one actuator 1 provided by the actuator system 1000 through high-friction force treatment, the lead error can be reduced compared to an actuator system equipped with actuators that are not subjected to high-friction force treatment, thereby improving the operational accuracy of the end effector 200.

[0134] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the spirit of the present invention are also included. Furthermore, the components shown in the above-described embodiment and the following modifications can be combined as appropriate.

[0135] (Variation 1) In the above embodiment, the parallel link mechanism 100 comprises two arms 110 (a first arm 110a and a second arm 110b), but the configuration of the parallel link mechanism is not limited thereto. The parallel link mechanism may be configured to control the position and orientation of the end effector by one arm, or it may be configured to control the position and orientation of the end effector by three or more arms.

[0136] Even if the parallel link mechanism has one or three or more arms, by applying a high-friction force treatment to at least one of the guide portion 42s that supports the slide member 30 and the holding portion 44 that holds the position of the guide portion 42 relative to the motor 11 in the actuator 1 of the arms, lead errors of the actuator 1 can be suppressed and the operational accuracy of the parallel link mechanism in the actuator system can be improved.

[0137] (Modification 2) In the above embodiment, the actuator 1 rotatably supports the rotor 11b with a first bearing 14, a second bearing 15, and a third bearing 16, but the configuration of the actuator is not limited thereto.

[0138] The actuator only needs to be able to rotatably support the rotor, and may be configured to rotatably support the rotor by a mechanism other than bearings (first bearing 14, second bearing 15, and third bearing 16).

[0139] (Variation 3) In the above embodiment, the arm portion 110 is equipped with two actuators 1, but the configuration of the arm portion is not limited thereto. The number of actuators 1 equipped in the arm portion may be one or three or more.

[0140] If the arm portion is equipped with one actuator 1, for example, the link mechanism comprising the arm portion becomes a serial link mechanism. Even if the link mechanism driven by the actuator 1 is a serial link mechanism, the operational accuracy of the serial link mechanism (link mechanism) can be improved by suppressing the lead error of the actuator 1 through high-friction force processing. [Explanation of Symbols]

[0141] 1000 Actuator System 100 Parallel link mechanism (link mechanism) 110a First arm 110b Second arm 1 Actuator 11 Motor 12 Housing 13 nuts 20 Screw shaft 30 Sliding member 41 Fixing member 41a Threaded insert 42 Guide section 42s Holding part 44 Holding part SC screw component 200 End Effectors A-axis M rotation axis

Claims

1. It features a multi-degree-of-freedom link mechanism driven by multiple actuators, At least one of the plurality of actuators is Motor and, A sliding member moves back and forth in the axial direction from which the motor's rotation shaft extends, due to the rotational force of the motor, A guide portion that supports the slide member so that it can move back and forth in the axial direction, A holding part that holds the position of the guide part relative to the motor, It has, The guide portion has a portion to be held that contacts the holding portion, At least one of the holding portion and the held portion is subjected to a high-friction force treatment that increases the frictional force generated between the held portion and the held portion. Actuator system.

2. The aforementioned high-friction treatment is a blast treatment. The actuator system according to claim 1.

3. The aforementioned high-friction treatment is a coating treatment using a high-friction coating agent. The actuator system according to claim 1.

4. The aforementioned high-friction treatment is a textured finish. The actuator system according to claim 1.

5. The aforementioned high-friction treatment is a diamond coating using diamond particles. The actuator system according to claim 1.

6. The actuator is A nut that rotates around the rotating shaft by the rotational force of the motor, The screw shaft moves back and forth in the axial direction in conjunction with the rotational movement of the nut and is connected to the slide member, A housing for the motor, A fixing member, which includes the aforementioned holding portion and is fixed to the housing, A pair of guide portions are arranged facing each other with the slide member in between, It has, The guide portion and the fixing member are fastened together by a screw member that engages with a screw insert provided on the fixing member. The actuator system according to any one of claims 1 to 5.

7. The link mechanism is connected to an end effector which includes a work point for performing a predetermined operation, The link mechanism includes a first arm and a second arm, each having two actuators, The first arm is capable of moving and tilting the second arm connected to the first arm by driving the actuator. The second arm is capable of moving and tilting the end effector connected to the second arm by driving the actuator. The actuator system according to any one of claims 1 to 5.

8. The end effector includes instruments for ophthalmic surgery. The actuator system according to claim 7.

9. Motor and, A sliding member moves back and forth in the axial direction from which the motor's rotation shaft extends, due to the rotational force of the motor, A guide portion that supports the slide member so that it can move back and forth in the axial direction, A holding part that holds the position of the guide part relative to the motor, Equipped with, The guide portion has a portion to be held that contacts the holding portion, At least one of the holding portion and the held portion is subjected to a high-friction force treatment that increases the frictional force generated between the held portion and the held portion. Actuator.

10. The aforementioned high-friction treatment is a blast treatment. The actuator according to claim 9.

11. The aforementioned high-friction treatment is a coating treatment using a high-friction coating agent. The actuator according to claim 9.

12. The aforementioned high-friction treatment is a textured finish. The actuator according to claim 9.

13. The aforementioned high-friction treatment is a diamond coating using diamond particles. The actuator according to claim 9.

14. A nut that rotates around the rotating shaft by the rotational force of the motor, The screw shaft moves back and forth in the axial direction in conjunction with the rotational movement of the nut and is connected to the slide member, A housing for the motor, A fixing member, which includes the aforementioned holding portion and is fixed to the housing, A pair of guide portions are arranged facing each other with the slide member in between, Equipped with, The guide portion and the fixing member are fastened together by a screw member that engages with a screw insert provided on the fixing member. The actuator according to any one of claims 9 to 13.

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