Sensing apparatus for detecting multi-turn and robot arm having the same

Abstract

The present invention discloses a multi-turn sensing device configured to measure the amount of rotational displacement of a rotating body using a resistance value corresponding to the displacement of the rotating body. The multi-turn sensing device comprises: a base formed to be rotatable around a single axis; a rotating disk having a spiral groove formed on one surface of the base extending spirally with respect to the single axis; a slide potentiometer having a slider fixedly installed on one surface of the base and disposed to cover a portion of the spiral groove, inserted into the spiral groove, and configured to be linearly movable in the radial direction of the base when the rotating disk rotates; and a control unit configured to measure the amount of rotational displacement of the rotating disk based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer.

Description

Technology Field

[0001] The present invention relates to a multi-turn sensing device for sensing the multi-turn of a rotating body and a robot arm equipped with the same, and more specifically, to a multi-turn sensing device configured to measure the amount of rotational displacement of a rotating body using a resistance value corresponding to the displacement of the rotating body and a robot arm equipped with the same. Background Technology

[0002] An encoder is a device that holds position and velocity information of an object undergoing rotational or linear motion, counts the movement, or outputs it as an electrical signal that can be read by a control device such as a PLC.

[0003] Encoders can be classified into rotary encoders and linear encoders depending on the motion method of an object. A rotary encoder is a device that provides feedback on the position of a rotating object, while a linear encoder is a device that provides feedback on the position of an object undergoing linear motion.

[0004] A rotary encoder generally consists of circular scales and a head that reads the intervals between the scales. The head reads pulse signals at each interval between the scales and converts the analog signals into digital electrical pulse signals. It is used to measure the position, speed, and rotation angle of a rotating object, or to measure the rotational speed and amount of rotation of a rotating motor. It is typically used in a form where the scale is mounted on a moving object and the head is fixed.

[0005] However, conventional rotary encoders can generally sense one rotation of a rotating object within a range of 0 to 360 degrees, and require high manufacturing costs and high assembly precision. The problem to be solved

[0006] One objective of the present invention is to provide a multi-turn sensing device capable of multi-turn sensing of a rotating object and having a more concise structure, and a robot arm equipped with the same. means of solving the problem

[0007] To achieve the objective of the present invention, a multi-turn sensing device according to one embodiment of the present invention comprises: a base formed to be rotatable about an axis; a rotating disk having a spiral groove formed on one surface of the base extending spirally with respect to the axis; a slide potentiometer having a slider fixedly installed on one surface of the base and disposed to cover a portion of the spiral groove, and inserted into the spiral groove and formed to be linearly movable in the radial direction of the base when the rotating disk rotates; and a control unit configured to measure the amount of rotational displacement of the rotating disk based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer.

[0008] According to one example related to the present invention, the spiral groove is formed to gradually move away from the axis from one end to the other, and a part of the spiral groove may be located on the inner side of the other end in the radial direction of the base.

[0009] According to one example related to the present invention, when the slider is positioned at one end, the slide potentiometer exhibits minimum resistance, and when the slider is positioned at the other end, the slide potentiometer may exhibit maximum resistance.

[0010] According to one example related to the present invention, when the slider is positioned at the one end and the other end, the slider can function as a stopper that limits the rotation of the rotating disk.

[0011] According to one example related to the present invention, the control unit may be configured to calculate the rotational displacement amount by correcting the resistance value corresponding to the position of the slider obtained from the slide potentiometer using linear interpolation.

[0012] According to one example related to the present invention, a resistor is formed on one surface of the base in an arc shape extending around the axis, and a variable contact terminal is fixedly installed on one surface of the base such that the contact position with respect to the resistor changes when the rotating disk rotates, and the control unit may be configured to correct the amount of rotational displacement based on a resistance value corresponding to the position of the variable contact terminal on the resistor.

[0013] According to one example related to the present invention, the spiral groove may be arranged to surround the resistor.

[0014] According to one example related to the present invention, the control unit may be configured to sense the number of turns of the rotating disk based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer, and to sense the single-turn reference rotation angle of the rotating disk based on a resistance value corresponding to the position of the variable contact end on the resistor.

[0015] A multi-turn sensing device according to another embodiment of the present invention comprises: a rotating shaft formed to be rotatable around an axis and having a spiral groove extending spirally on its outer surface; a slide potentiometer having a slider fixedly installed on one side of the rotating shaft and positioned to cover a portion of the spiral groove, and inserted into the spiral groove and formed to be linearly movable in the axial direction of the rotating shaft when the rotating shaft rotates; and a control unit configured to measure the amount of rotational displacement of the rotating shaft based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer.

[0016] According to one example related to the present invention, the spiral groove is formed to extend upward along the outer circumference of the rotation axis from one end to the other, and a part of the spiral groove may be located below the other end in the axial direction of the rotation axis.

[0017] According to one example related to the present invention, when the slider is positioned at one end, the slide potentiometer exhibits minimum resistance, and when the slider is positioned at the other end, the slide potentiometer may exhibit maximum resistance.

[0018] According to one example related to the present invention, the control unit may be configured to calculate the rotational displacement amount by correcting the resistance value corresponding to the position of the slider obtained from the slide potentiometer using linear interpolation.

[0019] According to one example related to the present invention, a resistor is formed extending in an arc shape around the upper or lower surface of the rotational shaft, and a variable contact terminal is fixedly installed on the upper or lower surface of the rotational shaft such that the contact position with respect to the resistor changes when the rotational shaft rotates, and the control unit may be configured to correct the amount of rotational displacement based on a resistance value corresponding to the position of the variable contact terminal on the resistor.

[0020] According to one example related to the present invention, the control unit may be configured to sense the number of turns of the rotation axis based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer, and to sense the single-turn reference rotation angle of the rotation axis based on a resistance value corresponding to the position of the variable contact end on the resistor.

[0021] A robot arm according to another embodiment of the present invention comprises: a first joint portion; a second joint portion rotatably connected to the first joint portion; a joint rotatably connecting the first joint portion and the second joint portion; and a multi-turn sensing device provided in the joint to sense a rotational displacement amount of the second joint portion relative to the first joint portion, and according to any one of claims 1 to 14. Effects of the invention

[0022] The effects of the present invention obtained through the above-described solution are as follows.

[0023] The multi-turn sensing device of the present invention comprises a rotating disk having a rotating base and a spiral groove extending spirally on one surface of the base, a slide potentiometer having a slider fixedly installed on one surface of the base and inserted into the spiral groove to be linearly movable in the radial direction of the base, and a control unit that measures the amount of rotational displacement of the rotating disk based on a resistance value corresponding to the position of the slider.

[0024] According to the configuration of such a multi-turn sensing device, a slider that moves linearly in the radial direction of the base is provided on the slide potentiometer, and the slider is configured to be guided on a spiral groove of the base mounted on the rotating body. Accordingly, a sensing device capable of multi-turn sensing of the rotating body can be provided, which has a simpler structure than conventional ones and converts the rotational motion of the rotating body into linear motion according to the spacing of the spiral groove and the linear movement distance of the slider of the slide potentiometer. Brief explanation of the drawing

[0025] FIG. 1 is a conceptual diagram of a robot arm equipped with a multi-turn sensing device according to one embodiment of the present invention. FIG. 2 is a conceptual diagram of a multi-turn sensing device according to one embodiment of the present invention. FIG. 3 is a drawing showing the rotating disk and slide potentiometer of the multi-turn sensing device shown in FIG. 2, respectively. FIG. 4 is a conceptual diagram showing an example of how the lever of a slide potentiometer operates as the base of the multi-turn sensing device illustrated in FIG. 2 is rotated. FIG. 5 is a conceptual diagram showing the path in which a spiral groove is formed on the upper or lower surface of the base shown in FIG. 2. FIG. 6 is a conceptual diagram of a multi-turn sensing device according to another embodiment of the present invention. FIG. 7 is a conceptual diagram showing an example of how the slider of a slide potentiometer operates as the rotation axis of the multi-turn sensing device illustrated in FIG. 6 is rotated. FIG. 8 is a conceptual diagram of a multi-turn sensing device according to another embodiment of the present invention. FIG. 9 is a diagram showing graphs to explain errors that may occur due to assembly tolerances or nonlinearity of the slide potentiometer equipped in the multi-turn sensing device of the present invention. Figure 10 is a graph showing a method for correcting errors related to the slide potentiometer illustrated in Figure 9. Specific details for implementing the invention

[0026] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components are assigned the same reference number regardless of the drawing symbols, and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably solely for the ease of drafting the specification and do not have distinct meanings or roles in themselves. Furthermore, in describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art could obscure the essence of the embodiments disclosed in this specification, such detailed description will be omitted. Additionally, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification; the technical concept disclosed in this specification is not limited by the attached drawings, and it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the invention.

[0027] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0028] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0029] A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0030] In this application, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0031] FIG. 1 is a conceptual diagram of a robot arm (10) equipped with a multi-turn sensing device (100) according to one embodiment of the present invention.

[0032] Referring to FIG. 1, the robot arm (10) includes a first joint part (11), a second joint part (12), joints (15a, 15b, 15c) and a multi-turn sensing device (100). For reference, FIG. 1 is a planar view of a multi-jointed robot arm (10).

[0033] The first joint part (11) is connected to the second joint part (12) described later to form a joint of the robot arm (10).

[0034] The second joint part (12) is rotatably connected to the first joint part (11). The robot arm (10) may be provided with a plurality of joint parts. For example, as shown in FIG. 1, a third joint part (13) may be further provided to be rotatably connected to the second joint part (12). That is, the first joint part (11) may be connected to one end of the second joint part (12), and the third joint part (13) may be connected to the other end of the second joint part (12).

[0035] In addition, the robot arm (10) may have a second joint (12) connected to one end of the first joint (11), and a fourth joint (14) rotatably connected to the other end of the first joint (11). The fourth joint (14) may be configured as an end effector. For example, the fourth joint (14) may be configured to perform tasks such as picking up or moving an object.

[0036] The joint (15a) is configured to rotatably connect the first joint portion (11) and the second joint portion (12). The joints (15a, 15b, 15c) may each be formed at the portions where the first to fourth joint portions (14) are interconnected.

[0037] A multi-turn sensing device (100) is provided in the joint (15a) to sense the amount of rotational displacement of the second joint part (12) relative to the first joint part (11). The multi-turn sensing device (100) may be configured in the same or different ways or forms for each of the plurality of joints (15a, 15b, 15c).

[0038] The amount of rotational displacement of the second joint part (12) relative to the first joint part (11) can occur in a multi-turn, that is, more than one rotation and more than 360 degrees. Accordingly, the multi-turn sensing device (100) requires a mechanism for measuring the amount of rotational displacement for more than one rotation and more than 360 degrees of rotation occurring in a rotating body such as joints (15a, 15b, 15c).

[0039] The multi-turn sensing device (100) will be described in more detail below with reference to FIGS. 2 to 5.

[0040] FIG. 2 is a conceptual diagram of a multi-turn sensing device (100) according to an embodiment of the present invention. FIG. 3 is a diagram showing the rotating disk (110) and the slide potentiometer (120) of the multi-turn sensing device (100) shown in FIG. 2, respectively. FIG. 4 is a conceptual diagram showing an example of the lever of the slide potentiometer (120) operating as the base (111) of the multi-turn sensing device (100) shown in FIG. 2 rotates. FIG. 5 is a conceptual diagram showing the path in which a spiral groove (112) is formed on the upper or lower surface of the base (111) shown in FIG. 2.

[0041] Referring to FIGS. 2 to 5, the multi-turn sensing device (100) includes a rotating disk (110), a slide potentiometer (120), and a control unit.

[0042] The rotating disk (110) can be formed in the shape of a disk. The rotating disk (110) may have a base (111) and a spiral groove (112).

[0043] The base (111) is formed in the shape of a disc to form the exterior of the rotating disc (110). The base (111) may be mounted on a rotating body and configured to rotate together with the rotating body. The rotating body may be, for example, a joint (15a, 15b, 15c) of the robot arm (10) described with reference to FIG. 1. The base (111) may be formed in the shape of a ring with an opening formed in the center, as shown in FIG. 2. A part of the rotating body on which the rotating disc (110) is mounted may be inserted into the opening.

[0044] The spiral groove (112) may be formed on one side of the base (111) and extended spirally with respect to the one axis (A1). The spiral groove (112) may be recessed on one side of the base (111) to form a groove structure.

[0045] A slide potentiometer (120) may be fixedly installed on one side of a base (111) and positioned to cover a portion of a spiral groove (112). The slide potentiometer (120) is provided with a slider (121). The slider (121) may be formed to be inserted into the spiral groove (112) and capable of linear movement in the radial direction (D1) of the base (111) when the rotating disk (110) rotates. The slider (121) may be formed to protrude from the main body (120a) of the slide potentiometer (120) so as to be inserted into the spiral groove (112). The slider (121) may be formed to be inserted into the spiral groove (112) and directly connected to the spiral groove (112). The main body (120a) of the slider potentiometer (120) may be provided with a guide hole (120a1) that extends in one direction to guide the linear movement of the slider (121).

[0046] The slide potentiometer (120) may be provided with a fixed plate (120b) that is fixedly installed on a base (111) and on which the main body of the slide potentiometer (120) is mounted on one side. The fixed plate (120b) may be provided with a through hole (120b1) through which a bolt or the like is fastened to fix the fixed plate (120b) to the base (111).

[0047] The two ends of the spiral groove (112) can be formed to correspond to one end of the path where the slider (121) moves on the main body of the slide potentiometer (120) and the other end, respectively. That is, one end (112a) of the spiral groove (112) is extended to correspond to the position of one end of the path where the slider (121) moves, and the other end of the spiral groove (112) is extended to correspond to the position of the other end of the path where the slider (121) moves.

[0048] The control unit may be configured to measure the amount of rotational displacement of the rotating disk (110) based on the resistance value corresponding to the position of the slider (121) obtained from the slide potentiometer (120). The slide potentiometer (120) may be configured to generate an output voltage directly proportional to the input displacement by utilizing the change in the resistance value through voltage division.

[0049] Meanwhile, referring to FIG. 5, the sensing sensitivity (mm / deg) through the slide potentiometer (120) can be defined as the value obtained by dividing the spacing of the spiral groove (112), i.e., the pitch (P), by 360 degrees. That is, the sensing sensitivity of the multi-turn sensing device (100) can be adjusted by adjusting the size of the pitch (P) of the spiral groove (112).

[0050] In addition, the sensing range (deg) of the multi-turn sensing device (100) can be defined as the number of rotations of the screw thread of the spiral groove (112) multiplied by 360 degrees. That is, when the number of rotations of the screw thread of the spiral groove (112) is 2, the sensing range (deg) of the multi-turn sensing device (100) can be set to 720 degrees.

[0051] An example of the operation of the above-mentioned multi-turn sensing device (100) will be explained below with reference to FIG. 4.

[0052] FIG. 4(a) shows the state before the rotating disk (110) performs a rotational movement, FIG. 4(b) shows the state after the rotating disk (110) has rotated once clockwise, and FIG. 4(c) shows the state after the rotating disk (110) has rotated twice by adding one more clockwise rotation.

[0053] As shown in FIG. 4(a), the slider (121) of the slide potentiometer (120) can be positioned at one end (112a) of the spiral groove (112). Then, as shown in FIG. 4(b), when the rotating disk (110) rotates to complete one full rotation, the slider (121) of the slide potentiometer (120) moves linearly in the radial direction (D1) of the base (111) to a position approximately in the middle of the spiral groove (112). At this time, the control unit can be configured to measure the amount of rotational displacement of the rotating disk (110) based on the resistance value corresponding to the position of the slider (121).

[0054] Next, as illustrated in FIG. 4 (c), when the rotating disk (110) rotates one more time clockwise, the slider (121), which was located in the middle of the spiral groove (112), moves further upward relative to the drawing and can be positioned at the other end (112b) of the spiral groove (112). At this time, the control unit may be configured to measure the amount of rotational displacement of the rotating disk (110) using a resistance value corresponding to the position of the slider (121) at the other end (112b) of the spiral groove (112).

[0055] For reference, FIG. 4 illustrates an example of a case where the rotating disk (110) rotates clockwise. When the rotating disk (110) rotates counterclockwise again in (c) of FIG. 4, the slider (121) of the slide potentiometer (120) can be guided along the spiral groove (112) and moved linearly downward relative to the drawing.

[0056] Meanwhile, the spiral groove (112) may be formed to gradually move away from the above-mentioned axis (A1) as it moves from one end (112a) to the other end (112b). Also, a part of the spiral groove (112) may be located on the inner side of the other end of the spiral groove (112) in the radial direction (D1) of the base (111). For reference, the drawings of the present invention show the spiral groove (112) extended two turns from one end (112a) to the other end (112b).

[0057] Here, the fact that a part of the spiral groove (112) is located on the inner side of the other end (112b) of the spiral groove (112) may mean that a part of the spiral groove (112) is located on a line perpendicular to the radial direction (D1) of the other end (112b) from the other end. That is, the spiral groove (112) can be formed so that at least one point passes on a straight line perpendicular to the radial direction (D1) of the other end of the spiral groove (112).

[0058] In other words, the spiral groove (112) is extended at least once from one end (112a) to the other end (112b) around the axis (A1), and the slider (121) can be formed to be movable between the one end (112a) and the other end (112b).

[0059] Additionally, the slide potentiometer (120) may be configured to indicate minimum resistance when the slider (121) is positioned at the first end (112a), and to indicate maximum resistance when the slider (121) is positioned at the other end (112b). In this way, the slide potentiometer (120) can obtain and provide a resistance value corresponding to the current position of the slider (121) between the minimum resistance and the maximum resistance.

[0060] Additionally, when the slider (121) is positioned at the first end (112a) and the other end (112b), the slider (121) can function as a stopper that limits the rotation of the rotating disk (110). That is, the rotation range of the rotating disk (110) can be limited to the range in which the slider (121) can move. Accordingly, the rotation range of the rotating disk (110) can be set by adjusting the linearly movable distance of the slider (121).

[0061] A multi-turn sensing device (200) according to another embodiment of the present invention will be described in more detail below with reference to FIGS. 6 and 7.

[0062] FIG. 6 is a conceptual diagram of a multi-turn sensing device (200) according to another embodiment of the present invention. FIG. 7 is a conceptual diagram showing an example in which a slider (221) of a slide potentiometer (220) operates as the rotation axis (210) of the multi-turn sensing device (200) shown in FIG. 6 is rotated.

[0063] Referring to FIGS. 6 and 7, the multi-turn sensing device (200) includes a rotation axis (210), a slide potentiometer (220), and a control unit (not shown).

[0064] The rotation axis (210) is formed to be rotatable around an axis (A2) and may be provided with a spiral groove (211) that extends spirally on the outer surface.

[0065] The slide potentiometer (220) may be fixedly installed on one side of the rotation axis (210) and positioned to cover a part of the spiral groove (211). The slide potentiometer (220) may be provided with a slider (221) that is inserted into the spiral groove (211) and formed to be linearly movable in the axial direction (D2) of the rotation axis (210) when the rotation axis (210) rotates.

[0066] The control unit may be configured to measure the amount of rotational displacement of the rotation axis (210) based on the resistance value corresponding to the position of the slider (221) obtained from the slide potentiometer (220).

[0067] Meanwhile, the spiral groove (211) is formed to extend upward along the outer circumference of the rotation axis (210) from one end (211a) to the other end (211b), and a part of the spiral groove (211) may be located below the other end (211b) in the axial direction (D2) of the rotation axis (210).

[0068] Additionally, when the slider (221) is positioned at the first end (211a), the slide potentiometer (220) may indicate minimum resistance, and when the slider (221) is positioned at the other end (211b), the slide potentiometer (220) may indicate maximum resistance. Accordingly, the slide potentiometer (220) can obtain and provide a resistance value corresponding to the position of the slider (221) between the minimum resistance and the maximum resistance.

[0069] An example of the operation of the above-mentioned multi-turn sensing device (200) will be explained below with reference to FIG. 7.

[0070] FIG. 7 (a) shows the state before the rotation axis (210) performs a rotation operation, FIG. 7 (b) shows the state after the rotation axis (210) has rotated one full clockwise rotation, and FIG. 4 (c) shows the state after the rotation axis (210) has rotated two full clockwise rotations by adding one more clockwise rotation.

[0071] As shown in FIG. 7(a), the slider (221) of the slide potentiometer (220) can be positioned at the lower end (211a) of the spiral groove (211). Then, as shown in FIG. 7(b), when the rotation axis (210) rotates to complete one full rotation, the slider (221) of the slide potentiometer (220) moves linearly in the axial direction (D2) of the rotation axis (210) and moves upward to a position approximately in the middle of the spiral groove (211). The control unit can be configured to measure the amount of rotational displacement of the rotation axis (210) based on the resistance value corresponding to the position of the slider (221).

[0072] Next, as illustrated in Fig. 7 (c), when the rotation axis (210) rotates one more time clockwise from the state of Fig. 7 (b), the slider (221), which was located in the middle of the spiral groove (211), can move further upward relative to the drawing and be positioned at the upper end (211b) of the spiral groove (211). At this time, the control unit may be configured to measure the amount of rotational displacement of the rotation axis (210) using a resistance value corresponding to the position of the slider (221) at the end of the spiral groove (211).

[0073] For reference, FIG. 7 illustrates an example of a case where the rotation axis (210) rotates clockwise. When the rotation axis (210) rotates counterclockwise again in (c) of FIG. 7, the slider (221) of the slide potentiometer (220) can be guided along the spiral groove (211) and configured to move linearly downward from the rotation axis (210) relative to the drawing.

[0074] Additionally, the resistor may be formed on the upper or lower surface of the rotation shaft (210) in an arc shape extending around the axis (A2). Furthermore, a variable contact terminal may be fixedly installed on the upper or lower surface of the rotation shaft (210), wherein the contact position with respect to the resistor changes when the rotation shaft (210) rotates.

[0075] Here, the control unit may be configured to correct the amount of rotational displacement of the rotation axis (210) based on the resistance value corresponding to the position of the variable contact terminal on the resistor.

[0076] Additionally, the control unit can sense the number of turns of the rotation axis (210) based on the resistance value corresponding to the position of the slider (221) obtained from the slide potentiometer (220). Furthermore, the control unit can be configured to sense the single-turn reference rotation angle of the rotation axis (210) based on the resistance value corresponding to the position of the variable contact end on the resistor.

[0077] The resistor and the variable contact terminal provided in the multi-turn sensing device (200) will be described later with reference to FIG. 8.

[0078] A multi-turn sensing device (100) according to another embodiment of the present invention will be described below with reference to FIG. 8.

[0079] FIG. 8 is a conceptual diagram of a multi-turn sensing device (100) according to another embodiment of the present invention.

[0080] Referring to FIG. 8, a resistor (131) may be formed extending in an arc shape around the axis (A1) on one side of the base (111) of the rotating disk (110). A central axis (134) may be provided at the center of the resistor (131) to which a variable contact terminal (132) and a third terminal (133c), which will be described later, are connected. A gap (135) may be formed on one side of the resistor (131). A first terminal (133a) may be connected to one end of the resistor (131) adjacent to the gap (135), a second terminal (133b) may be connected to the other end of the resistor (131), and a third terminal (133c) may be disposed between the first and second terminals (133a, 133b). The third terminal (133c) can be extended to the central axis (134) and electrically connected to the variable contact terminal (132) described later. The first terminal (133a) can be connected to the power supply (V), and the second terminal (133b) can be connected to the ground (GND). Additionally, when the rotating disk (110) rotates, the first to third terminals (133a, 133b, 133c) can be configured to rotate clockwise or counterclockwise together with the resistor (131). In contrast, the variable contact terminal (132) described later is positioned in a fixed state even when the rotating disk (110) rotates, so that its relative position to the resistor (131) changes.

[0081] Additionally, a variable contact terminal (132) may be fixedly installed on one side of the base (111), wherein the contact position with respect to the resistor (131) changes during rotation of the rotating disk (110). The variable contact terminal (132) may be connected to a central axis (134) and electrically connected to a third terminal (133c). Here, the control unit may be configured to correct the amount of rotational displacement based on a resistance value corresponding to the position of the variable contact terminal (132) on the resistor (131).

[0082] Meanwhile, similarly, the multi-turn sensing device (200) described above with reference to FIGS. 6 and 7 has a resistor formed extending in an arc shape around a single axis (A2) on the upper or lower surface of the rotation axis (210), and a variable contact terminal, which changes the contact position with respect to the resistor when the rotation axis (210) rotates, may be fixedly installed on the upper or lower surface of the rotation axis (210). The control unit may be configured to correct the amount of rotational displacement based on a resistance value corresponding to the position of the variable contact terminal on the resistor. Here, the resistor and the variable contact terminal have the same or similar features in terms of structure and function as the resistor (131), variable contact terminal (132), and first to third terminals (133a, 133b, 133c) described with reference to FIG. 8, except that the position where they are placed is the upper or lower surface of the rotation axis. Therefore, the description related thereto will be replaced by the description with reference to FIG. 8.

[0083] Additionally, the spiral groove (112) can be positioned to surround the resistor (131). As such, by being positioned outside the resistor (131) on the upper or lower surface of the base (111), the spiral groove (112) can secure a wider area for placement. Accordingly, a wider range of the settable range for the screw pitch (P), which is related to the number of rotations of the spiral groove (112) and sensing precision, can be provided.

[0084] In addition, the control unit can sense the number of turns of the rotating disk (110) based on the resistance value corresponding to the position of the slider (121) obtained from the slide potentiometer (120). Furthermore, the control unit can be configured to sense the single-turn reference rotation angle of the rotating disk (110) based on the resistance value corresponding to the position of the variable contact terminal (132) on the resistor (131).

[0085] Hereinafter, a method for correcting errors related to the slide potentiometers (120, 220) will be explained with reference to FIG. 9 and FIG. 10.

[0086] FIG. 9 is a graph showing an error that may occur due to assembly tolerance or non-linearity of a slide potentiometer (120, 220) provided in the multi-turn sensing device (100, 200) of the present invention. FIG. 10 is a graph showing a method for correcting an error related to the slide potentiometer (120, 220) illustrated in FIG. 9.

[0087] First, as illustrated in FIG. 9 (a), an error may occur in the measured resistance value due to the assembly tolerance of the slide potentiometer (120, 220), as shown by the respective dotted lines above and below the solid line of the graph. Consequently, a difference may occur between the sensed resistance value and the actual position value of the rotating disk (110) or the rotation axis (210). Next, as illustrated in FIG. 9 (b), a non-linear difference may occur between the resistance value and the angle value due to the non-linearity of the slide potentiometer (120, 220) itself.

[0088] Referring to FIG. 10, the control unit of the multi-turn sensing device (100, 200) of the present invention may be configured to calculate the rotational displacement amount by correcting the resistance value corresponding to the position of the slider (121, 221) obtained from the slide potentiometer (120, 220) using linear interpolation. For example, the rotation disk (110) or the rotation axis (210) may be rotated at a certain angle, and the resistance value may be recorded for each designated unit angle to correct the detailed position through the linear interpolation. The linear interpolation refers to a method of calculating linearly based on straight-line distance to estimate the value located between points when the value of the endpoint is given.

[0089] Here, the amount of rotational displacement calculated by the control unit may be the rotation angle of the rotating disk (110) or the rotation axis (210) connected to the rotating body that is the target of multi-turn sensing.

[0090] Meanwhile, the above detailed description should not be interpreted restrictively in all respects but should be considered exemplary. The scope of the invention shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the invention are included within the scope of the invention. Explanation of the symbols

[0091] 10: Robotic Arm 11: First joint 12: Second joint 13: Third joint 14: 4th joint 15a, 15b, 15c: Joint 100 : Multi-turn sensing device 110: Rotating disk 111 : Bass 112 : Spiral groove 112a: One end of the spiral groove 112b: The end of the spiral groove 120 : Slide potentiometer 120b1 : Through hole 121 : Slider 131 : Resistor 132 : Variable contact terminal 133a : First terminal 133b : Second terminal 133c : Third terminal 134 : Central axis 135 : Gap 200: Multi-turn sensing device 210 : Rotation axis 211 : Spiral Home 211a: One end of the spiral groove 211b: The end of the spiral groove 220 : Slide potentiometer 221 : Slider D1: Radial direction D2: Axial direction

Claims

Claim 1 A multi-turn sensing device comprising: a base formed to be rotatable around an axis, and a rotating disk having a spiral groove formed to extend spirally with respect to the axis on one surface of the base; a slide potentiometer having a slider fixedly installed on one surface of the base and arranged to cover a part of the spiral groove, inserted into the spiral groove, and formed to be linearly movable in the radial direction of the base when the rotating disk rotates; and a control unit configured to measure the amount of rotational displacement of the rotating disk based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer. Claim 2 A multi-turn sensing device according to claim 1, wherein the spiral groove is formed to gradually move away from the axis as it goes from one end to the other, and a part of the spiral groove is located on the inner side of the other end in the radial direction of the base. Claim 3 A multi-turn sensing device according to paragraph 2, characterized in that when the slider is positioned at one end, the slide potentiometer exhibits minimum resistance, and when the slider is positioned at the other end, the slide potentiometer exhibits maximum resistance. Claim 4 A multi-turn sensing device according to paragraph 2, characterized in that, when the slider is positioned at the first end and the other end, the slider functions as a stopper that limits the rotation of the rotating disk. Claim 5 A multi-turn sensing device according to claim 1, characterized in that the control unit calculates the rotational displacement amount by correcting the resistance value corresponding to the position of the slider obtained from the slide potentiometer using linear interpolation. Claim 6 A multi-turn sensing device according to claim 1, wherein a resistor is formed extending in an arc shape around an axis on one surface of the base, a variable contact terminal is fixedly installed on one surface of the base such that the contact position with respect to the resistor changes when the rotating disk rotates, and the control unit is configured to correct the amount of rotational displacement based on a resistance value corresponding to the position of the variable contact terminal on the resistor. Claim 7 A multi-turn sensing device according to claim 6, characterized in that the spiral groove is arranged to surround the resistor. Claim 8 A multi-turn sensing device according to claim 6, wherein the control unit is configured to sense the number of turns of the rotating disk based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer, and to sense the single-turn reference rotation angle of the rotating disk based on a resistance value corresponding to the position of the variable contact end on the resistor. Claim 9 A multi-turn sensing device comprising: a rotating shaft formed to be rotatable around a single axis and having a spiral groove extending spirally on its outer surface; a slide potentiometer having a slider fixedly installed on one side of the rotating shaft and positioned to cover a portion of the spiral groove, inserted into the spiral groove, and formed to be linearly movable in the axial direction of the rotating shaft when the rotating shaft rotates; and a control unit configured to measure the amount of rotational displacement of the rotating shaft based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer. Claim 10 A multi-turn sensing device according to claim 9, wherein the spiral groove is formed to extend upward along the outer circumference of the rotation axis from one end to the other, and a part of the spiral groove is located below the other end in the axial direction of the rotation axis. Claim 11 A multi-turn sensing device according to claim 10, characterized in that when the slider is positioned at one end, the slide potentiometer exhibits minimum resistance, and when the slider is positioned at the other end, the slide potentiometer exhibits maximum resistance. Claim 12 A multi-turn sensing device according to claim 9, characterized in that the control unit calculates the rotational displacement amount by correcting the resistance value corresponding to the position of the slider obtained from the slide potentiometer using linear interpolation. Claim 13 A multi-turn sensing device according to claim 9, wherein a resistor is formed extending in an arc shape around the axis on the upper or lower surface of the rotation axis, a variable contact terminal is fixedly installed on the upper or lower surface of the rotation axis such that the contact position with respect to the resistor changes when the rotation axis rotates, and the control unit is configured to correct the amount of rotational displacement based on a resistance value corresponding to the position of the variable contact terminal on the resistor. Claim 14 A multi-turn sensing device according to claim 13, wherein the control unit is configured to sense the number of turns of the rotation axis based on a resistance value corresponding to the position of the slider obtained from the slide potentiometer, and to sense the single-turn reference rotation angle of the rotation axis based on a resistance value corresponding to the position of the variable contact end on the resistor. Claim 15 A robot arm comprising: a first joint portion; a second joint portion rotatably connected to the first joint portion; a joint rotatably connecting the first joint portion and the second joint portion; and a multi-turn sensing device provided in the joint to sense the rotational displacement amount of the second joint portion relative to the first joint portion, and according to any one of claims 1 to 14.

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