JP2017120243A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor equipped with a transmission member that tolerates appropriate elastic deformation while maintaining appropriate rigidity.SOLUTION: Provided is a torque sensor comprising: a first rotor; a second rotor; a transmission member capable of elastic deformation and transmitting the rotation of the first rotor to the rotation of the second rotor; and an angle sensor for detecting a difference in rotation angle between the first rotor and the second rotor arising from the elastic deformation of the transmission member. The transmission member has a plurality of elastic bars, with the transmission of rotation from the first rotor to the second rotor being achieved via the plurality of elastic bars.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a torque sensor suitable for application to, for example, a robot arm, a joint module including the torque sensor, a robot system including the joint module, and the like.

  Conventionally, various methods exist for the torque detection principle of the torque sensor. For example, Patent Document 1 discloses a torque sensor that uses a driving rotating body, a driven rotating body, and an annular deformation body disposed between them as a basic configuration, and detects torque using the deformation of the annular deformation body. ing.

  In such a type of torque sensor in which a deformable body is interposed in the middle of the power transmission system, the torque detection accuracy greatly depends on the ease of deformation of the intervening deformable body. That is, if a material that easily deforms can be selected, a minute torque can be detected, but the upper limit value of the detectable torque is limited, and there is a possibility that a delay in power transmission and a satisfactory strength cannot be obtained. . On the other hand, if you select a material with high rigidity that is difficult to deform, you can obtain benefits such as higher upper limit of detectable torque and no control delay, but it is difficult to detect minute torque. There is a risk. The ease of deformation of this deformable body varies depending on the material, size, shape, etc. of the material, but it is generally difficult to adjust them to obtain appropriate torque detection accuracy.

Japanese Patent No. 4963134

  The objective of this invention is providing the torque sensor provided with the transmission member which accept | permits moderate elastic deformation, maintaining moderate rigidity.

  The above technical problem can be solved by a torque sensor, a joint module, a robot system, a robot arm assembly set, and a program having the following configuration.

  That is, the torque sensor according to the present invention is elastically deformable with the first rotating body, the second rotating body, and transmits the rotation of the first rotating body to the second rotating body. A transmission member; and an angle sensor configured to detect a rotation angle difference between the first rotating body and the second rotating body caused by elastic deformation of the transmitting member. The transmission member has a plurality of elastic rods, and transmission of rotation from the first rotating body to the second rotating body is performed via the plurality of elastic rods.

  According to such a configuration, it is possible to provide a torque sensor including a transmission member that allows moderate elastic deformation while maintaining appropriate rigidity by distributing the load to a plurality of elastic rods. .

  At this time, the plurality of elastic rods may be customizable.

  According to such a configuration, the number, material, shape, etc. of the elastic rods can be arbitrarily customized according to the range of the torque to be detected, so that a torque sensor having optimum characteristics can be easily provided.

  In a preferred embodiment of the present invention, the transmission member is coupled to the first rotating body at a first end along the rotation center axis of the transmission member, and the transmission member includes the plurality of elastic bars. A hollow body in which the body is arranged in an annular shape, encloses the first rotating body, rotates with the first rotating body as a center of rotation, and the transmission member rotates the transmission member. The second rotating body is coupled to the second rotating body at a second end along the central axis, and the second rotating body is hollow and includes the transmission member, and rotates with the transmission member and the rotation center as one. May be.

  According to such a configuration, the first rotating body, the transmission member, and the second rotating body are arranged so as to be included in each other while keeping the rotation center as one, so that the torque sensor can be accommodated in a limited space. it can.

  In a preferred embodiment of the present invention, a self-recoverable torque release mechanism that operates when a predetermined torque is exceeded may be interposed in a coupling portion between the first rotating body and the transmission member.

  According to such a configuration, even when an excessive torque is applied to the second rotating body side, the torque release mechanism works, so that the mechanism on the first rotating body side is not damaged. Further, since the torque release mechanism can self-return, it can be continuously operated even after slipping without performing a resetting operation or the like.

  In a preferred embodiment of the present invention, the torque sensor, a drive unit that rotationally drives the first rotating body of the torque sensor, and the first rotating body and the second based on the output of the angle sensor. There may be provided a drive system including a control unit including detection means for detecting the presence or absence of slip between the rotating body and the rotating body.

  According to such a configuration, since the design can be made in consideration of slippage due to overload, a more reliable system can be constructed. Here, the drive system may be realized as a single device, or may be realized as a system including a plurality of devices physically separated from each other. Therefore, for example, the torque sensor, the drive unit, and the control unit may all be disposed in a single device, or the torque sensor and the drive unit may be the same device (for example, a joint module, a robot system, etc. ), The control unit may be arranged in an external device (external PC or the like).

  In a preferred embodiment of the present invention, the torque sensor further includes an input side angle sensor for measuring a rotation angle of the first rotating body, and the control unit of the drive system is configured to output the angle sensor. A slip amount detecting means for detecting a slip amount between the first rotating body and the second rotating body, a correction amount calculating unit for calculating a predetermined correction amount based on the slip amount, and the correction And a reflection processing unit that reflects the amount on the output value of the input side angle sensor or the rotation command value to the driving unit.

  According to such a configuration, even in the case of continuous operation after the occurrence of slipping, control can be performed by correcting the slippage amount, so that highly accurate control can be performed.

  In a preferred embodiment of the present invention, the torque sensor, a drive unit that rotationally drives the first rotating body, a housing that houses the torque sensor and the drive unit and has an attachment unit for attaching an arm member; , A joint module may be provided.

  According to such a configuration, since the drive sources are concentrated in the housing, it is possible to provide a joint module that can easily construct a robot system.

  In a preferred embodiment of the present invention, a robot system including at least one of the joint modules and a control unit that controls the joint modules may be provided.

  According to such a configuration, the robot system can be easily constructed by using the joint module in which the drive sources are integrated.

  In a preferred embodiment of the present invention, the control unit of the robot system detects slippage between the first rotating body and the second rotating body based on the output of the angle sensor. Means may be further provided.

  According to such a configuration, since the design can be made in consideration of slippage due to overload, a more reliable system can be constructed.

  In a preferred embodiment of the present invention, the torque sensor further includes an input side angle sensor that measures a rotation angle of the first rotating body, and the control unit of the robot system is based on an output of the angle sensor. A slip amount detecting means for detecting a slip amount between the first rotating body and the second rotating body, a correction amount calculating section for calculating a predetermined correction amount based on the slip amount, and the correction amount And a reflection processing unit that performs a reflection process on the output value of the input side angle sensor or the rotation command value to the drive unit.

  According to such a configuration, even in the case of continuous operation after the occurrence of slipping, control can be performed by correcting the slippage amount, so that highly accurate control can be performed.

  In a preferred embodiment of the present invention, a robot arm assembly set including the joint module and an arm member may be provided.

  According to such a configuration, since the joint module and the arm member in which the driving sources are integrated are set, it is possible to provide a set for assembling a robot arm that can be easily assembled while having a high degree of design freedom.

  In a preferred embodiment of the present invention, there is provided a program for the robot system, wherein the computer detects the presence or absence of slippage between the first rotating body and the second rotating body based on the output of the angle sensor. A program for executing the slip detection step may be provided.

  According to such a configuration, since it is possible to design in consideration of slippage due to overload, more reliable control can be performed. It is possible to perform a predetermined process such as an emergency stop by detecting the presence or absence of the slip, and it is also possible to continuously operate while performing a correction process as described later.

  In a preferred embodiment of the present invention, there is provided a program for the robot system, wherein the torque sensor further includes an input side angle sensor for measuring a rotation angle of the first rotating body, and the angle sensor is included in a computer. A slip amount detecting step for detecting a slip amount between the first rotating body and the second rotating body on the basis of the output of the first rotation body; and a correction amount calculating step for calculating a predetermined correction amount based on the slip amount; A reflection processing step of reflecting the correction amount to the output value of the input side angle sensor or the rotation command value to the drive unit may be provided.

  According to such a configuration, even after a slip occurs, the control can be performed by correcting the slip amount, so that highly accurate control can be performed.

  ADVANTAGE OF THE INVENTION According to this invention, the torque sensor provided with the transmission member which accept | permits moderate elastic deformation, maintaining moderate rigidity can be provided.

FIG. 1 is an exploded perspective view showing the entire main components of the torque sensor. FIG. 2 is an explanatory diagram of a power transmission mode from the input stage to the output stage. FIG. 3 is a perspective view showing the appearance of the joint module. FIG. 4 is an overall cross-sectional view of the joint module. FIG. 5 is an external perspective view showing an assembled state of the torque sensor. FIG. 6 is an exploded perspective view showing the entire main components of the joint module. FIG. 7 is a partial cross-sectional view showing a configuration of an input stage of a torque sensor including a motor and a speed reducer. FIG. 8 is an explanatory view showing the rotation direction of the motor and the speed reducer as the center. FIG. 9 is a partial cross-sectional view illustrating a configuration of a torque sensor including a transmission member. FIG. 10 is an exploded perspective view of the frictional coupling mechanism. FIG. 11 is a cross-sectional view of a torque sensor including a frictional coupling mechanism. FIG. 12 is a partial cross-sectional view showing the configuration of the output stage of the torque sensor including the output flange. FIG. 13 is a flowchart illustrating slip correction processing. FIG. 14 is a perspective view showing the appearance of the robot arm.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. Torque sensor>
First, an embodiment of a torque sensor according to the present invention will be described with reference to FIGS.

<1.1 Configuration>
FIG. 1 is an exploded perspective view for explaining the entire main components of a torque sensor according to the present invention. The torque sensor 10 mainly includes an input shaft 11 (first rotating body), a transmission member 14 coupled to a tip portion of the input shaft 11 via a frictional coupling mechanism 13, and a coupling member 14 coupled to the transmission member 14. An output flange 12 (second rotating body) that rotates in a straight line, a code wheel 151 attached to the tip of the input shaft 11, and a code reading plate 152 provided on the output flange 12, and the input shaft and the output flange And a magnetic absolute encoder 15 (first angle sensor) for detecting a relative angle difference between the first and second sensors. The code wheel 151 is fixed to the input shaft 11 by a bolt 17 via a washer 18. In the present embodiment, the absolute encoder 15 for detecting the relative angular difference between the input shaft 11 and the output flange 12 is a single-turn 18-bit encoder, and its resolution is 262144 [P / R]. .

  The input shaft 11 (first rotating body) is directly or indirectly connected to a rotational drive source. For example, the input shaft 11 may be a motor output shaft itself or an output shaft after the motor is decelerated. Good. In this embodiment, the input shaft 11 is manufactured from a rigid material such as chrome molybdenum steel that is relatively resistant to elastic deformation, and has dimensions of 14 mm in diameter and 30 mm in length.

  The frictional coupling mechanism 13 between the input shaft 11 and the transmission member 14 assures that the input shaft 11 is tightened, and also serves as a torque limiter capable of self-return, as will be described later.

  The transmission member 14 includes an input side holder 141, an output side holder 143, and a plurality of elastically deformable elastic rods 142 arranged therebetween. The plurality of elastic rods 142 are annularly arranged so as to surround the input shaft 11. The elastic deformation of the elastic rod 142 causes deformation necessary for torque detection. The input side holder and the output side holder are manufactured from a metal material such as iron in the present embodiment, and the elastic rod 142 that causes the elastic deformation is manufactured from, for example, duralumin or the like in the present embodiment.

  The elastic rod 142 is coupled to the input side holder 141 and the output side holder 143 through bolts at both ends thereof, and the number, material, shape, etc. can be customized arbitrarily according to the range of torque to be detected. Yes. In the present embodiment, for example, the plurality of elastic rods are configured by twelve rods having a diameter of 6 mm and a length of 24 mm that are annularly arranged at equal intervals.

  The coupling portion between the output flange 12 and the transmission member 14 has an annular shape so as to surround the transmission member 14, and the rotation centers of both members are the same. That is, the input shaft 11, the transmission member 14, and the output flange 12 all have the same rotation center axis. In the present embodiment, the output flange 12 is made of a metal material and has a structure that is relatively resistant to elastic deformation due to its large diameter.

  The torque sensor according to the present embodiment includes an input shaft 11 (first rotating body), an output flange 12 (second rotating body), and is elastically deformable. The rotation of the input shaft 11 is transferred to the output flange 12. And an angle sensor 15 for detecting a rotational angle difference between the input shaft 11 and the output flange caused by elastic deformation of the transmission member 14. The transmission member has a plurality of elastic rods 142, and transmission of rotation from the input shaft 11 to the output flange 12 is performed via the plurality of elastic rods 142.

  According to such a configuration, the load torque is distributed to the plurality of elastic rods 142. Therefore, a torque sensor provided with a transmission member that allows appropriate elastic deformation while maintaining appropriate rigidity is provided. can do.

  The plurality of elastic rods 142 can be attached and detached and can be customized. According to such a configuration, the number, material, shape, and the like of the elastic rod 142 can be arbitrarily customized in accordance with the range of torque to be detected, so that a torque sensor having optimum characteristics can be easily provided. For example, in the present embodiment, although the number of elastic rods is 12, the number of the rods can be adjusted. For example, the stress applied to each elastic rod may be adjusted by pulling out several evenly. Thereby, it is also possible to adjust the sensing sensitivity of torque.

  Although not essential for the purpose of only torque detection, a magnetic absolute encoder 16 (second angle sensor) comprising a code wheel 161 and a code reading plate 162 for detecting the rotation angle of the input shaft 11 is used. ) May be provided separately. By using such an absolute encoder 16 as well, as will be described later, it is possible to perform appropriate correction processing or the like even when slippage occurs between the input shaft 11 and the frictional coupling mechanism 13. . In the present embodiment, the absolute encoder 16 for detecting the angle of the input shaft 11 is a single-turn 18-bit encoder, and its resolution is 262144 [P / R].

<1.2 Operation>
Next, the operation of the torque sensor, that is, the principle of torque detection will be described with reference to FIGS.

  First, when the input shaft 11 rotates, the rotation is transmitted to the transmission member 14 via the frictional coupling mechanism 13. More specifically, the input from the input shaft 11 is transmitted to the input side holder 141 via the frictional coupling mechanism 13.

  Next, as shown in FIG. 2A, the rotational force transmitted to the input side holder 141 of the transmission member 14 is transmitted to the output side holder 143 through the elastic rod 142.

  Thereafter, as shown in FIG. 2B, the rotation of the output side holder 143 is transmitted to the output flange 12. An angle difference between the input shaft 11 and the output flange 12 is detected using an absolute encoder 15. As described above, rotation is transmitted from the input stage (input shaft 11) to the output stage (output flange 12).

  Here, the angle difference between the input shaft 11 and the output flange 12 will be further described. When the input shaft 11 and the output flange 12 are coupled via a rigid body that does not undergo elastic deformation, an angle difference does not naturally occur between them. However, in the present invention, the input shaft 11 and the output flange 12 are coupled via a transmission member 14 that can be elastically deformed. Therefore, when an inertia of the output flange 12 itself or a load in the rotational direction is applied to the output flange 12 from the outside, an angle difference is generated between the input shaft 11 and the output flange 12, and this angle difference is Since the torque is in a predetermined proportional relationship with the torque in the torsion direction, the torque is substantially expressed. For example, in the torque sensor including the above-described absolute encoder 15 according to the present embodiment, when a torque of 50 Nm is applied to the output flange 12, the output value of the absolute encoder 15 is about 200 pulses, that is, the resolution described above. If converted into an angle based on the above, a variation of 0.27 ° can be seen. Thus, the predetermined torque applied to the output flange 12 can be sensed as the amount of change in angle.

  In the present embodiment, the transmission member 14 is coupled to the input shaft 11 at the first end portion along the rotation center axis of the transmission member 14. The transmission member 14 has a hollow shape in which a plurality of elastic rods 142 are arranged in an annular shape, includes the input shaft 11, and rotates with the input shaft 11 as the center of rotation. Further, the transmission member 14 is coupled to the output flange 12 at the second end portion along the rotation center axis of the transmission member. On the other hand, the output flange 12 has a hollow shape, includes the transmission member 14, and rotates with the transmission member 14 as the center of rotation.

  According to such a configuration, the first rotating body, the transmission member 14 and the output flange 12 are arranged so as to be contained within each other while keeping the rotation center as one, so that the torque sensor can be accommodated in a limited space. .

<2. Joint module with built-in torque sensor>
Next, an embodiment of a joint module for a robot system (for example, a robot arm) incorporating the above-described torque sensor will be described with reference to FIGS. In addition, the same code | symbol is used about the structure similar to the structure already demonstrated.

<2.1 Configuration>
FIG. 3 is a perspective view showing an appearance of the joint module 20 according to the present embodiment. As is apparent from the figure, the joint module 20 is covered with a housing 22 and a rear cover 23, and has a mounting portion 21 for coupling with an external element (for example, an arm member or another joint module).

  FIG. 4 is an overall cross-sectional view of the joint module obtained by cutting the joint module including the torque sensor according to the present invention along the cross section indicated by the arrow in FIG. 3. As is apparent from the figure, in the joint module 20, a drive source including a motor 24 is disposed in the housing 22, while other circuits (including a microcomputer and the like) including a drive circuit of the motor 24 are mounted. The substrate 25 is disposed on the back side of the motor and is covered by the rear cover 23.

  In the figure, an output shaft 26 of a motor 24 is coupled to a harmonic drive (registered trademark) 27 that is a speed reducer, and an output shaft 28 of the harmonic drive 27 after deceleration is frictionally coupled as an input shaft to a torque sensor. It is coupled to one end of the transmission member 14 via the mechanism 13. The other end of the transmission member 14 is coupled to the output flange 12 and applies rotational power to an external element connected to the joint module 20. These configurations are supported by bearings as appropriate for smooth rotation.

  According to the configuration as described above, since the drive sources are concentrated in the housing, it is possible to provide a joint module that can easily construct a robot system.

  FIG. 5 shows a configuration mainly related to a power source in the joint module 20, that is, the motor 24, the speed reducer 27, the input shaft 28, the frictional coupling mechanism 13 and the transmission member 14 together with other members such as bearings and structural members. FIG. 4 is an external perspective view showing an assembled state covered with an internal cover 29. FIG. In the figure, by further attaching the output flange 12 to the transmission member side, it is possible to transmit the rotational power to the outside.

  FIG. 6 is an exploded perspective view showing main components of the joint module 20. In the figure, a motor 24 as a drive source and a harmonic drive 27 as a speed reducer are further added to the torque sensor already described. For this reason, the same reference numerals are used for parts similar to those of the torque sensor already described.

  The output shaft 26 of the motor 24 is coupled to a harmonic drive 27 which is a speed reducer. More specifically, the harmonic drive 27 includes a wave generator 272, a circular spline 273, and a flex spline 271. The flex spline 271 is coupled to the input shaft 28 that is the output shaft of the reduction gear. When the torque sensor is the center, this output shaft corresponds to the input shaft. As described above, the input shaft 11 is coupled to the input side holder 141 of the transmission member 14 via the frictional coupling mechanism 13 at the tip, and to the output flange 12 via the plurality of elastic rods 142. At this time, a first angle sensor 15 is provided between the tip of the input shaft and the output flange 12, and a second angle sensor 16 is provided at the base of the input shaft.

<2.2 Operation>
Next, the state in which the rotation is transmitted from the input stage, that is, the drive input side to the output stage, that is, the output flange 12 will be described in order with reference to FIGS.

  First, the rotation transmission mode from the motor 24 to the transmission member 14 will be described with reference to FIGS. FIG. 7 is a partial cross-sectional view showing a configuration of an input stage of a torque sensor including a motor and a speed reducer, and FIG. 8 is an explanatory view centering on the rotation direction of the motor 24 and a harmonic drive 27 as a speed reducer.

  In the figure, first, the output shaft 26 of the motor 24 fixed in the housing 22 is coupled to a wave generator 272 having an elliptical shape. At this time, the rotation direction of the wave generator 272 is the same direction as the output shaft 26 of the motor 24. Subsequently, when the wave generator 272 rotates inside the flex spline 271, the flex spline 271 rotates in the direction opposite to the rotation direction of the output shaft 26 of the motor and the wave generator 272 inside the circular spline 273. That is, the input shaft 28 that is the output shaft of the speed reducer rotates in the opposite direction to the output shaft 26 of the motor. The rotation of the input shaft 28 is transmitted to the input side holder 141 of the transmission member 14 and the code wheel of the angle sensor 15 through the frictional coupling mechanism 13 in the same direction.

  Next, a transmission mode of rotation from the input shaft 28 to the transmission member 14 will be described with reference to FIG. FIG. 9 is a partial cross-sectional view showing the configuration of the torque sensor including the transmission member 14. As is apparent from the figure, the frictional coupling mechanism 13 is interposed between the input shaft 28 and the input side holder 141 of the transmission member 14, and the input shaft 28 and the transmission member 14 rotate as a unit by frictional coupling. Let

  Here, the frictional coupling mechanism 13 will be described in more detail with reference to FIGS.

  FIG. 10 is an exploded perspective view of the frictional coupling mechanism 13. The frictional coupling mechanism 13 includes a hollow cylindrical body tightening member 132 having a tapered inner surface, a hollow cylindrical body tightening member 131 having a convex portion to be inserted into the tightening member 132, and a bolt 133 for coupling them. It consists of.

  FIG. 11 is a cross-sectional view of the torque sensor including the frictional coupling mechanism 13 and shows a state in which the input shaft 28 is firmly held by the frictional coupling mechanism by tightening the bolt 133. First, as shown in FIG. 6A, even if the inner peripheral surface of the member 131 to be tightened is not completely in contact with the input shaft 28 or is not in contact with the input shaft 28 before the bolt 133 is tightened. Thus, no tightening stress is generated. Thereafter, as shown in FIG. 5B, when the bolt 133 is tightened, the outer surface of the convex portion of the member to be tightened 131 is guided by the tapered inner peripheral surface of the tightening member 132, thereby causing the input shaft 28 to move. Tighten in the radial center direction. That is, the fastening member 131 is fastened to the input shaft 28 by tightening the bolt 133, and the integration of the input shaft 28, the fastened member 13 and the transmission member 14 is realized by the frictional force on the contact surface. It becomes. Moreover, since the outer peripheral surface of the fastening member 132 is pressed against the inner peripheral surface of the input side holder 141 by this tightening, the frictional coupling mechanism 13 and the transmission member 14 can be integrated. It becomes. In the present embodiment, the contact area between the frictional coupling mechanism 13 and the transmission member 14 is larger than the contact area between the input shaft 28 and the frictional coupling mechanism 13. Therefore, the static friction force between the frictional coupling mechanism 13 and the transmission member 14 is larger than that between the input shaft 28 and the frictional coupling mechanism 13. That is, slippage at the time of overload in the present embodiment occurs between the outer peripheral surface of the input shaft 28 and the inner peripheral surface of the frictional coupling mechanism 13.

  According to such a coupling method by friction, the coupling between the input shaft 28 and the transmission member 14 can be maintained up to the limit of static friction, while input is performed when excessive torque is generated on the output flange 12 side. A slip occurs between the shaft 28 and the transmission member 14 to release the torque. That is, since the frictional coupling mechanism 13 functions as a torque release mechanism (or torque limiter), it is possible to prevent the input side mechanisms such as the input shaft 28 and the speed reducer from being damaged.

  In addition, since the coupling method is a friction coupling method, even if a slip occurs once, if the load is removed, it can autonomously return to the fixed state again by friction. That is, since the torque release mechanism is capable of self-return, continuous operation can be performed without performing a reset operation after slipping. However, it is desirable to perform a correction process related to the slip amount described later after the slip.

  Next, a transmission mode of rotation from the transmission member 14 to the output flange 12 will be described with reference to FIG. FIG. 12 is a partial cross-sectional view showing the configuration of the output stage of the torque sensor including the output flange 12. The rotational force transmitted from the input shaft 28 to the transmission member 14 is output to the output flange 12. Here, the output flange 12 includes an inner output flange 121 and an outer output flange 122, which are coupled to each other via a bolt 123. The inner output flange 121 is coupled to the output side holder 143 via a bolt (not shown). Further, the rotational force is transmitted to an external element such as an arm member by the outer output flange 122.

<2.3 Slip correction processing>
In the torque sensor according to the present embodiment, the frictional coupling mechanism 13 is employed as a coupling means between the input shaft 28 and the transmission member 14 as described above. Therefore, for example, when the upper limit value of the static friction is exceeded due to a large load applied to the output flange, there is a possibility that slip occurs between the input shaft 28 and the transmission member 14. Here, although the friction type coupling mechanism 13 is a self-returning type torque release mechanism, continuous operation is also possible. There is a possibility that deviation from the operation assumed before the occurrence of the slip occurs. Here, the open loop control refers to control for controlling the motor based on the estimated angle. Therefore, the following describes the slip detection and slip amount correction processing when slipping occurs.

  FIG. 13 shows, for example, correction processing of slip between the input shaft 28 and the frictional coupling mechanism 13 performed by a control unit such as a microcomputer (not shown) in the joint module 20, that is, detection of slip, calculation of a correction amount, and The flowchart of the software which performs the reflection process is shown.

  When the process starts, first, the sensor value, that is, the angle information is read from the absolute encoder 15 which is the first angle sensor (S101). Next, it is determined whether or not the sensor value exceeds a predetermined threshold (S102). Here, since the angle change detected by the slip is generally sufficiently larger than the angle change obtained by the elastic deformation, it is possible to distinguish the angle change due to the elastic deformation and the angle change due to the slip by a threshold value.

  If it is determined that the angle does not exceed the predetermined threshold (NO in S102), it is determined that no slip has occurred, and the angle information reading process is repeated again (S101). On the other hand, if it is determined that the angle has exceeded the predetermined threshold (YES in S102), it is determined that slip has occurred, and correction amount calculation processing is started based on the output value of the first angle sensor, that is, the absolute encoder 15. (S103). Here, slip is detected based on whether or not the angle value exceeds a predetermined threshold value, but slip occurs when there is a discontinuous change by observing the amount of change in the angle value over time. Other detection methods, such as determining a thing, may be used.

  Here, the correction amount will be further described. In the open loop control, it is assumed that the input shaft 28 and the output flange 12 are rotated at the same angle, that is, the output flange also has the input shaft angle acquired by the second angle sensor (absolute encoder 16). It is assumed that they are in the same angle state. Therefore, in order to guarantee the operation assumed even after the occurrence of the slip and before the occurrence of the slip, the value of the first angle sensor 15 representing the slip amount needs to be used as the correction amount. For example, when the input shaft 28 and the output flange 12 are displaced by 30 ° due to slippage, the correction amount is 30 °.

  When the correction amount calculation process (S103) is completed, the correction amount reflection process is performed in order to guarantee the operation assumed before the occurrence of the slip even after the slip has occurred (S104). Here, the reflection process refers to, for example, adding / subtracting the correction amount to a predetermined numerical value. The correction amount may be reflected in a predetermined state amount (for example, the current angle value of the current input shaft 28) or may be reflected in a command value to the motor 24. After this reflection process, the process ends. According to the correction process described above, it is possible to perform the control according to the operation assumed before the slip. In addition, continuous operation can be performed even when slipping occurs.

  According to the configuration as described above, since a design considering slippage due to an overload can be performed, a more reliable system can be constructed. Further, even after slipping, control can be performed by correcting the amount of slipping, so that highly accurate control can be performed.

<3. Robot arm with joint module>
FIG. 14 is a perspective view showing an appearance of the robot arm 40 including the joint module 20 described above. The robot arm 40 includes a total of five joint modules 20, and the joint modules 20 are connected by arm members 41 and 42 or directly connected to other joint modules. An end effector 43 is directly coupled to the joint module 20 at the end. Each joint module is connected to a control unit (CPU or the like) (not shown) that controls the entire robot arm 40 or a PC or the like including them. Note that the PC may perform the above-described slip correction process, for example.

  As described above, the robot system (the robot arm 40 in the present embodiment) can be easily constructed by using the joint module 20 in which the drive sources are integrated.

  The robot arm 40 according to the present embodiment may be manufactured and sold as a set of parts, that is, a robot arm assembly set.

  According to such a configuration, it is possible to provide a set for assembling a robot arm that can be easily assembled while having a high degree of design freedom.

  The torque sensor according to the present invention can be used in all industrial fields necessary for rotational torque detection, and the drive system, joint module, robot system, robot arm assembly set, and program are at least industrial robots and experimental robots. It can be used in the robot industry including

DESCRIPTION OF SYMBOLS 10 Torque sensor 11 Input shaft 12 Output flange 121 Inner output flange 122 Outer output flange 123 Bolt 13 Friction type coupling mechanism 131 Tightened member 132 Tightening member 133 Bolt 14 Transmission member 141 Input side holder 142 Elastic rod body 143 Output side holder 15 Absolute encoder (first angle sensor)
151 Code wheel 152 Code reading board 16 Absolute encoder (second angle sensor)
161 Code Wheel 162 Code Reading Board 17 Bolt 18 Washer 20 Joint Module 21 Mounting Portion 22 Housing 23 Rear Cover 24 Motor 25 Substrate 26 Motor Output Shaft 27 Harmonic Drive (Deceleration Mechanism)
271 Flex Spline 272 Wave Generator 273 Circular Spline 28 Input Shaft 29 Inner Cover 40 Robot Arm 41 Arm Member 42 Arm Member 43 End Effector

Claims (13)

A first rotating body;
A second rotating body;
A transmission member that is elastically deformable and transmits the rotation of the first rotating body to the second rotating body;
An angle sensor for detecting a rotation angle difference between the first rotating body and the second rotating body caused by elastic deformation of the transmission member,
The transmission member includes a plurality of elastic rods, and transmission of rotation from the first rotating body to the second rotating body is performed via the plurality of elastic rods.   The torque sensor according to claim 1, wherein the plurality of elastic rods are customizable. The transmission member is coupled to the first rotating body at a first end along the rotation center axis of the transmission member;
The transmission member has a hollow shape in which the plurality of elastic rods are arranged in an annular shape, includes the first rotating body, rotates with the first rotating body as a center of rotation,
The transmission member is coupled to a second rotating body at a second end along the rotation center axis of the transmission member;
The second rotating body has a hollow shape, includes the transmission member, and rotates with the transmission member as a center of rotation.
The torque sensor according to claim 1.   The torque sensor according to claim 1, wherein a self-recoverable torque releasing mechanism that operates when a predetermined torque is exceeded is interposed in a coupling portion between the first rotating body and the transmission member. The torque sensor according to any one of claims 1 to 4,
A drive unit that rotationally drives the first rotating body of the torque sensor;
And a control unit including a detection unit configured to detect the presence or absence of slip between the first rotating body and the second rotating body based on an output of the angle sensor. The torque sensor further includes an input side angle sensor for measuring a rotation angle of the first rotating body,
The control unit of the drive system includes:
A slip amount detecting means for detecting a slip amount between the first rotating body and the second rotating body based on an output of the angle sensor;
A correction amount calculation unit that calculates a predetermined correction amount based on the slip amount;
A reflection processing unit that reflects the correction amount to an output value of the input side angle sensor or a rotation command value to the driving unit;
The drive system according to claim 5, further comprising: The torque sensor according to any one of claims 1 to 4,
A drive unit that rotationally drives the first rotating body;
A joint module comprising: a housing that houses the torque sensor and the drive unit and has a mounting portion for mounting an arm member. At least one joint module according to claim 7;
And a control unit that controls the joint module. The control unit of the robot system includes:
9. The robot system according to claim 8, further comprising a slip detection unit configured to detect presence or absence of slip between the first rotating body and the second rotating body based on an output of the angle sensor. The torque sensor further includes an input side angle sensor for measuring a rotation angle of the first rotating body,
The control unit of the robot system includes:
A slip amount detecting means for detecting a slip amount between the first rotating body and the second rotating body based on an output of the angle sensor;
A correction amount calculation unit that calculates a predetermined correction amount based on the slip amount;
A reflection processing unit that reflects the correction amount to an output value of the input side angle sensor or a rotation command value to the driving unit;
The robot system according to claim 9, further comprising: The joint module according to claim 7,
A set for assembling a robot arm. A program for a drive system according to claim 5,
On the computer,
The program which performs the slip detection step which detects the presence or absence of the slip between the said 1st rotary body and the said 2nd rotary body based on the output of the said angle sensor. A program for the robot system according to claim 5,
The torque sensor further includes an input side angle sensor that measures a rotation angle of the first rotating body,
On the computer,
A slip amount detecting step for detecting a slip amount between the first rotating body and the second rotating body based on an output of the angle sensor;
A correction amount calculating step of calculating a predetermined correction amount based on the slip amount;
A reflection processing step of reflecting the correction amount to an output value of the input side angle sensor or a rotation command value to the drive unit.

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