JP6792687B2 - Link actuator - Google Patents

Description

The present invention relates to a link actuating device used for collaborative work with equipment and humans that require high speed, high accuracy, and a wide operating range such as medical equipment and industrial equipment.

Patent Documents 1 and 2 propose parallel link mechanisms used in various working devices. The parallel link mechanism of Patent Document 1 has a relatively simple configuration, but since the operating angle of each link is small, if the operating range of the traveling plate is set large, the link length becomes long and the size of the entire mechanism becomes large. There is a problem. The parallel link mechanism of Patent Document 2 has a configuration in which the link hub on the distal end side is connected to the link hub on the proximal end side so that the posture can be changed via three or more sets of link mechanisms in a four-node chain. Despite its compact size, it is capable of precise and wide operating range operation.

Japanese Unexamined Patent Publication No. 2000-94245 U.S. Pat. No. 5,893,296

In all conventional link actuating devices such as the parallel link mechanism of Patent Document 2, it is necessary to attach an expensive sensor in order to detect the force acting on the tip of the parallel link mechanism.
For link actuating devices used for collaborative work with humans, such as medical equipment, it is required for safety to be able to escape immediately and freely if a person's hand or arm accidentally interferes. For that purpose, it is necessary to detect and deal with the force acting on the tip of the link actuating device. Further, in medical equipment and industrial equipment, it is required to be able to detect the force acting on the tip of the link operating device in order to perform the work with high accuracy.

An object of the present invention is to solve the above-mentioned problems, to detect external forces acting on the tip of the device from various directions with a simple and inexpensive configuration, to improve the safety of the entire device, and to collaborate with humans. It is to provide a link actuating device that can be used.

In the link actuating device of the present invention, the link hub on the tip end side is connected to the link hub on the proximal end side so as to be able to change the posture via three or more sets of link mechanisms, and each of the link mechanisms is connected to the proximal end. Both ends are rotatably connected to the side link hub and the tip side link hub, and the other ends of the proximal end side and the distal end side end link members and the proximal end side and the distal end side end link members. Each of the central link members is rotatably connected, and each link mechanism has a geometric model in which the link mechanism is represented by a straight line, and the central link member has a proximal end side portion and a distal end side portion with respect to the central portion. Are symmetrical shapes, and an attitude control actuator that allows two or more sets of the three or more sets of link mechanisms to arbitrarily change the attitude of the tip side link hub with respect to the base end side link hub. In the link actuating device provided with
A controller for controlling each attitude control actuator is provided, and the controller is provided with an attitude control means for outputting a command to each attitude control actuator, and a load estimation means for estimating a load acting on the link hub on the tip side. The load estimation means has a collision detection function for detecting a collision acting on the link hub on the tip side based on the amount of torque change acting on each attitude control actuator.
The collision response control means is provided so that the operation of each attitude control actuator is turned off and freed by the collision detection of the load estimation means.

According to this configuration, the link hub on the proximal end side, the link hub on the distal end side, and three or more sets of link mechanisms rotate the link hub on the distal end side about two axes orthogonal to the link hub on the proximal end side. A free two-degree-of-freedom mechanism is constructed. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub on the tip side can be widened. By controlling the operation of each attitude control actuator, the attitude of the link hub on the distal end side can be arbitrarily changed with respect to the link hub on the proximal end side.

In the link operating device having such a configuration, each of the attitude control actuators may have torque detecting means, and the load may be estimated by the load estimating means from the detection signals of these torque detecting means. Since each attitude control actuator is provided with a torque detecting means and a load estimating means for estimating the load acting on the link hub on the tip side from the detection signal of the torque detecting means, another sensor is provided on the link hub on the tip side or the like. The load can be estimated without providing it on the moving part. Since the load of the link hub on the tip side is transmitted to each attitude control actuator via the link mechanism, the load of the link hub on the tip side can be calculated from the torque of each attitude control actuator. The torque detecting means for detecting the torque of the attitude control actuator can be configured by a simple detecting means such as a sensor for detecting the current applied to the attitude control actuator.
In this way, the torque detecting means is provided in the attitude control actuator, and the load acting on the link hub on the tip side is estimated without providing another sensor on the movable part such as the link hub on the tip side. This will lead to overall compactness and cost reduction.
Further, since the link operating device having the above configuration has no singular point within its movable range and can move smoothly in all directions, the attitude control actuator is provided even when a load is applied to the link hub on the tip side from various directions. Torque is reliably transmitted to the hub, and the load can be estimated accurately.

In the present invention, the three or more sets of link mechanisms may be arranged at equal intervals in the circumferential direction in which the link mechanisms are lined up, and the attitude control actuators may be provided for all of the link mechanisms.
By arranging three or more sets of link mechanisms at equal intervals and providing attitude control actuators in all the link mechanisms in this way, torque is transmitted to each attitude control actuator in a well-balanced manner. Therefore, the load can be estimated more accurately by using the detection signal of the torque detecting means provided in the attitude control actuator.

In the basic configuration of the link operating device of the present invention, the attitude control actuator is provided for the three or more sets of link mechanisms.
When three sets of link mechanisms are used, interference between the link mechanisms is reduced, the operating range is increased, and the number of parts is small, which leads to cost reduction. Further, if there are three sets of link mechanisms and the attitude control actuator is provided for these three sets of link mechanisms, torque transmission can be performed in a well-balanced manner. Therefore, since the load acting on the tip of the device is obtained from the torque detecting means of each attitude control actuator, the calculation can be easily performed and the load can be estimated more accurately.

In the present invention, the load estimating means may have a function of detecting a collision acting on the link hub on the tip side from the amount of torque change detected by the torque detecting means.
When the link hub on the tip side or something mounted on it collides with something, the torque acting on the attitude control actuator changes abruptly. Therefore, it is possible to detect a collision in various directions based on this torque fluctuation amount. With the configuration in which the load estimation means is provided with a collision detection function in this way, even if the link operating device comes into contact with a person or an object, it is possible to take measures such as detecting the contact and stopping the device for safety. Is improved.

The link operating device of the present invention has a function of the load estimating means to detect a load value acting on the link hub on the tip side and a direction in which the load acts from each torque value of the torque detecting means.
The torque acting on each posture control actuator with respect to the load acting on the tip is measured in advance, and a table or the like that defines the relationship between the torque acting on each posture control actuator and the load acting on the tip is created. If a calculation formula for calculating the load acting on the tip from the torque acting on each posture control actuator by mechanism analysis is established, the load on the tip side can be estimated from the torque value detected by the torque detecting means. When the load acting on the tip is detected with high accuracy, the work by the end effector or the like attached to the link hub on the tip side can be performed with high accuracy.

In the link actuator of the present invention, the link hub on the tip end side is connected to the link hub on the proximal end side so as to be able to change the posture via three or more sets of link mechanisms, and each of the link mechanisms is connected to the proximal end. Both ends are rotatably connected to the side link hub and the tip side link hub, and the other ends of the proximal end side and the distal end side end link members and the proximal end side and the distal end side end link members. Each of the central link members is rotatably connected, and each link mechanism has a geometric model in which the link mechanism is represented by a straight line, and the central link member has a proximal end side portion and a distal end side portion with respect to the central portion. Are symmetrical shapes, and an actuator for attitude control that allows two or more of the three or more linkages to arbitrarily change the attitude of the front end side link hub with respect to the base end side link hub. In the link operating device provided with the above, a controller for controlling each of the attitude control actuators is provided, and this controller acts on the attitude control means for outputting a command to each of the attitude control actuators and the link hub on the tip side. A load estimation means for estimating the load to be applied is provided, and the load estimation means has a collision detection function for detecting a collision acting on the link hub on the tip side from the amount of torque change acting on each posture control actuator. Since it is equipped with a collision response control means that turns off the operation of each attitude control actuator by collision detection of the load estimation means to make it free, external forces acting on the tip of the device from various directions can be easily and inexpensively applied. It can be detected with various configurations, and the safety of the entire device can be improved.

It is a front view which omitted a part of the link actuating apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which combined the cross-sectional view of the link hub etc. on the base end side of the link actuating device, and the block diagram of the conceptual structure of a control system. It is a schematic diagram which represented one link mechanism of the link actuating device by a straight line. It is a perspective view of the actuating device main body of the link actuating device. It is a perspective view which shows the operating state different from FIG. 4 of the link actuating apparatus. It is a graph which shows the relationship between the torque used by the load estimation means of the link actuating device, and the occurrence of a collision. It is explanatory drawing of the table which shows the relationship between the torque, the acting force, and the acting direction in the load estimation means of the link actuating device. It is a front view which omitted a part of the link actuating apparatus which concerns on other embodiment of this invention. It is explanatory drawing which combined the cross-sectional view of the link hub etc. on the base end side of the link actuating device, and the block diagram of the conceptual structure of a control system. It is explanatory drawing which combined the front view which omitted a part of the link actuating apparatus which concerns on still another Embodiment of this invention, and the block diagram of the conceptual structure of the control system. It is a cross-sectional view of a link hub and the like on the base end side of the link operating device.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 7. The link operating device 1 is a parallel link mechanism 9, an attitude control actuator 10 for operating the parallel link mechanism 9, and a controller 3 for controlling the attitude control actuator to change the attitude of the parallel link mechanism 9 (FIG. It is composed of 2).

FIG. 1 is a front view of the link operating device, and FIGS. 4 and 5 are perspective views showing different states of the link operating device. The parallel link mechanism 9 is formed by connecting the link hub 13 on the distal end side to the link hub 12 on the proximal end side in a posture-changeable manner via three sets of individual link mechanisms 14. Note that FIG. 1 shows only one set of link mechanisms 14. In this embodiment, the three sets of link mechanisms 14 are arranged at equal intervals in the circumferential direction in which the link mechanisms 14 are arranged, and the attitude control actuators 10 are provided for all of the link mechanisms 14. The internal space of the arrangement of the three sets of link mechanisms 14 is the internal space S of the parallel link mechanism 9. The number of link mechanisms 14 may be 4 or more.

Each individual link mechanism 14 is composed of an end link member 15 on the proximal end side, an end link member 16 on the distal end side, and a central link member 17, and forms a four-node chain link mechanism composed of four rotating pairs. .. The end link members 15 and 16 on the proximal end side and the distal end side have an L shape, and one end thereof is rotatably connected to the link hub 12 on the proximal end side and the link hub 13 on the distal end side, respectively. In the central link member 17, the other ends of the end link members 15 and 16 on the proximal end side and the distal end side are rotatably connected to both ends.

The parallel link mechanism 9 has a structure in which two spherical link mechanisms are combined, and each rotation pair of the link hubs 12 and 13 and the end link members 15 and 16 and the end link members 15 and 16 and the central link member 17 The central axes of each rotational pair of the above intersect at the spherical link centers PA and PB (FIG. 3) on the proximal end side and the distal end side, respectively. Further, on the base end side and the tip end side, the distances from the rotational pairs of the link hubs 12 and 13 and the end link members 15 and 16 and the respective spherical link centers PA and PB are the same, and the end link members 15 and The distances from each rotation pair of the 16 and the central link member 17 and the respective spherical link centers PA and PB are also the same. The central axes of each rotational pair of the end link members 15 and 16 and the central link member 17 may have a certain crossing angle γ (FIG. 1) or may be parallel.

FIG. 2 is a cross-sectional view of a link hub 12 on the proximal end side, an end link member 15 on the proximal end side, and the like with blocks of the conceptual configuration of the controller 3 added. FIG. 6 shows the relationship between the central axis O1 of each rotational pair of the link hub 12 on the proximal end side and the end link member 15 on the proximal end side and the spherical link center PA. The shapes and positional relationships of the front end side link hub 13 and the front end side end link member 16 are the same as those in FIG. 2 (not shown). In the example of the figure, the central axis O1 of each rotation pair of the link hubs 12 and 13 and the end link members 15 and 16 and the central axis O2 of each rotation pair of the end link members 15 and 16 and the central link member 17 The angle α formed by the above is 90 °, but the angle α may be other than 90 °.

The three sets of link mechanisms 14 have the same geometric shape. As shown in FIG. 3, the geometrically identical shape is represented by a geometric model in which each link member 15, 16 and 17 is represented by a straight line, that is, each rotation pair and a straight line connecting these rotation pairs. It is said that the model has a shape in which the base end side portion and the tip end side portion with respect to the central portion of the central link member 17 are symmetrical. FIG. 3 is a diagram showing a set of link mechanisms 14 as a straight line. The parallel link mechanism 9 of this embodiment is a rotationally symmetric type, and includes a link hub 12 on the proximal end side and an end link member 15 on the proximal end side, and a link hub 13 on the distal end side and an end link member 16 on the distal end side. The positional relationship is such that the central link member 17 is rotationally symmetric with respect to the center line C. The central portion of each central link member 17 is located on a common orbital circle D.

With the link hub 12 on the proximal end side, the link hub 13 on the distal end side, and three sets of link mechanisms 14, the link hub 13 on the distal end side can rotate about two orthogonal axes with respect to the link hub 12 on the proximal end side. A degree mechanism is constructed. In other words, it is a mechanism that allows the link hub 13 on the tip side to change its posture with two degrees of freedom in rotation with respect to the link hub 12 on the base end side. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 13 on the distal end side with respect to the link hub 12 on the proximal end side can be widened.

For example, a straight line passing through the spherical link centers PA and PB and intersecting the central axes O1 (FIG. 2) of the rotating pairs of the link hubs 12 and 13 and the end link members 15 and 16 at right angles is the central axis of the link hubs 12 and 13. In the case of QA and QB, the maximum value of the bending angle θ (FIG. 3) between the central axis QA of the link hub 12 on the proximal end side and the central axis QB of the link hub 13 on the distal end side can be set to about ± 90 °. it can. Further, the turning angle φ (FIG. 3) of the link hub 13 on the tip side with respect to the link hub 12 on the base end side can be set in the range of 0 ° to 360 °. The bending angle θ is the vertical angle at which the central axis QB of the link hub 13 on the distal end side is inclined with respect to the central axis QA of the link hub 12 on the proximal end side, and the turning angle φ is the link hub on the proximal end side. It is a horizontal angle at which the central axis QB of the link hub 13 on the tip side is tilted with respect to the central axis QA of 12.

The posture of the link hub 13 on the distal end side with respect to the link hub 12 on the proximal end side is changed with the intersection O of the central axis QA of the link hub 12 on the proximal end side and the central axis QB of the link hub 13 on the distal end side as the center of rotation. Will be FIG. 4 shows a state in which the central axis QA of the link hub 12 on the proximal end side and the central axis QB of the link hub 13 on the distal end side are on the same line, and FIG. 5 shows the central axis QA of the link hub 12 on the proximal end side. A state in which the central axis QB of the link hub 13 on the tip side has a certain operating angle is shown. Even if the posture changes, the distance L (FIG. 3) between the spherical link centers PA and PB on the proximal end side and the distal end side does not change.

In this parallel link mechanism 9, the angle of the central axis O1 (FIG. 2) of the rotation pairs of the link hubs 12 and 13 and the end link members 15 and 16 in each link mechanism 14 and the length from the spherical link centers PA and PB are The central axes O1 of the rotation pairs of the link hubs 12 and 13 of each link mechanism 14 and the end link members 15 and 16 and the central axes O2 of the rotation pairs of the end link members 15 and 16 and the central link 17 that are equal to each other. However, the spherical link centers PA and PB intersect on the proximal end side and the distal end side, and the geometrical shapes of the proximal end side end link member 15 and the distal end side end link member 16 are the same, and the central link member When the shape of 17 is the same as that of the distal end side, the angular positional relationship between the central link member 17 and the end link members 15 and 16 with respect to the symmetrical plane of the central link member 17 is determined between the proximal end side and the distal end side. If the sides are the same, due to geometric symmetry, the base end side link hub 12 and the base end side end link member 15 and the tip end side link hub 13 and the tip end side end link member 16 are It works the same.

As shown in FIG. 1, the base end side link hub 12 is composed of the base member 6 and three rotating shaft connecting members 21 provided integrally with the base member 6. The base member 6 has a circular through hole 6a (FIG. 2) in the central portion, and three rotating shaft connecting members 21 are arranged around the through hole 6a at equal intervals in the circumferential direction. The center of the through hole 6a is located on the link hub central axis QA on the proximal end side. A rotating shaft 22 whose axis intersects the link hub central axis QA is rotatably connected to each rotating shaft connecting member 21 by a bearing 23. The bearing 23 is installed on the rotating shaft connecting member 21 together with the spacer 24. One end of the end link member 15 on the base end side is fastened to the rotating shaft 22 with a nut 22c and connected to the rotating shaft 22.

The rotating shaft 22 is arranged coaxially with the output shaft of the speed reduction mechanism 52. Further, one end of the end link member 15 on the base end side is connected to the output shaft of the speed reduction mechanism 52 by a bolt 29 via a spacer 28 so as to rotate integrally with the output shaft of the speed reduction mechanism 52. The bolt 29 is fastened from the inside of the notch 25 formed at one end of the end link member 15 on the base end side.
A notch 26 is provided at the other end of the end link member 15 on the base end side, and a rotating shaft 35 rotatably connected is connected to one end of the central link member 17 arranged in the notch 26. Will be done.

As shown in FIGS. 1, 4, and 5, the link hub 13 on the tip side has a flat tip member 40 and three rotating shafts provided on the bottom surface of the tip member 40 in a circumferential direction. It is composed of a connecting member 41. An end effector (not shown) that serves as a working machine is attached to the tip member 40 according to the application of the link operating device 1. The center of the circumference on which each rotating shaft connecting member 41 is arranged is located on the link hub central shaft QB on the distal end side. Each rotating shaft connecting member 41 is rotatably connected to a rotating shaft 42 (FIG. 4) whose axis intersects the link hub central axis QB. One end of the end link member 16 on the tip side is connected to the rotation shaft 42 of the link hub 13 on the tip side. A rotary shaft 45 rotatably connected to the other end of the central link member 17 is connected to the other end of the end link member 16 on the distal end side. The rotary shaft 42 of the link hub 13 on the distal end side and the rotary shaft 45 of the central link member 17 also have the same shape as the rotary shaft 35, and the rotary shaft connecting member 41 and the rotary shaft connecting member 41 via two bearings (not shown) They are rotatably connected to the other ends of the central link member 17.

The attitude control actuator 10 of the link operating device 1 is a rotary actuator provided with a deceleration mechanism 52, specifically, a servomotor with a deceleration mechanism, and is mounted on the upper surface of the base member 6 of the link hub 12 on the proximal end side. , Is installed coaxially with the rotating shaft 22. The attitude control actuator 10 and the deceleration mechanism 52 are integrally provided, and the deceleration mechanism 52 is fixed to the base member 6 by the motor fixing member 53. In this example, attitude control actuators 10 are provided in all three sets of link mechanisms 14. If the attitude control actuators 10 are provided in at least two of the three sets of link mechanisms 14, the posture of the link hub 13 on the distal end side with respect to the link hub 12 on the proximal end side can be determined.

In FIG. 2, the controller 3 is a device that controls the parallel link mechanism 9 of the link actuating device 1, and is a posture change given by a higher-level control means (not shown) or a manually input operating means (not shown). According to the above command, each attitude control actuator 10 is provided with an attitude control means 4 that outputs a command of a rotation angle. The attitude command of the change destination to the controller 3 is given by, for example, the turning angle φ (FIG. 3) and the bending angle θ, but the attitude control means 4 predetermined commands of the given turning angle φ and the bending angle θ. It is converted into a command of the rotation angle of each attitude control actuator 10 according to the calculation formula of, and is output to each attitude control actuator 10. Further, the attitude control means 4 performs feedback control by a servo mechanism (not shown) using a detection signal of a rotation angle detector (not shown) provided in each attitude control actuator 10. When the parallel link mechanism 9 is provided with the end effector (not shown), the controller 3 also controls the end effector.

The controller 3 is provided with a load estimating means 5 for estimating the load acting on the link hub 13 (FIG. 1) on the tip side. Each of the attitude control actuators 10 has a torque detecting means 8, and the load estimating means 5 estimates the acting load of the link hub 13 on the tip side from the detection signals of the torque detecting means 8. The torque detecting means 8 includes, for example, a current sensor that detects a current flowing through each attitude control actuator 10.

The estimation of the acting load of the link hub 13 on the tip side by the load estimation means 5 does not necessarily have to be estimated as a numerical value, and may be a stepwise estimation to the extent that it can be determined whether or not a collision has occurred, for example. .. FIG. 6 shows an example of collision detection, in which the vertical axis shows the torque value detected by each torque detecting means 8 and the horizontal axis shows the passage of time. In the example of the figure, the torque value at the time of acceleration of the attitude control actuator 10 is shown, and the torque value of each attitude control actuator 10 is gradually increasing, but is rapidly increasing at the time t1. .. The load estimating means 5 is a link hub on the tip side from the torque change amount (represented by the gradient of the torque change curve in the figure), which is the change amount of the torque detected by each torque detecting means 8 per unit time. It may be possible to detect that 13 has collided. In this collision detection, it is sufficient to know whether or not the torque change amount exceeds the threshold value, for example. In this collision detection, the load estimating means 5 may determine that the collision is determined when the detection value of any one of the torque detecting means 8 exceeds the threshold value among the detected values of the torque detecting means 8. Further, the collision may be determined by comprehensively judging from the detected values of each torque detecting means 8 according to a predetermined rule.

When the load estimation means 5 has a collision detection function as described above, the attitude control actuator 10 of the controller 3 or the attitude control means 4 is subjected to collision detection by the load estimation means 5. A collision response control means (not shown) that allows the operation to be freely operated by servo-off or the like may be provided. By allowing the parallel link mechanism 9 to move freely by turning off the servo in this way, safety is improved.

In this embodiment, in addition to the collision detection function, the load estimation means 5 has a load value acting on the link hub 13 on the tip side and a direction in which the load acts from each torque value of the torque detecting means 8. Can be detected.
In this example, specifically, the torque acting on each attitude control actuator 10 with respect to the load acting on the link hub 13 on the tip side is measured in advance, and the measurement result is used for each attitude control actuator 10. A table 7 (FIG. 7) is created in which the relationship between the acting torques T1, T2 and T3 and the load acting on the link hub 13 on the tip side is defined, and the detected values of the respective torques T1, T2 and T3 are set as described above. The acting force and direction are obtained by collating with Table 7. The direction in the table 7 is, for example, the turning angle φ of the link hub 13 on the tip side shown in FIG.

Instead of using the table 7 of FIG. 7, the load estimating means 5 is provided with a calculation formula for calculating the load acting on the link hub 13 on the tip side from the torque acting on each attitude control actuator 10 by mechanical analysis. The load acting on the link hub 13 on the distal end side may be estimated from the torque values T1, T2, and T3 detected by the torque detecting means 8.

According to the link actuating device 1 having this configuration, as described above, the link hub 12 on the proximal end side, the link hub 13 on the distal end side, and three or more sets of link mechanisms 14 form the link hub 12 on the proximal end side. On the other hand, a two-degree-of-freedom mechanism is configured in which the link hub 13 on the tip side is rotatable around two orthogonal axes. Although this two-degree-of-freedom mechanism is compact, the movable range of the link hub 13 on the tip side can be widened. By controlling the operation of each attitude control actuator 10, the attitude of the link hub 13 on the distal end side can be arbitrarily changed with respect to the link hub 12 on the proximal end side.

In the link operating device 1 having such a configuration, the torque detecting means 8 is provided in the attitude control actuator 10, and the load estimating means 5 estimates the load acting on the link hub 13 on the tip side from the detection signal of the torque detecting means 8. Therefore, the load can be estimated without providing another sensor on the movable portion such as the link hub 13 on the tip side. Since the load of the link hub 13 on the tip side is transmitted to each attitude control actuator 10 via the link mechanism 14, the load of the link hub 13 on the tip side can be calculated from the torque of each attitude control actuator 10. The torque detecting means 8 can be configured by a simple detecting means such as a sensor that detects a current applied to the attitude control actuator 10.

In this way, the torque detecting means 8 is provided in the attitude control actuator 10, and the load acting on the link hub 13 on the tip side is estimated without providing another sensor on the movable part such as the link hub 13 on the tip side. This leads to compactness of the entire device and cost reduction.
Further, since the link operating device 1 having the above configuration has no singular point within its movable range and can move smoothly in all directions, the attitude control is performed even when a load is applied to the link hub 13 on the tip side from various directions. Torque is reliably transmitted to the actuator 10, and the load can be estimated accurately.

In this embodiment, since the three or more sets of link mechanisms 14 are arranged at equal intervals and the attitude control actuators 10 are provided in all of the link mechanisms 14, torque is transmitted to each attitude control actuator 10 in a well-balanced manner. Will be done. Therefore, the load can be accurately estimated by using the detection signal of the torque detecting means 8 provided in the attitude control actuator 10. Further, since the link mechanism 14 has three sets, the mutual interference of the link mechanism 14 is reduced, the operating range is increased, and the number of parts is reduced, which leads to cost reduction.

Further, the load estimating means 5 has a function of detecting a collision acting on the link hub 13 on the tip side from the amount of torque change detected by the torque detecting means 8.
When something mounted on the link hub 13 on the tip side, for example, an end effector (not shown) collides with something, the torque acting on the attitude control actuator 10 suddenly changes (see the figure). Therefore, it is possible to detect a collision in various directions based on this torque fluctuation amount. With the configuration in which the load estimation means 5 is provided with the collision detection function in this way, even if the link operating device 1 comes into contact with a person or an object, it is possible to take measures such as detecting the contact and stopping the device. , Safety is improved.

The load estimating means 5 further has a function of detecting the load value acting on the link hub 13 on the tip side and the direction in which the load acts from the respective torque values of the torque detecting means 8. If the table 7 or the like is created as described above or a calculation formula is established, the load on the tip side can be estimated from the torque value detected by the torque detecting means 8. When the load acting on the tip is detected with high accuracy, the work by the end effector or the like attached to the link hub 13 on the tip side can be performed with high accuracy.

8 and 9 show other embodiments. Except for the matters to be described in particular, the same is true for the first embodiment shown in FIGS. 1 to 7, so duplicate description will be omitted. In this embodiment, as shown in FIGS. 8 and 9, the link hub 13 on the distal end side is formed in a polygonal shape, and the link hub 12 on the proximal end side is a polygonal base on the base member 6 via a spacer 65. The link hub 12 on the end side is installed. An end effector (not shown) is installed on the link hub 13 on the tip side. Further, the attitude control actuator 10 is connected as shown in FIG.

All three sets of link mechanisms 14 of the parallel link mechanism 9 are made to rotate the end link member 15 on the proximal end side to arbitrarily change the attitude of the link hub 13 on the distal end side with respect to the link hub 12 on the proximal end side. An attitude control actuator 10 and a deceleration mechanism 71 that decelerates and transmits the amount of movement of the attitude control actuator 10 to the end link member 15 on the proximal end side are provided. The attitude control actuator 10 is a rotary actuator, more specifically a servomotor with a speed reducer 52, which is fixed to the base member 6 by a motor fixing member 53. The speed reduction mechanism 71 includes a speed reducer 52 of the attitude control actuator 10 and a gear-type speed reduction unit 73. In the following, spur gears are used for the reduction mechanism 71, but other mechanisms (for example, bevel gears and worm mechanisms) may be used.

The gear-type reduction gear 73 is fixed to a small gear 76 connected to the output shaft of the attitude control actuator 10 via a coupling 75 so that rotation can be transmitted, and an end link member 15 on the base end side, and the small gear is fixed. It is composed of a large gear 77 that meshes with 76. In the illustrated example, the small gear 76 and the large gear 77 are spur gears, and the large gear 77 is a fan-shaped gear in which teeth are formed only on the peripheral surface of the fan shape. The large gear 77 has a larger pitch circular radius than the small gear 76, and the rotation of the output shaft of the attitude control actuator 10 is decelerated and transmitted to the end link member 15 on the proximal end side.

Even when the parallel link mechanism 9 and the attitude control actuator 10 are configured as in this embodiment, the load estimation means 5 of the controller 3 is used to act on the tip of the device from various directions as in the first embodiment. The external force can be detected with a simple and inexpensive configuration, and the safety of the entire device can be improved.

10 and 11 show still other embodiments. Except for the matters to be described in particular, the same is true for the first embodiment shown in FIGS. 1 to 7, so duplicate description will be omitted. In this embodiment, the base end side link hub 12 and the tip end side link hub 13 have a donut shape in which a through hole is formed in the center thereof and the outer shape is spherical. The end link member 15 on the base end side and the end link member 16 on the tip end side rotate at equal intervals in the circumferential direction of the outer peripheral surfaces of the link hub 12 on the base end side and the link hub 13 on the tip end side, respectively. It is freely connected.

FIG. 11 is a cross-sectional view showing a rotational pair portion of the base end side link hub 12 and the proximal end side end link member 15, and a rotational pair portion of the proximal end side end link member 15 and the central link member 17. is there. The link hub 12 on the base end side has three radial shaft holes 81 formed on the outer peripheral portion in the circumferential direction, and the shaft member 83 is rotatably supported by two bearings 82 provided in each shaft hole 81. Has been done. The center of the shaft member 83 coincides with the central axis of the rotational pair of the link hub 12 on the proximal end side and the end link member 15 on the proximal end side. The outer end portion of the shaft member 83 projects from the link hub 12 on the proximal end side, and the end link member 15 on the proximal end side is coupled to the protruding screw portion 83a and is tightened and fixed by the nut 94.

The bearing 82 is a rolling bearing such as a deep groove ball bearing, the outer ring (not shown) of which is fitted to the inner circumference of the shaft hole 81, and the inner ring (not shown) is the outer circumference of the shaft member 83. Fitted in. The outer ring is prevented from coming off by the retaining ring 85. Further, a spacer 86 is interposed between the inner ring and the end link member 15 on the proximal end side, and the tightening force of the nut 84 is transmitted to the inner ring via the end link member 15 on the proximal end side and the spacer 86. Therefore, a predetermined preload is applied to the bearing 82.

Two bearings 89 are provided in the communication holes 88 formed at both ends of the central link member 17 for the rotational pair portion of the end link member 15 and the central link member 17 on the base end side, and these bearings 89 provide the base end side. The shaft portion 90 at the tip of the end link member 15 is rotatably supported. The bearing 89 is tightened and fixed by the nut 92 via the spacer 91.

The bearing 89 is a rolling bearing such as a deep groove ball bearing, the outer ring (not shown) of which is fitted to the inner circumference of the communication hole 88, and the inner ring (not shown) is the outer circumference of the shaft portion 90. Fitted in. The outer ring is prevented from coming off by the retaining ring 93. The tightening force of the nut 92 screwed to the tip threaded portion 90a of the shaft portion 90 is transmitted to the inner ring via the spacer 91 to apply a predetermined preload to the bearing 89. In FIG. 11, the bevel gear 57, which will be described later, is omitted.

The rotation pair portion of the base end side link hub 12 and the base end side end link member 15 and the rotation pair portion of the base end side end link member 15 and the central link member 17 have been described above. The rotary pair portion of the link hub 13 and the end link member 16 on the distal end side, and the rotary pair portion of the end link member 16 and the central link member 17 on the distal end side have the same configuration (not shown).

In this way, the four kinematic pairs of rotation in each link mechanism 14, that is, the kinematic pair of rotation of the base end side link hub 12 and the base end side end link member 15, the tip end side link hub 13 and the tip end side end. Bearings 82 are attached to the rotating pair of the portion link member 16, the proximal end side link member 15, the central link member 17, the rotating pair, and the distal end link member 16 and the central link member 17. By adopting the structure provided with, 89, the frictional resistance at each rotational pair can be suppressed to reduce the rotational resistance, smooth power transmission can be ensured, and durability can be improved.

In FIG. 10, a link hub 12 on the base end side is fixed to the upper surface of the base member 6 via a spacer 65. The attitude control actuator 10 is attached to the lower surface of the base member 6 in a hanging state. The number of attitude control actuators 10 is three, which is the same as that of the link mechanism 14. The attitude control actuator 10 is a rotary actuator, and the bevel gear 56 attached to the output shaft thereof and the fan-shaped bevel gear 57 attached to the shaft member 83 (FIG. 5) of the link hub 12 on the proximal end side are meshed with each other.
In this example, the same number of attitude control actuators 10 as the link mechanism 14 are provided, but if at least two of the three sets of link mechanisms 14 are provided with the attitude control actuator 10, the base end The attitude of the link hub 13 on the tip side with respect to the link hub 12 on the side can be determined.

In this parallel link mechanism 9, by rotationally driving each attitude control actuator 10, the rotation is transmitted to the shaft member 83 via a pair of bevel gears 56 and 57, and the base with respect to the link hub 12 on the proximal end side. The angle of the end link member 15 on the end side is changed. As a result, the position and orientation of the link hub 13 on the distal end side with respect to the link hub 12 on the proximal end side are determined. Here, the bevel gears 56 and 57 are used to change the angle of the end link member 15 on the base end side, but other mechanisms (for example, spur gears and worm mechanisms) may be used.

Even when the parallel link mechanism 9 and the attitude control actuator 10 are configured as in this embodiment, the load estimation means 5 of the controller 3 is used to act on the tip of the device from various directions as in the first embodiment. The external force can be detected with a simple and inexpensive configuration, and the safety of the entire device can be improved.

Although the embodiments for carrying out the present invention have been described above based on the examples, the embodiments disclosed here are examples in all respects and are not limiting. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 ... Link operating device 3 ... Controller 4 ... Attitude control means 5 ... Load estimation means 6 ... Base member 8 ... Torque detecting means 9 ... Parallel link mechanism 10 ... Attitude control actuator 12 ... Base end side link hub 13 ... Tip side Link hub 14 ... Link mechanism 15 ... End link member 16 on the base end side ... End link member 17 on the tip side ... Central link member O1 ... Central axis O2 of rotation pair of link hub and end link member ... End Central axis of rotation pair of link member and central link member PA, PB ... Spherical link center QA, QB ... Central axis of link hub S ... Internal space

Claims (2)

The link hub on the tip side is connected to the link hub on the base end side so that the posture can be changed via three or more sets of link mechanisms, and each of the link mechanisms is connected to the link hub on the base end side and the tip side, respectively. The base end side and tip side end link members rotatably connected to the link hub at one end, and the center rotatably connected to the other ends of these base end side and tip end end link members, respectively. Each link mechanism is a link member, and each link mechanism has a geometric model in which the link mechanism is represented by a straight line, and the proximal end side portion and the distal end side portion with respect to the central portion of the central link member form a symmetry. A two-degree-of-freedom mechanism in which two or more of the three or more sets of link mechanisms are provided with an attitude control actuator that arbitrarily changes the attitude of the tip-side link hub with respect to the base-end-side link hub. In the link activator
A controller for controlling each attitude control actuator is provided, and the controller is provided with an attitude control means for outputting a command to each attitude control actuator, and a load estimation means for estimating a load acting on the link hub on the tip side. The load estimation means has a collision detection function for detecting a collision acting on the link hub on the tip side based on the amount of torque change acting on each attitude control actuator.
A link operating device including a collision response control means that turns off the operation of each attitude control actuator by collision detection of the load estimation means to make it free. The link operating device according to claim 1, wherein each of the attitude control actuators has a torque detecting means, and the load is estimated by the load estimating means from the detection signals of the torque detecting means.

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