JP3573731B2 - Wrist mechanism for master arm - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a master arm for operating a robot or the like in a master-slave manner, and more particularly to a wrist mechanism for accurately feeding back torque of a slave arm.
[0002]
[Prior art]
In a human cooperative and coexisting robot system, a lightweight and portable master arm used for remotely controlling a humanoid robot is required.
The master arm moves the slave arm to be operated, for example, the arm of a humanoid robot, by a person's hand, and can be operated lightly, and the force and torque received by the slave arm can be accurately transmitted to the pilot through the master arm. Feedback is required.
[0003]
2. Description of the Related Art Conventionally, industrial robots and the like use a wrist mechanism having a configuration similar to that of a wrist of a robot arm, and use a master arm that is operated by grasping a lever corresponding to a hand. In this type of master arm, the torque generated in the slave arm is transmitted to the operator's hand as a reaction force of a lever having one end fixed to the rotating shaft. Even with a strong torque, the sensation experienced by the pilot changes depending on the direction. Further, since the counter balance is provided to facilitate the movement of the hand, the overall weight becomes large and the device cannot be easily carried.
When a master arm incorporating a gimbal mechanism is used on the wrist, the operator can feel the torque accurately because the operation is performed while grasping the intersection of the rotation axes. However, since the links are connected in series, the gimbal mechanism becomes large and it is difficult to reduce the weight of the master arm.
[0004]
Furthermore, two links that are orthogonal to the root of the joystick are connected so that the inclination of the joystick is related to the rotation angle of the link shaft. Two degrees of freedom torque are fed back via the rotation angle of the link shaft. A joystick is provided (eg, an Impulse Engine manufactured by Immersion Inc., USA). Such a joystick can be reduced in weight because a motor or a detector for force feedback is not placed on the movable part, but cannot transmit a correct force because the torque is fed back as a parallel force. Further, since the grip portion of the joystick is twisted by the movement of two degrees of freedom, the joystick can be freely rotated around the axis and twisted, so that force feedback cannot be performed for three degrees of freedom.
[0005]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to provide a wrist mechanism of a master arm that is lightweight and that can accurately transmit the torque generated by a slave arm to an operator regardless of the direction.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, a wrist mechanism for a master arm of the present invention includes an arm joint and a grip, and the arm joint has a connection mechanism with an arm at the center and grips at both ends. First and second side beams are supported between the first and second side beams, and one end of the grip portion is connected to the first and second side beams by first and second link mechanisms, respectively. Each of the first and second link mechanisms includes a first link and a second link, and one end of the first link is rotatably connected to the side beam by a first rotation shaft. And the other end of the second link are rotatably connected to each other by a second rotation shaft, and the other end of the second link is rotatably connected to one end of the grip portion by a third rotation shaft. An extension of the first, second, and third rotation axes passes near a rotation center point corresponding to a position where the operator grips the grip portion.
[0007]
In the wrist mechanism for the master arm of the present invention, since the extension of the rotation axis of the link is gathered near the rotation center in the grip portion, when the operator moves the grip portion, it rotates about the position gripped by hand, When teaching the operation to the slave arm, the position of the hand does not change unlike the lever type. Further, since the supporting link mechanism can be configured to be lightweight by combining two links, it is easy to carry the master arm to a required place and use it.
If the rotation center point of the grip is further on the axis of the connection mechanism with the arm, the movement of the wrist can be traced more accurately. In addition, since the system is simplified, the calculation regarding the transmission of the force is simplified. Furthermore, if the connection mechanism is configured to rotate around the axis, the side beams rotate together when the operator rotates the grip, so that the pilot's wrist hits the side beams during the operation. Nothing in the way.
[0008]
The wrist mechanism for the master arm of the present invention is configured such that the outer side of the grip portion rotates by に 対 し て with respect to a change in the intersection angle between the second link of the first link mechanism and the second link of the second link mechanism. Is preferred.
The driver operates while gripping the outer surface of the grip portion. If the grip portion surface is fixed to one of the links, the grip portion is twisted in accordance with the movement of the link and cannot transmit a correct force. In addition, if the grip is made to rotate freely, twisting of the wrist cannot be transmitted. However, if the intermediate position is maintained between the two link mechanisms, rotation of the wrist can also be transmitted.
Therefore, by using a gear mechanism or the like to make the movement of the two links just half the opening and closing movement, the movement of the grip surface caused by the displacement of the link is canceled to maintain the neutrality. I made it.
[0009]
In addition, two motors and two rotation detectors are fixed to the arm joint corresponding to the pair of link mechanisms, and the motor and the rotation detector are connected to the first rotation shaft by, for example, a belt. Can be
It is desired that the operator can operate the master arm to give commands to the robot arm and obtain a force sense on the wrist of the robot arm. For this reason, a rotation detector for measuring the rotation of the first rotation axis is provided to convert the change in the posture of the wrist into the movement of the arm of the slave robot, and the force generated by the slave arm is transmitted via the torque generated by the motor. A master arm wrist is transmitted so that a force sense can be presented to the pilot.
[0010]
In the conventional master arm, these detectors and motors are attached to the movable part, so the weight of the part moved by the operator becomes excessive and extra inertial force acts, resulting in poor maneuverability and accurate force sense. It was difficult to communicate.
In the wrist mechanism of the present invention, since the motor and the rotation detector are fixed to the arm joint, the weight of the movable part handled by the operator's hand is reduced, the maneuverability and the force presentation performance are improved, and the wrist mechanism can be used. Portability is improved.
[0011]
Further, the force sensor may be arranged at the end where the counterweight is installed, which is located on the opposite side of the end of the grip from which the link mechanism is connected.
When a link is connected to one end of the grip, it is preferable to provide a counterweight at the opposite end so that these loads can be offset. Therefore, by providing a force sensor for measuring the force applied to the wrist by the operator together with the counterweight as a part of the counterweight, it is possible to avoid an increase in load due to the attachment of the sensor and to achieve a lightweight wrist mechanism. be able to.
[0012]
Further, the wrist mechanism of the present invention receives the pilot's wrist by expanding the angle formed by the first rotation axis of the first link mechanism and the first rotation axis of the second link mechanism, that is, the base angle to an obtuse angle. It is preferable to make the grip part easy to handle.
The range in which the grip portion can be tilted differs between the direction sandwiched between the two side beams (X-axis direction) and the direction parallel to the two side beams (Y-axis direction), and also differs depending on the base angle. . Further, the angle varies depending on the angle between the first rotation axis and the second rotation axis. As this angle decreases, the movable range in the X-axis direction increases, and the movable range in the Y-axis direction decreases.
[0013]
Therefore, by appropriately selecting the angle formed by the first rotation axis and the second rotation axis with respect to the base angle, the movable range of the X axis and the Y axis can be set to a predetermined value. When the base angle is set to an obtuse angle, the X-axis and the Y-axis can be balanced in the movable range of the grip portion by setting the angle to an acute angle.
If the angle between the first rotation axes of the two link mechanisms is about 120 ° and the angle between the first and third rotation axes in the link mechanism is about 80 °, the XY It is particularly preferable because the same movable range of about 75 ° can be obtained in the axial direction.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a wrist mechanism for a master arm of the present invention will be described in detail based on embodiments with reference to the drawings.
FIG. 1 is a perspective view showing a wrist mechanism of this embodiment, FIG. 2 is a partially cutaway perspective view showing a gear mechanism of a grip portion in this embodiment, and FIG. 3 is a partially cutaway view showing a counterweight portion of the grip portion. FIG. 4 is a perspective view showing a state in which the wrist mechanism of the present embodiment is incorporated in a master arm, FIG. 5 is a plan view of the grip portion for explaining a base angle and the like, and FIG. 6 and FIG. FIG. 5 is a diagram illustrating a movable range of a unit.
[0015]
As shown in FIG. 1, a wrist mechanism 100 for a master arm according to the present embodiment includes a bridge unit 1 and a grip unit 3. The bridge portion 1 is formed in a U-shape by a base 11 and side beams 12 and 13 provided at side ends thereof.
The base 11 has a connection shaft 14 connected to the arm of the master arm, a motor for driving the connection shaft via a belt, and a rotation sensor 15 for measuring the number of rotations of the connection shaft.
Each of the side beams 12 and 13 includes rotation sensors 16 and 17 and motors 18 and 19 having a common axis at the base of the base, and pulleys 20 and 21 at the ends of the axes. Pulleys 22 and 23 are provided at the ends of the side beams 12 and 13, respectively. These pulleys are connected by belts 24 and 25 and rotate together with the root side pulleys 20 and 21.
[0016]
The grip section 3 includes a grip section 31 and link mechanisms 32 and 33.
The link mechanisms 32 and 33 include first links 34 and 35 and second links 36 and 37 formed in an L-shape, respectively.
The first links 34 and 35 have first rotating shafts 38 and 39 at one end, and the rotating shafts are fixed to the root pulleys 22 and 23 of the side beams 12 and 13, and the links are integrated with the pulleys. It is designed to rotate. The other ends of the first links 34 and 35 are rotatably connected to one ends of the second links 36 and 37 via second rotation shafts 40 and 41.
[0017]
The axis extension of the first rotation shafts 38 and 39 and the axis extension of the second rotation shafts 40 and 41 are arranged so as to intersect the axis extension of the grip portion 31 at substantially one point O. The point O is the center of rotation of the grip 31.
The other ends of the second links 36 and 37 are independently rotated with respect to a third rotation shaft 42 provided together at the tip of the grip portion 31 so as to coincide with the axis of the grip portion 31. It is supposed to.
The grip portion 31 has a cylindrical portion that is gripped by the operator, and has a counter weight 61 attached to an end on the opposite side of the third rotation shaft 42.
[0018]
Note that a gear mechanism 51 as shown in FIG. 2 is provided on the third rotating shaft portion. The gear mechanism 51 has a first gear 52 fixed to the second link 37 of the second link mechanism 33 and a second gear fixed to a shaft 53 rotatably set on the second link 36 of the first link mechanism 32. It comprises a gear 54, a third gear 55, and a fourth gear 57 provided at the tip of a shaft 56 fixed to the outer cylinder of the grip portion 31.
When the gear ratio between the first gear 52 and the second gear 54 is 1: 1 and the gear ratio between the third gear 55 and the fourth gear 57 is 1: 2, the second link 37 of the second link mechanism is connected in the figure. When the right gear is opened to the right, the first gear rotates left and the second gear rotates right by the same angle as the opening angle, so the fourth gear driven by the third gear rotating integrally with the second gear is the second link. Rotate counterclockwise by half the opening angle.
[0019]
Further, when the second link 37 of the second link mechanism is stationary and the second link 36 of the first link mechanism opens to the left in the drawing, the fourth gear 47 rotates the rotation angle of the third gear 55. Rotate right by 1/2.
Therefore, the outer cylinder of the grip portion fixed to the fourth gear 47 is held at a neutral position with respect to the second links 36 and 37.
[0020]
As can be seen from FIG. 3 in which a part of the grip portion is cut away, a counter weight portion 61 for storing a counter weight for canceling the influence of the load of the link mechanism is provided at the end of the grip portion 31. However, a force sensor 62 for measuring a force applied to the grip portion 31 by the operator can be housed here. If all or part of the counterweight is replaced by the load of the force sensor 62, no useless load will be added even if a force sensor is added to the movable part.
[0021]
The wrist mechanism 100 of the present embodiment is attached to the tip of the master arm 200 using the connection mechanism 14, as shown in FIG. 4, for example. The master arm 200 is provided with a rotation detector that measures the rotation around the axis for each link and a motor that generates a force fed back from the slave arm. Then, based on the movement of the link mechanism of the master arm, the amount of movement of the link mechanism of the slave arm is calculated and taught, and feedback is provided so that the reaction force generated by the slave arm can be sensed by the operator. In addition, a counterweight is provided for each link so that the operator can easily move the link mechanism by canceling the load weight on the link.
[0022]
When the operator inclines the grip portion 31, the first rotation shafts 38 and 39 rotate, and the rotation detectors 16 and 17 detect the amount of rotation, and an arithmetic circuit (not shown) outputs the grip portion 31 from the output. Is calculated, and the corresponding link change amount of the slave arm is calculated to change the wrist posture. In addition, since the rotation center position O of the grip portion 31 maintains its spatial position even if the posture changes as long as the wrist mechanism 100 does not move, the inclination can be easily calculated.
[0023]
When the pilot gives an instruction of the posture, if the rotation center O of the grip portion 31 is squeezed to the center of the hand, unlike the conventional control stick type posture indicating mechanism, the posture change of the hand is not performed. , The pilot can more naturally and intuitively operate.
Further, since the heavy motor and the detector are installed in the bridge section 1, the steering can be performed with a small force without causing inertial resistance to the movement of the wrist. Although the force sensor 62 for detecting the rotational force of the wrist is attached to the grip portion 31, it is used as a counterweight, so that there is no extra inertial resistance.
[0024]
Further, when the torque generated by the slave arm is fed back to the master arm 200 and the wrist mechanism 100 thereof, the force transmitted to the grip portion 31 is also transmitted from the motors 19 and 20 through the first rotation via the belts 24 and 25. By rotating the shafts 38, 39, it is given to the pilot's hand as a couple about the rotation center O. That is, since the moment is transmitted purely as compared with the conventional example in which the lever is tilted to transmit the force and transmitted as a parallel force, the slave arm is accurately steered based on accurate force feedback. be able to.
[0025]
When the outer cylinder of the grip portion 31 is rotated around the axis with respect to the neutral position, the rotational force is measured by the force sensor 62 and transmitted to the slave arm to rotate the wrist by a corresponding amount. Can be.
In the case where the connection mechanism 14 is configured to rotate in accordance with the rotation of the grip portion 31, even if the arm rotates with the wrist of the operator holding the grip portion 31, the connection mechanism 14 may be moved in accordance with the movement of the arm. Since the entire wrist mechanism 100 rotates, there is no inconvenience that the arm hits the side beams 12 and 13 and cannot be moved any more.
[0026]
In order to make it easier for the operator to insert the wrist when grasping the grip portion 31, as shown in FIG. 5 in which the grip portion is viewed from above, the first rotation shaft 38 of the first link mechanism and the second rotation mechanism of the second link mechanism are used. The angle α between one rotation shaft 39 is an obtuse angle such as 120 °. Here, this angle α is called a base angle.
Note that there is a limit to the inclination angle of the grip portion 31 due to the relationship between the links, and furthermore, the direction between the two side beams 12 and 13 (X-axis direction) and the direction parallel to the two side beams (X axis direction). (Y-axis direction). Also, it varies depending on the base angle α, and further varies depending on the angle θ between the first rotation axis and the second rotation axis. The angle θ is called a link spread angle, and the bending angle φ of the first links 34 and 35 is called a link angle. The link angle φ and the link spread angle θ are complementary to each other.
[0027]
FIG. 6 illustrates the result of observing the operating angle range of the grip portion 31 when the base angle α is 90 ° while changing the link angle φ. FIG. 7 is a diagram in which the operation range when the base angle α is 120 ° is plotted with respect to the link angle φ.
From these two diagrams, it can be seen that as the link angle φ increases, that is, as the link spread angle θ decreases, the movable range in the X-axis direction increases and the movable range in the Y-axis direction decreases. When the base angle is 90 °, the tiltable operating angles in the X-axis direction and the Y-axis direction become substantially equal when the link angle φ is around 93 °, and when the base angle φ is 120 °, the link angle φ is approximately It can be seen that at 98 ° the operating angles are approximately equal and about 75 °.
Therefore, when the base angle α of 120 ° at which the wrist is easy to be inserted is selected and the link angle φ is set to 100 ° and the link spread angle θ is set to 80 °, the wrist can be inclined almost equally in any direction. .
It should be noted that by selecting the link spread angle θ, it is also possible to weight and adjust so that the operation angle range depending on the direction becomes an appropriate ratio.
[0028]
As described above, according to the wrist mechanism for the master arm of the present embodiment, the motor and the detector are arranged in the bridge portion without being arranged in the grip portion, and the force sensor is arranged in the counter balance position. The weight can be reduced, and it is possible to easily cope with a case where the device is used by moving to a necessary place.
Further, since the rotation center is located inside the grip portion, the torque generated in the hand of the slave arm can be fed back as a couple, and the torque presentation is isotropic. Furthermore, since the grip portion moves neutrally with respect to the movement of the link, the rotational motion of the hand can be transmitted accurately.
Furthermore, since the base angle and the link spread angle are appropriately selected, the wrist can be easily inserted, and the tiltable range of the grip portion is substantially equal in all directions.
[0029]
In the wrist mechanism of the present embodiment, the second link of the first link mechanism and the second link of the second link mechanism are rotatably connected to the same end of the grip portion, but are separately connected to both ends. Needless to say, they belong to the same technical idea and exhibit the same functions and effects.
Also, the wrist mechanism of the present embodiment has been described as being incorporated in a master arm fixed on a desk, but it may be incorporated in a master arm in which the arm is arranged along the operator's arm. .
Furthermore, in the figure, the motor and the rotation detector are shown as separate ones. However, even if the motor and the rotation detector are integrated, such as one that detects the rotation speed from the magnetizing current of the motor, Good.
[0030]
【The invention's effect】
As described above, when the master arm wrist mechanism of the present invention is used by being attached to the master arm, the wrist mechanism is small and lightweight, has low inertia resistance, and can control the posture of the hand without being interfered with the position control of the hand. Further, since the torque generated in the slave arm is isotropically fed back to the operator's hand, the hand of the slave arm can be operated based on a feeling close to the actual feeling.
[Brief description of the drawings]
FIG. 1 is a perspective view of a wrist mechanism for a master arm according to an embodiment of the present invention.
FIG. 2 is a partially cutaway perspective view showing a gear mechanism of a grip portion in the embodiment.
FIG. 3 is a partially cutaway perspective view showing a counterweight portion of the grip portion in the embodiment.
FIG. 4 is a perspective view showing a state where the wrist mechanism of the present embodiment is attached to a master arm.
FIG. 5 is a plan view of the grip portion of the present embodiment as viewed from above.
FIG. 6 is a diagram showing a movable range of a grip portion in the embodiment.
FIG. 7 is a second diagram showing a movable range of the grip portion in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Bridge part 3 Grip part 11 Base 12, 13 Side beam 14 Connection axis 15 Rotation sensor 16, 17 Rotation sensor 18, 19 Motor 20, 21, 22, 23 Pulley 24, 25 Belt 31 Handle part 32, 33 Link mechanism 34, 35 First link 36, 37 Second link 38, 39 First rotating shaft 40, 41 Second rotating shaft 42 Third rotating shaft 51 Gear mechanism 52 First gear 53 Shaft 54 Second gear 55 Third gear 56 Shaft 57 Fourth gear 61 Counter weight 62 Force sensor 100 Master arm wrist mechanism 200 Master arm

Claims (8)

A wrist mechanism for a master arm having an arm joint and a grip, wherein the arm joint has a connecting mechanism with an arm in the center and supports a grip at both ends between the first and second wrist mechanisms. A side beam is provided, and one end of the grip portion is connected to the first side beam and the second side beam by first and second link mechanisms, respectively, and the link mechanisms are respectively a first link. And a second link, one end of the first link is rotatably connected to the side beam by a first rotation shaft, and the other end of the first link and one end of the second link are connected to the second link. The other end of the second link is rotatably connected to one end of the grip portion by a third rotation shaft, and the other end of the second link is rotatably connected to the one end of the grip portion by a driving shaft . The extension of the rotation axis and the second rotation axis intersect at one point fixed to the arm joint in the grip. To form a rotation center point of the grip portion, the operator wrist mechanism master arm, characterized in that configured to be operable by gripping the該握Ri portion in the rotational center point position. 2. The wrist mechanism for a master arm according to claim 1, wherein a rotation center point of the grip portion is on an extension of an axis of the connection mechanism, and the connection mechanism rotates around the axis. 3. The grip according to claim 1, wherein the grip portion is configured to make a half turn with respect to a change in an intersection angle between the second links of the first and second link mechanisms. 4. Wrist mechanism for master arm. The arm joint further includes a motor that transmits a reaction force generated in the slave arm to the grip, and a rotation detector that detects a movement of the first rotation axis. 4. The wrist mechanism for a master arm according to claim 1, wherein the wrist mechanism is connected to a motor and the rotation detector. The wrist mechanism for a master arm according to any one of claims 1 to 4, wherein a force sensor is arranged at an end of the grip portion opposite to an end to which the link mechanism is connected. The angle between the first rotation axes of the first and second link mechanisms is formed at an obtuse angle so that the grip portion can be easily handled by the operator's hand. Wrist mechanism for master arm. 7. The master arm for a master arm according to claim 6, wherein an angle formed by the first rotation axis and the third rotation axis is selected so as to adjust a tiltable angle of the grip portion to a range determined by a direction. Wrist mechanism. An angle formed by the first rotation axes of the first and second link mechanisms is about 120 °, and an angle formed by the first rotation axis and the second rotation axis is about 80 °. The wrist mechanism for a master arm according to any one of claims 1 to 5, wherein

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