JP2003145455A - Wrist mechanism for master arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight wrist mechanism for a master arm which can correctly transmit the torque generated by a slave arm to a steering operator irrespective of the direction. SOLUTION: This wrist mechanism comprises an arm joining part 1 having a connection mechanism 14 to an arm, a first side beam 12 and a second side beam 13, and a grip part 31 supported between two side beams by connecting an end part to a space between the first and second side beams by a first link mechanism 32 and a second link mechanism 33. The link mechanisms 32 and 33 comprise first links 34 and 35 and second links 36 and 37 turnably connected to each other by second turning shafts 40 and 41. One end of the first links is turnably connected to the side beams by first turning shafts 38 and 39, and one end of the second links is turnably connected to one end of the grip part by a third turning shaft 42. Extensions of the first and second turning shafts pass in the vicinity of the center O of rotation corresponding to the position of the gripping position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master arm for operating a robot or the like in a master-slave system,
In particular, it relates to a wrist mechanism for accurately feeding back the torque of the slave arm.

[0002]

2. Description of the Related Art A human collaborative / coexistence type robot system requires a lightweight and portable master arm used for remotely controlling a humanoid robot. The master arm is moved manually by a person, and the movement is controlled by the slave arm,
For example, in order to move the arm of a humanoid robot, it is required to be lightly operated and to accurately feed back the force and torque received by the slave arm to the operator through the master arm.

Conventionally, in industrial robots and the like, a wrist mechanism having a structure similar to that of the wrist of a robot arm has been used, and a master arm for grasping and operating a lever corresponding to the hand has been used. This type of master arm transmits the torque generated in the slave arm to the operator's hand as the reaction force of the lever with one end fixed to the rotating shaft, and the torque is converted into a parallel force instead of a couple force. Even with strong torque, the sensation experienced by the driver changes depending on the direction. Further, since the counter balance is provided to facilitate the movement of the hand, the weight of the whole is large and it cannot be easily carried. If a master arm incorporating a gimbal mechanism is used on the wrist, the operator grasps the intersection of the rotation axes and operates, so that the operator can feel the torque accurately. 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.

Further, two links which are orthogonal to the root of the joystick are connected to associate the inclination of the joystick with the rotation angle of the link shaft. Two degrees of freedom torque is transmitted through the rotation angle of the link shaft. A joystick that can provide feedback is provided (for example, Immersion Inc. Impulse Engine). Such a joystick can be reduced in weight because a motor for force feedback and a detector are not placed on the movable part, but the torque is fed back as a parallel force, so that correct force transmission cannot be performed. Further, since the grip portion of the joystick is twisted by the movement of two degrees of freedom, the joystick is allowed to freely rotate around the axis to take the twist, so that the force feedback cannot be performed for the three degrees of freedom.

[0005]

The problem to be solved by the present invention is to provide a wrist mechanism of a master arm which is lightweight and which can accurately transmit the torque generated in the slave arm to the operator regardless of the direction. Is to provide.

[0006]

In order to solve the above problems, a wrist mechanism for a master arm of the present invention is provided with an arm joint and a grip, and the arm joint has a connection mechanism with the arm at the center. Provided at both ends are first and second side beams that support the grip portion between each other, and the first and second side beams are respectively provided between one end portion of the grip portion and the first side beam and the second side beam. Connect by link mechanism. The first and second link mechanisms are respectively configured by a first link and a second link, and one end of the first link is rotatably connected to the side beam by the first rotation shaft. The other end of the second link and one end of the second link are rotatably connected to each other by the second rotation shaft, and the other end of the second link is rotatably connected to one end of the grip portion by the third rotation shaft. The extension of the first rotation axis, the second rotation axis, and the third rotation axis passes near the rotation center point corresponding to the position where the operator grips the grip portion.

In the wrist mechanism for the master arm of the present invention, the extension of the rotary shaft of the link is gathered in the vicinity of the center of rotation in the grip, so that when the operator moves the grip, it is centered on the position gripped by the hand. The position of the hand does not change when rotating and teaching the operation to the slave arm unlike the lever type. Further, since the supporting link mechanism can be constructed by combining two links to be lightweight, the master arm can be easily carried and used where necessary. Furthermore, if the center of rotation of the grip is on the axis of the connecting mechanism with the arm, the movement of the wrist can be traced more accurately. Further, since the system is simple, the calculation related to the force transmission becomes simple. Furthermore, if the connection mechanism is configured to rotate about the axis, the side beams will rotate together when the operator rotates the grip, so that the wrist of the operator hits the side beams during steering. It doesn't get in the way.

In the master arm wrist mechanism of the present invention, the outer side of the grip portion is rotated by a half rotation with respect to the change in the crossing angle between the second link of the first link mechanism and the second link of the second link mechanism. Is preferably configured. The driver grips the outer surface of the grip to drive, but if the surface of the grip is fixed to one of the links, the grip twists according to the movement of the link, and the correct force cannot be transmitted. Further, if the grip portion is allowed to rotate freely, the twist of the wrist cannot be transmitted. However, if the intermediate position is held between the two link mechanisms, the rotation of the wrist can be transmitted. Therefore, for example, by using a gear mechanism or the like, the movement of the grip portion surface caused by the displacement of the links is canceled by keeping the neutrality by moving the movement of the links by half. I chose

Further, two motors and two rotation detectors are fixed to the arm joints respectively corresponding to the pair of link mechanisms, and the motor and the rotation detector are attached to the first rotating shaft by, for example, a belt. It can be connected. It is desired that the operator can operate the master arm to give a command to the robot arm and obtain a force sensation applied to the wrist of the robot arm. Therefore, a rotation detector that measures the rotation of the first rotation axis is provided to convert the posture change 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. The master arm is designed so that it can be transmitted to the wrist so that the force can be presented to the operator.

In the conventional master arm, since these detectors and motors are attached to the movable part, the weight of the part moved by the operator becomes excessive and an excessive inertial force acts, resulting in poor maneuverability and accuracy. It was difficult to transmit such a force sense. In the wrist mechanism of the present invention, since the motor and the rotation detector are fixed to the arm joint portion, the weight of the movable portion handled by the operator's hand is reduced, the maneuverability and the force presentation performance are improved, and the wrist mechanism is flexible. Portability is improved.

Furthermore, the force sensor may be arranged at the end of the grip portion, which is opposite to the end to which the link mechanism is connected and where the counter weight is normally installed. When the link is connected to one end of the grip portion, it is preferable to provide a counterweight at the opposite end portion so as to cancel these loads. Therefore, a force sensor that measures the force applied to the wrist by the operator is provided as a part of this counter weight together with the counter weight to avoid an increase in load due to the attachment of the sensor, and to provide a lightweight wrist mechanism. be able to.

Further, according to the wrist mechanism of the present invention, the angle formed by the first rotating shaft of the first link mechanism and the first rotating shaft of the second link mechanism, that is, the base angle is expanded to an obtuse angle to allow the operator to operate. It is preferable that the wrist is easily received and the grip is easily handled. The range in which the grip portion can be tilted differs between the direction sandwiched by the two side beams (X-axis direction) and the direction parallel to the two side beams (Y-axis direction), and also depends on the base angle. . Further, it also changes depending on the angle formed by the first rotation axis and the second rotation axis, and as this angle becomes smaller, X
The movable range in the axial direction becomes large, and the movable range in the Y-axis direction becomes small.

Therefore, the movable range of the X-axis and the Y-axis can be set to a predetermined value by properly selecting the angle formed by the first rotary shaft and the second rotary shaft with respect to the base angle. . When the base angle is an obtuse angle, if the angle is an acute angle, it is possible to balance the movable range of the grip portion between the X axis and the Y axis. When the angle formed by the first rotating shafts of the two link mechanisms is about 120 ° and the angle formed by the first rotating shaft and the third rotating shaft in the link mechanism is about 80 °, both XY This is particularly preferable because a movable range of about 75 ° can be taken 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, and FIG.
Is a partially cutaway perspective view showing the gear mechanism of the grip portion in this embodiment, FIG. 3 is a partially cutaway perspective view showing the counterweight portion of the grip portion, and FIG. 4 is the wrist mechanism of this embodiment as a master arm. FIG. 5 is a perspective view showing the assembled state, FIG. 5 is a plan view for explaining the base angle and the like seen from above the grip portion, and FIG.
FIG. 7 is a diagram showing a movable range of the grip portion.

As shown in FIG. 1, the master arm wrist mechanism 100 of this embodiment comprises a bridge portion 1 and a grip portion 3. The bridge portion 1 is formed in a U-shape by a base 11 and side beams 12 and 13 provided at the side ends thereof. Foundation 1
1 is equipped with a connecting shaft 14 connected to the arm of the master arm, a motor for driving the connecting shaft 14 via a belt, and a rotation sensor 15 for measuring the number of rotations of the connecting shaft. Also, the side beams 12,
13 is a rotation sensor 1 sharing a shaft at the base side
6, 17 and motors 18, 19 and pulleys 20, 21 at the tip of the shaft. Further, pulleys 22 and 23 are provided at the tips of the side beams 12 and 13, respectively, and these pulleys are connected by belts 24 and 25 to form base side pulleys 20 and 21.
It is designed to rotate with.

The grip part 3 includes a grip part 31 and a link mechanism 3.
It is composed of 2, 33. The link mechanisms 32 and 33 are composed of first links 34 and 35 and second links 36 and 37, respectively, which are L-shaped. The first links 34, 35 have first rotating shafts 38, 39 at one ends thereof, and these rotating shafts serve as side beams 1.
It is fixed to the root side pulleys 22 and 23 of 2, 13,
The link rotates together with the pulley. The other ends of the first links 34, 35 are connected to the second rotation shaft 4
It is rotatably connected to one ends of the second links 36 and 37 via 0 and 41.

The axial extension of the first rotary shafts 38 and 39 and the axial extension of the second rotary shafts 40 and 41 are arranged so as to intersect the axial extension of the grip portion 31 at approximately one point O. The point O is the center of rotation of the grip 31. Further, the other ends of the second links 36 and 37 are independently rotated with respect to a third rotation shaft 42 which is provided so as to be brought together at the tip of the grip 31 and to coincide with the axis of the grip 31. It is supposed to do. The grip 31 is
The portion gripped by the operator is formed into a cylindrical shape, and the third rotation shaft 42
A counterweight 61 is attached to the opposite end of the counterweight.

A gear mechanism 51 as shown in FIG. 2 is provided on the third rotating shaft portion. The gear mechanism 51 is
The first fixed to the second link 37 of the second link mechanism 33
The gear 52, the second gear 54 and the third gear 55 fixed to the shaft 53 rotatably set on the second link 36 of the first link mechanism 32, and the shaft 56 fixed to the outer cylinder of the grip 31. The fourth gear 57 is provided at the tip of the. The gear ratio of the first gear 52 and the second gear 54 is 1: 1.
When the gear ratio of the third gear 55 and the fourth gear 57 is set to 1: 2, when the second link 37 of the second link mechanism is opened to the right in the figure, the first gear rotates counterclockwise and the second gear moves. Since it rotates clockwise by the same angle as the opening angle, the fourth gear driven by the third gear that rotates integrally with the second gear rotates counterclockwise by half the opening angle of the second link.

When the second link 37 of the second link mechanism is stationary and the second link 36 of the first link mechanism opens leftward in the drawing, the fourth gear 47 is the third gear 5.
Rotate to the right by 1/2 of the rotation angle of 5. Therefore, the outer cylinder of the grip portion fixed to the fourth gear 47 is held at the neutral position with respect to the second links 36 and 37.

As can be seen from FIG. 3 in which a part of the grip portion is cut out, a counterweight portion 61 for accommodating a counterweight for canceling the influence of the load of the link mechanism is provided at the end of the grip portion 31. A force sensor 62 for measuring the force applied to the grip 31 by the operator is provided here.
Can be stored. If all or part of the counter weight is replaced by the load of the force sensor 62, adding a force sensor to the movable portion does not add unnecessary load.

The wrist mechanism 100 of this embodiment uses a master arm 2 with a connecting mechanism 14 as shown in FIG. 4, for example.
It is attached to the tip of 00. 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, and the operator grasps the grip 31 to define the position of the hand. Then, based on the movement of the link mechanism of the master arm, the amount of movement of the slave arm in the link mechanism is calculated and taught, and the reaction force generated by the slave arm is fed back so that it can be sensed by the operator. In addition, a counterweight is provided for each link in order to cancel the load weight on the links so that the operator can easily move the link mechanism.

When the operator tilts the grip 31, the first rotation shafts 38 and 39 rotate, and the rotation amount is detected by the rotation detector 16 and the rotation detector 16.
17, the arithmetic circuit (not shown) calculates the inclination of the grip 31 from the output, calculates the link change amount of the slave arm corresponding to this, and changes the posture of the wrist. In addition, the rotation center position O of the grip 31 is the wrist mechanism 10
As long as 0 does not move, the spatial position is maintained even if the posture changes, so the tilt calculation is easy.

When the operator gives a posture instruction, if the rotation center O of the grip portion 31 is grasped at the center of the hand, the hand does not change position unlike the conventional control stick type posture instruction mechanism. The operator can instruct the robot more naturally and intuitively. In addition, since the heavy motor and detector are installed in the bridge portion 1, they do not act as inertial resistance to the movement of the wrist and can be operated with a small force. The force sensor 62 for detecting the rotational force of the wrist is attached to the grip portion 31, but since it is used as a counter weight, it does not cause extra inertial resistance.

Further, even when the torque generated in the slave arm is fed back to the master arm 200 and its wrist mechanism 100, the force transmitted to the grip portion 31 is transmitted from the motors 19 and 20 via the belts 24 and 25 to the first position. By rotating the 1 rotary shafts 38 and 39, a couple force around the rotation center O is given to the operator's hand. That is, as compared with the conventional example in which the lever is tilted to transmit a force and the force is transmitted as a parallel force, the moment is purely transmitted, so that the slave arm is accurately controlled based on accurate force feedback. be able to.

When the outer cylinder of the grip 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, and the wrist is moved by the corresponding amount. It can be rotated. The connection mechanism 14
When the grip portion 31 rotates with the rotation of the grip portion 31, even if the arm rotates with the wrist of the operator who grips the grip portion 31, the entire wrist mechanism 100 responds to the movement of the arm. Since the arm rotates, there is no inconvenience that the arm hits the side beams 12 and 13 and cannot move further.

In order to make it easier for the operator to insert his / her wrist when gripping the grip portion 31, as shown in FIG. 5 when the grip portion is viewed from above, the first rotating shaft 38 and the second link 38 of the first link mechanism are connected. The angle α between the first rotation shafts 39 of the mechanism 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 31 due to the relationship between the links, and moreover, the direction sandwiched between the two side beams 12 and 13 (X-axis direction) and the direction parallel to the two side beams ( (Y-axis direction). It also varies depending on the base angle α, and further changes depending on the angle θ formed by the first rotation axis and the second rotation axis. The angle θ is called the link spread angle,
The bending angle φ of the first links 34, 35 is called the link angle. The link angle φ and the link spread angle θ are complementary to each other.

FIG. 6 shows the results of observation of the operating angle range of the grip 31 when the base angle α is 90 ° and the link angle φ is changed. In addition, FIG. 7 shows the operating range when the base angle α is 120 ° as the link angle φ.
It is the diagram plotted with respect to. From these two diagrams, it can be seen that the movable range in the X-axis direction increases and the movable range in the Y-axis direction decreases as the link angle φ increases, that is, the link spread angle θ decreases. Then, when the base angle is 90 °, the tiltable operation angles in the X-axis direction and the Y-axis direction become substantially equal when the link angle φ is around 93 °, and the base angle φ is 120 °.
When, the link angle φ is about 98 ° and the operating angles are almost equal to about 75 °. Therefore, when the base angle α of 120 ° where the wrist is easily inserted is selected, if the link angle φ is 100 ° and the link spread angle θ is 80 °, the wrist can be tilted almost equally in any direction. . By selecting the link spread angle θ, weighting can be adjusted so that the operation angle range depending on the direction has an appropriate ratio.

As described above, according to the wrist mechanism for the master arm of this embodiment, the motor and the detector are not arranged in the grip portion but in the bridge portion, and the force sensor is arranged in the counter balance position. The wrist mechanism can be made lighter in weight, and can be easily accommodated when it is moved to a required place and used. Also, because the center of rotation is inside the grip,
The torque generated in the hand of the slave arm can be fed back as a couple, and the torque presentation is isotropic.
Further, since the grip portion moves neutrally with respect to the movement of the link, the rotational movement of the hand can be accurately transmitted. Further, 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 the same in all directions.

In the wrist mechanism of this embodiment, the first link mechanism and the second link of the second link mechanism are rotatably connected to the same end of the grip, but they are separately attached to both ends. It goes without saying that the connected ones also belong to the same technical idea and exhibit the same action and effect. Further, although the wrist mechanism of the present embodiment has been described as being incorporated in the master arm fixed on the desk, it may be incorporated in the master arm so that the arm is arranged along the arm of the operator. . Furthermore, although the motor and the rotation detector are shown separately in the figure, even if the motor and rotation detector are integrated, such as those that detect the rotation speed from the motor's revolving current, Good.

[0030]

As described above, when the wrist mechanism for a master arm of the present invention is used by being attached to the master arm, it is small and lightweight, has a small inertial resistance, and the hand posture can be controlled without being interfered with the hand position control. You can control. Further, since the torque generated in the slave arm is isotropically fed back to the operator's hand, it is possible to operate the hand of the slave arm based on a feeling close to the actual feeling.

[Brief description of 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 present embodiment.

FIG. 3 is a partially cutaway perspective view showing a counterweight portion of a grip portion in the present embodiment.

FIG. 4 is a perspective view showing a state in which the wrist mechanism of this embodiment is attached to a master arm.

FIG. 5 is a plan view of the grip of the present embodiment as seen from above.

FIG. 6 is a diagram showing a movable range of a grip portion in the present embodiment.

FIG. 7 is a second view showing the movable range of the grip portion in the present embodiment.
FIG.

[Explanation of symbols]

1 bridge section 3 grip part 11 foundation 12,13 Side beam 14 connection axis 15 Rotation sensor 16,17 Rotation sensor 18, 19 motor 20, 21, 22, 23 pulleys 24,25 belt 31 grip 32,33 link mechanism 34,35 1st link 36,37 2nd link 38, 39 First rotation axis 40, 41 second rotation axis 42 Third rotation axis 51 gear mechanism 52 1st gear 53 shaft 54 second gear 55 Third Gear 56 shaft 57 4th gear 61 Counter weight part 62 force sensor 100 Wrist mechanism for master arm 200 master arm

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryota Ianaka             118 Futatsuka, Noda City, Chiba Prefecture Kawasaki Heavy Industries             Noda Factory Co., Ltd. F-term (reference) 3C007 JT05 KS33                 3J105 AA02 AA12 AB47 AB50 AC01

Claims (8)

[Claims] 1. A wrist mechanism for a master arm comprising an arm joint and a grip, wherein the arm joint has a connecting mechanism with an arm at the center thereof, and both ends support the grip between them. 1
And a second side beam, the one end of the grip and the first side
The side beams and the second side beams are connected by the first and second link mechanisms, respectively, and the link mechanisms are respectively configured by the first link and the second link, and one end of the first link is the first link. One pivot shaft is rotatably connected to the side beam, and the other end of the first link and one end of the second link are pivotally connected to each other by a second pivot shaft. The other end is rotatably connected to one end of the grip portion by a third rotation shaft, and the grip portion has a rotation center point corresponding to a position gripped by an operator, and the first rotation shaft and the first rotation shaft. 2. A wrist mechanism for a master arm, characterized in that the extension of two pivots passes near the center of rotation. 2. The wrist for a master arm according to claim 1, wherein the center of rotation of the grip portion is on an extension of the axis of the connection mechanism, and the connection mechanism rotates about the axis. mechanism. 3. The outside of the grip portion is 1 with respect to a change in crossing angle between the second links of the first and second link mechanisms.
3. The wrist mechanism for a master arm according to claim 1 or 2, wherein the wrist mechanism for a master arm is configured so as to rotate by 1/2 rotation. 4. The arm joint part is further provided with a motor for transmitting a reaction force generated in a slave arm to the grip part and a rotation detector for detecting the movement of the first rotation shaft, and the first joint part is provided. The wrist mechanism for a master arm according to any one of claims 1 to 3, wherein a rotation shaft is connected to the motor and the rotation detector. 5. The wrist for a master arm according to claim 1, wherein a force sensor is arranged at an end portion of the grip portion opposite to an end portion to which the link mechanism is connected. mechanism. 6. The handle according to claim 1, wherein an angle formed between the first rotating shafts of the first and second link mechanisms is an obtuse angle so that the grip portion can be easily handled by the operator's hand. The wrist mechanism for a master arm according to any one. 7. The angle formed by the first rotating shaft and the third rotating shaft is selected so as to adjust the tiltable angle of the grip portion within a range determined by the direction. Wrist mechanism for the described master arm. 8. The angle formed by the first rotating shafts of the first and second link mechanisms is about 120 °, and the angle formed by the first rotating shaft and the second rotating shaft is about 80 °. The wrist mechanism for a master arm according to any one of claims 1 to 5, wherein