JP3725355B2 - Arm drive mechanism of robot device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an arm drive mechanism of a robot apparatus.
[0002]
[Prior art]
FIG. 5 is an explanatory diagram showing each joint angle of a conventional robot.
In order for the finger 107 loaded with a transported object such as a substrate to move on a straight track while maintaining a constant posture, the rotation angle θ 1 of the first arm 101, the rotation angle θ 2 of the second arm 102, and the finger 107 The rotation angle θ3 must always maintain a 1: 2: 1 relationship.
[0003]
FIG. 6 is a mechanism diagram showing the structure of an arm drive mechanism in a conventional robot apparatus. In FIG. 6, reference numerals 141 and 142 rotate the first arm 101 and the second arm 102 at the first joint J1 and the second joint J2. , 131 is a speed reducer with the output shaft of the motor 141 as an input, 132 is a speed reducer with the output shaft of the motor 142 as an input, and the outputs of the speed reducers 131 and 132 are sent via a timing pulley and a timing belt. It is comprised so that a rotational force may be transmitted to the drive shafts 191 and 192.
[0004]
The motor 141 and the motor 142 generate reverse rotational forces at the same rotational speed.
The rotation of the motor 142 is transmitted to the timing pulley 153 via the speed reducer 132 and the transmission shaft 191. From the timing pulley 153, the timing belt 161 is used to transmit the rotation to the timing pulley 154 having the same diameter as the timing pulley 153, and the timing pulley 154 is integrated with the first arm 101 at the first joint J1. The first arm 101 rotates at the same rotational speed as the speed reducer output at one joint J1.
[0005]
The rotation of the motor 141 is transmitted to the timing pulley 151 through the speed reducer 131 and the drive shaft 192. The timing pulley 151 transmits the rotation to the timing pulley 152 having the same diameter as the timing pulley 151 by using the timing belt 162, and is integrated with the timing pulley 152 at the first joint J1 regardless of the first arm 101. The rotation is transmitted to the timing pulley 155. The timing pulley 155 uses the timing belt 163 to transmit the rotation to the timing pulley 156 having a half diameter of the timing pulley 155, and the timing pulley 156 is integrated with the second arm 102 at the second joint J2, thereby In the two joints J2, the second arm 102 rotates at a speed twice that of the motor 141. Since the motor 141 and the motor 142 have the same rotation speed, the first arm 101 and the second arm 102 rotate at a rotation speed of 1: -2.
[0006]
The finger 107 is connected to a shaft 110 fixed to the base 108, timing pulleys 157, 158, and 159 having the same diameter, by a timing belt. Each timing pulley 157, 158, 159 is rotatably supported so that it can freely rotate at each joint. As a result, the finger 107 maintains a fixed posture with respect to the base 108 regardless of the rotation of each arm.
[0007]
[Problems to be solved by the invention]
In the conventional robot apparatus, power is transmitted by a timing belt that is rigidly weak on the output side of the speed reducer. Therefore, low-frequency vibration is generated due to the rigidity of the timing belt, and the operation speed is increased. There was an obstacle.
[0008]
Further, since the low-frequency vibration is a lateral shake in the transfer direction, for example, in transferring a semiconductor wafer, there is a problem that causes interference between the wafer and the cassette in the cassette.
[0009]
Furthermore, since the power transmission shaft is on the output shaft side of the reduction gear, very large power must be transmitted, and the shaft diameter becomes large. For example, in the case of a robot used in a vacuum environment, the atmospheric environment and the vacuum environment The magnetic fluid seal unit that seals the size of the robot becomes very large, increasing the size and weight of the robot as a whole, which is disadvantageous from the standpoint of maintainability of the robot.
[0010]
The present invention has been made to solve the above-described problems, and has an object to obtain an arm drive mechanism of a robot apparatus that can improve the rigidity of a transmission system, enable high-speed operation, and reduce the size and weight. And
[0011]
[Means for Solving the Problems]
The arm drive mechanism of the robot apparatus according to the present invention is arranged at a first joint which is a rotation center of a first arm supported rotatably with respect to a base, and the first arm rotates the first arm by its output. A speed reducer, a second speed reducer disposed at a second joint, which is a center of rotation of a second arm rotatably supported by the first arm, and rotates the second arm by its output; A motor provided on the base side that transmits power to the input shafts of the first reducer and the second reducer, and a power transmitted from the motor to the input shafts of the first reducer and the second reducer Power transmission mechanism, a finger rotatably supported on the second arm by a third joint, and a posture of the finger with respect to the base, and a movement of the first arm and the second arm by a link mechanism Regardless It is obtained by so and a posture maintaining mechanism for lifting.
[ 0012 ]
The arm drive mechanism of the robot apparatus according to the present invention transmits the power from the motor to the input shaft of the first speed reducer, and at the same time, is fixed to the transmission shaft passing through the hollow portion of the first speed reducer. And a power transmission mechanism for transmitting to the input shaft of the second reducer via the timing pulley and a timing belt engaged with the timing pulley.
[ 0013 ]
The arm drive mechanism of the robot apparatus according to the present invention includes a magnetic fluid seal unit that seals a space provided with a base-side motor against a vacuum region in which the arm operates.
[ 0014 ]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a structural diagram showing the overall configuration of the arm drive mechanism of the robot apparatus according to the first embodiment. FIG. 2 is a partial structural diagram of the arm drive mechanism of the robot apparatus according to the first embodiment. In these drawings, 1 is a first arm, 2 is a second arm, 4 is a motor, 7 is a finger, 8 is a base, 9 is a transmission shaft directly connected to the output shaft of the motor 4, J1 is a first joint, J2 Is the second joint, J3 is the third joint, 31 is the reduction gear (first reduction gear) arranged at the position of the first joint J1, and 32 is the reduction gear (second reduction gear) arranged at the position of the second joint J2. , 51 is a timing pulley (power transmission mechanism) fixed to the transmission shaft 9.
[ 0015 ]
2, 10a is an input shaft to the speed reducer 31, 10b is a transmission shaft (power transmission mechanism), 10d is a shaft (posture holding mechanism) fixed to the base 8, and 10e is integrated with an output shaft of the speed reducer 32. This is the axis. 11a, 11b, 11d, and 11e are link fixing plates (posture holding mechanisms), 11c is a shaft (posture holding mechanism) integrally connecting the link fixing plate 11b and the link fixing plate 11e, and 52 is fixed to the transmission shaft 10b. A timing pulley (power transmission mechanism) 61 is a timing belt (power transmission mechanism) connecting the timing pulley 52 and the input shaft of the speed reducer 32.
[ 0016 ]
Next, the operation will be described.
When the motor 4 rotates according to a command from a controller (not shown), the rotation is transmitted to the timing pulley 51 via the transmission shaft 9. Further, it is transmitted from the timing pulley 51 through the timing belt to the input shaft 10a and the transmission shaft 10b to the speed reducer 31 disposed at the first joint J1. From the transmission shaft 10b, the rotation is transmitted to the input shaft of the speed reducer 32 disposed at the second joint J2 via the timing pulley 52 and the timing belt 61. As a result, the same rotational speed is input to the speed reducer 31 disposed at the first joint J1 and the speed reducer 32 disposed at the second joint J2.
[ 0017 ]
In order for the finger 7 to take a linear trajectory, the displacement θ1 of the first joint J1 and the displacement θ2 of the second joint J2 must always be 1: -2. In the transfer robot according to the first embodiment, the reduction ratios of the reduction gear 31 arranged at the first joint J1 and the reduction gear 32 arranged at the second joint J2 are mutually output when the same rotation speed is input. The ratio of shaft rotational speed is always set to 1: -2. The first arm 1 is integrated with the output of the speed reducer 31, and the second arm 2 is rotated by a shaft 10e integrated with the output shaft of the speed reducer 32. As a result, the ratio of the rotation angles of the first arm 1 and the second arm 2 is 1: -2.
[ 0018 ]
In the robot according to the first embodiment, the same rotation is input to the speed reducer 31 and the speed reducer 32 as described above. Therefore, when the motor 4 rotates, the first joint J1 is set according to the set reduction ratio. The second joint J2 always operates with a rotational displacement of 1: -2, and the finger 7 can move on the linear trajectory.
[ 0019 ]
Next, a method for keeping the posture of the finger 7 constant will be described.
In the first joint J1, the shaft 10d is fixed to the base 8 that does not rotate during operation. The shaft 10d passes through the hollow portion of the speed reducer 31 and is integrated with the link fixing plate 11a. The link fixing plate 11a forms a parallel link with the link fixing plate 11b of the second joint J2 in the first arm 1, and the link fixing plate 11a and the link fixing plate 11b always have a fixed positional relationship. I keep it.
[ 0020 ]
The link fixing plate 11b is integrally fixed to a shaft 11c supported so as to be able to rotate independently of the first arm 1 and the second arm 2 at the second joint J2, and the shaft 11c is fixed inside the second arm 2. It is fixed to the link fixing plate 11e arranged in the. The link fixing plate 11e forms a parallel link with the link fixing plate 11d of the third joint J3 in the second arm 2, and the link fixing plate 11e and the link fixing plate 11d always have a fixed positional relationship. I keep it. The link fixing plate 11d is integrated with the finger 7 at the third joint J3.
[ 0021 ]
As a result, the link fixing plate 11a and the finger 7 are configured to always operate while maintaining a certain relationship, and the link fixing plate 11a is fixed to the base 8 so as not to rotate during operation. The base 8 can always maintain a constant posture.
With these structures, a transported object such as a wafer mounted on the finger 7 can move on a linear track while maintaining a constant posture.
[ 0022 ]
As described above, according to the first embodiment, since the timing belt that is weak in the transmission system is arranged on the input side of the speed reducer, it acts on the timing belt as compared with the conventional arrangement. The moment of inertia is the square of 1 / reduction ratio, and the resonance frequency of the timing belt alone increases. For this reason, there is an effect of obtaining an arm drive mechanism of a robot apparatus in which the rigidity of the transmission system, which has been a big problem for high speed and high accuracy, is improved.
[ 0023 ]
Embodiment 2. FIG.
FIG. 3 is a structural diagram showing the overall configuration of the arm drive mechanism of the robot apparatus according to the second embodiment. In FIG. 3, the same or equivalent parts as in FIG. In FIG. 3, 13 is a magnetic fluid seal unit that seals the atmospheric environment and the vacuum environment.
[ 0024 ]
In the second embodiment, the rotational drive force transmission shaft 9 passing through the magnetic fluid seal unit 13 is for transmitting the output from the motor 4 to the input shafts of the speed reducers 31 and 32, and its allowable transmission torque. What is necessary is just to exceed the maximum output torque of the motor 4 at most.
[ 0025 ]
For this reason, compared to the case where the driving force from the output shaft of the speed reducer is transmitted as in the case of a conventional transfer robot, if the torque required for transfer is assumed to be the same, the transfer torque will be 1 / reduction ratio, and the shaft will twist. The moment of inertia applied to the axis that affects the resonance frequency is 1 / square of the reduction ratio. For example, when the reduction ratio is 50, the transmission torque is reduced to 1/50 and the moment of inertia is reduced to 1/2500.
[ 0026 ]
The magnetic fluid seal unit 13 is composed of a flange that supports the entire robot and a multi-axis magnetic fluid seal, and the ratio of the weight to the entire robot is very large. The size of the transmission shaft 9 depends largely on the diameter.
[ 0027 ]
In the second embodiment, as described above, the shaft transmission torque is smaller and the shaft diameter is smaller than that of the conventional method, so that the arm drive mechanism of the robot apparatus that can reduce the weight of the seal unit and the entire robot can be obtained. is there.
[ 0028 ]
Embodiment 3 FIG.
FIG. 4 is a structural diagram showing the overall configuration of the arm drive mechanism of the robot apparatus according to the third embodiment. 4 that are the same as or equivalent to those in FIG. 1 and FIG. In the figure, 3 is a speed reducer that receives the output shaft of the motor 4, 60a is a connecting shaft that integrally connects the link fixing plate 61d and the link fixing plate 61e, and 60b is a spur gear (rotational speed conversion mechanism, A fixed shaft (second arm rotating link mechanism) 62 fixing the second arm rotating link mechanism) 62 to the second arm 2, and 60c a fixed shaft (posture holding) fixing the link fixing plate 61g to the base 8. Mechanism), 60d is a connecting shaft integrally connecting the link fixing plate 61h and the link fixing plate 61i, 61a and 61b are link fixing plates (first arm rotating link mechanism), 61c, 61d, 61e, 61f. Is a link fixing plate (second arm rotating link mechanism), and 61g, 61h, 61i, 61j are link fixing plates (posture holding mechanism). A gear tooth portion is formed around the link fixing plate 61f, and is engaged with the spur gear 62 by the gear tooth portion. The pitch circle diameter of the link fixing plate 61f and the spur gear 62 is set to 2: 1.
[ 0029 ]
Next, the movement of each joint when the motor 4 is rotated by a command from a controller (not shown) will be described.
First, the first arm 1 in the first joint J1 includes a link fixing plate 61a integrated with a transmission shaft 9 directly connected to the output shaft of the speed reducer 3, and a link fixing plate that forms a parallel link with the link fixing plate 61a. The rotational force is transmitted by 61b and rotates at the same rotational speed as the transmission shaft 9.
[ 0030 ]
Next, rotation of the second arm 2 at the second joint J2 will be described.
First, the link fixing plate 61c integrated with the transmission shaft 9 of the speed reducer 3, the link fixing plate 61d forming a parallel link with the link fixing plate 61c, and the first joint J1 irrespective of the first arm 1 The rotation is transmitted to the link fixing plate 61e integrated with the link fixing plate 61d via the rotation-supported connecting shaft 60a.
By forming a parallel link with the link fixing plate 61e and the link fixing plate 61f arranged in the vicinity of the second joint J2, the rotation of the shaft 60a is transmitted to the link fixing plate 61f.
[ 0031 ]
A gear tooth portion is formed on the outer periphery of the link fixing plate 61f so as to mesh with the spur gear 62, and the pitch circle diameter of the link fixing plate 61f and the spur gear 62 is set to 2: 1. Due to the meshing of the plate 61f and the spur gear 62, the spur gear 62 rotates at a rotational displacement of -2 times the rotational displacement of the link fixing plate 61f.
[ 0032 ]
Since the fixed shaft 60b integrated with the spur gear 62 is fixed to the second arm 2, the second arm 2 in the second joint J2 is in response to the rotation of the transmission shaft 9 directly connected to the output shaft of the speed reducer 3. Thus, it rotates at a rotational displacement of -2 times, and at the same time, it rotates at a rotational displacement of -2 times that of the first arm 1 in the first joint J1.
[ 0033 ]
Finally, the rotation of the finger 7 at the third joint J3 will be described. The structure in which the finger 7 is maintained in a fixed posture at the third joint J3 is a fixed shaft 60c fixed to the base 8 that is independent of the rotation of the transmission shaft 9 directly connected to the output shaft of the speed reducer 3 at the first joint J1. A link fixing plate 61g formed integrally with the link fixing plate 61g, forming a parallel link with the link fixing plate 61g, a link fixing plate 61i integrally fixed with the link fixing plate 61h by a connecting shaft 60d, It is comprised by the link fixing plate 61j which forms a parallel link with the link fixing plate 61i.
[ 0034 ]
The finger 7 rotates integrally with the link fixing plate 61j at the third joint J3. Since the link fixing plate 61g and the link fixing plate 61h, the link fixing plate 61i and the link fixing plate 61j each form a parallel link, and the link fixing plate 61h and the link fixing plate 61i rotate together, the link fixing plate The finger 7 fixed to the link fixing plate 61j and the link fixing plate 61j perform the same rotational movement, and the link fixing plate 61g is fixed to the base 8. Therefore, the finger 7 is always in relation to the base 8. The same constant posture can be maintained.
[ 0035 ]
As described above, according to the third embodiment, the rotational displacement of the first arm 1 and the second arm 2 is always kept at 1: -2, and the posture of the finger 7 is kept constant. The rotation of the motor 4 is transmitted to each axis through the speed reducer 3, and there is an effect that an arm drive mechanism of a robot apparatus that can transport a transported object such as a wafer in a linear path is obtained.
[ 0036 ]
Further, since a metal link mechanism is used for the transmission mechanism instead of the conventional resin timing belt, there is an effect that an arm drive mechanism of the robot apparatus capable of enhancing the rigidity of the transmission system can be obtained.
[ 0037 ]
【The invention's effect】
As described above, according to the present invention, the first deceleration is arranged at the first joint, which is the center of rotation of the first arm that is rotatably supported with respect to the base, and rotates the first arm by its output. And a second speed reducer that is disposed at a second joint that is a rotation center of a second arm that is rotatably supported by the first arm, and that rotates the second arm by its output, and the base side A power transmission mechanism for transmitting power from the motor provided to the input shaft of the first speed reducer and the second speed reducer, and a finger rotatably supported by a third joint to the second arm And a posture holding mechanism that holds the posture of the finger with respect to the base by a link mechanism regardless of the movement of the first arm and the second arm. No longer, faster, and improves the rigidity of the transmission system for high accuracy, there is no vibration in a low frequency of operation, it is possible to perform high-speed operation, there is an effect that it is possible to shorten the access time.
[ 0038 ]
According to the present invention, the power from the motor is transmitted to the input shaft of the first speed reducer, and at the same time, the transmission shaft penetrating the hollow portion of the first speed reducer, the timing pulley fixed to the transmission shaft, Since the power transmission mechanism for transmitting the power from the motor to the input shaft of the second speed reducer via the timing belt engaged with the timing pulley is provided, the power from the motor is transmitted to the second speed reducer. The resonance frequency of the power transmission mechanism, including the transmission mechanism that transmits to the input shaft, is increased, the rigidity of the transmission system is improved for high speed and high accuracy, and low frequency vibration during operation is eliminated, allowing high speed operation. This has the effect of shortening the access time.
[ 0039 ]
According to this invention, since the magnetic fluid seal unit that seals the space provided with the motor on the base side against the vacuum region in which the arm operates is provided, the rotational force transmission shaft passing through the magnetic fluid seal unit is Since it is not the output side of the speed reducer but the output side of the motor, the transmission torque applied to the rotational force transmission shaft is reduced, and the shaft diameter of the rotational force transmission shaft can be reduced. Since the entire unit can be reduced in size and the ratio of the weight of the magnetic fluid seal unit to the total weight of the robot is very large, the weight of the entire robot can be reduced.
[Brief description of the drawings]
FIG. 1 is a structural diagram showing an overall configuration of an arm drive mechanism of a robot apparatus according to a first embodiment of the present invention.
FIG. 2 is a partial structural diagram of an arm drive mechanism of the robot apparatus according to the first embodiment of the present invention.
FIG. 3 is a structural diagram showing an overall configuration of an arm drive mechanism of a robot apparatus according to a second embodiment of the present invention.
FIG. 4 is a structural diagram showing an overall configuration of an arm drive mechanism of a robot apparatus according to a third embodiment of the present invention.
FIG. 5 is an explanatory diagram showing each joint angle of a conventional robot.
FIG. 6 is a mechanism diagram showing a structure of an arm driving mechanism in a conventional robot apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st arm, 2nd arm, 4 motor, 7 finger, 8 base, 10b transmission shaft (power transmission mechanism), 10d, 11c shaft (posture holding mechanism), 11a, 11b, 11e, 11d, 61g, 61h, 61i, 61j Link fixing plate (posture holding mechanism), 13 magnetic fluid seal unit, 31 reducer (first reducer), 32 reducer (second reducer), 51, 52 timing pulley (power transmission mechanism), 60b Fixed shaft (second arm rotating link mechanism), 60c Fixed shaft (posture holding mechanism), 61 Timing belt (power transmission mechanism), 61a, 61b Link fixing plate (first arm rotating link mechanism), 61c, 61d, 61e, 61f Link fixing plate (second arm rotation link mechanism), 62 spur gear (rotation speed conversion mechanism, second arm rotation link mechanism), J1 first joint , J2 second joint, J3 third joint.

Claims (3)

A first speed reducer that is disposed at a first joint that is a rotation center of a first arm that is rotatably supported with respect to a base, and that rotates the first arm by its output;
A second speed reducer that is disposed at a second joint that is a rotation center of a second arm that is rotatably supported by the first arm, and that rotates the second arm by its output;
A motor provided on the base side for transmitting power to the input shafts of the first reducer and the second reducer;
A power transmission mechanism for transmitting power from the motor to the input shafts of the first reduction gear and the second reduction gear;
A finger rotatably supported by a third joint to the second arm;
An arm drive mechanism of a robot apparatus, comprising: a posture holding mechanism that holds a posture of the finger with respect to the base by a link mechanism regardless of movements of the first arm and the second arm. The power transmission mechanism
The power from the motor is transmitted to the input shaft of the first speed reducer, and at the same time, the transmission shaft penetrating through the hollow portion of the first speed reducer, the timing pulley fixed to the transmission shaft, and the timing pulley engaged. claim 1 Symbol mounting arm driving mechanism of the robotic device, characterized in that transmitted to the input shaft of the second reduction gear via a timing belt. 2. The arm drive mechanism of the robot apparatus according to claim 1, further comprising a magnetic fluid seal unit that seals a space in which the motor on the base side is provided against a vacuum region in which the arm operates.

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