JPH0453674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a horizontal articulated link type industrial robot that precisely transfers, loads, and assembles work objects on a flat surface.

BACKGROUND ART Conventionally, most planar industrial robots that mainly move horizontally are horizontal multi-jointed robots having serial arms, so-called scalar robots, the specific configuration of which is shown in FIG.

This consists of a support column 2 integrated with a base 1, a first arm 3 rotatably coupled to it, a first motor 4 for driving it, and a first reduction gear (generally represented by a harmonic reduction gear). (not shown), a second arm 6 rotatably coupled to the other end of the first arm, a second motor 7 and a second speed reducer (not shown) for driving the second arm 6. Furthermore, the other end of the second arm is interlocked with an actuator 9 for vertical movement (generally a small motor equipped with a fluid cylinder or a deceleration means such as a ball screw) and a motor actuator 10 attached to the support column 2. belt 11
It is equipped with a rotating means that is transmitted by a motor or the like.

In the above configuration, the working area is limited by the support column 2, and even if the working area is expanded by rotating the left and right arms, it is difficult to quickly move across the entire working area.

In order to improve this point, a robot having an arm configuration shown in FIG. 8 has been developed. The second arm 13 is attached to one end of the first arm 12, the drive motor 14 of the second arm 13 is attached to the connection point of the first arm and the second arm, and the drive motor 14 of the second arm 13 is attached to the other end of the second arm 13 for vertical and rotational movement. Means 15 is provided.

Similarly to the robot shown in FIG. 7, the robot with the above configuration also has a large self-inertia torque due to the weight of the arm and prime mover, and since the arms are connected in series, the first arm 12 and the second arm 13 are Mutual interference torque occurs that interferes with each other, deteriorating the robot's controllability and positioning accuracy.
It had drawbacks such as a limit to speeding up.

In order to reduce the weight of the motor due to the series arm, a robot constructed using parallel links as shown in FIG. 9 has been proposed (see FIG. 2 of Japanese Patent Laid-Open No. 57-33993).

Two motors 17 and 18 are arranged and fixed on a fixed base 16 so that the motor shafts are concentrically opposed to each other.
A first arm 19 and a fourth arm 20 are fixed to each motor shaft, a second arm 21 is attached to the tip of the first arm 19, and a third arm 2 is attached to the tip of the fourth arm 20.
one end of the third arm 22 is pivotally connected to the second arm 22, and the tip of the third arm 22 is
This is a robot in which a second arm 21 is pivoted at the middle part of the arm 21 and protrudes by a predetermined length, and a tool 23 and a tool rotation motor 24 are attached to the tip of the second arm 21.

The robot with the above configuration can prevent an increase in inertia torque due to the motor's own weight, but the motor support is located at the back, which limits the working area of the arm, and there is no means for raising and lowering the hand 25, and the tool rotation motor 24 is Since it is provided at the tip of the hand part, the load concentrates on the tip, and mutual interference torque that interferes with each other between the first arm 19 and the fourth arm 20 is generated, resulting in deterioration of controllability of the motor. However, it has disadvantages such as limitations in speed and positioning accuracy.

Therefore, the present inventors proposed an industrial robot using parallel links, as shown in FIG. 10, in order to eliminate the above-mentioned drawbacks (Japanese Patent Laid-Open No. 59-243760).

The driving motor 27 of the first arm 26 and the driving motor 29 of the fourth arm 28 are held by a column 30, and the actuators 32 and 33 for vertical and rotational driving of the tip hand part 31 are connected to the second arm 34 and the driving motor 29 of the fourth arm 28. Near the connection point of the three arms 35, that is, regarding the rotation center 36 of the third arm 35 and the fourth arm 28,
The first arm 26 and the fourth
Reducing the mutual interference torque occurring between the arms 28,
It enabled a compact configuration with a prime mover with a small load capacity, and improved positional accuracy and high-speed performance.

Problems to be Solved by the Invention However, in the above configuration, the support 3
0, the working range is still limited, and the vertical and rotational drive actuators are both connected to the third arm 3.
5, the self-inertia torque increases due to the weight of these actuators.

Furthermore, in order to maintain the rotation angle of the hand portion 31 at a constant angle, it is necessary to constantly control the position of the rotation actuator 33, which may lead to an increase in the cost of the control system.

The present invention was made in view of the above problems, and
The interference torque between the arms and the self-inertia torque of the arms are reduced, and the small and compact configuration enables
It is an object of the present invention to provide an industrial robot that improves the positional accuracy and high-speed performance of a tip hand section, and further facilitates fixed position control regarding the rotational posture of the tip hand section.

Means for Solving the Problems In order to solve the above-mentioned problems, the industrial robot of the present invention includes: a support vertically disposed on a base; a first arm rotatably coupled to the support; a second arm coupled to the other end of the first arm so as to be rotatable about the vertical axis; a third arm coupled to the other end of the second arm so as to be rotatable about the vertical axis; a fourth arm rotatably coupled to the column and rotatably coupled to the column at the other end at a longitudinally intermediate position of the third arm, the fourth arm being coaxial with the column; a first prime mover which is held in such a manner as to rotate the fourth arm about its axis; a second prime mover; a tool attached to the tip of the third arm that is movable up and down and rotatable; and a tool attached to the joint between the second arm and the third arm or on the third arm in the vicinity. , a third prime mover that moves the tool up and down via a first transmission means, and a fourth prime mover that is mounted on a base and rotationally drives the tool via a second transmission means, and the second transmission means. means, the rotation angle of the tool with respect to the base is the third
It is constructed so that it is always maintained constant regardless of the position of the arm.

Effect The present invention has the above-mentioned configuration, and the first, second, and fourth
By installing the prime mover on the base, the load weight on the arm is reduced, and the third prime mover is placed on the third arm on the opposite side of the hand section with respect to the rotation center of the second and fourth arms. Therefore, the 10th
For the same reason as the conventional example shown in the figure, the arm length of each arm (first, second, third, fourth
The arm lengths are l ₁ , l ₂ , l ₃ , and l ₄ respectively)) Arm mass (the masses of the first, second, third, and fourth arms are m ₁ ,
h _{1 , h 2 , h3} , _h4
) is set to satisfy the condition m ₂ l ₁ h ₂ = m ₃ l ₂ l ₃ , which reduces the mutual interference torque that occurs between the first arm and the fourth arm, and controllability is improved, and high speed and high precision can be achieved with a prime mover with a small load capacity. Also, the first pillar
By aligning the rotation centers of the prime mover and the second prime mover and holding them together, the rotation range of each arm is expanded. Further, a fourth prime mover is fixedly installed on the base, and a means for transmitting rotational motion to the rotation axis of the hand portion via the rotation centers of the first and second prime movers and the rotation centers of the third arm and the fourth arm. If the rotation of the fourth prime mover is fixed at a fixed position by transmitting the rotation using a timing belt or the like, the rotational position of the tip of the hand will be fixed at a fixed position even if the first arm and the fourth arm move. As a result, even in the industrial robot having the above configuration, fixed position control becomes easy.

Embodiment An industrial robot according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a plan view of an industrial robot according to an embodiment of the present invention. Further, FIG. 2 is a front view, and FIG. 3 is a schematic side view.

In FIG. 3, 40 is the base, 41 is the first prime mover, 42 is the second prime mover, and 43 is the first and second prime mover.
It is a hollow support that has a common axis with the prime movers 41 and 42 and holds them. In FIG. 1, 44 is the first motor connected to the output shaft of the second prime mover 42.
An arm 45 is a second arm rotatably coupled to the other end of the first arm 44; 46 is a second arm 45;
a third arm rotatably coupled at the other end, 47;
is connected to the output shaft of the first prime mover 41, and the other end is rotatably connected to the middle of the third arm 46.
The first to fourth arms form a closed loop link arm. In FIG. 2, 48 is a hand portion, and 49 is a third motor disposed on the third arm, which is opposite to the hand portion 48 with respect to the rotation axis 50 connecting the third arm 46 and the fourth arm 47. be installed in the position of Reference numeral 51 denotes a first timing belt that transmits the rotational force of the third prime mover 49 to the hand portion 48 . 52 is a fourth prime mover fixedly installed on the base 40.

FIG. 4 is a schematic diagram of the transmission mechanism of the fourth prime mover 52, in which 53 is a first spur gear, 54 is a second spur gear meshingly engaged with the first spur gear 53, and 55 is a second spur gear. It is a first timing pulley that shares a rotating shaft 56 coaxial with 54. The ratio of the number of teeth between the first spur gear 53 and the second spur gear 54 is set to 1:1 or 1:10 or less. Further, in FIG. 1, reference numeral 57 denotes a second timing belt that transmits rotation from the first timing pulley 55. Also, in Fig. 3, 58 and 5
Second and third timing pulleys 9 have the same axis as the support column 43, and are engaged with the second timing belt 57. The second timing pulley 58 and the third
The timing pulley 59 is integrated, and the bearing 6
0 and 61 to the support column 43.
The second timing belt 57 is attached to the second timing pulley 58 so as to transmit rotational force thereto. 62 is a third timing belt, and 63 is a rotation center shaft 50 of the third arm 46 and the fourth arm 47.
This is the fourth timing pulley that is installed to share the same axis with. The third timing belt 62 is coupled to transmit the rotational force of the third timing pulley 59 to the fourth timing pulley 63.

FIG. 5 is a sectional view of the rotation shaft portions of the third arm 46 and the fourth arm 47. A fifth timing pulley 64 is integrated with the fourth timing pulley 63 and is rotatably attached to a fixed shaft 65 provided protruding from the third arm 46 via bearings 66 and 67. 68 is a fixed shaft provided protruding from the third arm 46, and the fourth arm 47 and the bearing 69
and 70, and is rotatably installed.

FIG. 6 is a sectional view of the distal end hand portion. Reference numeral 71 denotes a fourth timing belt, and the hand portion 48 is attached to transmit rotational force to a sixth timing pulley 73 provided on the rotating shaft 72. 74 is a spline shaft that can rotate and slide vertically; 75 and 76;
is a bearing. 77 is a seventh timing pulley that engages with the first timing belt 51 that transmits rotational force from the third prime mover 49. 78 is the hand part 4
8 is a nut portion of the ball screw 79 which performs the vertical movement, and the nut portion 79 and the spline shaft 74 are fixedly engaged by a bracket 80.
81 is a holder that holds these, and 82 is a bracket that fixes and integrates the holder 81 and the third arm.

Next, in FIG. 3, 83 is the output shaft of the first prime mover 41, and 84 is the output shaft of the second prime mover 42, which are each directly attached to the fourth arm 47 and the first arm 44 without a reduction gear or the like. .

Further, the support column 43 is hollow and accommodates wiring such as power lines and signal lines for the second and third prime movers 42, 49, etc. introduced through the connector 85.

The operation of the industrial robot constructed as described above will be explained below with reference to FIGS. 1, 2, and 3.

In general, industrial robots that mainly perform work on a flat surface are required to move to arbitrary positions on a flat surface. In the industrial robot of the present invention, by operating the first prime mover 41 and the second prime mover 42, the fourth arm 47 and the first arm 44 move by a predetermined angle and are rotatably engaged with them. A hand portion 48 installed at the tip of the third arm 46 moves to a predetermined position by a closed loop link mechanism formed by the second and third arms 45 and 46.
Next, positioning by vertical and rotational movement of the distal end hand portion 48 will be explained. For vertical movement, the rotational force is transmitted to the ball screw 78 shown in FIG. 6 by the first timing belt 51 disposed in the third arm by the operation of the third prime mover 49, and the ball screw 78 is moved to an arbitrary height. The rotational movement of the hand section 48 is caused by the operation of the fourth prime mover 52, and the sixth timing pulley 73, which is engaged with the spline shaft 74 of the hand section 48, is operated by the second, third, and fourth timing belts 57, 62, and 71. A rotational force is transmitted to the rotation angle, and a predetermined rotation angle can be set. Here, at least the first, fourth, fifth, and sixth timing pulleys have the same pitch circle diameter, and the rotation angle of the fourth prime mover 52 is accurately transmitted to the spline shaft 74 via the sixth timing pulley 73. be done. Furthermore, by maintaining the rotation angle of the fourth prime mover 52 constant through the configuration of this transmission system, the rotation of the rotating shaft 72 at the tip of the hand is also maintained at a constant angle with respect to the base, making it easy to control the posture at a constant angle. Furthermore, as described above, the length, mass, and center of gravity of each arm are determined by utilizing the configurations of the hand portion 48, the third motor 49, and the first, second, third, and fourth arms 44, 45, 46, and 47. By setting the conditions to satisfy certain conditions, interference torque between the arms can be suppressed, and as a result, the first and second
Disturbance terms exerted on the prime movers 41 and 42 are reduced, and control of the prime movers is improved. Furthermore, by installing the fourth prime mover 52 on the base 40, the load applied to the arm, that is, the self-inertia of the arm, is reduced, and a small-capacity prime mover can be used.

Furthermore, since the support column 43 is provided to share the rotation axis of the first and second prime movers 41 and 42, the first and second prime movers 41 and 42
The support column 43 does not become an obstacle to the rotation of the fourth arms 44, 47, making it possible to rotate the fourth arms 44, 47 by more than 360 degrees, thereby significantly expanding the working range. Further, by making the support 43 hollow and introducing the wiring into it, processing of the wiring becomes easy.

Next, the third and fourth prime movers 49 and 52 move the hand section 48 vertically and rotationally, and the transmission mechanism is set to transmit this rotation at a reduction ratio of 1:1 or 1:10 or less. In addition to the fact that the output shafts of the first prime mover 41 and the second prime mover 42 are directly attached to the fourth arm 47 and the first arm 44, it is possible to teach the movement position with extremely small force. Teaching performance is significantly improved.

Effects of the Invention As described above, the present invention includes a column vertically installed on a base, a first arm rotatably coupled to the column, and a second arm rotatable about a vertical axis at the other end of the first arm. a second arm rotatably coupled to the second arm; a third arm rotatably coupled to the other end of the second arm rotatably about a vertical axis; and the other end rotatably coupled to the column. is coupled to a longitudinally intermediate position of the third arm so as to be rotatable about the vertical center; a first prime mover that rotates around the center; a second prime mover that is also held by the column so as to be coaxial with the column and rotates the first arm about the axis; and a second prime mover that rotates about the axis of the third arm; a tool that is attached to the joint part of the second arm and the third arm, or is attached to the third arm in the vicinity thereof, and that moves the tool up and down through a first transmission means; a third prime mover that rotates the tool, and a fourth prime mover that is mounted on a base and rotationally drives the tool via a second transmission means, and a fourth prime mover that rotates the tool with respect to the base. By configuring it so that it is always maintained constant regardless of the arm position, self-inertia torque and mutual interference torque between the arms during high-speed operation are reduced, and a small and compact configuration is achieved using a prime mover with small load capacity. It also improves the controllability of the prime mover, improving the positional accuracy of the tip hand.
High-speed performance can be improved, and fixed position control regarding the rotational posture of the distal end hand section can be facilitated.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an industrial robot according to an embodiment of the present invention, Fig. 2 is a front view of Fig. 1, Fig. 3 is a schematic side view of Fig. 1, and Fig. 4 is a schematic diagram of the fourth prime mover. A schematic diagram of the transmission mechanism, FIG. 5 is a sectional view of the rotation shaft portion of the third arm and the fourth arm, FIG. 6 is a sectional view of the tip hand portion, FIGS. 7, 8, 9, FIG. 10 is a block diagram of a conventional industrial robot. 40... Base, 41... First prime mover, 42...
...Second prime mover, 43...Strut, 44...First arm, 45...Second arm, 46...Third arm,
47...Fourth arm, 48...Hand portion, 49...
...Third prime mover, 51...First timing belt,
52... Fourth prime mover, 57... Second timing belt, 62... Third timing belt, 71...
4th timing belt, 74...spline shaft,
78...Ball screw.

Claims (1)

[Scope of Claims] 1: a column vertically installed on a base; a first arm rotatably coupled to the column; and a first arm rotatably coupled to the other end of the first arm about a vertical axis. a third arm rotatably coupled to the other end of the second arm about a vertical axis; and a third arm rotatably coupled to the support column, the other end of which is rotatably coupled to the third arm. a fourth arm coupled to a longitudinally intermediate position so as to be rotatable about a vertical center; and a fourth arm is held by the column so as to be coaxial with the column, and drives the fourth arm to rotate about the axis. a first prime mover; a second prime mover that is also held on the column so as to be coaxial with the column and drives the first arm to rotate about its axis; and a second prime mover that is attached to the tip of the third arm and that moves vertically. a movable and rotatable tool; and a joint between the second arm and the third arm;
or mounted on the third arm nearby,
a third prime mover that drives the tool up and down via a first transmission means; and a fourth prime mover mounted on a base and rotationally drives the tool via a second transmission means; An industrial robot, characterized in that the means is configured such that the rotation angle of the tool with respect to the base is always maintained constant regardless of the position of the third arm. 2. The industrial use according to claim 1, characterized in that the output shaft of the first prime mover and the fourth arm and the output shaft of the second prime mover and the first arm are both directly coupled without a reduction gear or the like. Robot. 3. The industry according to claim 1, wherein the output shafts of the third prime mover and the fourth prime mover are engaged with the vertical axis and rotation axis of the tool by a transmission means having a reduction ratio of 1:1 or 10:1 or less. Robots for use. 4. The industrial robot according to claim 1, wherein the support supporting the first prime mover and the second prime mover is hollow, and power lines and signal lines necessary for driving the prime movers are introduced into the hollow space.