JPH048152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a positioning control method for a multi-axis robot, and more specifically, to controlling the starting timing of a plurality of traveling units by starting and stopping a single motor. The present invention relates to a positioning control method for a multi-axis robot that is sequentially controlled.

2. Description of the Related Art Multi-axis robot devices are widely used as automatic control devices for spot welding guns in, for example, automobile body assembly lines. A multi-axis robot device is usually composed of a plurality of traveling units that move in different directions, and each traveling unit is provided with a drive device such as a motor.

Problems to be Solved by the Invention When trying to make the multi-axis robot device smaller and lighter as described above, if a drive motor is dedicated to each traveling unit as seen in conventional devices, it is difficult to The space occupied by the motor increases, which greatly impedes the ability to make the device more compact. Furthermore, because conventional multi-axis robot equipment uses a positioning control method that selectively starts multiple motors with different rotational characteristics, the same number of motor drivers as motors are required. Problems arose in that the control device became larger, the cost increased, and the control became more complicated.

A primary object of the present invention is to provide a solution to the above-mentioned problems found in conventional positioning control means for multi-axis robotic devices.

Means for Solving the Problems In view of the above object, the present invention provides a multi-axis robot in which a tool is mounted on a drive unit connected to the final stage of a plurality of traveling units. A spline shaft is provided in the unit parallel to the direction of movement, and the spline shaft of the front-stage traveling unit and the spline shaft of the rear-stage traveling unit are connected to each other via a gear spline-fitted onto the spline shaft of the front-stage traveling unit. interlockingly connected, and
A single motor installed in the first-stage traveling unit moves the spline shafts of each traveling unit simultaneously, and the transmission of driving force to each traveling unit is transmitted from the spline shaft of each traveling unit to the respective clutches. The timing of the driving force transmission to each traveling unit by the clutch/brake is set such that when the preceding traveling unit shifts from the travel mode to the stop mode, the following traveling unit moves from the stop mode. This mode is controlled in chronological order so as to shift to a mode, and the positioning control of each traveling unit is sequentially performed by a single motor.

Function The positioning control system for each axis of a multi-axis robot according to the present invention attempts to sequentially drive the traveling units that constitute each axis with one motor, and for this purpose, each traveling unit is equipped with a spline shaft. These spline shafts are meshed and connected to each other via gears, so that driving force is transmitted to each traveling unit by one motor. Each traveling unit is equipped with a clutch/brake for disconnecting/connecting the driving force, and these are disconnected/braked in chronological order.
I try to control it directly.

As a result, in each traveling unit, first, the clutch and brake of one traveling unit as instructed by a program etc. are selectively connected, and the clutches and brakes of all other traveling units are set to a disconnected state. In this state, the motor is driven and its driving force is transmitted to the traveling unit through the clutch/brake, and only this traveling unit is subjected to positioning control operations as instructed by a program or the like. When the positioning control operation of this traveling unit is completed, the clutch/brake of the next traveling unit instructed by the program etc. is connected, and the above motor is driven again for this traveling unit, as instructed by the program etc. Positioning is controlled. From then on, by performing similar operations one after another,
The tool is moved to a position instructed by a program or the like.

As described above, according to the present invention, it is possible to drive a multi-axis robot with a single motor, and the installation space for the motor can be reduced from the traveling units that make up each axis. The robot only needs to be equipped with one spline shaft and a clutch/brake, making the multi-axis robot smaller and lighter, and requiring only one motor driver.
The motor control device can be downsized and costs can be reduced.

Embodiment FIG. 1 is a perspective view illustrating the overall structure of the device of the present invention, and FIG. 2 is an explanatory diagram of its power transmission path. As seen in these drawings, a tool, such as a spot welding gun 1, moves to a predetermined operating position and performs work according to a workpiece machining program.
A multi-axis robot device is constructed by mounting this on a drive unit 6 connected to the final stage of the traveling unit 2. The multi-axis robot device includes a first traveling unit 2x for moving the moving tables 3, 4, and 5 along the X-axis direction, and a second traveling unit 2x for moving the moving tables 3, 4, and 5 along the Z-axis direction.
A traveling unit 2z and a third traveling unit 2y for moving along the Y-axis direction are arranged with their traveling directions perpendicular to each other. These traveling units 2x, 2z, and 2y each move to a predetermined operating position according to the workpiece machining program, and perform welding work by driving the drive unit 6 of the spot welding gun 1 connected to the third traveling unit 2y. position. Therefore, the first
The traveling unit 2x is the traveling unit 2x,
A spline shaft 9x, to which rotational driving force is transmitted from a motor 7 with a reducer 8 that functions as a common power source for 2z and 2y, rotates while sliding along the axial direction of the spline shaft, and rotates while sliding along the axial direction of the spline shaft. A bevel gear 10x that transmits rotational driving force to the traveling unit 2z, a brake shaft 14x connected to the spline shaft 9x via a timing belt 13x wound around pulleys 11x and 12x, and a brake shaft 14x arranged in sequence on the brake shaft. Clutch/brake 15x, ball screw 16x, ball nut 17x and first
A rotary encoder 18 functions as a stop position detector for the moving table 3 of the traveling unit 2x.
It is formed from x. On the other hand, the second traveling unit 2z has a spline shaft 9z having a driven bevel gear 19z that meshes with the bevel gear 10x fixed to one end;
A bevel gear 10z and a pulley 11 rotate while sliding along the axial direction of the spline shaft and transmit rotational driving force to the subsequent third traveling unit 2y.
Timing belt 13z wrapped around z, 12z
A brake shaft 14z connected to the spline shaft 9z via a brake shaft 14z, a clutch/brake 15z, a ball screw 16z, a ball nut 17z, and a stop position of the movable table 4 of the second traveling unit 2z, which are sequentially arranged on the brake shaft. It is formed from a rotary encoder 18z that functions as a rotary encoder. In the illustrated embodiment, the moving table 4 of the second moving unit 2z is supported on the moving unit so as to be movable along the vertical direction, so that the weight of the moving table 4 is not balanced. As a means, a balance cylinder 20 is attached to the side end surface of the second traveling unit 2z. Between the second traveling unit 2z and the third traveling unit 2y is a power transmission shaft 22 having a driven bevel gear 19y fixed to one end that meshes with the bevel gear 10z, and a driving bevel gear 21 fixed to the other end. Correspondingly, the third traveling unit 2y includes a spline shaft 9y to which a second driven bevel gear 23 that meshes with the drive bevel gear 21 is fixed, and a spline shaft 9y along the axial direction of the spline shaft. It is connected to the spline shaft 9y via a timing belt 13y wound around a spur gear 24 and pulleys 11y and 12y, which rotate while sliding and transmit rotational driving force to the drive unit 6 of the subsequent spot welding gun 1. a brake shaft 14y, a clutch brake 15y sequentially arranged on the brake shaft,
It is composed of a ball screw 16y, a ball nut 17y, and a rotary encoder 18y that functions as a stop position detector for the moving table 5 of the third traveling unit 2y. On the other hand, the drive unit 6 of the spot welding gun 1 includes a spur gear 26 to which rotational driving force is transmitted from the spur gear 24, a drive unit having the spur gear 26 fixed to one end and a clutch/brake 15t attached to the other end. a shaft 27, a mounting shaft 2 of the spot welding gun 1 which engages with the drive shaft 27 via the clutch/brake 15 so as to be freely connectable/separable;
8 and a rotary encoder 29 for detecting the position of the spot welding gun 1. below,
The positioning procedure for a multi-axis robot will be explained. The rotational driving force of the motor 7 is transmitted to each of the traveling units 2x, 2z, and 2y in time series through the gear train, clutch brake, and ball screw mechanism, thereby moving the moving tables 3, 4, and 5. Sequentially position them at predetermined positions. To explain in more detail, at the start of positioning, the first
The clutch installed on the traveling unit 2x of
Only brake 15x remains connected, the second
and clutch brakes 15z and 15 provided on the third traveling units 2z and 2y.
y is placed in an unconnected state. In this way, only the moving table 3 moves in the X-axis direction according to a workpiece machining program (in this embodiment, a spot welding program for an automobile body) that has been input in advance to a computer attached to the vehicle body assembly line.
When the final movement position of the moving table 3 is detected by the rotary encoder 18x, this detection signal causes the first clutch/brake 15x to
is switched to the disconnected state, and the second clutch brake 15z is switched to the engaged state instead.
As a result, the rotational driving force of the motor 7 is transmitted only to the second travel unit 2z via the power transmission path, causing the movable table 4 to move along the Z-axis direction. When the final movement position of the moving table 4 is detected by the rotary encoder 18z, this detection signal causes the second clutch/brake 15z to be switched to the disconnected state, and the third clutch/brake 15z is switched to the disconnected state instead.
The clutch brake 15y is switched to the connected state. In this way, the rotational driving force of the motor 7 is transmitted only to the third travel unit 2y via the power transmission path, causing the movable table 5 to move along the Y-axis direction. When the final moving position of the moving table 5 is detected by the rotary encoder 18y provided at the last stage (2y in this example) of the traveling unit, this detection signal is used to control the clutch.
The brake 15y is switched to the disconnected state, and as a result, all the movable tables 3, 4, and 5 constituting the multi-axis robot device are positioned at predetermined positions specified in the spot welding program. When the clutch/brake 15y disposed at the last stage of the traveling unit is switched to the disconnected state, a detection signal transmitted from the rotary encoder 18y of the third traveling unit 2y causes the clutch brake 15y to remain in the disconnected state until then. Drive unit 6 that was placed
The clutch brake 15t is switched to the connected state, and in this state, the spot welding gun 1 is positioned at a predetermined welding work position by starting the motor 7.

Effects of the Invention As can be understood from the above explanation, in the present invention, power is sequentially transmitted to at least two sets of traveling units from a common motor in a time-series switching mode. The traveling units are moved individually in different directions so that a tool mounted on a drive unit connected to the last stage of the traveling unit acquires a predetermined operating position. That is, according to the present invention, power for positioning control can be transmitted from a single motor to two or more sets of traveling units in a sequential manner, so that the power for positioning control can be transmitted sequentially to two or more sets of traveling units. Inconveniences such as increased size and cost of a multi-axis robot device or control device, increased cost, and complicated control caused by the combined use of multiple motors are effectively eliminated. Thus, the present invention can exhibit an effect that greatly exceeds that of conventional devices in reducing the size and cost of multi-axis robot devices.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the overall structure of the device of the present invention, and FIG. 2 is an explanatory diagram of its power transmission path. 1...Tool [spot welding gun], 2x, 2
z, 2y... Traveling unit, 3, 4, 5... Moving table, 6... Tool drive unit, 7...
Motor, 9x, 9z, 9y...Spline shaft, 1
0x, 10y...drive gear [bevel gear], 11x,
12x, 11z, 12z, 11y, 12y... Pulley, 13x, 13z, 13y... Timing belt, 15x, 15z, 15y... Clutch/brake, 16x, 16z, 16y... Ball screw, 17x, 17z, 17y... ball nut,
18x, 18z, 18y, 29...Position detector.

Claims (1)

[Claims] 1. In a multi-axis robot in which a tool is mounted on a drive unit connected to the final stage of a plurality of traveling units, each traveling unit is provided with a spline shaft parallel to the direction of movement. , the spline shaft of the front-stage travel unit and the spline shaft of the rear-stage travel unit are meshed and connected to each other via a gear spline-fitted onto the spline shaft of the front-stage travel unit, and
A single motor installed in the first-stage traveling unit moves the spline shafts of each traveling unit simultaneously, and the transmission of driving force to each traveling unit is transmitted from the spline shaft of each traveling unit to the respective clutches. The timing of the driving force transmission to each traveling unit by the clutch/brake is set such that when the preceding traveling unit shifts from the travel mode to the stop mode, the following traveling unit moves from the stop mode. A method for controlling the positioning of a multi-axis robot, characterized in that the positioning control of each traveling unit is sequentially performed by a single motor.