JPH0811381B2 - Robot with reinforcing arm - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a robot provided with a reinforcing arm for compensating for the reduction in rigidity due to the weight reduction of a robot arm.

(Prior Art) A conventional robot arm is thick and heavy in order to have rigidity so as not to bend with respect to a load. However, in the case where the robot's weight-to-weight ratio is improved and the robot arm is narrow, Considering the workability of, the weight reduction and size reduction of the robot arm are essential conditions. Therefore, for example, in the robot arm disclosed in Japanese Patent Laid-Open No. 61-125786, a sub-arm that does not receive a load is installed in parallel with the main arm, and a change in relative position with the sub-arm due to bending of the main arm is detected. The detection amount is input to the control signal of the main arm drive device as a correction signal to position the tip of the main arm.

In this way, in principle, the main arm tip can be accurately positioned without increasing the rigidity of the main arm, but in reality, the arm deformation amount increases as the arm rigidity decreases. As a result, it becomes difficult to make corrections, which inevitably causes a decrease in position accuracy and a vibration problem.

(Object of the Invention) Therefore, an object of the present invention is to provide a robot arm capable of maintaining a required rigidity despite the weight reduction of the arm.

(Structure of the Invention) A robot according to the present invention includes a reinforcing arm that is provided in parallel with the main arm in order to suppress bending of the main arm, and a holding member that holds the reinforcing arm substantially parallel to the main arm. However, this holding member is provided on the outer periphery of the main arm so as to be coaxially rotatable with respect to the main arm. Further, the bending direction detecting means for detecting the bending direction of the main arm and the holding member corresponding to the bending direction of the main arm detected by the detecting means are rotated to cause the reinforcing arm to bend the main arm. Drive means for moving along the outer periphery of the main arm to a position where the above can be suppressed.

(Effect of the Invention) According to the present invention, since the reinforcing arm is configured to immediately move to the position where the bending of the main arm can be suppressed in accordance with the bending direction of the main arm, it is lightweight and highly rigid. You can get a robot arm.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an overall view of the robot, and FIG. 2 shows its arm. Reference numeral 1 is a main arm, 2 is an arm hand, and 3 is a reinforcing arm that also serves as an arm hand drive shaft. The reinforcing arm 3 is provided on the outer periphery of the main arm 1 at predetermined intervals in the axial direction thereof and is held by eyeglass-shaped holding members 4a and 4b so as to be provided substantially parallel to the main arm 1. As shown in FIG. 3, the holding members 4a and 4b are coaxially rotatably provided on the outer periphery of the main arm 1 via a bearing 5 and rotate the reinforcing arm 3 via a conical bearing 6. It supports movably. Gears 7a and 7b are respectively formed on the outer circumferences of the holding members 4a and 4b over a predetermined angle range, and the gears 7a and 7b are provided on a direction control drive shaft 9 which is rotationally driven by a motor 8. The gears 10a and 10b are meshed with each other, and the holding members 4a and 4b are configured to be rotated coaxially with the main arm 1 by the motor 8.
The direction of the reinforcing arm 3 with respect to the main arm 1 is controlled in accordance with the rotation of the holding members 4a and 4b. The direction control drive shaft 9 is supported by bearings 11a and 11b fixed to the main arm 1.

On the other hand, the reinforcing arm 3 also serving as the arm hand drive shaft is provided with gears 12a and 12b at both end positions thereof,
The gear 12a on the tip end side is a gear for driving the arm hand, and meshes with the gear 13 attached to the arm hand 2.
Further, the gear 12b on the base end side meshes with an idler gear 15 rotatably provided on the outer periphery of the main arm 1 via a bearing 14 as shown in FIG. This idler gear 15
A gear 17 attached to the arm-hand drive shaft 16 meshes with the. Therefore, the rotation of the arm hand drive shaft 16 is transmitted to the arm hand 2 through the gear 17, the idler gear 15, the gear 12b, the reinforcing arm 3, the gear 12a, and the gear 13.

Further, a plurality of strain sensors 18 such as strain gauges are attached to the outer peripheral surface of the main arm 1, and the output signals of these strain sensors 18 are amplified by an amplifier 19 and then sent to a motor control circuit 20. The motor control circuit 20 analyzes the signals sent from the plurality of strain sensors 18 and detects the direction in which the load is applied to the main arm 1. And the reinforcing arm 3 viewed from the direction in which the load is applied and the main arm 1.
The holding member by driving the motor 8 so that the direction of
The reinforcing arms 3 are moved along the outer periphery of the main arm 1 by rotating 12a, 12a. As a result, the rectangle formed by the main arm 1, the reinforcing arm 3 and the holding member 12a or 12b becomes parallel to the load direction, the second moment of area increases, the arm strength improves, and the bending of the main arm 1 is suppressed. . The relative coordinates of the gear 17 and the gear 13 do not change even if the reinforcing arm 3 moves to any position on the outer circumference of the main arm 1. Therefore, it is not necessary to correct the position of the arm hand driving motor. Absent.

Next, FIG. 5 is a block diagram showing the control circuit of the direction control motor 8, and FIG. 6 is a flow chart showing the control flow.

In step S1 of FIG. 6, the main stress direction applied to the main arm 1 is determined based on the output of the strain sensor 18. In the next step S2, the current position of the reinforcing arm 3 is referred to from the output of the encoder 21 indicating the rotational position of the motor 8, and in the next step S3, the moving direction and the moving angle of the reinforcing arm 3 are determined. It is stored in the storage device 22.
In the next step S4, the moving direction and the moving angle of the reinforcing arm stored in the storage device 22 are read to drive the motor 8. The rotation position of the motor 8 is coded by the encoder 21. In the next step S5, the current principal stress direction is determined from the output of the strain sensor 18, and it is determined in step S6 whether this principal stress direction and the position of the reinforcing arm 3 match or not. If YES, the control is ended, and if NO, the process returns to step S1 and the above-described flow is repeated.

The above is a description of an example configuration and operation of a robot having a reinforcing arm according to the present invention. According to the present embodiment, the arm hand drive shaft can effectively function as a reinforcing arm, and it is lightweight and A highly rigid robot arm can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view of a robot embodying the present invention, FIG. 2 is a perspective view of its robot arm, and FIGS. 3 and 4 are lines III-III and FIG. FIG. 5 is a block diagram of the control circuit, and FIG. 6 is a flow chart. 1 ... Main arm, 2 ... Arm hand 3 ... Reinforcing arm, 4a, 4b ... Holding member 7a, 7b, 10a, 10b, 12a, 12b, 13, 17 ... Gear 8 ... Motor, 9 ... … Direction control drive shaft 15 …… Idler gear 16 …… Arm hand drive shaft 18 …… Strain sensor, 20 …… Motor control circuit

Claims (1)

[Claims] 1. A reinforcing arm provided in parallel with a main arm of the robot for suppressing bending of the main arm, and provided on the outer periphery of the main arm so as to be coaxially rotatable with respect to the main arm. A holding member for holding the reinforcing arm substantially parallel to the main arm, a bending direction detecting means for detecting a bending direction of the main arm, and a bending direction of the main arm detected by the detecting means. And driving means for rotating the holding member in response to the movement of the reinforcing arm along the outer circumference of the main arm to a position where the reinforcing arm can suppress the bending of the main arm. A robot having a reinforcing arm.