JPS63185540A - Assembly alignment device - Google Patents

Abstract

PURPOSE:To prevent a robot main unit from being influenced and from receiving the limitation in a work direction, by connecting the main unit with a clamping device through a hollow bellow-shaped soft member, able to softly extend, contract and flex, so as to adjust a pressure of fluid in a bellows in accordance with an output of a fit detecting sensor. CONSTITUTION:A fitting substance is fed to be transferred to a position of the objective substance, and if both the substances are brought into contact with mutually chamfering parts, a cross-shaped diaphragm type force detecting sensor part 3 detects contact force in the vertical direction outputting an instruction so as to adjust a pressure to be reduced of fluid in a hollow bellow-shaped soft member 2. Consequently, a clamping device mounting member 1 is released from mechanical restriction by a spring 5, and a connection member 6 is lifted till it is adapted to a stopper 7, accordingly, the fitting substance, while it is brought into one point contact with the objective substance, is placed in a condition able to only horizontally move through a ball bearing 8 by a softness effect of the hollow bellow-shaped soft member 2, passively performing a position correction.

Description

[Detailed description of the invention] (a) Industrial application field In the production process, there are many tasks in which two objects are fitted together and assembled, and fitting between objects with a gap of only about micrometers is difficult. Because it is a delicate work, it is difficult for humans to do it for a long time. In order to automate such precision assembly work, it is necessary to provide the machine with the ability to adapt to relative positional and angular deviations between two objects.

The present invention relates to an assembly centering device that utilizes compliance to precisely assemble 2111 bodies by being installed at the tip of an arm system of an industrial robot between a gripping device that grips an object and a robot arm. It is something.

(b) Prior Art Various fitting methods have been proposed for precision assembly work as described above.

-The first is an active position control method using sensors.
These methods include a method of controlling the axis of the joints of the robot body, and a method of position control using a positioning mechanism provided in the hand.

The second is a passive position correction method that uses an articulated robot called a SCARA type and compliance called an RCC device.

(c) The problem that the invention seeks to solve.

Among conventional technologies, the active position control method using the first sensor detects the insertion force according to the fitted state of the two objects and corrects the position aSS by feedback control. Robots have become complicated and large, or the axis control circuit of the robot body has become complicated and expensive.

Among the second passive position correction methods using compliance, the former SCARA type generates compliance in the horizontal direction by controlling the axis of the robot body.
There is no angular deviation correction function, and it also affects the control system of the robot body.

The latter RCC device has a very simple mechanism that can be adapted to correct positional and angular deviations, and is small enough to be easily attached to the tip of a robot arm like the present invention, but vibration prevention due to compliance Therefore, it has a stiff spring constant and is suitable for assembly work that requires a relatively large force, making it unsuitable for objects that are easily damaged. Furthermore, it requires an RCC device that is suitable for the size of the mating object, which has the disadvantage of lacking in versatility.

The purpose of the present invention is to have a simple structure that is suitable for precision assembly and insertion work, does not affect the mechanism of the robot body, can be controlled by simple signal exchange with a force sensor, and does not place a burden on the main controller. Moreover, it is an object of the present invention to provide an assembly centering device that does not have any directionality in its work.

(D) Means for Solving the Problems The present invention basically utilizes flexibility to perform fitting, and also when flexibility is not necessary or when flexibility has a negative effect, that is, when the object In order to ensure hardness and rigidity when grasping or transferring an object, we have adopted a compliance function that uses a hollow bellows-like flexible member with high elasticity, flexibility, and rotational rigidity, and a cross-shaped diaphragm type force relaxation function that has been proposed in the past. The shortcomings of the conventional method have been solved by developing a simple mechanism that combines a force-sensing control function using a sensor.

To explain the present invention based on the drawings, in FIG. 1,
The assembly centering device of the present invention is composed of a flexible mechanism section A and a support case section B, and the flexible mechanism section A is supported and housed within the support case section B.

The flexible mechanism section A is composed of a gripping device mounting member 1, a hollow bellows-like flexible member 2, and a cross-shaped diaphragm-type force sensor part 3, which are coaxial with each other. A device for gripping a fitting object is attached to the lower end of the gripping device attachment member 1, and the upper end is coupled to the center portion of the diaphragm of the cross-shaped diaphragm type force sensor part 3. A strain gauge element 4 is attached to the cross-shaped diaphragm type force sensor part 3 so as to be sensitive to uniaxial force in the vertical direction and biaxial torque around the plane, and detects the fitted state by force sense. It has the function of This cross-shaped diaphragm type force sensor part 3
The lower end of the peripheral dead zone is elastically supported by a spring 5, and the upper end is fixed to a connecting member 6 and is normally pushed up via a ball bearing 8 to a stopper 7 formed in the support case part B. One end of the hollow bellows-like flexible member 2, which has the function of being able to flexibly expand, contract and bend, is fixed to the top plate 9 of the support case part B, and the other end is fixed to the connecting member 6.
Since the gripping device mounting member 1 is fixedly connected to the gripping device mounting member 1, the gripping device mounting member 1 can freely move and swing in the horizontal and vertical directions together with the cross-shaped diaphragm type force sensor portion 3.

The support case part B supports and accommodates the flexible mechanism part A, and plays the role of connecting it to an arm of an assembly machine or robot, and mechanically restrains the top plate 9, the stopper 7, and the gripping device mounting member 1. It is formed from a mechanical restraining member lO and a case 11. This support case portion may be integral or may simply be in a fixed relationship.

(e) Operation The operation will be explained in the case where the assembly centering device configured as described above is attached to the arm of an assembly machine or a robot to perform the fitting operation of two objects.

First, when gripping a fitting object, the hollow bellows-shaped flexible member 2
When the fluid pressure inside is adjusted to a high pressure state of a predetermined pressure higher than the elasticity of the spring 5, this hollow bellows-shaped flexible member 2 extends in the vertical direction, and the gripping device mounting member 1 is fixed in a fixed position by the mechanical restraint member 1G. be restrained. Therefore, the mating object gripped by the gripping device is in a very hard and rigid state at this time, so that it can be stably transported without vibration during transport by the robot.

Next, when the mating object is transferred to the target object position and the two objects are brought into contact with each other at their chamfered portions, the cross-shaped diaphragm type force sensor part 3 senses the vertical contact force, and the hollow bellows-like flexible A command is issued to reduce the fluid pressure in the member 2. Therefore, the gripping device mounting member 1 is released from mechanical restraint by the spring 5, and the connecting member 6 is pushed up until it hits the stopper 7, so that it is shaped like a hollow bellows. Due to the flexibility of the flexible member 2, the fitting object is in contact with the target object at one point and can only move horizontally via the pole bearing 8, and the position is passively corrected.

If there is an angular error between the two objects, the mating object that moves horizontally will come into contact with the target object at two points during the pushing operation, so the cross-shaped diaphragm force sensor part 3 will move parallel to the target object. Torques around two axes on a plane are sensed, and a command is issued to increase the fluid pressure within the hollow bellows-like flexible member 2 to a predetermined pressure at which the connecting member 6 separates from the stopper 7. At the same time, when the output from the sensor is equal to or higher than a predetermined value 111a, a horizontal movement command is issued to the robot arm so that the sensor output becomes zero. As a result, the flexibility of the hollow bellows-like flexible member 2 acts, resulting in a state of high compliance in which fitting can be performed without causing the so-called sticking phenomenon.

In this state, as the pushing operation progresses further, the insertion reaction force generated due to contact acts, and the mating is completed while the position and angle of the mating objects are corrected until the axes of both objects coincide. do. Note that the horizontal movement amount of the robot arm based on the force sensor output does not require much positional accuracy, and the fitting work is basically performed by the effect of the flexibility of the hollow bellows-shaped flexible member 2, so it is an auxiliary method. It is also possible to monitor overload abnormalities during fitting using a force sensor.

The operation of the fitting operation by the assembly centering device of the present invention has been explained using an example of vertical work. However, this device can also be used for horizontal work other than vertical work due to the effect of the mechanical restraint mechanism. It can be applied by simply changing the initial setting value and m value.

(F) Embodiment FIG. 2 shows another embodiment in which one end of the hollow bellows-like flexible member 2 is fixed to the connecting member 6, and the other end is fixed to the rotating shaft member 12 on the same axis.

The rotating shaft member 12 is fitted into bearings 13 and 14 of the support case part B, and is rotatably supported by other transmission means such as gears or belts. Therefore, if the rotation of the rotating shaft member is controlled by a drive device such as a motor provided in the robot body, the gripping device mounting member l will rotate via the hollow bellows-shaped flexible member 2 with high rotational rigidity, and the gripping device will be easily attached to the gripping device. A twisting function can be added to the .

(G) Effects of the Invention The present invention corresponds to the wrist of a human hand as an assembly centering device for two objects during fitting and insertion work in precision assembly, and the arm tip of a general industrial robot and a fitting object. It can be easily installed between a gripping device and perform its functions, and has the following effects not found in the prior art.

By developing a mechanism that utilizes multi-functional and highly flexible element members, no special driving energy is required, just using the reaction force and fluid pressure during insertion.

Due to its simple mechanism and small size, it is easy to attach to assembly machines such as industrial robots and does not affect the structure of the robot body.Also, the rigidity can be increased with a mechanical restraint mechanism, so there is no restriction on the direction of work. .

Since it has a force sense function as well as a passive compliance function, an active suppression system can be constructed, and a simple O
Flexibility and rigidity can be switched just by N/OFF control, so there is no burden on the main controller.

As long as rotational power is supplied from the machine body side, a twisting function can be easily added to the object gripping device.

As described above, although the present invention has a very simple mechanism and control, it is possible to perform flexible work movements equivalent to the sophisticated human wrist.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the assembly centering device, and FIG. 2 is a sectional view showing an embodiment related to fixing of a hollow bellows-shaped flexible member. A-----Flexible mechanism part, B----- Support case part 1, --- Grip device mounting member, 2- Hollow bellows-shaped flexible member, 3 Part of +-shaped diaphragm type force sensor 4-Strain meter element, 5-Spring 6-Connection member,
7-stopper 8 ball bearing, 9 top plate 10 mechanical restraint member, 11 case 12-one rotation shaft member, 13-bearing 14 bearing

Claims (3)

[Claims] (1) A device designed to be attached to an assembly device for fitting a target object and a mating object, which grips one of the objects and freely moves the mating object on a plane parallel to the target object. An assembly center characterized in that an assembly device main body and a gripping device are connected to each other by a hollow bellows-like flexible member having the function of being able to flexibly expand, contract, and bend in order to enable horizontal movement and swinging. Aligning device. (2) By adjusting the fluid pressure pressurized from the outside into the hollow bellows-like flexible member based on the output of a sensor that detects the fitted state, the flexible member expands and contracts, mechanically restraining the gripping device. 2. The assembly centering device according to claim 1, further comprising a mechanism capable of releasing restraints and increasing flexibility. (3) One end of the hollow bellows-shaped flexible member is fixed to a gripping device mounting member for attaching the gripping device, and the other end is fixed to a rotating shaft member capable of rotating the gripping device. The assembly centering device according to paragraphs 1 and 2.