Material or article handling – Vertically swinging load support – Grab
Patent
1983-10-25
1986-02-18
Jones, Larry
Material or article handling
Vertically swinging load support
Grab
901 45, 29714, 33185R, B66C 100, B25J 1100
Patent
active
045711488
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a system for manipulating and holding an article, for example for use in an industrial robot or a co-ordinate table.
In manipulating systems comprising a robot arm and a robot gripper, there are known devices, called Remote Compliance Centres, which are placed between the robot arm and the robot gripper to provide the robot gripper with the compliance necessary to realise insertions of components in required locations. However, these devices are passive, i.e. they are provided with no sensing means to monitor the misalignments, nor with motors or other forms of actuators to realise the necessary adjustments.
High positioning accuracy is required in particular when robots are used for automatic assembly. Some work undertaken by research groups is attempting to sense the misalignment of components and correct it by adjusting the position of the robot arm.
Because robot arms are relatively heavy, it is difficult to make minute adjustments ranging from a few hundredths of millimeters up to a few millimeters.
According to the present invention, there is provided a system for holding and manipulating an article, the system comprising a housing in which there are: a member connected to means for holding the article; position sensing means for sensing the position of the member in the housing; and actuating means connected to the sensing means for producing movements of the member within the housing, wherein the position sensing means comprises: a sensor member having a nozzle; a first gas line with constricting means for supplying gas to the nozzle via the constricting means, the nozzle being disposed opposite the first member, whose position is to be sensed; and a second gas line, connected to the first gas line between the nozzle and said actuating means, the arrangement being such that, if the said first member moves towards or away from the nozzle, the gas pressure at the constricting means increases or decreases respectively, causing gas to flow towards or away from the actuating means via the second gas line to cause the actuating means to cause movement of the said first member. The actuating means may comprise bellows, or a pliable capsule, connected to the second gas line to allow the passage of gas into and out of the bellows or capsule, and which abuts the sensor members to cause movement thereof and thereby movement of the said first member.
The examples of the present invention to be described with reference to the accompanying drawings each comprises a system which is capable of both a sensing and an actuating function. the system is mounted at the end of the robot arm and provides the base for the robot hand (gripper). The system itself realises the corrective movement without resorting to using the arm's actuators. Because much smaller weights are manipulated than in the case of adjusting the whole robot arm, it is easier to realise minute adjustments required for the alignment of a component held by the robot hand.
In the system described below, misalignment of components between an inner member comprising such a first member and a sensor member of the sensing means is sensed, whilst the correction action is generated between an outer member comprising such a housing and the sensor member. The sensor member therefore acts as a mediator between the inner and outer members.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a diagram for explaining the principle of examples of the invention;
FIGS. 2 and 4 show different kinds of misalignment which can be compensated for by different examples of the invention;
FIGS. 3a and 3b are respectively a partially cut-away side view and a plan view of an example of the invention for compensating for types of misalignments according to FIG. 2;
FIG. 5 is a partially cut-away side view of an example of the invention for compensating for types of misalignments according to FIG. 4;
FIG. 6 is a side view of another example of the invention for compensating
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patent: 3824674 (1974-07-01), Inoyama et al.
patent: 3893217 (1975-07-01), Edmond
patent: 3963271 (1976-07-01), Sugino et al.
patent: 4048687 (1977-09-01), Kato et al.
patent: 4098001 (1978-07-01), Watson
patent: 4398350 (1983-08-01), Inoue
An Anatomy of Industrial Robots and Their Controls, Luh, IEEE Transactions on Automatic Control, vol. AC28, No. 2, Feb. 1983.
Pneumatic Touch Sensor, Garrison and Wang, IBM Technical Disclosure Bulletin, vol. 16, No. 6, Nov. 1983.
Jones Larry
National Research Development Corporation
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