GB2100826A - Remotely controlled arm - Google Patents

Abstract

A remotely controlled arm comprises a core (10) of flexible inextensible material secured at one end to a support (11). At least two tubes 12 of flexible extensible material are secured to the core along spaced lines parallel to the longitudinal axis (13) of the core. Each tube (12) is capable of longitudinal extension without radial extension. Control means (14) are provided operable to apply fluid under pressure to one or more of the tubes (12) to cause movement of the outer end of the core. <IMAGE>

Description

SPECIFICATION Remotely-controlled arm Remotely-controlled arms are used in a wide range of applications, ranging from automatic computer controlled machines to arms controlled by an operator from a distance for safety reasons.

In all cases the mechanism of the arm is complex, after providing up to six degrees of freedom.

Inevitably, such arms are very expensive, and often provide facilities far in excess of those required. Two or three degrees of freedom is frequently sufficient for simple applications.

It is an object of the present invention to provide a simple and relatively inexpensive remotely-controlled arm.

According to the present invention there is provided a remotely-controlled arm one end of which is movable about two perpendicular axes with respect to the other end, which includes a core member of flexible inextensible material secured at one end to a support, at least two tubes of flexible material secured to the core member along spaced lines parallel to the longitudinal axes of the core, each tube being capable of longitudinal extension without radial extension and each having a closed end adjacent to the other end of the core member, and control means operable to apply fluid under pressure to at least one of the tubes to cause movement of said one end of the arm.

The invention will now be described with reference to the accompanying drawings, in which: Figures 1 and 2 are schematic diagrams illustrating the principle of operation; Figure 3 is a sectional view of an arm according to a first embodiment of the invention; Figure 4 is a sectional view of an arm according to a second embodiment of the invention; Figures 5 and 6 are sectional side and end views of a further embodiment of the invention; and Figure 7 shows an arrangement for providing a further degree of movement.

Referring now to Figures 1 and 2, these show side and sectional views of a core member 10 of flexible but inextensible material secured at one end to a support 1 A tube 12 is secured to the core member 10 along a line parallel to the longitudinal axis 1 3 of the core member. The tube 12 is closed at the end adjacent to the free end of the core member 10, and is of such a construction that it is capable of longitudinal extension but not of any significant radial extension. Fluid under pressure may be applied to the tube 12, from either a hydraulic Qr a pneumatic source under the control of control means 14. If such pressure is applied to the tube 12, the tube 12 will attempt to lengthen. However, since it is secured along a line to the inextensible core member 10, such extension is impossible.Instead, the tube 1 2 will bow, due to the extension of only that part of the tube remote from the core member 1 0.

Accordingly the entire core member will bow into a position such as that shown in broken outline.

The principle outlined above may be used to provide an arm with movement about two perpendicular axes. In its simplest form the arm comprises the same inextensible but flexible core member 10 with two tubes 12 attached to it, spaced at 900 around the periphery of the core member as shown in section in Figure 3. The application of pressure to either one of the tubes will result in movement of the free end of the core member as shown by the arrows 21 and 22.

Hence the application of the appropriate pressures to the two tubes simultaneously will allow the free end of the core member to be moved to any position within the quadrant defined by the two arrows.

A wider range of movement may be obtained by using three tubes 12 equally spaced 1200 apart around the periphery of the core member 10 as shown in section in Figure 4. This arrangement will allow movement over the entire plane of the drawing.

The tubes 1 2 may conveniently be of bellows form as shown in Figures 5 and 6, since this provides a tube having adequate longitudinal extension with little or no radial extention. If tubes of this form are used it is preferable to shape the surface of the core 10 member to match that of the tube, so as to improve the contact and fixing between them. The whole construction may then be covered with a flexible outer sleeve 50.

The arm described above only provides movement in one plane, if one neglects the longitudinal movement resulting from the bowing of the core member. Longitudinal movement may also be provided if required. Figure 7 shows an arm in which this is provided by a further bellows 70 of which forms the support for the core member. Alternative means may be used to provide such movement, such as a piston and cylinder arrangement.

One of the features which makes the conventional type of remotely controlled arm so costly is the need for accurate measuring systems to determine the position of the arm. In systems which are controlled visually by an operator this is not necessary but the automatic arm controlled, say, by a computer requires this high accuracy. The measuring components are built into each joint of the arm, thus increasing the cost.

A simple measuring system, suitable if the arm is movable over a fairly small area, is described in our co-pending applications numbers 8113135 and 8117009. Such systems require the free end of the arm to carry a small light source, the position of which may be determined. A second measuring system arranged at right angles to the first will measure changes in the length of the arm.

The remotely controlled arm described above is a much simpler and cheaper arrangement than many which exist at the present time, though it may be somewhat limited in its applications. It is, however, perfectly suitable for simple movements over short distances. No mention has been made of the attachments which may be used with the arm for holding tools or workpieces, since such attachments are well known.

Claims (8)

1. A remotely controlled arm one end of which is movable about two perpendicular axes with respect to the other end, which includes a core member of flexible inextensible material secured at one end to a support, at least two tubes of flexible material secured to the core member along spaced lines parallel to the longitudinal axes of the core, each tube being capable of longitudinal extension without radial extension and each having a closed end adjacent to the other end of the core member, and control means operable to apply fluid under pressure to at least one of the tubes to cause movement of said one end of the arm.

2. An arm as claimed in Claim 1 which includes two tubes secured to the core along lines spaced 900 apart around the periphery of the core.

3. An arm as claimed in Claim 1 which includes three tubes secured to the core along lines spaced 1200 apart around the periphery of the core.

4. An arm as claimed in any one of Claims 1 to 3 in which each tube is constructed in the form of a bellows.

5. An arm as claimed in Claim 4 in which the outer surface of the core is shaped to engage the outer surface of each tube along said spaced line.

6. An arm as claimed in any one of Claims 1 to 5 in which the support for the core is a remotely controlled movable member.

7. An arm as claimed in any one of the preceding claims in which the control means operates to apply hydraulic pressure to said tubes.

8. A remotely controlled arm substantially as herein described with reference to the accompanying drawings.