GB2191827A - Master/slave manipulators - Google Patents

Abstract

For detecting a fault in a flexible gaiter enclosing the slave arm of a master/slave manipulator used in the nuclear industry, valve means 4 comprising oppositely acting non- return valves 5, 6 are arranged in the wall 1 of the gaiter. On extension and retraction of the slave arm the valves operate to equalise pressure differences at opposite sides of the gaiter. Failure of the valves to function during extension and retraction of the slave arm can indicate a fault, such as a tear, in the gaiter. <IMAGE>

Description

SPECIFICATION Improvements in and relating to manipulators The present invention concerns manipulators for remote handling operations.

Manipulators, known as master/slave manipulators, are used in the nuclear industry for remote handling and other operations on radioactive materials. A master/slave manipulator comprises three main mechanically interlinked components, namely, a master arm, a through-wall unit and a slave arm. The master arm is operable by an operator in a safe environment and its movements are reproduced by the slave arm which is situated in an active or hostile environment behind a shielding wall, the two arms being interlinked by the throughwall unit. It is usual to enclose that portion of the slave arm which extends from the through-wall unit to a wrist adjacent the free end of the slave arm within a gaiter. The gaiter comprises a flexible bellows-like member which can be secured at one end to the shielding wall about the through-wall unit and at its opposite end to the wrist of the slave arm.The gaiter serves two main functions.

First, it protects the slave arm from contamination thereby easing problems arising from maintenance and repair operations. Second, it provides a seal about the through-wall unit.

During operation of the manipulator the slave arm can undergo repeated extensions and retractions with resulting volume, and hence pressure, changes within the gaiter. The pressure changes, which can be considerable, influence the load to be overcome by an operator and increase the risk of gaiter failure. Further, if the gaiter is secured to the wrist of the slave arm or the shielding wall when the slave arm is in a retracted position, then extension of the arm will result in a pressure reduction within the gaiter. In such a situation the gaiter can collapse on to the slave arm with risk of tearing. It is also desirable that an operator is aware of any failure in the gaiter.

To avoid the above problems there is provided according to the present invention a gaiter for a master/slave manipulator having valve means operable to compensate for pressure changes within the gaiter during operation of the manipulator.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawing which depicts an embodiment of pressure compensation means mounted in a wall of a gaiter for a master/slave manipulator.

In the drawing, a portion of a gaiter wall is indicated by the reference numeral 1. The gaiter, in use, envelopes the slave arm of a manipulator as previously mentioned. Reference numerals 2 and 3 respectively denote regions within and outside the gaiter. Thus the slave arm is within the region 2 and region 3 is the hostile environment outside the gaiter and behind shielding of a containment.

A valve means 4, comprising first and second valve members 5 and 6 respectively, is mounted in the gaiter wall 1 and at a position which is visible to an operator through a window in the shielding. The valve members 5 and 6 comprise ball valves which function as non-return valves.

In operation, an extension of the slave arm will result in a fall in pressure within region 2.

As a result the ball of valve member 5 is lifted off its seat to compensate and equalise the pressure difference between the regions 2 and 3. The ball of the valve member 6 remains on its seat. During retraction of the slave arm the converse occurs with the ball of valve member 6 being lifted off its seat and the ball of valve member 5 remaining on its seat. Conveniently, the valve members are formed from a transparent material, such as perspex, and the balls can be coloured so as to be readily visible. Consequently, if during operation of the manipulator an operator fails to observe movement of the balls this will be indicative of a fault or tear in the gaiter resulting in a leak.

Alternatively, the balls can be urged into engagement with their seats by means of springs. Further, the balls can be formed from electrically conducting material cooperable with contacts at the valve seats to complete an electrical circuit containing a warning or alarm device. The arrangement can be such that a warning signal which can be visual or audible, is actuated on operation of the manipulator and in the event of gaiter damage resulting in leakage.

As the air sucked into the region 2 is likely to be contaminated by radioactivity in the region 3, a filter 7 can be arranged in the flow path through the valve member 5.

1. A flexible gaiter, in particular a gaiter enclosing a slave arm of a master/slave manipulator, including valve means operable to compensate and equalise pressure differences at opposite sides of the gaiter during extensions and retractions of the slave arm.

2. A gaiter as claimed in claim 1 in which the valve means comprises first and second oppositely acting non-return valves.

3. A gaiter as claimed in claim 2 in which the non-return valves comprise spring-loaded valve members.

4. A flexible gaiter for enclosing a slave arm of a master/slave manipulator substantially as herein described with reference to and as illustrated in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in and relating to manipulators The present invention concerns manipulators for remote handling operations. Manipulators, known as master/slave manipulators, are used in the nuclear industry for remote handling and other operations on radioactive materials. A master/slave manipulator comprises three main mechanically interlinked components, namely, a master arm, a through-wall unit and a slave arm. The master arm is operable by an operator in a safe environment and its movements are reproduced by the slave arm which is situated in an active or hostile environment behind a shielding wall, the two arms being interlinked by the throughwall unit. It is usual to enclose that portion of the slave arm which extends from the through-wall unit to a wrist adjacent the free end of the slave arm within a gaiter. The gaiter comprises a flexible bellows-like member which can be secured at one end to the shielding wall about the through-wall unit and at its opposite end to the wrist of the slave arm.The gaiter serves two main functions. First, it protects the slave arm from contamination thereby easing problems arising from maintenance and repair operations. Second, it provides a seal about the through-wall unit. During operation of the manipulator the slave arm can undergo repeated extensions and retractions with resulting volume, and hence pressure, changes within the gaiter. The pressure changes, which can be considerable, influence the load to be overcome by an operator and increase the risk of gaiter failure. Further, if the gaiter is secured to the wrist of the slave arm or the shielding wall when the slave arm is in a retracted position, then extension of the arm will result in a pressure reduction within the gaiter. In such a situation the gaiter can collapse on to the slave arm with risk of tearing. It is also desirable that an operator is aware of any failure in the gaiter. To avoid the above problems there is provided according to the present invention a gaiter for a master/slave manipulator having valve means operable to compensate for pressure changes within the gaiter during operation of the manipulator. The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawing which depicts an embodiment of pressure compensation means mounted in a wall of a gaiter for a master/slave manipulator. In the drawing, a portion of a gaiter wall is indicated by the reference numeral 1. The gaiter, in use, envelopes the slave arm of a manipulator as previously mentioned. Reference numerals 2 and 3 respectively denote regions within and outside the gaiter. Thus the slave arm is within the region 2 and region 3 is the hostile environment outside the gaiter and behind shielding of a containment. A valve means 4, comprising first and second valve members 5 and 6 respectively, is mounted in the gaiter wall 1 and at a position which is visible to an operator through a window in the shielding. The valve members 5 and 6 comprise ball valves which function as non-return valves. In operation, an extension of the slave arm will result in a fall in pressure within region 2. As a result the ball of valve member 5 is lifted off its seat to compensate and equalise the pressure difference between the regions 2 and 3. The ball of the valve member 6 remains on its seat. During retraction of the slave arm the converse occurs with the ball of valve member 6 being lifted off its seat and the ball of valve member 5 remaining on its seat. Conveniently, the valve members are formed from a transparent material, such as perspex, and the balls can be coloured so as to be readily visible. Consequently, if during operation of the manipulator an operator fails to observe movement of the balls this will be indicative of a fault or tear in the gaiter resulting in a leak. Alternatively, the balls can be urged into engagement with their seats by means of springs. Further, the balls can be formed from electrically conducting material cooperable with contacts at the valve seats to complete an electrical circuit containing a warning or alarm device. The arrangement can be such that a warning signal which can be visual or audible, is actuated on operation of the manipulator and in the event of gaiter damage resulting in leakage. As the air sucked into the region 2 is likely to be contaminated by radioactivity in the region 3, a filter 7 can be arranged in the flow path through the valve member 5. CLAIMS

1. A flexible gaiter, in particular a gaiter enclosing a slave arm of a master/slave manipulator, including valve means operable to compensate and equalise pressure differences at opposite sides of the gaiter during extensions and retractions of the slave arm.

2. A gaiter as claimed in claim 1 in which the valve means comprises first and second oppositely acting non-return valves.

3. A gaiter as claimed in claim 2 in which the non-return valves comprise spring-loaded valve members.

4. A flexible gaiter for enclosing a slave arm of a master/slave manipulator substantially as herein described with reference to and as illustrated in the accompanying drawing.