FIELD OF THE INVENTION

The invention relations to robotic muscles. In particular, the invention relates to fluid actuated muscles, and robotic muscle attachment devices.

BACKGROUND ART

Figures IA to ID illustrates an air muscle 1 of the prior art. As illustrated in figures IA to ID an air muscle comprises: an expandable hollow tube 40, generally of an elastomeric material, surrounded by a braided sheath 30; a first closure arrangement 20 having an air inlet/outlet port 10; a second closure arrangement 50, such as a bung, provided at the opposite end of the expandable tube 40; and connection devices 60, 70.

The introduction of air, or another suitable fluid, under pressure, in to the expandable tube 40 via the air inlet port 10 and first closure arrangement 20 causes the tube 40 to expand, which in turn, results in radial expansion of the braided sheath 30, as illustrated in figure IB.

It is a characteristic of the braided sheath 30, that radial expansion is accompanied by a contraction in its length, also illustrated in figure IB.

Figures 2A and 2B illustrate two air muscles IA, IB are connected to a first member 100 and a second member 110 at point 104 and 106 respectively. The second member 110 is fixed and the first member 100 is pivotal about point 102 with respect to the second member 110.

In figure 2A, the first air muscle IA is filled with pressurised air and the second air muscle IB is not. When the second air muscle IB is filled with pressurised air, and at the same time the air released from the first air muscle IA, the first member 100 pivots about point 102 in an anti-clockwise direction as indicated in figure 2B. Filling the first air muscle IA with pressurised air, and at the same time releasing the air from the second air muscle IB, results in the first member 100 pivoting about point 102 in a clockwise direction back to the position indicated in figure 2A.

The coupling of the first and second air muscles IA, IB, means that each air muscle is pulled out when the air is released so that the air muscle is able to deliver their full stroke when inflated.

However, the air muscles described above have several disadvantages. For example, the first closure arrangement 20, second closure arrangement 50 and connection devices 60, 70 take up a considerable amount of space, when combined having almost the same length as the tube 40 and braided sheath 30. This results in wasted space. In addition, this means that a considerable part of the air muscle (the first closure arrangement 20, the second closure arrangement 50 and connection devices 60, 70) is not doing work.

Therefore, the aim of the present invention is to provide an improved air muscle.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, a fluid actuated muscle for a robotic limb is provided. The fluid actuated muscle comprising: an expandable tube; a braided layer surrounding the expandable tube; a fluid inlet and outlet device provided at a first end of the expandable tube; and an attachment device attached to a second end of the expandable tube, opposite to the first end, the attachment device having a curved surface, and wherein the second end of the expandable tube follows the curvature of at least a portion of the curved surface.

According to another embodiment of the invention in use, inflation/deflation of the expandable tube rotates the attachment device about a pivot point. According to another embodiment of the invention the expandable tube comprises an elastomeric material.

According to another embodiment of the invention the expandable tube comprises natural rubber.

According to another embodiment of the invention the braided layer comprises a lattice of interconnected nylon strands.

According to another embodiment of the invention radial expansion of the braided layer results in contraction of the depth of the braided layer.

According to another embodiment of the invention the fluid is air.

According to one embodiment of the invention an attachment device for a robotic muscle is provided. The attachment device comprising a curved surface, wherein an end of the robotic muscle follows the curvature of at least a portion of the curved surface, such that expansion of the robotic muscle rotates the attachment device about a pivot point.

According to one embodiment of the invention an attachment device for a robotic muscle is provided. The attachment device comprising: a first member; a second member having a first surface configured to interconnect with a first surface of the first member; and a device for fixing the first and second members together, wherein in use, an end of a robotic muscle is provided between the first and second members, and the first and second members interconnect to grip the end of the robotic muscle.

According to another embodiment of the invention the first surface of the first member comprises an undulating surface and the first surface of the second member comprises an undulating surface. According to another embodiment of the invention the first surface of the first member comprises one or more convex portions and the first surface of the second member comprise one or more concave portions.

According to another embodiment of the invention the first surface of the first member comprises one or more convex portions and one or more concave portions, and the first surface of the second member comprise one or more concave portions and one or more convex portions.

According to another embodiment of the invention the first and second members comprise aluminium.

According to another embodiment of the invention a second surface of the first member, opposite to the first surface, is in contact with the robotic muscle.

According to another embodiment of the invention a second surface of the first member comprises a smooth surface.

According to one embodiment of the invention a fluid actuated muscle arrangement is provided. The fluid actuated muscle arrangement comprising: a first fluid actuated muscle; and a biasing device coupled to the first fluid actuated muscle, wherein the biasing device biases the first fluid actuated muscle to its original length when fluid is released from the first fluid actuated muscle.

According to another embodiment of the invention the biasing device comprises a second fluid actuated muscle, and wherein fluid is inserted into the second fluid actuated muscle when fluid is released from the first fluid actuated muscle to biases the first fluid actuated muscle to its original length. According to one embodiment of the invention a fluid inlet and outlet device for a fluid actuated muscle is provided. The fluid inlet and outlet device comprising: a first sealing member provided at a first end of an expandable tube of a fluid actuated muscle; a second sealing member provided adjacent to the first sealing member; an inlet/outlet passage provided in the second sealing member; and a fixing device connecting the second sealing member to the first sealing member, wherein a cavity is formed between the fixing device, the first sealing member and the second sealing member, and wherein an inlet/outlet passage is provided in the fixing device and/or the first sealing member so that fluid can be inserted into/ removed from the expandable tube.

According to one embodiment of the invention a robotic limb is provided. The robotic limb comprising: an upper body arrangement comprising: a first and second fluid actuated muscle device coupled together such that inflation of the first fluid actuated muscle device and deflation of the second fluid actuated muscle device results in rotation of the upper body arrangement in a first direction about a first axis, and deflation of the first fluid actuated muscle device and inflation of the second fluid actuated muscle device results in rotation of the upper body arrangement in a second direction, opposite to the first direction about the first axis.

According to another embodiment of the invention the robotic limb further comprises: a third and fourth fluid actuated muscle device coupled together such that inflation of the third fluid actuated muscle device and deflation of the fourth fluid actuated muscle device results in rotation of an upper arm arrangement coupled to the upper body arrangement in a third direction about a second axis orthogonal to the first axis, and deflation of the third fluid actuated muscle device and inflation of the fourth fluid actuated muscle device results in rotation of the upper arm arrangement in a fourth direction, opposite to the third direction, about the second axis.

According to another embodiment of the invention the upper arm arrangement comprises: fifth and sixth fluid actuated muscle devices coupled together such that inflation of the fifth fluid actuated muscle device and deflation of the sixth fluid actuated muscle device results in rotation of a connector disk in a fifth direction about a third axis orthogonal to the first and second axes, and deflation of the fifth fluid actuated muscle device and inflation of the sixth fluid actuated muscle device results in rotation of the connector disk in a sixth direction, opposite to the fifth direction, about the third axis.

According to another embodiment of the invention the upper arm arrangement further comprises: seventh and eighth fluid actuated muscle devices coupled together such that inflation of the seventh fluid actuated muscle device and deflation of the eighth fluid actuated muscle device results in rotation of the connector disk in a sixth direction about a fourth axis parallel to the second axis, and deflation of the seventh fluid actuated muscle device and inflation of the eighth fluid actuated muscle device results in rotation of the connector disk in a eighth direction, opposite to the seventh direction, about the fourth axis.

According to one embodiment of the invention robotic joint is provided. The robotic joint comprising: a first pivot point provided away from the centre of the robotic joint; and a second pivot point provided away from the first pivot point and the centre of the robotic joint.

BRIEF DESCRIPTION OF THE DRAWING

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made by way of example only to the accompanying drawings:

Figures IA to ID illustrate schematically an air muscle of the prior art;

Figures 2A and 2B illustrate schematically an air muscle arrangement of the prior art;

Figure 3 illustrates schematically a fluid actuated muscle of the invention;

Figure 4A illustrates schematically a side view of an attachment device of the invention for robotic muscles;

Figure 4B illustrates schematically a perspective view of the attachment device of figure 4A; Figure 4C illustrates schematically an attachment device of the invention connected to a fluid actuated muscle;

Figures 5A and 5B illustrates schematically a first fluid actuated muscle of the invention coupled to a fluid actuated muscle using an the attachment device of the invention;

Figures 6A and 6B illustrate schematically a fluid inlet/outlet device for use with a fluid actuated muscle of the invention;

Figure 7 and 8 illustrate schematically a robotic limb of the invention;

Figures 9 and 10 illustrate a robotic limb of the invention; and

Figures HA to HC illustrates schematically a robotic joint.

DETAILED DESCRIPTION

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings.

With reference to figure 3, it has been proposed to attach one end of a fluid actuated muscle 300 to a cylinder 310, such that the fluid actuated muscle 300 is sealed at the cylinder 310 end. The cylinder 310 is pivotal about point 302. This arrangement is advantageous since there is no wasted space, the fluid actuated muscle is connected directly to the joint (the pivot point 302). As a result of the fluid actuated muscle 300 being connected directly to the pivot point 302, the active part of the fluid actuated muscle is increased when compared to an air muscle of the prior art (as illustrated in figures 2A and 2B) which is connected to the pivot point 102 via the second closure arrangement 50, connection devices 60, 70 and connection point 104.

The arrangement of figure 3 is also advantageous since, when the fluid actuated muscle is inflated, the cylinder 310 can rotate anti-clockwise, as indicated by the arrow, which results in greater work being done by the fluid actuated muscle. A fluid actuated muscle of the invention comprises an expandable tube surrounded by a layer of braided material. The expandable inner tube may be any elastomeric material, such as natural rubber. The outer layer of braided material may be nylon. The outer layer of braided material may comprise a lattice work of nylon thread arranged such that when the material is radially expanded, the depth of the material contracts.

A property of the material of the outer layer is that the outer sheath contracts in length, when expanded radially. The outer sheath expand radially when the inner tube is expanded as a result of being filled with air, or some other suitable fluid. The fluid actuated muscle consequently works like a muscle of a mammal expanding in one direction when contracting in a second direction.

The material of the outer sheath can be slippery, which can resulting in the fluid actuated muscle not gripping the cylinder 310. In order to overcome this problem, an attachment device, as illustrated in figure 4A to 4C is provided.

Figure 4A illustrates a side view of the attachment device 400 of the invention and figure 4B illustrates a perspective view of the attachment device 400 of the invention. The attachment device 400 comprises a first (top) member 410 and second (bottom) member 420. The fluid actuated muscle is provided such that is it trapped between the first and second members 410, 420. The first and second members are then affixed together. In the attachment device illustrated, the first and second members are affixed using screws provided in the screw holes 430. However, other methods of affixing the first and second members could be used, such as welding.

Figure 4C illustrates a fluid actuated air muscle 300 provided in the attachment device 400.

In the attachment device illustrated in figures 4A to 4C the first member 410 comprises an undulating surface and the second member 420 comprises an undulating surface, such that the undulating surface of the first members 410 interconnects, is provided in a mating arrangement, with the undulating surface of the second member 420.

As illustrated in figure 4A, the first member 410 comprises two convex portions 412 and two concave portions 414, and the second member 420 comprises two concave portions 414 and two convex portions 412. The convex portions 412 of the first member 410 are provided in mating arrangement with the concave portions 414 of the second member 420, and the concave portions 414 of the first member 410 are provided in mating arrangement with the convex portions 412 of the second member 420.

The first member 410 may comprise more or less than two convex portions 412 and more or less than two concave portions 414. For example, the first section 410 may comprise one or three convex portions 412 and one or three concave portions 414. In addition, the second member 420 may comprise more or less than two convex portions 412 and more or less than two concave portions 414. For example, the second section 420 may comprise one or three convex portions 412 and one or three concave portions 414. However, any interconnection between the first and second members 410, 420, which prevents the fluid actuated muscle from slipping from the attachment device 400 can be used.

The first and second members 410, 420 are made from aluminium. However, other material could be used.

The outer surface of the first member 410, opposite to the undulating surface, is in contact with the outer layer of the air muscle 300, as illustrated in figure 4C. The outer surface of the first member 410 comprises a smooth surface.

The attachment device 400 seals the end of the expandable tube such that the fluid can not escape. In order for the fluid actuated muscle to regain its original length when the fluid is released, a first fluid actuated muscle of the invention is coupled to a second fluid actuated muscle of the invention, as illustrated in figure 5. The first fluid actuated muscle 300A is connected to a first attachment device 400A, such that the under surface of the fluid actuated muscle 300A is in contact with the upper surface of the first attachment device 400A (as illustrated in figure 5), and a second fluid actuated muscle 300B is connected to a second attachment device 400B such that the under surface of the fluid actuated muscle 300B is in contact with the upper surface of the first attachment device 400B.

As described above with reference to figure 2, when the first fluid actuated muscle 300A is inflated, the fluid actuated muscle 300A expands radially, and it's length contracts, at the same time fluid is released from the second fluid actuated muscle 300B. When the second fluid actuated muscle 300B is inflated, the fluid actuated muscle 300B expands radially, and it's length contracts, at the same time fluid is released from the first fluid actuated muscle 300A.

As illustrated in figures 5A and 5B, the first and second attachment devices 400A, 400B are provided on a cylinder 5000, such that the outer surface of the attachment devices 400A, 400B conform to the contours of a segment of the cylinder 5000. The cylinder 5000 is also provided with support members 500A, 500B. The first support member 500A is provided adjacent the first attachment device 400A and has an outer surface, a portion of which conforms to the contours of a segment of the cylinder 5000. The under surface of the first fluid actuated muscle 300A may contact a portion or the whole of the upper surface of the first support member 500A, depending on the angle of rotation of the cylinder 5000. The second support member 500B is provided adjacent the second attachment device 400B and has an outer surface, a portion of which conforms to the contours of a segment of the cylinder 5000. The under surface of the second fluid actuated muscle 300B may contact a portion or the whole of the upper surface of the second support member 500B depending on the angle of rotation of the cylinder 5000. The cylinder 5000 can rotate about the point X illustrated in figure 5A. As illustrated in figure 5B, the cylinder 5000 has rotated clockwise, consequently, a greater portion of the under surface of the first fluid actuated muscle 300A is in contact with most of the upper surface of the first support member 500A, whereas, a smaller portion of the under surface of the second fluid actuated muscle 300B is in contact with the upper surface of the second support member 500B.

In addition, as can be seen in figure 5B, only a portion of the outer surface of the first and second support members 500A, 500B conforms to the radius of the cylinder 5000. By providing the outer surface of the support members 500A, 500B (which the fluid actuated muscle follows) with a radius smaller than the cylinder, the angle of movement possible is increased.

The attachment device is described above with reference to a fluid actuated muscle, however, the attachment device can be used with any robotic muscle. For example, a robotic muscle may comprise an electo-actuated polymer. An electo-actuated polymer is a material which is solid, and when an electric current is applied to the electo-actuated polymer, the shape of the electo-actuated polymer changes.

For the avoidance of doubt, the other end of the first fluid actuated muscle 300A and second fluid actuated muscle 300B are connected to an air inlet/outlet device.

In conventional fluid actuated muscles the fluid inlet/outlet is provided at the top of the closure arrangement 20 (such as illustrated in figures IA and IB) or at the bottom of the closure arrangement 20 (such as illustrated in figures 2A and 2B). However, this arrangement take up valuable space.

The fluid actuated muscle of the invention uses a closure arrangement wherein the fluid inlet/outlet is provided at the side. Figures 6A and 6B illustrates an fluid inlet/outlet device for use with an fluid actuated muscle of the invention. As illustrated in figures 6A and 6B, an fluid inlet/outlet device comprises a first sealing member 680 provided at one end of the inner tube 640, sealing the inner tube 640. The sealing member 680 may be a rubber bung as known in the art. The other end of the inner tube is sealed either using the attachment device discussed above or using conventional sealing means. As discussed above, the inner tuber 640 is surrounded by a outer sheath 630.

The inlet/outlet arrangement of figure 6A also comprises a second sealing member 670. An inlet/outlet passage 610 is provided in the second sealing member 670. A fixing device 660 is provided connecting the second sealing member 670 to the first sealing member 680. In one embodiment, the fixing device 660 is a screw. O-rings 650 are provided at the points of contact between the second sealing member 670 and the fixing device 660, and at the points of contact between the second sealing member 670 and the first sealing member 680. The o-rings 650 are used to ensure that the cavity formed between the fixing device 660, the first sealing member 680 and the second sealing member 670 is secure, such that no fluid can escape. The fixing device 660 is also provided with a inlet/outlet passage 610.

Fluid is provided into the inner tube 640 via the inlet/outlet passage 610. The fluid passes through second sealing member 670 in to the formed cavity, it then enters the inlet/outlet passage 610 in the fixing device 660 to enter the inner tube 640. The arrangement of figure 6A enables a person skilled in the art to dismantle the inlet/outlet device and not waste time aligning the inlet/outlet passage 610 in the second sealing member 670 with the inlet/outlet passage 610 in the fixing device 660 when reassembling the inlet/outlet device. In fact it would be almost impossible to align the inlet/outlet passage 610 in the second sealing member 670 with the inlet/outlet passage 610 in the fixing device 660 when reassembling the inlet/outlet device. Therefore, the fluid inlet/outlet device provides a convenient single attachment for the fluid actuated muscle.

Figure 6B illustrates another arrangement of the inlet/outlet device. In this embodiment, inlet/outlet passages 610 are provided in the first sealing member 680 instead of in the fixing device 660. However, inlet/outlet passages 610 could be provided in both the fixing device 660 and the first sealing member 680.

The fluid actuated muscle described above can be used in robotic arms. Figures 7 and 8 illustrate schematically a robotic arm of the invention, and figures 9 and 10 are further figures of a robotic arm.

The robotic arm comprises two main parts, the upper body arrangement 700 and the upper arm arrangement 800.

The upper body arrangement 700 comprises four support members 706 which are provided for stability of the upper arm (only two are illustrated in figure 7, the other two support members are provided behind, but spaced apart from the two support member which are illustrated).

The upper body arrangement 700 comprises two conventional fluid actuated muscles 708 including attachment apparatus 710 and fluid inlet/outlet apparatus 712. The fluid inlet/outlet apparatus 712 may be any known fluid inlet/outlet apparatus or the fluid inlet/outlet apparatus described above with reference to figures 6A and 6B.

The two fluid actuated muscles 708 are coupled together such that inflation of the first fluid actuated muscle 708/deflation of the second fluid actuated muscle 708 results in rotation of the upper body arrangement 700 in a first direction about an axis Z illustrated, and inflation of the second fluid actuated muscle 708/deflation of the first fluid actuated muscle 708 results in rotation of the upper body arrangement 700 in a second direction, opposite to the first direction about the axis Z.

Although the fluid actuated muscles 708 are described as conventional fluid actuated muscles, fluid actuated muscles of the invention could also be used. The upper body arrangement 700 further comprises two fluid actuated muscle of the invention 704 attached to a cylinder 714, by way of the attachment device described above with reference to figures 5A and 5B.

The two fluid actuated muscles 704 are coupled together such that inflation of the first fluid actuated muscle 704/deflation of the second fluid actuated muscle 704 results in rotation of the upper arm arrangement 800 in a first direction about an axis Yl (through the page), and inflation of the second fluid actuated muscle 704/deflation of the first fluid actuated muscle 704 results in rotation of the upper arm arrangement 800 in a second direction, opposite to the first direction about the axis Yl.

Each fluid actuated muscle 708, 704 is attached to sensors, such that the rotation of the upper body arrangement 700 and rotation of the upper arm arrangement 800 and the pressure of the fluid applied to each fluid actuated muscle 708, 704 can be determined.

The upper arm arrangement 800 comprises four support members 806 which are provided for stability of the upper arm arrangement 800 (only two support members 806 are illustrated in figure 8, the other two support members are provided behind, but spaced apart from the two support member which are illustrated).

The upper arm arrangement 800 comprises two conventional fluid actuated muscles 810 including attachment apparatus 812 and fluid inlet/outlet apparatus 808. The fluid inlet/outlet apparatus 808 may be any known fluid inlet/outlet apparatus or the fluid inlet/outlet apparatus described above with reference to figures 6A and 6B.

The two fluid actuated muscles 810 are coupled together such that inflation of the first fluid actuated muscle 810/deflation of the second fluid actuated muscle 810 results in rotation of the connection plate 814 in a first direction about the pivot point at which it is connected to the upper arm 700 (an axis X), and inflation of the second fluid actuated muscle 810/deflation of the first fluid actuated muscle 810 results in rotation of connection plate 814 in a second direction, opposite to the first direction, about the pivot point at which it is connected to the upper arm 700 (the axis X).

Although the fluid actuated muscles 708 are described as conventional fluid actuated muscles, fluid actuated muscles of the invention could also be used.

The upper arm arrangement 800 further comprises two fluid actuated muscles of the invention 804 attached to a cylinder 816, by way of the attachment device described above with reference to figures 5A and 5B.

The two fluid actuated muscles 804 are coupled together such that inflation of the first fluid actuated muscle 804/deflation of the second fluid actuated muscle 804 results in rotation of the connection plate 816 in a first direction about an axis Y2 (through the page), and inflation of the second fluid actuated muscle 804/deflation of the first air muscle 804 results in rotation of the connection plate 816 in a second direction opposite to the first direction, about the axis Y2.

Each fluid actuated muscle 810, 804 is attached to sensors, such that the rotation of the upper body arrangement 700, and upper arm arrangement 800, and the pressure of the fluid applied to the air muscle 810, 804 can be determined.

In order to provide accurate displacement of a lower arm arrangement which may be connected to the connection plate 816 of the upper arm arrangement 800, it is necessary to use an adapted robotic joint.

Figure HA and HB illustrates a robotic joint of the prior art. As can be seen from figure HB, when a joint is coupling two components at 0° to one another the connection means only needs to travels distance A + B, whereas as illustrated in figure HA, when the joint is coupling two components at 90° to one another, the connection means travels distance A + B + C, because of the pivot point. It is not possible to have an infinitely small pivot point. This additional distance means that when the robotic muscle is moved from the 0° position to the 90° position, not only if there rotation along a first axis, there is rotation along a second axis. In order to compensate for this additional rotation, the arrangement of pivot points is used as illustrated in figure HC. Two pivot point are provide off centre.

Any suitable fluid could be used to expand the fluid actuated muscle, such as pressurised air.

Although two fluid actuated muscles coupled together so that the fluid actuated muscles to regain its original length when the fluid is released, a fluid actuated muscle of the invention could be provided with biasing means, such as a spring, which forces the fluid actuated muscle to regain its original length when the fluid is released.

The invention has been described with particular illustrative embodiments. It is to be understood that the invention is not limited to the above-described embodiments and that various changes and modifications may be made by those of ordinary skill in the art without departing from the scope of the invention.