The invention concerns an articulated element comprising two opposing faces for connection to other elements or units, a robotic snake comprising at least two articulated elements of the invention, a head unit for the robotic snake and a skin structure for the robotic snake and a use of the robotic snake for rescue operations or fire fighting purposes.

The element includes at least two hydraulic actuators adapted to articulate the articulated element in at least two dimensions and at least one control valve for each actuator. At least one articulated link allowing articulation in at least two dimensions connects the two opposing end faces. Each control valve is adapted to be connected to at least one logic unit. The element may also include a conduit for transferral of pressurised fluids through the element and an element for bleeding off pressurised fluids to the hydraulic actuators.

During various tasks relating to for instance fire fighting and search and rescue operations, it is a challenge to be able to do reconnaissance and perform various tasks due to hazardous conditions or limited space. In such conditions, it is advantageous to be able to substitute personnel with robots. However traditional wheeled or belt driven robots have limited ability to move past obstacles such as steps or furniture. They also have limited traction and will have problems pulling for instance a water hose for fire fighting purposes, unless the robot is large and cumbersome to use.

Accordingly, it would be advantageous to have a robot that can pull or move a long body, such as a hose, that can move in confined spaces such as ducts or collapsed buildings, that can move past obstacles such as furniture and steps, and that can be used to pass submerged or flooded areas, and that can provide information to a user and perform various tasks.

For reasons, mainly due to the ability to move in confined spaces, various robotic snakes have been suggested.

A mechanical toy snake able to simulate the movements of a biological snake is shown in US 2 194 537.

In US 5 906 591 it is shown a snake like endoscopic robot for being inserted in a body cavity for being moved in a predetermined direction with a so called inchworm-like motion. In this patent, it is suggested that the endoscopic robot can be used for diagnostic and/or surgical procedures in combination with suitable instruments such as micro cameras, laser emitters and the like.

Norwegian patent application 2002 2273 shows a system for exploiting a sinus shaped motion pattern. The system is primarily intended as a propulsion system for seagoing vessels, and may include hydraulic actuators.

US 5 662 587 shows a robot for performing endoscopic procedures in flexible and curved human or animal lumens. A plurality of segments is attached to each other. Traction segments embrace the lumens walls. Furthermore the publication shows a method to sequence the action of segments to cause inchworm-like or snake- like locomotion. Actuators in the robot can be driven by compressed gas, and the lead segment may include television cameras, ultrasound transducers, biopsy arms, drug delivery systems or other sensors, diagnostic aids, and surgical tools.

US 5 386 741 shows an improvement in a flexible robotic limb which can function as a robotic snake. The invention is particularly pertinent to miniaturization applications such as catheters or positioners for microsurgery, micro-assembly, micro-manipulation or micro-exploration. The object of the invention is to provide a flexible snake which can self-propel itself through tunnels, tubes or blood vessels and which can perform cleaning, sensing, cutting and removal operations therein. The robotic snake includes a plurality of articulation units, serially connected.

However none of the cited publications shows a controllable articulated element and a robotic snake adapted for search and rescue or fire fighting purposes as defined in the present claim set.

Accordingly, the present invention relates to a controllable articulated element comprising two opposing end-faces for connection to other elements or units, at least two hydraulic actuators adapted to articulate the articulated element in at least two dimensions, at least one control valve for each actuator, and wherein each control valve is adapted to be connected to a logic unit.

The logic unit may be integrated in the element.

The logic unit may be a microprocessor that communicates with other elements or microprocessors in other articulated elements. The communication may be through optical fibres, electric cables, through radio contact or in any other way. The logic unit is connected to the control valves, and is preferably placed in the articulated element. However, the unit may be situated elsewhere, and connected to the control valves in any way, well known in the area.

The articulated element may include sensors connected to the logic unit, for instance for sensing parameters indicative of the angular relationship between the two end faces.

Furthermore sensors may measure the force imposed by the element, the pressure in the hydraulic circuits, accelerometers etc.

The end faces may include connectors for transferral of energy or signals. The connectors may be of any kind well known in the area.

The element may include a flexible duct for pressurized fluid, going there through, and hydraulic channels between the flexible duct, the control valves and the actuators. The end faces may include connectors for transferral of the pressurized fluid.

The connectors for transferral of pressurized fluid may include seals such as gaskets, o-rings etc. Fluid sealed connections are well known from many technical fields.

One of the end faces may be connected to a nozzle for expelling fluids.

The pressured fluid may be water to be expelled through a nozzle at the end of the element for fire fighting purposes or for cutting through or removing obstacles. Alternatively, the fluid may be brought further for propulsion of other elements and returned back to a source, or just dumped to the surroundings. The water may in other words be used both as a hydraulic fluid, and for extinguishing a fire.

The element may include at least three pivotally interconnected parts forming two intersections, each intersection allowing articulation in one dimension.

The element may include at least two pivotally interconnected parts forming one intersection allowing articulation in two dimensions.

Furthermore the invention concerns a robotic snake comprising at least two articulated elements of the invention. The end faces of each element may be connected, face to face, permanently or releasable in any way, well known in the area. In the case where several articulated elements of the invention are permanently connected, the joints of each element may be connected pairwise, without connecting end faces.

In the case where each element is releasable from the other, the elements must be connected with a screw coupling, a bayonet socket, separate screws, a pin and box coupling, a locking pin, or in any other way well known in the area. The connections on the interconnected surfaces may be radial, or may include spring loaded contacts etc.

The elements may be permanently fixed to each other in groups of for instance ten, with faces for releasable connection to other groups of elements or other tools, such as nozzles for fire fighting, cameras, sensors, valves for dispensing fluids, and other suitable tools for instance for search and rescue operations in collapsed buildings etc.

The robotic snake may include a flexible outer skin, and low pressure hydraulic exhaust fluid from the control valves may be led to the inside of the skin.

The skin may be permeable to the low pressure hydraulic exhaust fluid to allow the fluid to leak out of the skin in order for the exhaust fluid to vaporize and cool the skin or just to be disposed of into the surroundings.

5 The skin may alternatively be impermeable to the low pressure hydraulic exhaust fluid, and the end faces may include connections for the returning low pressure hydraulic exhaust fluid.

The low pressure hydraulic exhaust fluid may alternatively be led in a separate io flexible channel, and the end faces may include connections for the low pressure hydraulic exhaust fluid.

Furthermore, the invention concerns a skin structure with a plurality of scale elements and a base structure, wherein each scale element includes a free end i ₅ and an end pivotally or flexibly connected to the base structure such that the scale elements can adopt a position substantially parallel to the base structure, and positions extended at inclined angles to the base structure.

Each scale element may include a hydraulic actuator for controlled extension at an 20 angle of the scale elements in relation to the base structure.

The hydraulic actuator for each scale element may include a flexible inflatable bellow.

2 ₅ The scale elements may alternatively be extended as a result of bending of the base structure.

Furthermore, the invention concerns a head unit for connection to an articulated element, comprising at least one nozzle for expelling fluids for fire fighting ₃ o purposes, a main valve for controlling the outlet of fluids and an electronic unit connected to sensors.

One of the end faces of the articulated element may be coupled to a head unit.

The head may include a house for at least one retracting extinguishing nozzle, a main valve for extinguishing fluid, an electronic centre with multiple sensors for parameters such as heat, gas, sound and position. An extendable sensor for stereographic imaging such as visual, IR, and radar may also be provided. The housing may include a void system for circulation of cooling water. The nozzle or nozzles must in the case where the fluid to be expelled is used as a hydraulic fluid, create sufficient backpressure to drive the articulated elements. A considerable part of a cross section of an element may be used to transport fluids for propulsive and fire fighting purposes.

A restriction for the fluid may be placed at the end of the snake to create sufficient backpressure for the hydraulic actuators. The restriction may be adjustable such that the backpressure can be controlled to for instance be able to increase the force imposed by the actuators if necessary.

The robotic snake of the invention may be used for other purposes than fire fighting, such as search in collapsed buildings, caves, mines etc. In this case, the snake may include a return line for hydraulic fluid and cameras and suitable sensors. If the snake is used in search and rescue operations, it may lead oxygen or drinks to trapped persons. It may also include means for communication.

It is also expected that the snake of the invention is suitable for military purposes.

In one embodiment, the element may include three parts connected in an oblique rotating relationship and two actuators for rotating the three parts to create angles between the three elements, adjustable in two degrees of freedom.

An element or group of elements may be covered by a protective sheath or skin. Brief description of the enclosed figures:

Fig. 1a shows a fire fighting robotic snake with an element according to the invention;

Fig.i b shows a detail of the fluid expelling nozzle shown on the robotic snake of fig. 1a;

Fig. 2 is a cross section of an articulated element according to one embodiment of the invention;

Fig. 3 is a cross section of the articulated element according to the embodiment of the invention shown in fig. 2, perpendicular to the cross section shown in fig. 2;

Fig. 4 shows an alternative embodiment of an articulated element, showing an endoskeletal hollow gimbal joint;

Fig. 5 shows yet another embodiment of the invention with an exoskeletal hollow gimbal joint;

Fig. 6 shows yet another embodiment of the invention with asymmetric exoskeleton;

Fig. 7 shows a cross section of an articulated element according to an embodiment of the invention;

Fig. 8 shows yet another cross section of an articulated element according to the invention;

Fig. 9 shows a cross section of yet another embodiment of an articulated element according to the invention;

Fig. 10 shows a cross section perpendicular to the cross section shown in fig. 9;

Fig. 11 shows a cross section of yet another embodiment of an articulated element according to the invention;

Fig. 12 shows a principal layout of an articulated element according to the invention;

Fig. 13 shows a skin for a robotic snake according to the invention;

Fig. 14 shows a detail of the skin shown in fig. 13, in cross section;

Fig. 15 - 18 shows another embodiment with coupled motion solution with a distributed motion.

Fig. 19 shows another embodiment of an element of the invention; and

Fig. 20 shows a twisting actuator that can be used in connection with the embodiment shown in fig. 19.

Detailed description of various embodiments of the invention:

Fig. 1a shows a robotic snake with articulated elements according to the invention. The various elements are indicated with lines, and the end of the robotic snake is shown with a snake head.

Fig. 1b shows the snake head on fig. 1a in detail. The snakehead may include a house for a retracted extinguishing nozzle 40, a main valve 41 , hydraulic manipulators for nozzle action, an electronic center with multiple sensors 43 for, for instance heat, gas, sound and position and an extendable arm 42 for, for instance a camera. The head may also include a fixed or variable restrictor for the fluid to be expelled through the nozzle to create a sufficient pressure in the snake to be able to use the same fluid as a hydraulic fluid in the actuators.

Fig. 2 shows an articulated element according to one embodiment of the invention, with two opposing faces 1 , 2 for interconnection with other similar elements, or other tools that may benefit from having a controlled adjustable angle. The element furthermore includes a gimbal joint with pivot joints 3, 4. The gimbal joint may be an ordinary universal joint with bearings and a gimbal joint centre unit 5 common in gimbal or universal joints. Hydraulic actuators 6, are shown as expandable hydraulic bellows that can be expanded or retracted by hydraulic pressure. Control valves 9 for each actuator are shown close to the end

face 2 of the element. A detail of the control valve 9 is shown with a dashed line to a micro controller for integrated valve control, which may receive signals from sensors for sensing for instance pressure and position. A signal transducer may also be included.

Fig. 3 is a cross section perpendicular to the cross section of the element shown in fig. 2, where the hydraulic actuators 6, 7, 8, and the pivot points 3, 4 for the gimbal joint is clearly shown. An inner duct 10 in the element is also shown. The inner duct 10 can be used to lead pressurized hydraulic fluid, for instance water for fire extinguishing purposes, and may also include other cables and equipment as appropriate.

Fig. 4 shows an articulated element according to another embodiment of the invention, and shows an endoskeletal hollow gimbal joint where pressure supply and other longitudinal structures may be routed inside the joint, while actuators and electronics are placed around the joint. The joint includes two end faces 1 , 2, gimbal joint pivot points 3, 4 and a gimbal centre unit 5.

Fig. 5 shows an exoskeletal hollow gimbal joint where the gimbal like joint is made larger so that most of, or all other structures may be placed within the hollow center of the joint. In this embodiment the joint components provide some mechanical protection for the components within. Similar to fig. 4, fig. 5 shows element end faces 1 , 2, gimbal joint pivot points 3, 4, and a gimbal joint centre unit 5.

Fig. 6 shows yet another embodiment of an articulated element according to the invention where an asymmetric exoskeleton is shown. This embodiment may be favourable to allow a larger angular excursion while still providing a fairly complete outer shell. The asymmetric exoskeleton is adapted to an asymmetrical element cross section, and includes element end faces 1 , 2 and pivot points 3, 4. To the right of fig. 6, the axis of rotation is shown with dashed lines.

Fig. 7 shows a cross section of an embodiment of the invention, where hydraulic actuators 6, 7, 8 are equally spaced around the high pressure inner duct 10.

Fig. 8 is an alternative embodiment of fig. 7, showing hydraulic actuators 6, 7 placed asymmetrically in the element. Shaded areas indicate where control valves 11 , 12 and electronics may be placed. A high pressure inner duct 10 is also shown in the drawing. In this embodiment, the high pressure inner duct or spinal duct 10 may be placed in the lower part of the cross section. Each element is actuated by two, two-way actuators placed above the, spinal duct. The two way actuators can "push or pull" to enable full articulation of the element. The articulated joint mechanism (not shown) may preferably be positioned such that the axis of articulation of the joint, is in the centre of the shaded spinal duct 10, as this embodiment will minimize the stress/strain on the duct during joint flexion.

Fig. 9 shows an embodiment of an articulated element according to the invention in cross section, with control valves and electronics 11 , 12, hydraulic channels 13, wiring and hydraulic supply or spinal duct 10, and hydraulic actuators 6, 7, 8.

Fig. 10 shows and alternative embodiment where the hydraulic actuators 6, 7 are shown as bellows rather than double acting pistons, and where a possible location for the control valves 11, 12 is suggested.

Fig. 11 is a cross section perpendicular to the cross section on fig. 9, where the hydraulic actuator 6 and the control valve and electronics 11 are clearly shown.

Fig. 12 shows hydraulic actuators shown as pistons, and control valves and electronics in addition to hydraulic channels.

Fig. 13 and fig. 14 shows a skin structure for a robotic snake with a base structure 31 and scale elements 30. The base structure 31 may be an exoskeletal structure of the robotic snake or a separate element. The scale elements 30 may be shaped as fish scale or as plates. The scale elements 30 may be placed overlapping on the base structure, resembling the skin of a biological fish or snake, alternatively the scale elements 30 may adjoin each other or may be placed at a certain distance from each other.

Although in fig. 13 and fig. 14 all scale elements 30 are shown having identical shape, some or all scale elements 30 may have different shapes and may be manufactures in different materials, adapted to their position and the intended function on the robotic snake. Accordingly, scale elements 30 that are intended to be in contact with the surface which the robotic snake to which the skin structure is fixed moves on, may have a shape and may be made of a material that creates the desired friction and mechanical robustness properties. The geometry and materials of scale elements 30 that are mainly intended to be exposed to the atmosphere and radiation surrounding the robotic snake may accordingly be optimised for this exposure.

As shown in fig. 14 the scale elements 30 may be pivotally connected to the base structure 31. In an alternative embodiment, the scale elements 30 may be connected to the base structure 31 via a flexible part that allows the scale s elements 30 to adopt a position substantially parallel to the base structure, and positions extended at inclined angles to the base structure. In yet another embodiment the scale elements 30 may be rigidly fixed to the base structure 31 while the scale elements 30, the base structure 31 , or both, may be made of a flexible material which allows the scale elements 30 to adopt a position o substantially parallel to the base structure, and positions extended at inclined angles to the base structure.

One purpose of the movability of the scale elements 30 with respect to the base structure 31 is to allow the scale elements 30 to overlap to a varying extent 5 according to the local curvature of the skin structure insofar as the distance between neighbouring scale elements 30 is reduced where the skin structure takes on a concave shape and increased where the skin structure takes on a convex shape, as illustrated in fig. 14. A particular embodiment includes scale elements 30 that are individually convex outwards and that are overlapping to the o extent that they still overlap even in the case of extreme local convexity of the skin structure.

A second purpose of the movability of the scale elements 30 with respect to the base structure 31 is to allow the overall friction between the skin structure and any

surface adjacent to the skin structure to be controlled by actively or passively changing the inclination of the scale elements 30 with respect to the base structure 31. For this purpose an actuator 32 can be placed at the base of each scale element 30. The actuator may be an inflatable bellow or flexible tube like structure, that when inflated, presses the scale element 30 outwards to an extended position to increase the friction between the scale element, and hence the skin structure, and a surface adjacent to the particular scale element 30. Sensors measuring the pressure in the actuator 32 may be used to monitor and control contact points and mechanical pressure on the skin structure. The scale actuators may be controlled by separate control valves (not shown), and may be driven by pressure bled off the main source of hydraulic pressure, for instance the high pressure inner duct 10.

Fig. 15 - 18 shows yet another embodiment of the invention. The figures show a coupled motion solution in which the angular joint motion is distributed across two physical joints. A potential problem associated with most or all of the gimbai like structures is the tendency of the mechanism to collide with itself during extreme angular excursions. This in practice limits the excursion possible for each joint. The figures 15, 16, 17 and 18 show an embodiment in which one degree of freedom is distributed across two physical joints, where the two joint angles always are equal due to two toothed arcs or semi wheels 15 shown in fig. 17, 18 whose teeth (teeth are not shown) are engaged in the middle of the figure. In fig. 16 and 18 it is shown an example of the mechanism in a bent configuration. This embodiment reduces the collision problem by a factor of two. It is noted that the coupling of the joints' motion may be implemented without toothed structures, for instance by means of two-way hydraulic actuators coupled back-to-back in a closed system. In this case one can even couple the motion of non-adjacent joints by connecting the corresponding actuators with flexible hydraulic hoses. The hydraulic motion coupling allows for distribution of motion in two perpendicular directions. A particular embodiment may include an articulated element corresponding to a cascade of N articulated elements of the types shown in fig. 2-6 and fig. 19, where the N articulated elements are referred to as articulated sub-elements. If pivot points 3 and 4 of the n'th articulated sub-element are referred to as pivot points 3 _n and A _n , respectively, where n=1 , 2, .., N, the

embodiment may comprise the mutual coupling of the motions about all the pivot points 3i, 3 ₂ , ..., 3N and also mutual coupling of the motions about all the pivot points 4i, 4 ₂ , ..., 4 _N . The resulting articulated element will exhibit two rotational degrees of freedom, each being distributed over N distinct joints.

Fig. 19 shows an alternative embodiment where an element includes at least three parts 22, 25, 26 pivotally connected at oblique angles 23, 24 and actuated by at least two twisting actuators. Upon twisting of the parts, the element will bend at an angle corresponding to the oblique angle and the relative position of the parts. It is noted that the oblique planes of rotation may or may not have the same angle with respect to the longitudinal axis of the element. Furthermore it is noted that each articulated element may comprise a cascade of several sub-elements corresponding to figure 19. It is also noted that two or more of the oblique joints may exhibit coupled motion in accordance with figures 15-18 in order to distribute the motion and reduce the angular excursion of each individual oblique joint.

Fig. 20 shows an embodiment of a hydraulic twisting actuator with a piston 21 in a curved cylinder 20, suitable for the embodiment shown in fig. 19. It is noted that the twisting movement may be implemented by any suitable kind of actuator known in the field.