Climbing robot, movable along a trestle structure, particularly of a pole for high-voltage overhead electric lines

Abstract: The invention concerns a robot apt to climb along a trestle structure, particularly the trestle of a pole for high-voltage overhead electric lines, in order to carry work-tools from the base to the top of the pole. According to the invention, the robot comprises: a main support body (1); at least one slide (7) movable along said body (1) according to a main mo­ ving axis substantially vertical and parallel to the pole surface; at least a first gripping hand (3) carried by the support body (1) and at least a second gripping hand (4) carried by the slide (7); shifting means to move said gripping hands (3,4) according to a transversal axis, substantially perpendicu­ lar to the pole surface, each gripping hand (3,4) being moreover equipped with clamping means to grip the angle bar forming an upright or a ledger of the trestle structure; at least one position sensor (2) associated to the main body (1), to acquire position data concerning the configuration of the trestle; and a processing system which controls the movements of said slide (7) and of said gripping hands (3,4), also using and/or storing the signals sent from said sensors (2).

Description: The invention concerns a robot apt to climb along a trestle structure, particularly the trestle of a pole for high-voltage overhead electric lines, in order to carry work-tools from the base to the top of the pole. More specifically, the robot according to the invention has been studied to carry up to the pole brackets for instance an equipment to wash the insulator chains, of the type described in EP-A1-0360012, filed by the same Applicant. For this reason, and also to make the description shorter, reference will be made hereinafter to the trestle structure of an electric line pole; it is however understood that the robot according to the invention can easily be used to perform different operations, on trestle structures other than those indicated hereabove, or on fixed or temporary trestlework or tubular scaffolding. In present technology, no apparatus is known to go up and down with its own means, from the base of a pole to the top thereof, by climbing along the trestle structure. In fact, each time an operation has to be performed at the top of the pole, or on its brackets, the operator has to go up himself by climbing along the pole, or using suitable ladders. The invention starts from the consideration that a trestle pole, or generally a trestle structure, consists of a plurality of angle bars, of standard size, positioned so as to form: four corner uprights, wherein the two flanges of the angle bar lie on the planes of two adjacent pole surfaces, and a plurality of oblique crossing ledgers, commonly called trestles, each having a flange on the plane of the pole surface; the other flange, perpendicular to the pole surface, respectively projects outwardly of the pole for a set of ledgers having the same inclination, and inwardly of the pole for the set of ledgers crossing with the first set. Actually, from US-A-4637494 a robot is known which can climb along the rungs of a ladder. However there is a substantial difference between the structure of a ladder and the one of a trestle pole. A ladder is formed of structural elements, i.e. rungs, all identical and placed according to a known and regular geometry, so as to form steps having the same distance between each other. As a consequence, a movable robot which works in an environment of this kind, known as a structured environment , has a particularly simple body and limbs, and usually requires neither sensors nor particular intelligence. According to US-A-4637494 the robot moves itself along a ladder with the sequence of movements shown, from which it clearly results that the robot is anchored to the ladder always with at least three gripping points. These three point locate a plane, which corresponds to a vertical fixed plane, coinciding with the plane on which the ledges of the ladder lay, so that this robot is not certainly able to pass over a change of inclination, like the one usually foreseen in a trestle pole structure. A trestle pole structure is besides formed by structural elements, i.e. uprights and ledgers, which are obtained starting from the sectional irons of a known general shape, i.e. some simple angle bars, which however: have dimensions of width and thickness not known beforehand; have dimensions which may vary along the height of the pole; and are placed according to a geometry, i.e. orientation with respect to the horizontal plane, not known beforehand and usually variable along the height of the pole. Besides this variable geometry, a trestle pole structure involves another difficulty with respect to a ladder; namely that along the pole there are "obstacles" whole positions are not previously known. These obstacles usually consist in the jointing points along the uprights and/or in the connection points of the ledgers with the uprights, and/or the cross point of the ledgers. Consequently, a movable robot which works in an environment of this kind, known as a partially structured environment , must have a structure which be able to overcome these difficulties. Aim of the present invention is then to propose a robot which is able to find out and overcome all these obstacles and which, in particular, is able to climb along the trestle pole surface also in the position in which this surface changes inclination. This aim is reached with a robot having the general structure described in the introductory part of the claim 1 (US-A-4637494), through the characteristics mentioned in the characterizing part of the claim 1 itself. Further characteristics and advantages of the robot according to the invention will anyhow be more evident from the following detailed description of some preferred embodiments thereof, given by way of example and illustrated on the accompanying drawings, in which: Fig. 1 is a diagrammatic front elevation, showing part of a pole trestle and a robot according to the invention climbing along one of the corner uprights of the pole; Fig. 2 is a diagrammatic plan view of the pole and of the robot of fig. 1; Figs. 3a to 3g show, on a reduced scale, a climbing sequence of the robot of fig. 1; Figs. 4a, 4b and 4c are diagrammatic plan views of a gripping hand of the robot shown in the previous figures; Fig. 5 shows the behaviour of the robot of fig. 1, in correspondence of a point where the front surface of the trestle pole changes inclination; Figs. 6a and 7a are a front view and, respectively, a side view of an embodiment of the robot according to the invention, apt to climb on a trestle pole holding onto the ledgers; Figs. 6b, 6c, 6d and, respectively, 7b, 7c, 7d, are views similar to those of figs. 6a and 7a, showing a climbing sequence of the robot according to this embodiment; Fig. 8a shows the detail of a gripping hand of the robot according to the embodiment of figs. 6 and 7; and Figs. 8b to 8f show a working sequence of the gripping hand of fig. 8a. As shown in the drawings, the body 1 of the climbing robot is positioned with its longitudinal axis substantially parallel to the upright M of the trestle pole, and is provided with a sensor 2 to scan the surface of the upright M, and with two gripping hands 3 and 4 to hold onto the upright M. The sensor 2 is apt to detect the areas of the uprights M - where there are no connections of the pole ledgers T and no upright joints - onto which can hold the gripping hands 3 and 4. Each hand 3, 4, is apt to support on its own the weight of the robot during its climbing along the pole P, while, during working of the equipment (not shown) carried by the robot, both gripping hands hold onto the upright M. As clearly shown in figures 1 and 2, and in further detail in figures 4a to 4c, the gripping hand 3 comprises two pairs of clamping fingers 3a and 3b, essentially in the form of hooks, and a dihedral bearing seat 3c; onto the seat 3c bears the corner edge Mc of the angle bar forming the upright M, while the hook ends of the clamping fingers 3a, 3b, hold onto the free edges Ma and Mb of its sides. The clamping fingers 3a and 3b are carried by a support body 3d and are hinged about respective vertical axes 3e, 3f (figs. 4), as well as being engaged in mutual rotation thanks to respective reciprocally engaging toothings 3g, 3h, provided at the hingeing ends of the fingers 3a, 3b. The bearing seat 3c is carried by - or directly formed into - the head of a control piston, movable according to the horizontal axis Y-Y of the gripping hand, for the function better described hereinafter. Said gripping hand 3 - like the hand 4 which is exactly alike - works as follows: when the gripping hand approaches the upright M, its fingers 3a, 3b, are wide apart (fig. 4a) and the hand draws close up to carrying the dihedral seat 3c against the edge Mc of the upright M. At least one of the fingers 3a, 3b, is then caused to rotate so as to in turn move close to the upright M ((fig. 4b), the other finger performing a symmetrical approaching movement due to engagement of the toothings 3g, 3h. The piston carrying the seat 3c is finally driven out, thereby pressing said seat against the edge Mc and causing, by reaction, the backing of the whole hand until the hooks of fingers 3a, 3b, hold onto the edges Ma, Mb. The stronger the action of said piston, the tighter the hold of said hooks and, respectively, of the seat 3c onto the upright M. The gripping hand 3 is mounted on a respective support arm 5 of prismatic shape, for instance rectangular, which is slidably mounted into a corresponding seat of a support core 6, according to the transversal axis Y-Y substantially perpendicular to the pole surface. The core 6 is in turn mounted rotatable about the horizontal axis X-X, perpendicular to the axis of the arm 5, into a seat formed in the slide 7, which latter is slidable into a guide 8 formed in the body 1. The axial movement of the arm 5 allows the gripping hand to draw close to or away from the body 1. The rotary motion of the core 6 allows the gripping hand to rotate on a vertical plane corresponding to the plane of figure 1. The motion of the slide 7 into the guide 8 allows a movement of the gripping hand in a direction substantially parallel to the upright M. The gripping hand 4 is fully identical to the hand 3 - i.e. it is carried by an arm 5a, by a core 6a and by a slide 7a - except that the guide 8a for the slide 7a is shorter and thus allows, as shown, a movement of this latter which is far more limited than that of the slide 7. In actual fact, as explained more in detail hereinafter, the movement of the slide 7a is not strictly necessary in the climbing step of the robot; it can instead be helpful to adjust the position of the main body 1 in the working step (not shown) of the equipment. All these movements of the gripping hands and fingers, as well as of the slides 7, 7a, in respect of the body 1, are controlled by motors (for instance, stepping or D.C. motors with numerical position control, not shown), operating under the control of a processing unit (also not shown) associated to the robot. Said processing unit is preferably equipped with a memory, into which is stored the fundamental data - or even detailed information, according to cases - concerning the configuration of the trestle structure, so that the only function of the sensor 2 is to acquire position data on the pole structure. In other words, since pole trestle structures normally have standardized configurations, these latter can be stored in a memory so that the robot is apt to move in an environment which is at least partly structured. The working of the robot described heretofore - in its climbing step along the pole - is clearly illustrated in figures 3a to 3g. Fig. 3a corresponds to fig. 1 and shows the two gripping hands 3 and 4 holding onto the upright M. In fig. 3b, the fingers of the hand 3 release the upright M and the arm 5 moves backward to draw said hand 3 away from the upright M. In fig. 3c, the slide 7 moves from the bottom to the top end of the guide 8. During this movement, the sensor 2 scans the surface of the upright M and, as said, supplies the consent signal to stop the slide 7 in a position along said upright where there are no obstacles, represented for example by the connections of the ledgers T or by the joints of the angle bars forming the upright. The positions - or, rather, the coordinates of the positions - along the trestle structure, where obstacles are detected by the sensor 2, as well as the positions in which the gripping hand 3 is authorized by the sensor to hold onto said structure, are stored into the processing unit so as to be subsequently used again for positioning the other gripping hand 4 in the climbing up step or, viceversa, for positioning both hands 3 and 4 as the robot climbs down the pole. In fig. 3d, after stopping of the slide 7, the arm 5 moves forward again to lead the hand 3 into engagement with the upright M and be firmly gripped thereon. In fig. 3e, the fingers of the hand 4 - which, in all the previous steps from 3a to 3d, were always tightly clamped onto the upright M - release the upright M, and the arm 5a moves backward freeing said hand from the upright itself. In fig. 3f, the slide 7 of the hand 3 moves down to the bottom end of the guide 8 and, due to the hand 3 being firmly gripped onto the upright M, the whole body 1 of the robot moves upward by reaction. In fig. 3g, the arm 5a moves forward again and the hand 4 holds once more onto the upright M. This position corresponds exactly to that of fig. 3a, except that the robot engages onto a higher point of the pole P. From this position a new climbing cycle can start - as that described above - to shift the robot upward by another step. From the above description, it clearly results that the slide 7a has performed no movements; this confirms what has already been stated, namely that the use of a second slide 7a is not strictly necessary, except that it provides the advantage of a more proper adjustment of the position of the body 1 in respect of the pole, in case of interference of the gripping hands with the positions of connection of the ledgers T onto the upright M, or with the upright joints. To cause the robot to climb down the pole, it is sufficient to reverse the sequence of the above cycle steps; it does not seem necessary to describe herein this reversed sequence, as it is within easy reach of a technician skilled in the art. It should merely be remembered that this downclimb is controlled by the processing unit thanks to the position data acquired and stored during the climbing up step, - as already said - or else by placing another position sensor (not shown in the drawings) in correspondence of the bottom end of the body 1 of the robot. From the above description it can be noted that also the cores 6, 6a, have performed no rotary movements. In fact, so long as the upright M is straight, the cores 6, 6a, are not caused to rotate. Said rotation is however indispensable - as shown in fig. 5 - when the surface of the pole P changes inclination, to allow the robot to get over the pendency variation point along the upright, where the inclined upright M of the lower part of the pole meets with the vertical upright M′ of the upper part of the pole. When the body 1 moves upward - as described with reference to fig. 3f - the sensor 2, which would be meeting the upright M′ in the position 2′ indicated in dashed lines in fig. 5, controls the progressive rotation of the core 6 in respect of the slide 7, and - taking into account the fact that the arm 5 is blocked onto said core and holds firmly onto the upright M - causes the rotation by reaction of said slide 7 and, with it, of the whole body 1 in respect of the core 6. At the same time, the arm 5 is caused to slide inside the core 6, so as to move the gripping hand 3 away from the body 1 of the robot. In this way, as the body 1 moves upward, it is progressively rotated and shifted so as to keep its upper end always at the same distance from the upright M′. The body 1 can thus reach the position shown in full lines in fig. 5, according to the new inclination of the upright M′. In this position, the arm 5a can be moved forward to cause the hand 4 to grip onto the upright M. Once the hand 4 holds tightly onto the upright M, the hand 3 can be released and shifted upward - just as shown in figs. 3b and 3c, - and subsequently caused to grip onto the upright M′. A correct grip is here guaranteed by the fact that the core 6 is again rotated, so as to position the arm 5 perfectly perpendicular in respect of the upright M′. Thus, the processing unit substantially produces a coordinate rotation of the cores 6, 6a - and thereby a shifting of the slides 7, 7a, and of the arms 5, 5a - such as to prevent any interference of the body 1 with the pole structure and, at the same time, keep the hands 3 and 4 always parallel and in a correct gripping position onto the pole upright. The above description refers to a robot climbing up and down the "edges" of the pole, that is, along one of the corner uprights M of the trestle structure. In the embodiment of figs. 6 to 8, the robot is instead configured so as to climb along a "wall" of the pole, that is, on the ledgers T of the trestle structure. As in the previously described embodiment, a slide 17 is slidably mounted on the body 10 of the robot and gripping hands are associated both to the body 10 and to the slide 17. In this case, however, instead of providing two pairs of fingers associated to each hand, use is made of two separate gripping hands 13, 13a, associated to the slide 17 and, respectively, of two gripping hands 14, 14a, associated to the body 1. Preferably, at least one of the two hands of each pair is mounted on a slider movable lengthwise, that is, parallely to the motion direction of the slide 7; thanks to this assembly, the two hands of each pair are apt to move one in respect of the other, with possibility to draw close or apart. More exactly, the gripping hand 14a is mounted on a slider (better described hereinafter) slidable into a guide 11 of the body 10, while the gripping hand 13 is mounted on a slider sliding into a guide 12 of the slide 17. This arrangement allows said hands to each grip onto a different ledger T, the ledgers normally being quite spaced apart and, furthermore, at varying mutual distances along the pole height. A position sensor 17A is associated to the upper end of the slide 17, and is apt to detect and store the positions of the ledgers T and possibly also their inclination. Preferably, a second sensor 10A is associated to the upper end of the body 10. As already said above, also in this case at least the general data and/or part of the position coordinates of the trestle configuration can be previously stored in the memory of the processing unit, starting from the data resulting from the pole project design. As known and already said, in trestle structures of this type, the angle bars forming the ledgers are positioned with a first flange on the plane of the pole surface and with a second flange perpendicular to said surface. Furthermore, to realize a proper crossing of the ledgers, the second flange of a set of such ledgers - all having a first equal inclination - projects outwardly of the pole, while the second flange of another set of such ledgers - all having a second equal inclination - projects inwardly of the pole, so as to properly cross with the first set. As described more clearly hereinafter, with reference to the details of figs. 8a to 8f, the hands of this robot are apt to grip onto the horizontal flanges of the ledgers T projecting outwardly of the pole. The working of this robot is quite similar to that of the previous embodiment: in figs. 6a and 7a, the robot holds with the lower hand 14a of the body 10 onto the ledger T1, with the upper hand 14 of the body 10 and with the lower hand 13a of the slide 17 onto the ledger T2, and with the upper hand 13 of the slide 17 onto the ledger T3. When the robot has to move up along the pole, the hands 14 and 14a are released and, while the hands 13 and 13a keep the slide 17 firmly anchored onto the ledgers T2 and T3, the body 10 is shifted along the slide 17 (figs. 6b and 7b). The body 10 slides upward until its sensor 10A - which detects the presence of the ledger T3 - causes the upper hand 14 to stop in correspondence of said ledger T3 and hold onto the same (figs. 6c and 7c). The body 10 being thus anchored, the gripping hand 14a is caused to slide along the guide 11 up to stopping in correspondence of the ledger T2 and hold onto the same (figs. 6d and 7d). From the position shown in figs. 6d and 7d, where all the hands 13, 13a, 14, 14a, are firmly anchored onto the respective ledgers, the successive step (not shown) provides for: the release of hands 13, 13a; the upward shifting of the slide 17 until the sensor 17A detects the ledger T4; the gripping of the upper hand 13 onto the ledger T4; the further sliding of the hand 13 in respect of its guide 12 and, consequently, the simultaneous shifting, by reaction, of the slide 17, up to carrying the hand 13a in correspondence of the ledger T3, whereon it grips. This position corresponds to that shown in figs. 6a and 7a, except that the robot is now at a higher level along the pole. Also in this case, when wishing the robot to climb down the pole, it is sufficient to reverse the sequence of operations of the previous cycle - in a manner within full reach of an expert of the art - using the information stored while the robot was climbing up the pole. Preferably, the lower hand 13a of the slide 17 is movable into a short transversal guide 12a, substantially perpendicular to the guide 12 and shown very diagrammatically in fig. 6c. This transversal movement is used just before operating the slide, or also while the body 10 is moving upward (in any case, when the gripping hands of the body 10 are disengaged from the respective ledgers T), in order to control the perfect vertical alignment of the robot. The same operation can be performed when the robot climbs down the pole. Figures 8 show, quite diagrammatically, a possible embodiment of a gripping hand to be used in a robot according to the embodiment of figures 5 and 6. This hand comprises: a slider 20 moving vertically, as already said, in respect of the guide 11 of the body 10, or of the guide 12 of the slide 17; a ring 21, mounted on the slider 20 rotatable about the transversal, horizontal axis Y-Y; a body 22, slidable in respect of said ring 21 in the direction of said axis Y-Y; and a hook finger 23, slidable in respect of the body 22, also in the direction of the axis Y-Y, and apt to cooperate with a counterfinger 24. The working of the above gripping hand - taking into account the movements already described with reference to figures 6 and 7 - is as follows: in fig. 8a, the hand is moving up according to the arrow Fa. This movement can be that determined by the motion of the body 10 or of the slide 17, or else that determined by the slider 20 into the guide 11 or 12; in fig. 8b, said upward movement is stopped. This stopping is first of all controlled by the processing unit which, as in the previous case, has stored the general configuration of the trestle. The stopping is however also controlled by a sensor which detects the presence and possibly the inclination of the ledger T. The final stopping position is anyhow stored in the processing unit so as to be used again; in fig. 8c, the finger 23 is caused to move in the direction of the arrow Fb, until the hook end 23′ of said finger projects beyond the inner edge T′ of the ledger T; in fig. 8d, the hand is moved down, according to the arrow Fc, until the finger 23 has come in contact with the upper surface of the ledger T. As known, this ledger is inclined so that the plane of its projecting flange is not horizontal; the finger 23 is however apt to bear exactly on this plane, thanks first of all to a rotation controlled by the processing unit according to the inclination detected by the sensor, and also thanks to the fact that the body 22 can be left free to rotate (arrow Fd) together with the ring 21, so as to bear on said plane; in fig. 8e, the body 22 is moved according to the arrow Fe, so that the counterfinger 24 is led to bear against the lower part of the ledger T; finally, in fig. 8f, the finger 23 is again moved backward (in the direction Ff), so that its end 23′ may hook onto the edge T′ of the ledger T. In practice, the projecting flange of the ledger T is thus strongly tightened between the end 23′ of the finger 23 and the counterfinger 24, whereby the hand is positively gripped on the ledger T. Also in this embodiment, should the pole surface change inclination and show a pendency variation, the gripping hand is controlled so as to move the body 22 according to the axis Y-Y, thereby drawing the robot close to and/or away from the pole surface, in a fully similar way to what has been previously described with reference to figure 5.

Claims: A climbing robot, movable along a trestle structure, particularly the trestle structure of a pole for high-voltage overhead electric lines, said pole having a plurality of angle bars forming uprights of changing inclination and also forming ledgers at varying mutual distances, said robot comprising: a) a main body (1; 10) b) four clamping finger means (3a, 3b, 4a, 4b; 13, 13a, 14, 14a), each one for gripping one of the plurality of said angle bars (M, T, T1, T2, T3) c) shifting means (5, 6, 7, 5a, 6a, 7a; 17, 22, 23, 24), to move each of said clamping finger means according to a main moving axis, substantially vertical and parallel to the pole surface and, respectively, according to a transversal axis substantially perpendicular to the pole surface; d) at least one position sensor (2; 17A) to acquire data on the position of the angle bars and/or the varying mutual distances between the ledgers, e) a processing system, which controls said shifting means, also using the signals sent from said sensors characterized in that f) a main slide (7, 17) is mounted movable along said main body (1, 10), parallely to said main moving axis g) two of said clamping finger means (4a, 4b; 14, 14a) are mounted on said main body (1, 10), at least one of them (4a, 4b ; 14a) being adjustable in position in respect of the main body, and h) two other clamping finger means (3a, 3b; 13, 13a) are mounted on said main slide (7; 17), at least one of them (3a, 3b; 13, 13a) being adjustable in position in respect of the main slide i) said position sensors (2, 17A) comprise means to acquire data on the changing inclination of the pole surface l) whereby the robot climbs up and down along the pole structure and over the changing inclination of its surface, by alternatively blocking on said pole structure the two clamping finger means associated to the main body or, respectively, the two clamping finger means associated to the main slide, while the other two clamping finger means are free to simultaneously move along the pole structure. Robot as in claim 1), wherein said clamping finger means comprise a dihedral bearing seat (3c) and two pairs of hook fingers (3a, 3b, 4a, 4b), the fingers of each pair being positioned at the two sides of said dihedral seat, this latter being apt to house the corner (Mc) of the angle bar forming an upright (M) of the trestle structure, and the two hook fingers being apt to grip onto the opposed edges (Ma,Mb) of said angle bar. Robot as in claim 2), wherein said dihedral bearing seat (3c) is carried by the head of a piston moving perpendicularly to said angle bar forming an upright, and said hook fingers are mounted rotatable in opposite directions on the case housing said piston. Robot as in claim 1), wherein said shifting means comprise an arm (5,5a) supporting said clamping finger means said arm (5,5a) being slidably mounted into a corresponding seat of a support core (6,6a), according to said transversal axis (Y-Y) perpendicular to the pole surface. Robot as in claim 4), wherein said support core (6,6a) is in turn mounted rotatable about a horizontal axis (X-X), transversal to said arm (5,5a) supporting the clamping finger means. Robot as in claim 5), wherein said support core (6,6a) is mounted on said movable slide (7,7a) rotatable in respect of the main support body (1). Robot as in claim 1) wherein, to said main support body (10) there are associated two mutually spaced clamping finger means (14, 14a), while two further claming finger means (13,13a) are associated to said main slide (17), sliding in respect of the main support body (10). Robot as in claim 7), wherein one clamping finger mean (14) is mounted in a fixed position of the main support body (10), while the other clamping finger mean (14a) is mounted on a secondary slide (20), slidable into a substantially vertical guide (11) formed in said support body (10). Robot as in claim 7), wherein one clamping finger mean (13a) is mounted in a fixed position of the main slide (17) and the other clamping finger mean (13a) is mounted in on a secondary slide (20), slidable into a substantially vertical guide (12) formed in said main slide (17). Robot as in claim 7), wherein at least one of said clamping finger means (13, 13a, 14, 14a) is moreover mounted onto a secondary slide (22), slidable into a substantially horizontal guide (21) formed in said support body and/or in said main slide. Robot as in claim 7), wherein said gripping hands each comprise a hook finger (23), slidable in respect of a fixed counterfinger (24) in said transversal direction substantially perpendicular to the pole surface, the counterfinger (24) being apt to form a lower bearing surface for the horizontal side of the angle bar (T) forming a ledger of the pole trestle, and the hook finger being apt to grip said angle bar onto its edge. Robot as in claim 11), wherein the slidable hook finger (23) and the fixed counterfinger (24) of said clamping finger means (13,13a,14,14a) are mounted onto a body (22) which is slidable, also in said transversal direction, in respect of a support ring (21). Robot as in claim 12), wherein said support ring (21) of the clamping finger mean is rotatable about an axis parallel to said transversal direction. Robot as in claim 13), wherein said rotatable support ring (21) is mounted on said secondary slide (20).

Inventors: PARIS LUIGI, PARIS, LUIGI
Applicants: PARIS LUIGI, PARIS, LUIGI
Application year: 1990
Main classification: B62D57
IPC codes: B62D57