Modular tensegrity vehicle

Abstract

A vehicle constructed using tensegrity principles in the design of the structural member of a skin-on- frame assembly, being composed of non-contiguous compressive elements and complementary tensile elements whose opposing forces result in a lightweight, stress dispersing and self-organizing geometry at equilibrium. The modularity of the compressive and tensile elements, the propulsion methods and the directional controls allows for conversion between land- and water-borne modes of conveyance, as well as simple folding and disassembly of the vehicle for storage and transportation.

Description

[0001] Description

[0002] Title of Invention: Modular Tensegrity Vehicle

[0003] Technical Field

[0004] The invention relates to the field of vehicles, and more particularly to the method of construction of low and zero-emissions land vehicles, as well as the method of construction of low and zeroemissions watercraft.

[0005] Background Art

[0006] The prevailing methods of construction in order to provide structural integrity and aero / hydrodynamic capability to a vehicle include skin-on-frame construction, in which a rigid or flexible skin is affixed to a rigid frame (i.e. which resists deformation via compressive and shear strength), for example as with traditional Inuit kayaks, or monocoque construction in which the external skin also comprises the structural member, for example as with fibreglass boat hulls and carbon fibre high performance human powered vehicles (HPVs) colloquially known as velomobiles. The present invention relates to an improvement of the former skin-on-frame category, through an application of the principles of tensegrity to the design of the vehicle frame. Tensegrities are a class of objects disclosed by the architect R. Buckminster Fuller (U.S. Patent No. 3,063,521) in which elements (such as beams or tubes) are suspended in a framework of tension elements (such as cables or ropes) such that no two rigid elements are in contact with one another and are held in place solely by means of the opposing tensile forces. As a consequence, the constitutive elements are either in pure tension or compression (c.f. the shear stresses of a compression-only frame) and with the correct equilibrium between tensile and compressive forces manifest a self-organizing, selfsupported geometry. They exist commonly throughout nature as they seem to present an optimal strength-to- weight ratio for structural bodies along with a variety of interesting secondary mechanical properties, such as the dispersion of incurred stresses throughout the entire structure. For example, the field of biotensegrity pioneered by Dr. Stephen Levin posits that vertebrate anatomy is grounded in the principles of tensegrity and not rigid structure.

[0007] Existing HPVs and watercraft, relying on rigid frames, suffer from a set of related difficulties: they are heavier than is practical, too expensive to become truly mass forms of mobility, and / or are difficult to transport and store owing to their mass and size. In order to provide the necessaiy strength and rigidity, their weight is generally disproportionate to the energy inputs freely available in the form of wind and human power and hence tend to require powerful engines to compensate, which then requires a stronger construction and therefore a more powerful means of propulsion and so on, leading to an upward spiral of weight and complexity. The introduction of tensegrity principles into vehicle frames mitigates these outstanding issues, leads to a downward spiral of weight, cost & complexity, while simultaneously introducing a set of new and useful capacities intrinsic to the design.

[0008] Disclosure of Invention

[0009] The present invention consists of a vehicle based on a tensegrity skin-on-frame system which can be freely converted between land and water-going modes, powered by freely available sources of energy in the form of human power and the wind, with the possibility of adding a motor for additional propulsion. A minimum of 6 compressive structural elements which serve as the compression elements are arranged such that no two of these are touching. At the end of each tube is a method of fastening the tensile structural elements which link each compressive structural element to those of its neighbouring vertices, forming in the possible embodiment of 6 compressive structural elements a 5-sided compressive-tensile vertex. The number, dimensions and position of tubes in a given plane can be varied to change the geometric properties of the structure, e.g. by adding extra compressive elements to lengthen the overall shape, changing orientations, or lengthening individual elements. At its minimum however this structure describes a tensegrity icosahedron with at least 6 compressive elements and 12 vertices (one at each end of the compressive elements). A flexible or rigid fairing or skin is attached around this base structure, in the case of land-bome conveyance for aerodynamic and weather-protection purposes, and in the case of water-borne conveyance to act as the hull of the boat. To the vehicle are attached either wheels and a steering system in land-going mode or a method of hydrodynamic control in water-going mode. In land-going mode the vehicle is propelled by a human-powered mechanical drivetrain and / or a motor affixed to the vehicle, and in water-going mode propulsion is provided by sails, oars and / or a motor likewise affixed to the vehicle. A means of accommodating one or more passengers is positioned roughly in the middle of the icosahedron and affixed to the vehicle. The compressive elements can be continuous or formed of a number of shorter struts that disassemble allowing for adjustment of compressive element length and storage. Furthermore, the vertex hubs and outer skin are removable, allowing for a simple conversion process between the two modes in which many of the structural elements overlap and the remainder (tensile elements, skin, steering, propulsion) represent a relatively negligible mass, allowing the parts necessary for conversion to one mode to be carried in the other.

[0010] The advantages of such a structure over a conventional frame or monocoque are manifold. Since stresses applied to a tensegrity structure are efficiently dispersed through the entire system instead of remaining more or less localized, each member is required to bear a lesser maximum stress and a given structure can be designed with significantly reduced weight for the same strength. As well, due the naturally streamlined shape of the tensegrity icosahedron, aero / hydrodynamics only suffer a negligible penalty compared to conventionally optimized aero / hydrodynamic vehicle fairings and boat hulls while being lighter and vastly simpler to manufacture; the aerodynamic efficiency and weight savings of this tensegrity vehicle are such that under human power alone any reasonably healthy person is predicted to be able to maintain a velocity far surpassing that of a conventional bicycle. Extant HPVs such as the Milan SL have reached this level of efficiency but with significant impracticalities in terms of weight (50-60 lbs despite a full carbon monocoque construction and this being one of the lightest exemplars), cost, and storability owing to its rigid construction and size, which restrict its usage to a largely recreational niche. An HPV constructed using tensegrity principles is projected to weigh in the realm of 30-40 lbs, cost significantly less to produce in terms of both materials and labour time, and be far more practical owing to its modularity, being capable of disassembly or folding for storage and transport. The weight savings and hydrodynamics of a small sailboat built on this principle should likewise lead to considerable efficiency, allowing for the transition from the displacement mode to semi-displacement or planing modes thanks to a low possible displacement / length ratio. Further, the occupant or occupants are fully enclosed in the tensegrity structure, which features intrinsic shock absorption and crash protection (owing to the stress distribution property described above), leading to further weight and cost reductions and increased occupant safety compared to existing rigid frame designs which must account for comfort and safety by incorporating increased material and complex technical features. In sum the present invention significantly reduces the weight and construction complexity of skin-on-frame vehicles, squaring the circle for the development of affordable and functional low or zero-emissions transportation.

[0011] Brief Description of the Drawings

[0012] Fig. 1: Simple tensegrity icosahedron

[0013] Fig. 2: Isometric view of HPV

[0014] Fig. 3: Isometric view of sailboat

[0015] Detailed Description of the Drawings

[0016] In the possible embodiment depicted in Fig. 2, 6 metal tubes (1, illustrative example) are arranged such that pairs of 2 tubes lie in-plane and parallel to each other in each dimension, with each pair sandwiching another pair lying perpendicularly. These tubes are composed of smaller tubing segments which are securely screwed into one another. The bottom longitudinal tube measures 93 inches, the upper longitudinal tube 87 inches (3 inches of offset on each end), the two transverse tubes 22 inches, and the two vertical tubes 33 inches. The longitudinal tubes are spaced 27 inches apart, the transverse tubes 33 inches apart and 9 inches vertically, and the vertical tubes 16 inches apart. The forward transverse tube is offset by 9 inches from the vertical tubes, 3 inches from the lower longitudinal tube and by 24 inches from the rear transverse tube. The vertical tubes are offset from the front of the vehicle by 39 inches. To the ends of each of these tubes is affixed a hub (2, illustrative example) with a rubber covering (3) which is inserted on one end into the tube and held in place via an internal wedge expander, and on the other features 5 protruding loops (4, illustrative example) spaced around the longitudinal axis. To each of these loops is attached a pin-jointed turnbuckle (5, illustrative example) attached to an eye-spliced synthetic rope (6, illustrative example), allowing for in-line adjustment of rope tension and tuning of the stiffness of the vehicle frame. The turnbuckle can be detached from its loop by removing a pin, allowing for the structure to be collapsed or disassembled. The end of tube is linked to those of its 5 immediate neighbours, forming in total an irregular icosahedron shape if one were to consider only the outer geometrical surface.

[0017] To the vertices of the front transverse tube are attached two wheels (7) via a variation on the hubs. A protruding plate is drilled to 33.9mm to accommodate a standard threadless bicycle headset holding a 28.6 diameter tube. To the protruding ends of this tube is clamped an aluminum plate into which custom steel 10mm thru-axles are threaded (8) to account for the single-sided support (c.f . two-sided for a normal bicycle). The wheels are of the 20” / 406mm standard, and feature a standard thru-axle disc brake hub (9) spoked to a rim and tire (10). A pivoting linkage (11) shorter than the total axle length is bolted on each side to these rotating plates so as to impart Ackermann steering to the wheels (i.e. turning at slightly different angles to account for the difference in turning radii). A low- elongation synthetic steering rope (12) is likewise anchored to the plates on each side. If we trace the route of this steering rope to its origin, it passes through a pulley lying in-plane on the opposite vertically aligned tube (13) before returning back to the counterpart pulley on its origin side, then upwards to another pulley attached to the vertical tube (14) at roughly the hand height of the occupant. This rope is attached to a circular plastic handle (15, Fig. 5) to which is attached another segment of rope and thence around and behind the seat (16) through another 2 pulleys (17) to rejoin the steering rope originating in the opposite wheel, forming a closed loop of low-elongation synthetic rope that allows for steering of the wheels via pushing and pulling.

[0018] The seat is composed of a bent tube bolted to the bottom of the vertical tubes and suspended with two ropes to their top, across which a textile webbing is woven to accommodate the occupant.

[0019] Standard bicycle brake levers (18) are attached to the steering handles, which are then connected by standard brake cables to the front wheel disc brakes. Further, standard bar-end bicycle shifters (19) are attached to the handles, which are connected via standard shifter cables to the front derailleur (20) and rear derailleur (21) to accommodate variations in terrain and differing rider power inputs. The front derailleur is part of the forward drivetrain assembly (22), a metal structure bolted to the lower longitudinal tube and which holds the front derailleur, 2 guide pulleys for the chain (23), a standard bicycle crankset (24), pedals (25) and BSA bottom bracket (26). This drivetrain assembly can be unbolted and slid along the tube to account for different occupant heights.

[0020] The rear wheel (27) which is of the 26” / 559mm standard is bolted to a metal fork (28) inserted into the end of the lower longitudinal tube and held in place by a wedge expander, which likewise features a mounting point for the rear derailleur and anchor loops for the tensile elements of this vertex. This wheel consists of a standard disc brake cassette hub spoked to an outer rim and tire.

[0021] Over this structure is overlaid a transparent or partially transparent skin (29, denoted by wavy line around the frame) which can be made of a textile material such as Mylar, nylon, thermoplastic polyurethane, etc. Holes are cut into the bottom of the skin to allow for the protrusion of the rear wheel and the front axle and steering linkage. A zipper (30) is sewn to the part on both sides of the skin corresponding to the middle triangular section, allowing for occupant ingress / egress, and wraps around the entire mid-section to permit removal. Ventilation holes (31) are cut into the high pressure zones on the nose and tail of the vehicle, allowing for air circulation and temperature stabilization inside the vehicle without unduly compromising aerodynamics.

[0022] This embodiment constitutes an application of the tensegrity principle to the design of an efficient HPV colloquially known as a velomobile, which can be embodied in other variations such as including multiple seats for more occupants, cargo space, more or less wheels, fairings and disc covers over the wheels to further reduce aerodynamic drag, electric propulsion, a different number and arrangement of compression elements etc.

[0023] In the possible embodiment depicted by Fig. 2, the same arrangement of 6 tubes (32, illustrative example) likewise outlines a tensegrity icosahedron, with the difference being slight changes in the lengths of the horizontal tubes and a more significant extension of the vertical ones. The same hubs (33, illustrative example) are inserted into the ends of these tubes and each tube is likewise connected to its 5 nearest neighbours via the same turnbuckle-rope assembly (34).

[0024] Onto the front transverse vertex hubs are attached pivoting lee-boards by means of a tube and aluminum block shaped for the purpose (35), which provide directional stability to a sailboat and resist the heeling forces of the wind. Stabilization to the lee-boards is provided via ropes attached to the upper longitudinal tube (36) and rear transverse tube (37), thus allowing for the lee-boards to be raised for tacking, shallow water conditions and transportation.

[0025] The same tube-webbing seat (38) is preserved from the land-based configuration, attached in the same manner to the vertical tubes and the top longitudinal tube.

[0026] To the rear transverse tube is bolted a spherical pivot (39) on which rests the handle of a yuloh-style rudder (40), a type of East Asian sculling oar. The yuloh acts as a simple integrated tiller and rudder, and can further be swept side-to-side in a sinuous motion to impart propulsion to the sailboat.

[0027] A hull skin (41, denoted by dashed line around circumference of the boat) composed of thermoplastic polyurethane-coated nylon wraps around the bottom of the tensegrity structure and rises over the medial rope circumference, lashed and tensioned to the lower longitudinal tube through eyelets evenly spaced around its border (not pictured for reasons of clarity).

[0028] Propulsion is generated via a set of 4 sails (42, denoted by the wavy lines and drawn only on one side for purposes of clarity) which are anchored via soft rope shackles (43, illustrative example) to the two transverse tubes and the upper longitudinal tube at their base, and at their apex by 4 sheets which pass through blocks (44) bolted to the top of the vertical tubes and which descend to capstans (45) at roughly-occupant height. The sails can be reefed or raised by means of this sheet. Another set of 4 sheets, attached to the feet of sails attached to the forward transverse tube, lead to a set of blocks (46) bolted to the middle of said transverse tube and then back to low friction rings (47) mounted below the capstans on the vertical tubes, thereupon wrapping back around a loop on the vertex hub and back to the sail feet to form closed loops. These sheet loops allow for adjustment of foresail trim for different points of sail. The main sails are trimmed via a sheet loop (48) leading from the trailing foot of the sail to blocks (49) bolted to the centre of the rear transverse tube, returning back through loops in the vertex hubs and thereupon back to the foot of the sail.

[0029] This embodiment constitutes an application of the tensegrity principle to the design of small sailboat, which can be embodied in other variations such as having different lengths and sail sizes, different ways of accommodating the occupant such as a solid deck instead of a seat, motorized propulsion, more sets of vertical tubes for different sail configurations etc.

Claims

AMENDED CLAIMS received by the International Bureau on 12 January 2026 (12.01.2026)1) A land-borne vehicle comprising: a frame in the form of a tensegrity structure comprising six, seven or eight compressive elements joined by tensile elements at vertices, wherein the outer contour of the configuration comprising six compressive elements defines an irregular 20-sided icosahedral geometry having non-uniform element lengths and any additional compressive elements beyond these base six are configured to longitudinally extend the structure along the front-to-rear axis, and wherein no two elements bearing a given compressive load are in direct contact; a passenger support structure operatively connected to said frame and configured to accommodate at least one passenger; a propulsion system operatively connected to said frame; a directional control system operatively connected to said frame; a plurality of wheels operatively connected to said frame.2) The vehicle of claim 1, wherein the relative dimensions and orientations of said compressive and tensile elements are variable, providing alternate spatial configurations while maintaining the relevant base tensegrity structure.3) The vehicle of claim 1, further comprising a rigid or flexible skin or covering operatively connected to said frame and substantially enclosing said frame.4) The vehicle of claim 1, wherein said propulsion system comprises at least one of a mechanical drivetrain and a motor operatively connected to at least one of said wheels.5) The vehicle of claim 1, further comprising a suspension system based on elastic properties of said tensile elements and the non-contiguous arrangement of said compressive elements within said tensegrity frame.6) [Cancelled]7) [Cancelled]8) [Cancelled]9) A water-borne vehicle, comprising: a frame in the form of a tensegrity structure comprising six, seven or eight compressive elements joined by tensile elements at vertices, wherein the outer contour of the configuration comprising six compressive elements defines an irregular 20-sided icosahedral geometry having non-uniform element lengths and any additional compressive elements beyond these base six are configured to longitudinally extend the structure along the front-to-rear axis, and wherein no two elements bearing a given compressive load are in direct contact; a rigid or flexible hull operatively connected to said frame; a passenger support structure operatively connected to said frame and configured to accommodate at least one passenger; a propulsion system operatively connected to said frame; a directional control system operatively connected to said frame.10) The vehicle of claim 9, wherein the relative dimensions and orientations of said compressive and tensile elements are variable, providing alternate spatial configurations while maintaining the relevant base tensegrity structure.11) The vehicle of claim 9, wherein said directional control system comprises at least one element selected from the group consisting of a tiller, oars, rudders, a keel, a centre-board, dagger-boards, and lee-boards.12) The vehicle of claim 9, wherein said propulsion system comprises at least one element selected from the group consisting of sails, a motor, and oars.13) [Cancelled]14) [Cancelled]15) [Cancelled]16) [Cancelled]17) The vehicle of claim 1, wherein said tensile elements are formed of materials selected from the group consisting of cables, ropes, wires, chains, straps, webbing, elastic cords, flexible rods, springs and tensioned membranes, and said compressive elements are formed of materials selected from the group consisting of struts, beams, tubes, pipes, rods, columns, and rigid plates.18) The vehicle of claim 1, wherein said compressive elements comprise multiple interlocking segments configured to permit their disassembly, and said tensegrity vertices comprise detachable joints configured to permit disassembly of said compressive elements and said tensile elements, allowing for the consequent folding of the structure.19) The vehicle of claim 9, wherein said tensile elements are formed of materials selected from the group consisting of cables, ropes, wires, chains, straps, webbing, elastic cords, flexible rods, springs and tensioned membranes, and said compressive elements are formed of materials selected from the group consisting of struts, beams, tubes, pipes, rods, columns, and rigid plates.20) The vehicle of claim 9, wherein said compressive elements comprise multiple interlocking segments configured to permit disassembly of said compressive elements, and said tensegrity vertices comprise detachable joints configured to permit disassembly of said compressive elements and said tensile elements, allowing for the consequent folding of the structure.21) The vehicle of claim 1, further comprising a conversion kit for enabling a water-borne mode, said kit comprising: a) a rigid or flexible hull configured to replace said vehicle's skin; b) a water-based propulsion system; c) fixtures required for the installation of said propulsion system; d) a water-based directional control system; e) fixtures required for the installation of said directional control system; f) a plurality of compressive element segments configured to lengthen the vehicle's compressive elements; and g) a plurality of alternate tensile elements; wherein the removal of the wheels, the land-based propulsion system and associated fixtures, the land-based directional control system and associated fixtures, and installation of components (a) through (g) configures the vehicle in a water-borne mode.22) The vehicle of claim 20, further comprising a conversion kit for enabling a land-borne mode, said kit comprising: a) a rigid or flexible skin configured to replace the vehicle's hull and substantially enclosing the vehicle’s frame; b) a plurality of wheels; c) fixtures required for the installation of said wheels; d) a land-based propulsion system; e) fixtures required for the installation of said propulsion system; f) a land-based directional control system; g) fixtures required for the installation of said directional control system; h) a plurality of alternate tensile elements; wherein the removal of the water-based propulsion system and associated fixtures, the water-based directional control system and associated fixtures, and a plurality of compressive element segments, and installation of components (a) through (h) configures the vehicle in a land-borne mode.[0001][0002]STATEMENT UNDER ARTICLE 19(1)[0003]The significant amendments made to the international application as-filed under Article 19(1) can be broadly grouped into two categories:[0004]1) Amendments addressing the icosahedral geometry. Claims 1 and 9 have been amended to correct the logical contradiction between the icosahedral geometry specified in original claims 1 and 9, and the language of original dependent claims 2 and 10 respectively that allows for variability in the number of compressive and tensile elements, which would broaden the icosahedral limitation rather than narrowing it. The language allowing for slight variability in the base tensegrity icosahedron geometry has been moved to the independent claims 1 and 9, resolving the contradiction, and clarified to be limited in scope to the variations explicidy disclosed in the description (which details longitudinal extension in general and with regard to the embodiments specifically). In limiting the open-endedness of this emergent contradiction, this amendment also clarifies that the claimed invention disclosed in the description as-filed (and in original claims 1 and 9) is limited to a narrow related subset within the generic class of tensegrity structures and not tensegrity structures in toto. The base six-compressive element geometry of the frame, as disclosed in the application as-filed, has also been clarified to be an irregular icosahedron not comprising structural elements of uniform lengths. The amendment to claim 5 is cascading from these amendments. The language of the claim has also been altered simply to better articulate the relationship between the structural elements and the geometric contour.[0005]2) Amendments clarifying the disclosed method of conversion between the land-based and water-based modes of the modular tensegrity vehicle. The ISR raised the objection that the language of claims 7-8 and 15-16 is vague and directed towards the desired result rather than the combination necessary to achieve this, and so the language of the claims has been amended to make explicit reference to the specific conversion methods disclosed in the description as-filed. These two sets of claims are recapitulated in new claims 21 and 22 respectively, and the basis as disclosed for this modularity is cited in both general terms and with regards to the specific embodiments in the accompanying letter. The application as-filed discloses conversion between the two modes in general, the inclusion in one mode of the set of components required for conversion to its reciprocal, and the specific methods whereby this is accomplished, namely in the modular components being bolted or otherwise reversibly affixed to the frame.[0006]The remaining amendments have been made for reasons of logical clarity or concision: claims 1, 3 and 9 have been amended to resolve a recursive contradiction between components mistakenly being specified as connected to the “vehicle” when they themselves are defined as constituting this vehicle, and new claims 17-20 consist of subject matter drawn from other claims. The cancelled claims have been replaced by or folded into new claims.

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