Patent Description:
One example of a modular vehicle of the kind, to which the presently disclosed subject matter refers, is described in <CIT>.

<CIT> Al discloses an articulated vehicle assembly comprising a master vehicle having a master steering system and an onboard sensor arrangement configured to monitor at least said master steering system; a slave vehicle having a slave steering system and an onboard actuator arrangement configured to manipulate at least said slave steering system; an articulation system for articulating in a queue the master and the slave vehicles along a common longitudinal axis; and a processing unit configured to receive input signals from the onboard sensor arrangement and produce corresponding output signals to the onboard actuator arrangement to manipulate said slave steering system so as to maintain the master vehicle and the slave vehicle aligned along the common longitudinal axis, at least when the master vehicle performs a turn on a horizontal plane.

According to the invention, there is provided a structural frame for use with a modular slave vehicle, said structural frame being simultaneously articulatable at rear end thereof to another structural frame of a modular slave vehicle, and at a front end thereof to a coupling portion of an independently driven master vehicle, said structural frame comprising:
a master coupling system in the form of a mechanical stress absorbing coupling mechanism mounted to said front end, said master coupling system being detachably articulatable to said coupling portion of the master vehicle so as to constrain, at least partially, all translational DOF of the vehicles relatively to each other, and leave at least one rotational DOF at least partially unconstrained;
characterized in that said structural frame further comprising:.

According to a preferred embodiment, there is provided a modular slave vehicle articulatable at one end thereof to another slave vehicle and at another end thereof to an independently driven master vehicle having a coupling portion, simultaneously, said slave vehicle comprising:.

Any one or more of the following features, designs and configurations can be applied to a modular slave vehicle and to a structural frame for use therewith, according to the present disclosure, separately or in various combinations thereof, as long as they fall under the scope of the appended claims:
The master coupling system can be configured to maintain a first offset distance between said slave vehicle and said master vehicle when the two are articulated thereby, and wherein said tandem coupling is configured to maintain a second offset distance between said structural frame of said slave vehicle and a structural frame of said another slave vehicle, when the two are articulated thereby, said second offset distance being smaller than said first offset distance.

The master coupling system can comprise a shaft mounted to said front end such that it permanently protrudes axially therefrom, said shaft having a length defining said first offset distance.

The modular slave vehicle can further comprise an accommodation space closer to said rear end than said front end, configured to accommodate at least said shaft of said another slave vehicle, when the latter is articulated thereto.

The accommodation space can be bounded, at least from below, by a protective plate configured to protect said shaft from debris approaching from the ground.

The rear end of the structural frame can be higher than said front end thereof.

The accommodation space can have a horizontal length corresponding to the first offset distance minus the second offset distance.

The master coupling system can comprise three elongate members, each configured to connect independently to said coupling portion of said master vehicle, where a center elongate member is constituted by said shaft.

Two side elongate members of said three elongate members can be detachable from said structural frame.

The first and second slave coupling devices can be readily connectable to each other.

The master coupling system can comprise means for quick-connection with the coupling portion.

The means can include a hitch suitable for connection with a tow ball of said coupling portion.

The tandem coupling can be configured to facilitate quick-connection between the first and second slave coupling devices.

The tandem coupling can include a twistlock mechanism, and each of said first and second slave coupling devices comprises corresponding portions thereof.

The first and second slave coupling devices can be aligned along a coupling longitudinal axis of the modular slave vehicle.

The modular slave vehicle can further comprise a load carrying platform with a rear load carrying surface extending above said rear end of the structural frame, and a front load carrying surface extending above said front end of said structural frame, wherein said two load carrying surfaces are disposed at the same height with respect to said structural frame such that when two slave vehicles are articulated, they form a common bed therebetween.

The modular slave vehicle according to any one of the preceding claims, wherein said at least one DOF being at least partially unconstrained allows free pitch movement between said master vehicle and said slave vehicle.

The master coupling system can be configured to partially constrain roll movement between said master vehicle and slave vehicle.

The master coupling system can be configured to constrain yaw movement of said slave vehicle with respect to said master vehicle.

The master coupling system can be configured to maintain said master vehicle and said slave vehicle aligned along a common longitudinal axis.

The driving system can comprise a road engaging arrangement consisting of a pair of wheels disposed on either side of the structural frame.

The modular slave vehicle can further comprise a control system operatively connected to said driving system, said control system being configured, when said slave vehicle is articulated directly or via one or more slave vehicles to the master vehicle, to:.

The control system can be configured to receive a third input signal indicative of at least one dimension of said master vehicle, and consider all three input signals during processing.

The driving parameter can be an angle of rotation of at least one wheel of the respective vehicle.

Attention is first directed towards <FIG> and <FIG> of the drawings illustrating a modular slave vehicle <NUM>, according to an example of the presently disclosed subject matter.

The slave vehicle <NUM> is a motorized load carrying vehicle, constituting a module for use in an articulated vehicle assembly including two or more vehicles, as illustrated in <FIG>.

In particular, the modular slave vehicle <NUM> is configured for dual use, i.e. for articulating at a front end 1a thereof as a trailer to an ordinary state of the art master vehicle, or to a slightly modified state of the art vehicle <NUM>, to form an articulated vehicle assembly <NUM> as seen in <FIG>, and for articulating at the front end 1a thereof and/or at a rear end 1b thereof, as either a trailer or a lead vehicle, to another, identical, slave vehicle <NUM>, to form an articulated vehicle assembly <NUM> consisting of slave vehicles as seen in <FIG>.

The master vehicle <NUM> can be manned or unmanned, and can be articulated to the slave vehicle <NUM> via a coupling portion 2a thereof, of which an example will be described hereinafter in more detail.

The slave vehicle <NUM> can also be simultaneously articulated at the front end 1a thereof to the manned vehicle <NUM>, and at the rear end thereof 1b to another slave vehicle <NUM>, to form an articulated vehicle assembly <NUM> as seen in <FIG>.

In turn, the another slave vehicle <NUM> can be articulated to yet another slave vehicle <NUM> at its free end, and so on, until driving in the manned vehicle <NUM> becomes too difficult for a driver thereof.

Each of the articulated vehicle assemblies <NUM>, <NUM>, <NUM>, enables independent driving thereof, i.e., without being articulated to any other vehicle. While at the assemblies <NUM>,<NUM> the master vehicle <NUM> is constantly the leading vehicle (expect while driving in reverse), at the assembly <NUM>, any one of the slave vehicles <NUM> can be constituted as a leading vehicle.

It should be appreciated that the slave vehicle <NUM> is configured for military purposes, i.e., configured to be functional for off-road articulated driving at high speeds. When too many slave vehicles are articulated to the manned vehicle <NUM>, driving off-road at high speed may cause instabilities in the articulated vehicle assembly.

With such arrangement, one or more slave vehicles <NUM> can drive to a destination while articulated to the master vehicle <NUM>, and upon arrival, deploy, i.e., split, to individual units. Individual units including two or more slave vehicles <NUM> can drive independently at the destination to pre-determined deployment locations thereof, while individual units including a single slave vehicle <NUM> can reach their deployment locations articulated to the master vehicle <NUM> or to a master vehicle/one or more slave vehicles of another articulated vehicle assembly arriving to the destination.

It should be appreciated that the modular slave vehicle <NUM> can include a self mobility aid system configured to facilitate independent limited maneuverability therefore, particularly for enabling an operator to slightly push or pull the modular slave vehicle <NUM> on top of comfortable ground and to a short distance, while the slave vehicle <NUM> is not articulated to any other vehicle.

The slave vehicle <NUM> comprises a slave structural frame, here in the form of chassis <NUM> (seen in greater detail in <FIG>), supporting a body <NUM> thereof and mounted with a plurality of coupling devices and mechanisms, as will be explained hereinafter.

In other embodiments of the presently disclosed subject matter, the slave structural frame can be constituted by another known in the art structure useful for supporting vehicles, e.g., a spaceframe, a unibody frame, etc..

The chassis <NUM> has a rear end 10b and a front end 10a, and is configured to support the body <NUM> of the slave vehicle <NUM> within their boundaries. In other embodiments of the presently disclosed subject matter, the body <NUM> can extend beyond the chassis <NUM>.

The front end 10a is mounted with a master coupling system in the form of a mechanical stress absorbing coupling mechanism <NUM>, via which the slave vehicle <NUM> is configured to detachably articulate to the master vehicle <NUM>, (seen in greater detail in <FIG>) and with two first slave coupling devices 15a, via which the slave vehicle <NUM> is configured to be articulated to another slave vehicle <NUM> at its front, while not articulated to the master vehicle <NUM>.

The rear end 10b is mounted with two second slave vehicle couplings 15b, via which the slave vehicle <NUM> is configured to be articulated to another slave vehicle at its rear.

As can be understood, the master coupling system <NUM> is mounted only to the front end 10a of the chassis <NUM>, as the slave vehicle <NUM> is designed for driving forward at high speeds, i.e., in the direction D from the rear end 1b to the front end 1a thereof, and such high speeds are expected to be reached when the slave vehicle <NUM> is articulated to the master vehicle <NUM>, which can be configured for driving independently at high speeds.

For enabling comfortable driving for the manned vehicle <NUM> while one or more slave vehicles, such as slave vehicle <NUM>, are articulated thereto, the master coupling system <NUM> is designed to damp stresses being transmitted from the slave vehicle <NUM> to the manned vehicle <NUM>, and vice versa. The damping herein is performed by partially allowing relative movement between the master vehicle <NUM> and the one or more slave vehicles <NUM> connected thereto, particularly by leaving some rotational Degrees Of Freedom therebetween unconstrained or partially constrained, as will be explained hereinafter.

To further enable comfortable driving of the master vehicle <NUM> when articulated to two or more slave vehicles, as in the assembly <NUM> of <FIG>, the first and second slave coupling devices 15a,15b, are designed to connect with each other to form a tandem coupling <NUM> constraining all DOF between the vehicles.

Such articulation renders the chassis <NUM> of the two or more slave vehicles <NUM> unified, and thereby facilitates a single area of free relative movement in the articulated vehicle assembly <NUM>, i.e., between the master vehicle <NUM> and the first slave vehicle <NUM> connected thereto, contributing to the overall stability and intactness of the articulated vehicle assembly <NUM>, particularly while driving at high speed and on rough terrain.

Such articulation also contributes to stability and intactness of an articulated vehicle assembly consisting of two or more slave vehicles, such as the assembly <NUM> of <FIG>, and for the ability thereof to carry common load spreading between the vehicles, as will be explained hereinafter.

To be able to connect when mounted to two identical slave vehicles <NUM>, each of the first slave coupling devices 15a is aligned with its respective second slave coupling device 15b, along a common longitudinal axis L1,L2, extending symmetrically on either side of a central longitudinal axis L of the slave vehicle <NUM>.

It should be appreciated that the slave vehicle <NUM> is a motorized vehicle having a driving system <NUM> with a motor (not seen) and road engaging members in form of two steerable and propellable wheels <NUM> operatively connected thereto at either side thereof. The driving system <NUM> enables the slave vehicle <NUM> to drive an articulated vehicle assembly consisting of slave vehicles, such as the assembly <NUM> of <FIG>, or ease articulated driving for the master vehicle <NUM>, as will be explained hereinafter.

As such, in an assembly of two or more slave vehicles, as the assembly <NUM> of <FIG>, any one of the driving systems <NUM> of the vehicles <NUM> can operate alone to propel the assembly <NUM> while the other is passive, or be operated in conjunction with the other driving system <NUM> to render the assembly <NUM> a 4X4 drive, depending on the operative need, and the control system available for operating the assembly <NUM>. In general, when more than two slave vehicles <NUM> are articulated together to form an articulated vehicle assembly, their driving system can facilitate nXn driving, where n stands for the number of wheels in the articulated vehicle assembly.

In other embodiments of the presently disclosed subject matter the road engaging members can be constituted by caterpillar tracks, ski slides, or any other known road engaging member useful for advancing vehicles.

The two wheels <NUM> herein are symmetrically aligned on either side of the slave vehicle <NUM>, such that they share a common rotation axis R at a straight orientation thereof, seen in the figures.

Having merely two wheels <NUM>, contributes to the stability of the slave vehicle <NUM> during driving, as it limits the location of sudden impacts from the road. When one or more slave vehicles <NUM> are articulated to the master vehicle <NUM>, as in the assembly <NUM>, having merely two wheels in each slave vehicle <NUM> contributes to the overall stability of the assembly <NUM> as described. Further, the distance of the wheels <NUM> from rear wheels <NUM>' of the master vehicle <NUM>, is also important for keeping the assembly <NUM> stable, and particularly may not exceed the distance between the rear wheels <NUM>' of the master vehicle <NUM>, and a front wheels <NUM>" thereof. As the wheels <NUM> of the slave vehicle <NUM> are fixed in their position, the distance between them and the rear wheels <NUM>' of the master vehicle <NUM> is determined by the couplings therebeween, and between slave vehicles when more than one is articulated thereto.

As can be seen in the figures, the master coupling system <NUM> has an operative length maintaining an offset distance OF1 between the front end 10a of the chassis <NUM> of the slave vehicle <NUM> and the coupling portion 2a of the manned vehicle <NUM>.

The offset distance OF1 enables pitch of one vehicle towards the other, and facilitates length for damping stresses passing between the vehicles.

As can be also seen in the figures, the tandem coupling <NUM> has a second operative length maintaining a second offset distance OF2 between the structural frames <NUM> of the respective slave vehicles <NUM> connected thereby. The second offset distance OF2 enables minor movements of non-structural elements of the two slave vehicles with respect to each other.

To facilitate comfortable driving in the master vehicle <NUM> when two or more slave vehicles <NUM> are articulated thereto, the two offset distances, and particularly the second offset distance OF2 should be minimal as possible, much shorter than the offset distance OF1, and particularly minimal to allow the rotation axes R of the wheels <NUM> of the respective slave vehicles <NUM> to come as close together as possible, and thereby increase the stability of the entire structure, particularly at high speeds, and limit the development of moment forces throughout the along the articulated vehicle assembly.

Attention is now directed to <FIG> of the drawings, showing a close up view of the stress absorbing coupling <NUM> as it articulates the slave vehicle <NUM> and the manned vehicle <NUM> together.

As can be seen, the stress absorbing coupling <NUM> comprises three elongate members 31a, 31b, and 31c, where a length of which defines the offset distance OF1.

The two side elongate members 31a and 31c being detachable from the slave vehicle <NUM>, as seen in <FIG>, while the central elongate member 31b, constituted by a shaft 31b herein, is permanently welded to the chassis <NUM>, protruding axially, i.e., along the longitudinal axis L of the slave vehicle <NUM>, and particularly normally horizontally therefrom.

As mentioned, the slave vehicle <NUM> is a directional vehicle configured to maintain a forward orientation, i.e., with the elongate members 31a,31b, and 31c protruding frontally thereto.

As such, in an articulated vehicle assembly of two or more slave vehicles, those elongate members, and particularly the central elongate member 31b, can interrupt close articulation of the slave vehicles <NUM>.

For overcoming such, the slave vehicle <NUM> comprises an accommodation space <NUM>, best seen in <FIG>, configured to accommodate the elongate members 31a,31c, and 31c, therein. Such arrangement allows the slave vehicle <NUM> to articulate with another slave vehicle <NUM> at its front, while maintaining the second offset distance OF2 between the vehicles chassis <NUM> shorter than the first offset distance OF1.

The accommodation space <NUM> is disposed at the rear end 1b of the vehicle <NUM>, with an opening <NUM> facing normally away from the rear end 1b. To accommodate the elongate members, the openings <NUM> have dimensions corresponding to those of the elongate members 31a, 31b, and 31c, and are disposed at the same height as the elongate members 31a, 31b, 31c, with respect to a lowermost portion of the wheels <NUM>. To facilitate maximal accommodation therein, the horizontal length of the accommodation space <NUM> corresponds to the length of the elongate members 31a,31b,31c, and particularly to the length of the shaft 31b.

The accommodation space <NUM> comprises a central protected zone <NUM> configured to receive and accommodate the central shaft 31b. The central protected zone <NUM> is bounded from below by a protective plate 43a protecting anything within the protected zone <NUM> from debris approaching from the ground.

The accommodation space <NUM> further comprises two open areas <NUM> configured to accommodate the side elongate members 31a and 31c. It should be appreciated that the central shaft 31b, being welded to the chassis <NUM>, is a rigid structure which, during driving, should not be subject to bouncing relatively to the chassis <NUM>, and therefore can be bounded within a protected space. On the other hand, the side elongate members 31a and 31c are detachably connectable to the chassis <NUM>, as seen in Fig. 4B, and may even comprise flexible portions, are very much subject to bouncing and preforming any other form of relative movement with respect to the chassis <NUM> during driving.

As such, the open areas <NUM> have dimensions which are substantially greater than those of the elongate members 31a and 31c, and particularly corresponding to the expected disposition of the edges of the elongate members 31a and 31c, during driving.

In other embodiments of the presently disclosed subject matter, all three elongate members 31a, 31b, and 31c, can be fixedly connected to the chassis <NUM>, and the protective plate 43a can spread throughout the accommodation space <NUM>, to define a greater protected area <NUM> capable of accommodating all three elongate members.

To facilitate that accommodation space <NUM>, the rear end 10b of the structural frame <NUM> has a different shape than the front end 10a thereof, namely, a shape bypassing the accommodation space <NUM>. Herein, the rear end 10b of the structural frame <NUM> is higher than the front end 10a of the structural frame <NUM>, so that the accommodation space <NUM> could be defined at the same height as the elongate members 31a,31b,31c, with respect to a lowermost portion of the wheels <NUM>.

It should be appreciated that the driving system <NUM> of one or more slave vehicles <NUM> can be adapted to not harm driving capabilities of the master vehicle <NUM>, when the one or more slave vehicles <NUM> are articulated thereto.

In particular, the slave vehicle <NUM> can be configured to drive at the same speed as the manned vehicle <NUM>, to not damage acceleration and maximal speed of the master vehicle <NUM>. The slave vehicle can also be configured to turn its wheels <NUM> in conjunction with the front wheels of <NUM>" of the manned vehicle <NUM>, to not damage the Instant center of rotation of the master vehicle <NUM>. When more than one slave vehicle <NUM> is connected to the master vehicle <NUM>, the driving system <NUM> of each of the slave vehicles <NUM> can be configured to consider the respective location of the slave vehicle on which it is mounted, i.e., the distance from the rear <NUM>' wheels of the master vehicle <NUM>, and adjust the rotation of its wheels <NUM> to not damage the natural ICOR of the master vehicle <NUM>.

The slave vehicle <NUM> can further comprise a control system <NUM> operatively connected to said driving system <NUM>, so as to control driving thereof, as described hereinabove.

The control system <NUM>, having an operational flow described in <FIG>, can be configured, when the slave vehicle <NUM> is articulated directly or via one or more other slave vehicles such as <NUM> to the master vehicle <NUM>, to drive the slave vehicle <NUM> based on the current position thereof with respect to the master vehicle <NUM>, and optionally the type of master vehicle being used, particularly the distance between the steerable and non-steerable wheels thereof. in particular, the control system <NUM> is configured to <NUM> receive, optionally via a can-bus network, a first input signal indicative of a value of at least one driving parameter of the master vehicle <NUM>, e.g., instant angle of rotation of its steerable wheels <NUM>", and receive <NUM> a second input signal indicative of the number of slave vehicles between the master vehicle <NUM> and the slave vehicle <NUM> of the control system. In case where the slave vehicle <NUM> is articulated directly to the master vehicle <NUM>, that number of vehicles would be <NUM>.

The control system <NUM> is further configured to process <NUM> those input signals, and produce in response instructions to the driving system <NUM>, based on said processing, to adjust the value of a corresponding driving parameter, e.g., angle of wheels <NUM> of the slave vehicle <NUM>, accordingly.

According to an example of the presently disclosed subject matter, the master vehicle comprises a monitoring system in communication with a can-bus network to which the control system <NUM> of the slave vehicle <NUM> can also connect. In such a case, the can-bus network can share between the vehicles all necessary information for instructing the wheels of the slave vehicle <NUM>. According to that example, the control system <NUM> can be configured to receive a third input signal indicative of at least one dimension of the master vehicle, e.g., the distance between the front and rear wheels thereof <NUM>", <NUM>' and consider all three input signals during processing.

In general, the control system <NUM> can be configured to consider all three inputs to determine the Instant Center Of Rotation of the master vehicle <NUM>, and instruct the driving system <NUM> to steer the wheels <NUM> in a manner maintaining that for the entire articulated vehicle assembly.

As such, for a master vehicle having non-steerable rear wheels, such as the vehicle <NUM>, to be able to drive comfortably, the distance between the wheels of the slave vehicle being articulated directly thereto, and the wheels of the rearmost slave vehicle, should not exceed the distance between the front steerable wheels and the rear non steerable wheels of the master vehicle.

In the examples shown herein, the maximal number of slave vehicles articulable to the master vehicle <NUM> in a manner allowing comfortable driving therefore is two.

It should be further appreciated that by means of the master coupling system <NUM>, the driving system <NUM> of one or more slave vehicles <NUM> can assist in driving the master vehicle <NUM>, when the one or more slave vehicles <NUM> are articulated thereto.

In particular, the mechanical stress absorbing coupling mechanism <NUM> is designed to allow free pitch movement, and partially restrict roll and yaw movements, of one vehicle with respect to the other, such that the vehicles articulated thereby are maintained aligned along the longitudinal axis L, while the translational DOF remain fully constrained.

The constraining of translational DOF's allows the slave vehicle <NUM> to hold back the master vehicle <NUM> using its brakes, while the restriction of yaw and roll movements allows the slave vehicle <NUM> to push the master vehicle <NUM>.

According to an example of the presently disclosed subject matter, the mechanical stress absorbing coupling mechanism <NUM> is constituted by the articulation system disclosed in <CIT>.

It should be appreciated that each of the stress absorbing coupling mechanism <NUM>, the female coupling device 15a, and the male coupling device 15b, is readily connectable to its respective coupling by a quick-connect mechanism, i.e., without performing any modifications thereof, without adding external parts to it, and optionally without using designated tools, thereby rendering the slave vehicle <NUM> a readily usable module for both uses abovementioned.

Such quick-connect allows intuitive articulation and inarticulation of the slave vehicle <NUM> to the master vehicle <NUM> and to another slave vehicle <NUM>, in field, by untrained personnel, rendering it suitable for combat missions.

In the examples shown herein, the tandem coupling <NUM> is constituted by a twistlock mechanism. The second coupling device 15b is constituted by a female, hollow casting 15b with an elongate hole 15b' in its front face 15b", while the first coupling device15a is constituted by a male, twistlock, having an elongate locking portion 15a' configured to be inserted through the hole 15a" and be rotated, optionally by <NUM>°, within the hollo so it cannot be withdrawn out therefrom.

Similarly, the three elongate members 31a,31b, 31c, each comprise a coupling head in the form of a hitch 31a', 31b', 31c', at its distal end from the vehicle <NUM>, suitable for connection with a tow ball.

In turn, the coupling portion 2a of the manned vehicle <NUM>, includes three tow balls 2a' spaced apart to a distance corresponding to the distance between hitches 31a',31b',31c', to which the hitches are configured to connect.

It should be appreciated that although most ordinary vehicles typically include <NUM> tow ball or no tow ball at all, modifying an ordinary vehicle to include such, is relatively easy to perform, particularly when compared to modifying a vehicle to include equipment which can be carried by the slave vehicle <NUM>, e.g., military antenna. As such, the slave vehicle <NUM> redundance the need for extreme modification of vehicles to be able to carry particular load, as it can carry the load in itself and be connected to any slightly modified ordinary vehicle.

In other embodiments of the presently disclosed subject matter the coupling portion 2a can include any other means of articulation corresponding to the master coupling system <NUM> of the slave vehicle <NUM>.

The slave vehicle <NUM> herein is configured to carry load. The load can be in any form e.g., heavy military equipment such as antennas, radar devices, supply containers, etc. The load can be joined integrally to the slave vehicle <NUM>, i.e., by welding thereof to the chassis <NUM> of the slave vehicle, or be detachably mounted thereto.

To facilitate carrying of detachable load, the slave vehicle <NUM> comprises a load carrying platform <NUM> with a rear load carrying surface 50b extending above the rear end 10b of the chassis <NUM>, and a front load carrying surface 50a extending above the front end 10a of the chassis. As can be seen in the figures, the two load carrying surfaces 50a and 50b are disposed at the same height with respect to the lowermost portion of the wheels <NUM>, such that when two slave vehicles <NUM> are articulated to one another, as seen in <FIG> they form a common bed therebetween configured for carrying common load.

Claim 1:
A structural frame (<NUM>) for use with a modular slave vehicle (<NUM>), said structural frame being simultaneously articulatable at a rear end (10b) thereof to another structural frame of a modular slave vehicle (<NUM>), and at a front end (10a) thereof to a coupling portion of an independently driven master vehicle, said structural frame comprising:
a master coupling system (<NUM>) in the form of a mechanical stress absorbing coupling mechanism mounted to said front end (10a), said master coupling system being detachably articulatable to said coupling portion of the master vehicle so as to constrain, at least partially, all translational DOF of the vehicles relatively to each other, and leave at least one rotational DOF at least partially unconstrained;
characterized in that said structural frame further comprises:
at least one first slave coupling device (15a) mounted to said front end (10a), distal from the master coupling system (<NUM>); and
at least one second slave coupling device (15b) mounted to said rear end (10b);
said first and second coupling devices (15a, 15b), when mounted to two adjacent structural frames intended to be connected to each other, are detachably connectable to each other to form a tandem coupling (<NUM>) configured to constrain all DOF therebetween.