Field of the invention

The present invention relates to the field of motorcycle riding simulation primarily directed to research and development purposes, especially but not exclusively with regard to vehicle safety, but also for training or simply for recreational purposes. More specifically, the invention relates to a motorcycle riding simulator with a gyroscopic oscillating station.

Background of the invention

Riding simulation is a fundamental tool applied for the purposes just described and requires the interaction between the human subject and a station that simulates the riding of the two-wheeled vehicle in the most realistic way possible, receiving from the subject in question the riding actions and commands, and returning to the subject the sensations correlated to the typical functional behaviour of the vehicle. However, the realism of the riding is difficult to approach due to the lack of the typical dynamic effects that are responsible for the balance during the non-rectilinear motion of single-track vehicles such as cycles and motorcycles, which in particular require high lean angles when cornering.

Various solutions based on active actuation systems have been proposed in the prior art to overcome the lack of these dynamic effects and to seek a realistic perception by the user. An example can be found in "Kovacsova et al. - Emergency braking at intersections: A motion-base motorcycle simulator study - Applied Ergonomics Volume 82, January 2020, 102970", which describes a simulator in which a motorcycle frame, supported at the base by a steerable platform capable of reproducing the lean movement (tilting sideways) is controlled in this movement by actuators that aim to provide the rider with the perception of riding a motorcycle engaged in a change of direction. Other active systems are provided in application to the steering, or to the frame itself to introduce further simulation movements in a coordinated/synchronised manner with a virtual riding scenario dynamically represented on a display (or other device that provides the user with a riding view, such as a face viewer), the whole being managed by a specially developed software control system.

Solutions of this kind are structurally and operationally very complex, raising problems of cost and reliability, imposing difficult and laborious setup operations, and moreover not achieving a satisfactory result from the point of view of responsiveness, since the calculation and actuation times, albeit short, tend to be noticeable to the user, compromising the realism of the experience. It should also be noted that the control of the active components is still linked to a modelling approach, and therefore to a simplification of the phenomenon that is intended to be simulated, which makes the occurrence of responses that are not fully realistic.

A further known simulator is described in patent publication JP3702003 (JPH08262971A). In this document, a motorcycle riding simulation system is described with a frame rotatably linked to a base so as to tilt around a lean axis. A powering system sets the front wheel into spinning, to create, with the rotation that the user transmits to the steering system through the handlebar, an effect of gyroscopic precession that seeks to promote a realistic transmission of the stimuli of movement to the user. As for the steering movement, it lacks any elastic contrast, and it is the angular position of the steering system to be detected and used as an input for the control of the simulation. This known device further comprises position constraints, also with active control, as far as the frame lean angle is concerned; the frame tilting movement also lacks any elastic contrast. These position constraints bring about, as in the already mentioned prior art, a critical factor, making the construction more complex. Notwithstanding this, the device has in any case, with regard to the tilting motion, a certain, albeit reduced, angular range of instability between the aforementioned constraints; however, in the constructive context just described, the contribution offered by the precession phenomena does not appear sufficient to ensure the stabilization of the frame, if not at the limit at the price of a strong effort of the rider, an effort that eventually precludes the exercise of a realistic control action on the steering.

Summary of the invention

Generally speaking, the search for a simulated riding experience that is ever closer to the real one in terms of quality and versatility, and that can be achieved as simply and cheaply as possible, encourages the development of new solutions compared to those already proposed; it is from this scenario and with these objectives that the present invention arises. The motorcycle riding simulator with gyroscopic effect according to the present invention achieves the intended purpose through the combination of essential characteristics defined by the appended claim 1. Other important additional characteristics are the subject matter of the dependent claims.

Brief description of the drawings

The characteristics and advantages of the motorcycle riding simulator with gyroscopic effect according to the present invention will be apparent from the following description of an embodiment thereof, given by way of a non-limiting example with reference to the attached drawings in which:

Figure 1 schematically illustrates the oscillating riding station of a simulator according to the present invention;

Figure 2 is a basic representation of the station in Figure 1, including a schematic representation of the user on board;

Figure 3 shows in greater detail, through a block diagram of the components and with reference to the relative circuit configuration, the riding station and the user on board.

Figure 4 is a high-level block diagram of the simulator as a whole, including the user, illustrating the functional model with representation of the interactions between the various blocks in terms also of the mutually exchanged fundamental quantities.

Detailed description of the invention

With reference to the above figures, a simulator according to the invention comprises three main elements, in an overall architecture which is not different from that of known simulators, comprising a riding station 1 , a control unit 2, and display means such as a screen or a system of screens 3. In principle, the control unit 2, including processor means provided with suitable software, exchanges data and signals with the riding station 1 and with the display means 3, so that a virtual riding scenario is represented to the user U who is active on the riding station 1, this scenario being dynamically coordinated with the actions of the user/rider, inducing them and at the same time changing according to them (or some of them). The software programming details pertaining specifically to this interaction are not described in detail, as they involve known technology outside the scope of the present invention. The riding station 1 is typically in the form of a motorcycle frame 11 with support means 11a for a user in a riding posture, typically a seat. Clearly, the frame lacks of the engine and of the rear wheel assembly, while it is instead provided with a real or realistic front wheel assembly comprising a front wheel 12 supported by a fork 13 with relative handlebar 13a, engaged with the frame 11 by means of a rotational link, in order to impart the steering command, through a steering joint 13b formed by a steering shaft and steering column that are coaxial on a steering axis S and provided with first elastic contrast means, in the form of simple springs or even and preferably (but not necessarily) of a first spring-damper system 13c. The front wheel 12 can more generically be represented and realised in terms of a flywheel mass, suitably calibrated, rotating with respect to the steering system (front wheel assembly including the fork, steering arms and other suspension components) around a flywheel axis V orthogonal with the symmetry plane of the front wheel assembly and taking the shape of a hub 12a. The frame 11 is sustained by a support 14 which rises from a basement 15 to which it is hinged by means of a lean rotational joint 16 to allow a lean movement around a lean axis R corresponding to the longitudinal axis of the vehicle and which, transposed into the virtual riding environment, sets the direction of the vehicle's advancement. To control the lean movement, the joint 16 is equipped with second elastic contrast means, also in this case comprising simple springs or, and preferably, integrated in a second springdampersystem 17 and configured in such a way that the motorcycle simulacrum or frame has a stable position in a vertical position, or in a position close to the vertical direction (within an angular range of few degrees).

From a kinematic point of view, as can be seen in Figure 2, the structural assembly of the station and of the user can be schematised in terms of three rigid elements (frame, front wheel assembly and user), and three rotational joints, the already mentioned physical joints, that is the lean joint 16 (between frame and basement/ground) and the steering joint 13b, and a virtual joint G that represents the relative rotation movement between the user and the frame, which is typically needed during riding to shift the weight of the body with the balance variations of the vehicle and which is reproduced in the simulated riding. The angles of relative rotation around these joints can be identified respectively as the lean angle cp of the frame 11 around the axis R, the steering angle 3 and the tilting angle 9 of the rider’s body relative to the frame, measured on a plane orthogonal with the lean axis R.

According to an aspect of the present invention, the front wheel 12 is operatively associated with a motor means 18, mounted on the front wheel assembly, which by means of a mechanical transmission 19, for example with belt, chain, gears also with direct drive, imparts to it a spinning motion around its flywheel axis V, with controlled speed w as will be explained shortly. A further aspect is linked the presence of a torque sensor associated with the steering joint 13b, adapted to detect the torque TS applied to the front wheel assembly through the joint. This sensor can be configured by suitably instrumenting the handlebar with strain gauges or also by mounting the handlebar on a bearing-supported system that decouples the rotation of the handlebar from the rotation of the fork, interposing between the two elements a force sensor whose straight line of action is spaced from the steering axis by a known amount (arm “b”). The steering torques are transmitted from the handlebar to the fork through the force sensor, whose signal processed and multiplied by the arm b provides a measure of the torque exerted by the user.

Other sensors that equip the riding station 1 may optionally comprise at least one among: - a lean angle cp sensor, associated with the base or lean joint 16; - a steering angle 6 sensor provided on the steering joint 13b; - a rider’s body tilting angle 0 sensor, for example an optical sensor that obtains the rider's position by means of machine vision techniques (this latter sensor may be replaced by an estimate of the aforesaid tilting angle 0 by means of a proportionality relationship with the lean angle cp, excluding gyroscopic effects, considering that there are no external actuators and all the other parameters are known); - a torque sensor of the torque T _O applied by the rider to the frame 11 around the lean axis R (it can be replaced, if necessary, by an estimate of this torque starting from the measurement of the lean angle, with a simple model similar to that of the dynamometer).

It should also be mentioned that, in addition to the steering command, the handlebar offers the rider the thrusting and braking commands typical of motorcycles, by means of the classic rotary grip and hand lever systems. These commands result in respective Thr, Brk signals which are transmitted from the riding station 1 to the control unit 2 for the translation thereof into values of displacement, speed and acceleration of the vehicle in the virtual environment.

With particular reference to Figure 3, the above-mentioned components are shown by means of a more detailed circuit representation, the connections of which are not exactly represented, being however of immediate understanding to the skilled person. The interfaces through which a torque is applied are also symbolically represented here, namely the application of the steering torque by the user, symbolised within the block located on the handlebar 13a, and above all a precession torque, the effect of the rotation of the wheel 12, exchanged between the front end and the frame (block Tg). The wheel or flywheel mass, by undergoing a rotation around an axis (the steering axis S) orthogonal with the axis with respect to which it spins reacts by gyroscopic effect inducing a force moment around a third axis orthogonal with the two previous ones, and therefore in the specific case with a substantial component around the lean axis R. With the appropriate sizing of the system, the entity of the resulting displacements is made substantial, and clearly it can be properly regulated.

To summarize, the scenario of the relevant quantities in the functional behaviour of the device can be expressed by way of example by the following box, which also includes intrinsic parameters of the system (inertias), obviously variable according to the design choices.

It should be noted that in possibly more advanced embodiments, and according to what can obviously be deduced by the person skilled in the art, further degrees of freedom may be introduced in the support of the station 1 , with consequent simulationof the pitch and yaw movements and detection of the relative angles p, >|/, as well as a coordinate Z (elevation displacement) of the vehicle in the virtual space.

How these values/signals are exchanged between the blocks of the simulator, including the directionality of the transmission, can be deduced from the substantially self-explanatory example of Figure 4, in which the exchange between display media 3 and user U is to be understood in terms of pure visual perception, while the represented bidirectional connections between the user U and the station 1 are exchanges of physical perception and of physical intervention on the station (steering, body displacement). The remaining connection lines represent actual data/signal exchanges, including the one F between the control unit 2 and the display means 3 which represents the video signal stream F to be represented, processed as output by the unit 2 on the basis of the received data/signals and of the relative programming.

Based on the above, in the functional behaviour of the simulator the rider therefore interacts with the riding station by providing steering input (variation of the angle 5) and by modifying his position (variation of the angle 0) and clearly also by transmitting the forces, and more precisely the respective torques, that are necessary to produce these effects. In return, the station makes the rider feel riding sensations by means of its tilting with respect to the ground (absolute and differential variation of the angle (p), affected by the gyroscopic precession torque caused by the rotation of the front wheel. The control unit derives from the measured data the already mentioned aggregated steering input, which expresses through a synthetic quantity the combination of the inputs provided by the user in order to obtain the virtual steering of the vehicle.

Various analytical expressions can be adopted to lead to the aggregated input, depending on the dynamic behaviour to be determined, possibly according to various selectable preset programs, and based on the boundary conditions. The torque measured at the steering T ₅ through the relative sensor is in any case to be considered a key element in whatever functional expression is chosen, combining it linearly with the lean angle and/or the steering angle and/or lean torque. The aggregated input may also be transmitted as a vector with several components.

Based on the aggregated steering input, as well as typically on the accelerator and brake inputs, the unit determines a position and a speed of the vehicle for the purpose of representation in the virtual environment, while the rotation speed co of the wheel 12 can be varied e.g., according to laws proportional to the virtual forward speed or by maintaining constant values.

It should be noted that the aggregated steering input and the wheel speed can generally be managed independently. The steering input is what determines the riding command in the virtual world, while the angular speed of the wheel is what determines the extent of the sensory feedback to the user. The two quantities (aggregated steering input and wheel angular speed) are in practice connected only by the user-supplied steering torque input, which determines the aggregated steering input and the sensory feedback.

The result of the dynamic riding processing carried out by the control unit is delivered to the screen in terms of representation of the riding environment. In all of this, the dynamic behaviour of the riding station is essentially passive by nature, i.e., solely induced, in addition to the rider's actions, by the gyroscopic precession effect that is triggered automatically, affecting the entire vehicle and without any active control or actuation on the lean axis.

In practice, the apparatus consists in an oscillating vehicle with a gyroscopic effect due to the rotation of the front wheel, combined with an elastic response to the steering (counter-steering riding with steering torque sensor), in order to achieve a highly realistic riding perception, with a system of remarkable structural and functional simplicity.

The small movements of the frame that transmit the typical sensations of transients (variations in direction, variations in trajectory, straight-line curve transition and vice versa) are realistically perceived by the rider; and the station responds automatically, promptly and without any control system to the riding inputs provided by the user (steering angle imposed to the handlebar).

To summarize, and ultimately, the present invention is based on the intuition that riding realism is obtained by letting the user/rider control the motorcycle by means of torque inputs at the steering (in counter-steering), with the front wheel assembly linked to the frame by means of springs (in addition to possible inputs related to the lean of the simulacrum or to the position of the user’s body), exploiting the rotation of the front wheel that in combination with the steering rotations commanded by the rider (and carried out in counter-steering fashion) produces torque components (effect of precession) around the lean axis of the frame, the leaning being governed passively through appropriate elastic contrast means (and possibly dampers). All this is clearly unfeasible with the known configuration described for example in JP3702003, in which the rotation of the handlebar, without elastic contrast, represents the main control input, and the leaning motion, when not imposed by actuator means (active end stops), is not in fact governable by the user.

The advantages of the simulator according to the present invention over the known ones can be summarised as follows:

• lower costs;

• quickness of response;

• low complexity;

• calibration simplicity;

• reliability;

• intrinsic realistic effect, as the realism is guaranteed regardless of the simplifications adopted in the simulation model and any programming bugs;

• operation intuitiveness, and consequently:

• low familiarisation time.

Although, by way of example, reference has been made to motorcycle riding as the most typical field of application of the invention, it is clear that the principles underlying the invention can be used more generally, with obvious adaptations, in other similar fields, i.e. in which a riding dynamics similar to that of a motorcycle must be simulated, hence the cycling field generally intended and even more generally that of land or even nautical vehicles (for example watercrafts, if necessary by setting the appropriate direction of rotation of the front wheel) in which a dynamic equilibrium is achieved during cornering by means of substantial inclination angles of the vehicle.

The present invention has been described herein with reference to preferred embodiments thereof. It should be understood that there may be other embodiments that relate to the same inventive concept, within the scope of the appended claims.