ADAPTIVE ROBOTIC FOOT

The present invention relates to an adaptive robotic foot of the type specified in the preamble of the first claim.

The object of the present invention is to be identified in a foot that functionally adapts to the actions of a robot in order to give balance and stability to the robot.

Currently, most robotic feet, such as flat ones with activated ankles, favor simplicity and robustness at the expense of a reduction in functionality.

In recent years, adaptive robotic feet have been developed, or rather able to change the shape of the foot to adapt to the ground, capable of giving greater stability and better perception of the ground.

A first example of an adaptive robotic foot involves the use of inflatable balls or other delicate soft components. For example, CN202624435 introduces the possibility of making a flexible foot consisting of a flat part with rubber pads to absorb impacts; US201831 1837 shows a mechanical embodiment of the sole of the foot divided into two parts; other examples involve the use of an airtight bag filled with granular material to be placed between the foot and the ground.

The known technique described includes some important drawbacks.

In detail, the known adaptive feet are difficult to use in difficult external environments and/or on soft and deformable ground such as sand or snow. Therefore, the adaptive feet are not currently able to work on all terrains guaranteeing adequate stability.

Other drawbacks of the known adaptive robotic feet are, for example, to be identified in the mechanical complexity which determines high costs, high weights and design difficulties; in the complicated modeling that complicates their study; in the complexities of control.

In this situation, the technical task underlying the present invention is to devise an adaptive robotic foot capable of substantially obviating at least part of the aforementioned drawbacks.

Within the scope of said technical task, an important object of the invention is to obtain an adaptive robotic foot that can be used in any condition.

Another important object of the invention is to provide an adaptive robotic foot which has relatively simple mechanics and therefore reduced costs, low weight and limited design and control difficulties.

The technical task and the specified aims are achieved by an adaptive robotic foot as claimed in the annexed claim 1. Examples of preferred embodiment are described in the dependent claims.

The characteristics and advantages of the invention are clarified below by the detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, in which: the Fig. 1 shows, in scale, a possible application of the robotic foot according to the invention; the Fig. 2 illustrates, in scale, a second view of Fig. 1 ; the Fig. 3 shows, in scale, an exploded view of the robot foot according to the invention; the Fig. 4 shows, in scale, the robotic foot in a different position; the Fig. 5 illustrates, in scale, the robotic foot in a further position; the Fig. 6 shows, in scale, the robotic foot in a third position; and the Fig. 7 shows, in scale, a possible robot comprising more robotic foot according to the invention. In the present document, the measurements, values, shapes and geometric references (such as perpendicularity and parallelism), when associated with words like “about” or other similar terms such as “approximately” or “substantially”, are to be considered as except for measurement errors or inaccuracies due to production and/or manufacturing errors, and, above all, except for a slight divergence from the value, measurements, shape, or geometric reference with which it is associated. For instance, these terms, if associated with a value, preferably indicate a divergence of not more than 10% of the value.

Moreover, when used, terms such as “first”, “second”, “higher”, “lower”, “main” and “secondary” do not necessarily identify an order, a priority of relationship or a relative position, but can simply be used to clearly distinguish between their different components.

The measurements and data reported in this text are to be considered, unless otherwise indicated, as performed in the International Standard Atmosphere ICAO (ISO 2533:1975).

Unless otherwise specified, as results in the following discussions, terms such as “treatment”, “computing”, “determination”, “calculation”, or similar, refer to the action and/or processes of a computer or similar electronic calculation device that manipulates and/or transforms data represented as physical, such as electronic quantities of registers of a computer system and/or memories in, other data similarly represented as physical quantities within computer systems, registers or other storage, transmission or information displaying devices.

With reference to the Figures, the robotic foot according to the invention is globally indicated with the number 1.

It is adapted to be constrained to an external object and preferably to a robot 10. The robotic foot 1 defines a contact area 1a of the foot 1 and therefore of said object external to a resting surface. The resting surface can be defined by a ground, a rock, a road or other structure on which the foot 1 can rest.

As described in detail below, the contact area 1 a can have a flat profile (or rather, be flat) or a deformed profile i.e. be bent and/or curved due, for example, to its contact with an irregular resting surface.

The robotic foot 1 defines a front face and a rear face. The contact area 1 a extends from said front face to said rear face. In detail, it mainly extends from the front to the rear face.

Preferably the robotic foot 1 can be used in robotics. It can therefore be part of a robot 10.

The robot 10 can comprise at least one module and in detail a plurality of mutually movable modules so as to allow said robot 10 to perform at least one operation and/or to move on a resting surface.

In particular, the robot 10 can comprise at least one module identifying a limb 1 1 configured to rest and therefore unload the weight of the robot 10 on a support surface and/or to allow said robot to move along said resting surface.

Preferably, the robot 10 can comprise several modules identifying limbs 11. For example, Fig. 7 shows a robot 10 comprising four modules each identifying a limb 1 1 and a fifth module identifying the central body of the robot 10 to which said limbs 1 1 are constrained.

Each limb 11 can comprise at least one robotic foot 1 .

Each limb 11 , illustrated in Figs. 1 and 2, can comprise an anchoring body 111 the robotic foot 1 to the rest of the lower limb 1 1 and therefore of the robot 10. It is highlighted how the robot 10 can comprise, in addition to modules identifying a limb 1 1 , modules configured to perform other functions such as identifying additional limbs such as gripping and/or handling of an object. For example, in an anthropomorphic robot the robot 10 can comprise two modules each identifying a limb 1 1 ; two modules each identifying an additional limb (in detail an upper limb); a module identifying the torso and a module identifying the head of said robot 10. The robot 10 can comprise at least one motor 12 for actuating said module.

The motor 12 can be configured to move the module with respect to a different module and in particular at least one module identifying the limb 1 1 with respect to the rest of the robot 10 so as to allow said robot 10 to move on said support surface. In some cases, the motor 12 can be configured to actuate at least one module allowing it to perform an operation such as a plug.

The motor 12 can be electric.

The robot 10 can comprise a control unit 13 of the robot 10 and in particular of the at least one motor 12.

The robot 10 can comprise a power supply system 14 of the robot such as a battery and/or a connection to an external network.

The robotic foot 1 can comprise an attachment 2, preferably integral, of the foot 1 to an external object, in detail to the robot 10, in more detail to the limb 11 and more in detail still to the anchoring body 1 1 1.

The robotic foot 1 can comprising a contact member 3 defining the contact area 1 a. The contact member 3 is configured to vary the profile of the contact area 1 a which can therefore be flat or deformed.

The contact member 3 can comprise at least one chain 31 defining the contact area 1 a. In detail, it comprises a plurality of chains 31 suitably parallel to each other. More in detail, the member 3 comprises at least three chains 31 and for example four. Each chain 31 defines a first end and a second end.

Preferably each chain 31 is an articulated chain. It can comprise at least one link 311 and in detail a plurality of links 31 1 mutually constrained so as to suitably rotate idly.

The axis of rotation between the links is substantially parallel to the contact area 1 a regardless of the profile of the contact area 1 a.

The links 31 1 belonging to distinct chains 31 may not be constrained to each other so as to allow independent deformation of the chains 31 .

Each chain 31 can comprise for each link 311 a cleat 312 defining at least one sector of the contact area 1 a.

The cleat 312 can be made of elastomeric material or other material configured to absorb the forces/impacts upon contact between the contact area 1 a and the restting surface.

The contact area can be defined by the area enclosing (circumscribed) to the portion of said at least one chain of contact with the resting surface, in detail to the links 311 in contact with the bearing surface and in more detail by the cleats 312 and in detail the surfaces of the studs 312 in contact with the bearing surface.

The contact member 3 can comprise a first support 32 constrained to each chain 31 at the first end and a second support 33 constrained to each chain 31 at the second end.

The first support 32 can be placed in correspondence with the front face.

The second support 33 can be placed in correspondence with the rear face.

The supports 32 and 33 enclose the at least one chain 31 between them.

The supports 32 and 33 identify the only constraints between links 31 1 of different chains 31 . The first support 32 is hinged to each chain 31 at the link 31 1 defining the first end allowing said links 31 1 to rotate with respect to the first support 32 suitably idly.

The axis of rotation between the first support 32 and at least one chain 31 is substantially parallel to the contact area 1 a.

The second support 33 is hinged to each chain 31 at the link 311 defining the second end allowing said link 31 1 to rotate with respect to the second support 33 suitably idly.

The axis of rotation between the second support 33 and at least one chain 31 is substantially parallel to the contact area 1 a.

The robotic foot 1 can comprise a joint block 4 of the contact member 3 to the attachment 2.

The joint block 4 is constrained in a compliant way and hinged in detail to the contact member 3.

It is constrained in a compliant way and hinged in detail to the attachment 2.

The joint block 4 can comprise a first arm 41 subtended between the first end of the chain 3 and attachment 2 and in detail between the first support 32 and attachment 2; and a second arm 42 subtended between the second end of the chain 3 and the attachment 2 and in detail between the second support 33 and the attachment 2. The first arm 41 is constrained, suitably not directly, to the chain 3 at the first end. In detail, it is hinged to the chain 3 and to be more precise to the first support 32.

The second arm 42 is suitably not directly connected to the chain 3 at the second end. In detail, it is hinged to the chain 3 and to be more precise to the second support 33.

The joint block 4 can comprise a first hinge 43 defining a first axis of rotation 1 b.

The first hinge 43 can be placed in correspondence with the front face and preferably external to the projection of the contact area 1 a, said projection being almost perpendicular to the contact area 1 a having a flat profile.

The first hinge 43 is configured to allow a first rotation, suitably idle, between the contact member 3 and the joint block 4. In particular, between the first arm 41 and the contact member 3. Preferably the first rotation is between the first arm 41 and the first support 32 and therefore between the first arm 41 and at least the chain 31 . The first axis of rotation 1 b can be practically transverse to the support area 1 a and preferably incident to the support area 1 a suitably at least in a flat profile.

The first axis 1 b can define with respect to the support area 1 a a first angle of inclination with an amplitude almost lower than 30° in detail substantially comprised between 30° and 1 °, preferably between 10° and 3°. The width of the first angle can be almost equal to 6°.

The joint block 4 can comprise a second hinge 44 defining a second axis of rotation 1 c.

The second hinge 44 is configured to allow a second rotation, suitably idle, between the contact member 3 and the joint block 4, in particular, between the second arm 42 and the contact member 3. Preferably the second rotation is between the second arm 41 and the second support 33 and therefore between second arm 41 and at least chain 31 . The second hinge 44 can be placed in correspondence with the rear face and preferably external to the projection of the contact area 1 a, said projection being almost perpendicular to the contact area 1 a having flat profile.

The second hinge 44 can be on the opposite side to the first hinge 43 with respect to the contact member 3 and, to be more precise, to the contact area 1 a.

The second axis of rotation 1 c can have an inclination opposite to the first axis 1 b. Preferably, the first axis 1 b and the second axis 1 c are substantially coplanar and to be precise, incident with each other.

The second axis 1 c can be substantially transverse to the area 1 a and in detail incident to the resting area 1 a suitably at least in a flat profile.

It can define with respect to the resting area 1 a a second angle of inclination substantially less than 30 ° in detail substantially comprised between 30° and 1 °, preferably between 10° and 3°. The width of the second angle can be almost equal to 6°.

It should be noted that the hinges 43 and 44 and therefore the rotations of the contact member 3 around the first axis 1 b and the second axis 1 c can be mutually independent. Therefore, the first hinge 43 and the second hinge 44 are configured to allow distinct rotations around the first axis of rotation 1 b and the second axis of rotation 1 c causing a variation in the profile of the contact area 1 a.

The joint block 4 can comprise an supplementary hinge 45 defining a supplementary axis of rotation 1d.

The supplementary hinge 45 is configured to allow an additional rotation, suitably idle, between the attachment 2 and the joint block 4 and in particular between the attachment 2 and each arm 41 and 42. The supplementary hinge 45 is configured to allow rotation between the arms 41 and 42 suitably insane.

The supplementary axis of rotation 1d can be practically parallel to the resting area 1 a and substantially incident in detail the projection of the center of gravity of the contact area 1 a having a flat profile.

The supplementary axis of rotation 1 d can be substantially perpendicular to the first rotation axis 1 b.

First axis 1 b and supplementary axis 1d can be skewed. It should be noted that the first arm 41 can be configured to distance the first hinge 43 and the supplementary hinge 45 and then the first axis 1 b and the supplementary axis 1 d from each other. The minimum distance, calculated along the perpendicular to the contact area 1 a when in flat profile, between said axes 1 b and 1 d is at least equal to 0.5 cm and in detail to 1 cm. It can be substantially comprised between 1 cm and 10 cm in detail between 2 cm and 5 cm and more precisely between 3 cm and 4 cm.

The supplementary axis of rotation 1d can be substantially perpendicular to the second rotation axis 1 c.

Second axis 1 c and additional axis 1 d can be skewed.

The second arm 42 can be configured to distance the second hinge 44 and the supplementary hinge 45 and therefore the second axis 1 c and the supplementary axis 1 d from each other. The minimum distance, calculated along the perpendicular to the contact area 1 a when in flat profile, between said axes 1 c and 1 d is at least equal to 0.5 cm and in detail to 1 cm. It can be substantially comprised between 1 cm and 10 cm in detail between 2 cm and 5 cm and more precisely between 3 cm and 4 cm.

When the resting area 1 a is in a flat profile, the additional axis 1 d can be equidistant from the ends of the chains 31 in detail from the supports 32 and 33.

The joint block 4 can comprise elastic means 46 adapted to mutually spread the arms 41 and 42 keeping the at least one chain 31 under tension and therefore opposing a deformation of said chain 31 when in contact with an irregular and/or non-flat resting surface.

The elastic means 46 can be associated with the supplementary hinge 45 so as to oppose a variation (in detail a decrease) in the spreading angle between the arms 41 and 42. They can comprise a torsional spring connecting the two arms 41 to each other and 42. The angle of spread can be centered on the supplementary axis of rotation 1d.

The joint block 4 can comprise at least one limit switch for the rotation of at least one and in detail of both arms 41 and 42 with respect to the supplementary axis of rotation 1 d. Preferably it can comprise a first limit switch 47 for the first arm 41 and a second limit switch 48 for the second arm 42.

Each limit switch 47 and 48 is configured to limit the mutual approach of the arms 41 and 42 and therefore defines a minimum value of the spreading angle between arms 41 and 42.

Said minimum value of the spreading angle can be at least equal to 0°. In detail at 10°. It is substantially comprised between 15° and 60° in detail between 30° and 50° and for example substantially equal to 40°.

The robotic foot 1 can comprise a sensor for measuring the deformation of the contact area 1 a and therefore configured to detect the profile of the contact area 1 a, or rather if the contact area 1 a is flat or irregular. The sensors can comprise at least one sensor for measuring at least one between a first rotation around the first rotation axis 1 b and a second rotation around the first rotation axis 1 c.

The at least one sensor can be in data connection with the control unit 13.

Said sensor system can comprise at least a first sensor 5 for measuring the first rotation around the first axis of rotation 1 b in data connection with the aforementioned control unit 13. The control unit 13 is therefore configured to control the robot 10 according to the size of the first rotation.

The first sensor 5 is configured to measure the rotation between the first arm 41 and the contact member 3.

The first sensor 5 can be an inertial sensor. It can be integrated in the first arm 41 and/or integrated in the contact member 3 and in detail in the first support 32. Preferably the sensors can comprise only one first sensor 5. Alternatively, the sensors can comprise two first sensors 5, one integrated in the first support 32 and one in the first arm 41 to estimate the relative angle between said components.

To be precise, a sensor placed as 5 in Fig. 3 will hardly be able to measure the relative angle between 41 and 3, even more so an inertial sensor cannot. At least two (inertial) sensors are needed, one on 41 and the other on 32 to estimate the relative angle.

The measure of the first rotation can be stored in the robot database.

The sensors can comprise at least a second sensor 6 for measuring the second rotation around the second axis of rotation 1 c in data connection with the control unit 13. The control unit 13 is therefore configured to control the robot 10 according to the measurement of the second rotation.

The second sensor 6 is configured to measure the rotation between the second arm 42 and the contact member 3.

The measurement of the second rotation can be stored in the robot database.

The sensors can comprise at least one additional sensor for measuring the additional rotation around the supplementary axis of rotation 1 d in data connection with said control unit 13.

The second sensor 6 can be an inertial sensor.

It can be integrated in the second arm 42 and/or integrated in the contact member 3 and in detail in the first support 33.

Preferably the sensors can comprise only one second sensor 6. Alternatively, the sensors can comprise two second sensors 6, one integrated in the second support 33 and one in the second arm 42 to estimate the relative angle between said components. The control unit 13 is therefore configured to control the robot 10 according to the extent of the additional rotation.

The additional sensor is configured to measure the rotation between the attachment 2 and at least one arm 41 and/or 42 and optionally between the arms 41 and 42. The additional sensor can be an inertial sensor.

Preferably the sensors can comprise a supplementary sensor for each arm in data connection with the control unit 13.

The measurement of each supplementary rotation can be stored in the robot database.

It can thus comprise a first supplementary sensor 7a for measuring the additional first rotation between the first arm 41 and attachment 2 around the supplementary axis of rotation 1 d; and a second supplementary sensor 7b for measuring the supplementary second rotation between second arm 42 and attachment 2 around the supplementary axis of rotation 1 d.

The first supplementary sensor 7a can be integrated into the first arm 41 .

It can be an inertial sensor.

The second supplementary sensor 7b can be integrated into the second arm 42.

It can be an inertial sensor.

The control unit 13 is configured to control the robot 10 as a function of the extent of the supplementary rotation of the second arm 42 with respect to the attachment 2. It is therefore configured to control the robot 10 as a function of the extent of the additional rotation of the first arm 41 with respect to attachment 2.

The control unit 13 is configured to control the motor 12 of the robot 10 and therefore the movement of at least one limb 11 (or rather the movements of the robot 10 on the support surface) as a function of at least one measured measurement from the first sensor 5, from the at least one additional sensor (in detail both the supplementary sensors 7a and 7b) and preferably from the second sensor 6.

In detail it is configured to define the profile of the contact area 1 a of each of the at least one foot 1 of a robot 10 according to the measurements obtained from the sensors of said foot 1 and therefore controlling the robot 10 according to the profile of said at least area 1 a.

The control unit 13 is configured to control the movement of at least one limb 1 1 defining for the robot a condition of equilibrium on the resting surface.

For this purpose, it can comprise a robot database comprising the physical and/or mechanical characteristics of the robot 10 (in detail of each module) so as to allow the unit to determine which movement to perform to define an equilibrium condition. Finally, it should be noted that the robotic foot 1 can be passive and therefore devoid of motors. The contact area 1 a is therefore configured to remain flat (thanks to the elastic means 46) and deform only when pressed against a suitably non-flat and therefore irregular support surface.

The operation of the robotic foot 1 and therefore of the robot 10 previously described in structural terms is as follows.

When the robot 10 moves along a support surface 1 a, the control unit 13 commands, for example, the lifting of the foot 10 from the resting surface and its resting in a different point of the resting surface.

Upon lifting, the contact area 1 a detaches from the support surface and therefore the weight of the robot 10 no longer presses the contact area 1 a against the resting surface. Consequently, the chains 31 are subject only to the action of the elastic means 46 which, by spreading the arms 41 and 42, stretch the chains 31 which therefore define a contact area 1 a with a flat profile. The rotation of the arms 41 and 42, measured by at least the supplementary sensors 7a and 7b, is detected by the control unit 13 which can thus identify the flat profile of the area 1 a.

It is highlighted how the lifting of the foot 1 , removing a support from the robot 10, can bring the robot 10 to a non-equilibrium condition. This condition can be identified by the unit by means of special sensors of the robot and/or by detecting a rotation by the sensors of at least a second foot 1 of the robot 10 different from the one being moved and still in contact with the resting surface.

Once the non-equilibrium condition has been detected, the control unit 13 defines, for example thanks to the robot database, a new equilibrium condition and therefore the profile that the contact areas 1 a must assume in order to obtain said configuration.

Then the unit commands a displacement of a module, such as to vary the shape of the contact area 1 a of at least one said second foot 1 . For example, it can command the motor 12 to move the limb 1 1 corresponding to the second foot 1 so as to alter the profile of the area 1 a (corresponding to a modification of the interaction and therefore of the forces exchanged between area 1 a and the contact surface) until the profile suitable for the new equilibrium condition is obtained.

When the foot 1 rests on said new point of the support surface, the contact area 1 a of this foot 1 can acquire a deformed profile due to the pressure given by the unloading of the weight of the robot 10 in said contact area 1 a against the resting surface. This deformation of the area 1 a involves a rotation of the joint block 4 with respect to the attachment 2 (for example an approach of the arms 41 and 42 in opposition to the elastic means 46) and I or a rotation of the contact member 3 with respect to the joint block 4. The amplitude of these rotations, detected by the sensors 5, 7a and 7b and if present 6, can be exploited by the control unit 13 to acquire the profile of the contact area 1 a and/or command a new movement of robot 10.

It can be seen how the support of foot 1 can define a condition of non-equilibrium and impose the assumption of a new condition of equilibrium.

The robotic foot 1 and therefore the robot 10 according to the invention achieve important advantages.

In fact, the robotic foot 1 is able to guarantee excellent stability on any type of support surface and therefore also in difficult external environments and I or on soft and deformable ground such as sand or snow. In fact, the adoption of one or more chains 31 , suitably with links 31 1 of different separate chains 31 , allows the contact area 1 a to perfectly adapt its shape to each support surface and therefore to all terrains. In particular, this adjustment allows the foot 1 to maximize the contact area 1 a actually in contact with the support surface and therefore guarantees a greater grip.

The stability is also given by the fact that the robotic foot 1 , thanks to said sensors, is able to detect the profile of the contact area 1 a and therefore to determine the reaction of the ground (in the direction towards and suitably in module thanks to the database robot). This aspect translates into the possibility of adapting the profile of the contact area 1 a in such a way as to have a reaction with the resting surface suitable for creating a condition of equilibrium for the robot 10.

It is evident that this result was obtained with extremely reduced sensors and therefore easy to manage. Another important advantage is represented by the constructive simplicity and therefore by the reduced costs and design simplicity of the foot 1 and consequently of the robot 10. The aforementioned advantages also result in a high ability of the foot 1 to imitate the compliance and adaptability of the human feet thus giving the robot 10 high moire capabilities.

The invention is susceptible of variants falling within the scope of the inventive concept defined by the claims. In this context, all the details can be replaced by equivalent elements and the materials, shapes and dimensions can be any.