STAIRWAY WITH INSTRUMENTED STEPS WITH LIFT ACTUATOR FOR ASSISTED ASCENT OR DESCENT

Description

Domaine technique

[0001] The present invention relates to the field of stair systems with steps for assisting individuals in moving.

[0002] The present invention mainly aims to improve instrumented and motorized stairs according to the state of the art, in particular in order to assist a user (with or without pathologies) to move from one floor to another, taking into account the characteristics of their gait as well as their balance. Technique antérieure

[0003] For assistance in moving from one floor to another, in addition to elevators, we know of escalators, also called rolling stairs or escalators.

[0004] An escalator is a transporter-elevator adapted for the transport of people, consisting of a staircase whose moving steps are mechanically driven while remaining permanently in a horizontal plane.

[0005] The advantages of an escalator over an elevator are, for a small number of floors, direct boarding without waiting, as well as a better flow of people in case of busy times.

[0006] Escalators are heavy and expensive installations, and are systematically installed in places where the difference in height is already significant.

[0007] Furthermore, they are not really suitable for people with reduced mobility.

[0008] Patents KR101023523B1 and KR100937044B1 disclose instrumented and motorized independent motorized step staircase systems whose purpose is to facilitate the ascent or descent of persons with reduced mobility (disabled persons, children, etc.). Each of the steps of the stairs described comprises a presence detector by weight measurement as well as an actuator for raising or lowering the step in question to the level of the adjacent step. The disclosed systems do not detect the characteristic of the user's gait, nor do they take into account the potential imbalance caused when raising the steps. In particular, the systems do not adapt to the speed of movement of the user (whether able-bodied or not). A system according to these patents is therefore intrinsically usable by an able-bodied person but does not adapt to their own characteristics.WO 2018 / 217843 A1 describes a mechanism for recycling energy from stairs, comprising a walking platform, movable between an upper position and a lower position, and an energy storage device coupled to the walking platform.

[0009] CN 105 565 113 A describes a flat-step staircase enabling people to ascend a staircase as if they were walking on flat ground.

[0010] US 2013 / 0168189 A1 describes a staircase comprising motorized steps between two fixed steps and in which each of the steps comprises a weight detector. The intermediate steps also comprise an actuator for raising or lowering the step in question to the level of the adjacent step.

[0011] There is a need to further improve stair-assisted systems, particularly so that they can best adapt to any user, whether able-bodied or not, especially if the user changes their gait during the journey.

[0012] The general aim of the invention is then to respond at least in part to this need. Exposé de l'invention

[0013] To do this, the invention firstly relates to a system for assisting with ascent or descent, comprising: a staircase comprising at least one instrumented moving step, equipped with at least one sensor for measuring the center of pressure of a user and at least one lifting actuator adapted to raise or lower the step according to a vertical degree of freedom; a calculation unit connected to the sensor for measuring the center of pressure and to the lifting actuator, the calculation unit being configured to calculate at least the position, the speed of movement and the acceleration of the user from the center of pressure measured by the sensor and, depending on the calculated values, control the lifting actuator.

[0014] By "center of pressure" is meant here and within the framework of the invention, the characteristic dynamic point of contact between the surface of a step of the staircase and a foot of the user.

[0015] The staircase may comprise a plurality of instrumented movable steps, adjacent to each other, the computing unit being configured to control each lifting actuator independently of the others.

[0016] Advantageously, the system further comprises at least two fixed steps, each equipped with at least one sensor for measuring the user's center of pressure, each of the two fixed steps respectively defining the upper and lower floors between which the staircase is arranged.

[0017] According to an advantageous embodiment, the center of pressure measuring sensor is a so-called 6-axis force sensor, suitable for force measurements on 6 axes (Fx, Fy, Fz, Mx, My, Mz). A 6-axis sensor allows the measurement of a complete force torsor, namely the three force components (Fx, Fy, Fz) and the three moment components (Mx, My, Mz) exerted by a user's foot on an instrumented step according to the invention.

[0018] According to an advantageous embodiment, the system further comprises at least one center of mass measurement sensor connected to the calculation unit, the latter being further configured to compare the measurement of the user's center of mass with that of the center of pressure, to deduce whether or not the user is unbalanced and, based on this comparison, to control the lifting actuator.

[0019] By "center of mass" is meant here and within the scope of the invention, the geometric point corresponding to the average value of the mass distribution of a user in space. Preferably, the center of mass measurement sensor is arranged near the staircase. For the measurement of the center of mass, it can be carried out in an alternative manner by embedding sensors on the user or equipment used by the latter.

[0020] According to this alternative, the center of mass measuring sensor is preferably one or more cameras or stereoscopic devices.

[0021] A first solution can thus consist of arranging specific markers on different parts of the user's body in order to define precise points of a "digital skeleton". From the position of these points which is extracted from the video streams of the stereoscopic cameras, it is possible to estimate the distribution of the masses of the user's limbs and therefore to estimate the Center of Mass.

[0022] A second solution consists of arranging inertial units on characteristic points of the user, coupled with a "digital skeleton". The element measured by these inertial units is the position of each limb by integrating the acceleration measurements twice.

[0023] According to another advantageous embodiment, the calculation unit integrates a learning algorithm adapted to acquire the characteristics of the gait of a given user from the measurements of the center of pressure sensor, and where appropriate from the center of mass measurement sensor, to recognize the latter and adapt the control of each lifting actuator according to the recognition carried out.

[0024] Thus, the invention essentially concerns a system comprising a staircase with instrumented step(s) for measuring the center of pressure and preferably the center of mass of a user, the information of which is centralized within a calculation unit, which, from the measurement signals, controls lifting actuators present on each step of the staircase on the basis of its on-board algorithm.

[0025] Taking into account the derivatives of the position of the center of pressure makes it possible to ensure the adaptation of the speed of elevation of the steps to adapt to the user, in particular if the latter modifies his gait during the movement.

[0026] The control of each actuator is carried out according to the position of the user in the staircase, his speed of movement deduced from the measured center of pressure and preferably the potential imbalance using the center of mass measurement.

[0027] The very precise control of the lifting actuators, controlled by knowledge of the centre of pressure and preferably the centre of mass, makes it possible either to help people with reduced mobility to take the stairs or to ensure a feeling of walking on a level floor for able-bodied people without imbalance.

[0028] With a system according to the invention, the height to which a user must raise his legs to move from a lower floor to an upper floor is greatly reduced, typically between 0 and 25 cm, while ensuring the walking speed, typically between 0 and 2 m / s along the horizontal, of the user.

[0029] The invention also relates to the use of the assistance system described above, to detect a user fall and in response to the detection, transmit an alert message to a remote server connected to the system.

[0030] To detect a fall, the calculation unit is advantageously adapted for analyzing the trajectories of the Center of Pressure and detecting a prolonged double press on two separate steps or on a single step, i.e. a press whose duration is greater than a predefined duration.

[0031] The invention also relates to the use of the assistance system described above, to detect a unipodal phase followed by a bipodal phase, corresponding to a potential fall of a user by stumbling and in response to the detection, to freeze the steps of the staircase or at least to reduce their lifting speed.

[0032] Other advantages and characteristics will become more apparent upon reading the detailed description, given for illustrative and non-limiting purposes, with reference to the following figures. Brève description des dessins

[0033] [ Fig 1 ] there figure 1 is a synoptic of an instrumented staircase system according to the invention. Fig 2 ] there figure 2 is a schematic view of an example of an instrumented staircase with a lifting actuator according to the invention. Fig 3 ] there figure 3 is a schematic perspective view of an exemplary embodiment of an instrumented step according to the invention integrating a 6-axis force sensor and an electric cylinder as a lifting actuator. Fig 4A ] there figure 4A is a schematic view illustrating a first step in the ascent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 4B ] there figure 4B is a schematic view illustrating the second step in the ascent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 4C ] there figure 4C is a schematic view illustrating the third step in the ascent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 4D ] there figure 4D is a schematic view illustrating the fourth step in the ascent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 5A ] there figure 5A is a schematic view illustrating a first step in the descent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 5B ] there figure 5B is a schematic view illustrating the second step in the descent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 5C ] there figure 5C is a schematic view illustrating the third step in the descent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 5D ] there figure 5D is a schematic view illustrating the fourth step in the descent of a user between two adjacent instrumented steps assisted by a system according to the invention. Fig 6 ] there figure 6 is a schematic view illustrating a first situation in which a user risks falling by stumbling following a collision with an obstacle, the system according to the invention being adapted to detect and respond to this first situation. Fig 7 ] there figure 7 is a schematic view illustrating a second situation in which a user risks falling by stumbling following a collision with an obstacle, the system according to the invention being adapted to detect and respond to this second situation. Description détaillée

[0034] Throughout the present application, the terms "low", "high", "below", "above", "lower" and "upper" are to be understood by reference to the arrangement of a staircase according to the invention between two floors.

[0035] It has been illustrated at the figure 1 , the synopsis of an assistance system 1 for ascent or descent according to the invention.

[0036] System 1 firstly comprises a staircase 10 with steps each moving between an extreme low position and an extreme high position. The movement of each step is ensured by a lifting actuator integrated into the step as detailed below.

[0037] The system also includes instrumentation 20 adapted to measure the position of the user's center of pressure and all its derivatives, on each step of the staircase and instrumentation 30 adapted to measure the user's center of mass (and all its derivatives).

[0038] A calculation unit 40 will adapt the control of each step lifting actuator according to the position of the user in the staircase, his speed of movement deduced from the measured center of pressure and the potential imbalance using the center of mass measurement.

[0039] The calculation unit 40 can further ensure, when a user is present in the staircase 10, that he has a good balance with respect to a data history and / or a pre-constituted database.

[0040] The algorithm embedded in the computing unit 40, preferably generated by learning, can thus verify that the center of pressure / center of mass relationship ensures the user's balance. In the event of an imbalance being observed, the system 1 can detect the user's fall.

[0041] An example of staircase 10 is shown schematically in figure 2 The staircase here consists of three instrumented steps M1, M2, M3 which are adjacent and are mounted mobile according to a course symbolized in dotted lines on the figure 2 , between an extreme low position and an extreme high position. To move each step M1 to M3, they incorporate a lifting actuator 11. Thus, a lifting actuator 11 has the function of raising a step M1 to M3 along the vertical along a stroke which allows it to position itself at the same level as an adjacent step.

[0042] Furthermore, each of the steps M1 to M3 is equipped with a 6-axis force sensor, referenced 20, making it possible to trace the position of a user's center of pressure on each step, as detailed below.

[0043] Typically, the tread of steps M1 to M3 is between 20 and 30cm.

[0044] The upstream steps Mi and downstream steps Ms of the staircase 10 which respectively define the lower floor and the upper floor are fixed but also each instrumented by means of a 6-axis force sensor. These two steps Mi, Ms have the function of measuring the user's gait, in order to predict his movement either when ascending or descending in the staircase 10. In other words, when a user approaches, upstream or downstream of the staircase 10, the measurement sensors 20, 30 record the characteristics of the center of pressure and mass, for example the positions, speeds, history, accelerations in space, in order to initiate the controlled movement of the steps M1 to M3.

[0045] An example of an instrumented and motorized M1 step in accordance with the invention is illustrated in figure 3 .

[0046] The lifting actuator is here an electric cylinder 11 arranged with its support 12 between a base 13 and an interface plate 14. The cylinder 11 and its support 12 are fixed to the base 13 and the rod of the cylinder 11 is fixed to the connecting plate 14 which ensures the vertical movement of the step.

[0047] The 6-axis force sensor 20 is arranged between a user interface plate 15 and the connecting plate 14.

[0048] For example, an electric cylinder 11 can have a maximum vertical displacement speed of 1m / s for a load of 100kg.

[0049] As symbolized on this figure 3 , the sensor 20 makes it possible to measure the forces along the X, Y, Z axes and the moments around each of these axes. The deformations considered along each of these axes are also symbolized respectively lx, ly, lz.

[0050] We now detail the determination of the center of pressure on a step by a 6-axis force sensor 20.

[0051] A step M1 to M3 is considered rigid, that is to say that it undergoes negligible deformation under stress, i.e. lz constant.

[0052] The user's force on the interface plate 15 is a pure resultant, i.e. no moment at the center of pressure. Subsequently, we note accordingly Lext=Mext=Next=0. The sum of the torsors on a given step M1, M2 or M3 can be written, according to the fundamental principle of dynamics applied to a step: in which: ( marche / 0) G marche : Dynamic torsor of the gait relative to the fixed reference 0 at point Gmarche, { ( Poids / marche } G marche : Static torque of the weight on the step at point Gmarche, { ( Ext / marche } M: Static torsor of the user's efforts on the step at point M, { ( capteur / marche } P : Static torque of the sensor forces on the step at point P.

[0053] We reduce all the equations to a single point P, the location of the measurement by the 6-axis force sensor 20.

[0054] With PM = lx x + ly y +lz z, the center of pressure is obtained by the parameters lx and ly, the parameter lz being considered by design as constant and known, as mentioned above (hypothesis of a rigid gait).

[0055] The different torsors are written T Poids / marche G marche = 0 0 − m marche ∗ g 0 0 0 G marche = 0 0 − m marche ∗ g 0 0 0 P with m step the mass of the step and the points Gstep and P aligned along the vertical axis y. T Ext / marche G marche = F x L ext F y N ext F z M ext M = F x L ext + L y ∗ F z − l z ∗ F y F y M ext + l z ∗ F x − l x ∗ F z F z N ext + l x ∗ F y − l y ∗ F x P T capteur / marche P = F xcap L cap F ycap N cap F zcap M cap P D marche / 0 P = 0 0 m marche ∗ y marche . . 0 0 0 P or the translation of the step along the vertical axis y.

[0056] We thus obtain the following equations: 0 = F x + F xcap 1 m marche ∗ y marche . . = − m marche ∗ g + F y + F ycap 2 0 = F z + F zcap 3 0 = L ext + l y ∗ F z + l z ∗ F y + L cap 4 0 = M ext + l z ∗ F x − l x ∗ F z + M cap 5 0 = N ext + l x ∗ F y − l y ∗ F x + N cap 6

[0057] From equations (1), (2) and (3), we can obtain the user's forces Fx, Fy and Fz, on a step, knowing that the other values ​​are known (m step, gravity g, acceleration along the y axis) or measurable. In particular, the value of the acceleration of the step corresponds to the acceleration applied by the electric cylinder 11, a known value because it is imposed when controlling the actuator.

[0058] The system of equations (4), (5) and (6) allows to determine the values ​​lx and ly since lz is considered constant and the moments created by the user are considered negligible (Lext, Mext and Next equal to 0).

[0059] In the end, we therefore have a number of three equations for two unknowns, the last equation allows us to verify that the value of lz is indeed the selected constant.

[0060] The acquisition module of the calculation unit 40 records the history of this measurement of lx and ly.

[0061] The calculation unit 40 can thus record the distance traveled, by integrating the movement signal, determine the movement speed (1st derivative), determine the movement acceleration (2nd derivative).

[0062] Near the staircase, a camera or stereoscopic device is arranged and can thus estimate the position of the user's center of mass.

[0063] THE figures 4A à 4D illustrate the operation of a system 1 according to the invention in the case of a user climbing stairs 10.

[0064] The user's presence is initially detected on a lower step M1 ( figure 4A ).

[0065] When the user places his foot on this step M1 and begins to climb, the actuator 11 raises this step M1 and the actuator 11 of the adjacent upper step M2 lowers it to the same level ( figures 4B, 4C ).

[0066] Once the user has transferred his center of pressure to step M2, the operation is repeated with the following steps M2, M3 until reaching the upper floor Ms ( figure 4D ). The unsolicited M1 step is returned to its initial position.

[0067] THE figures 5A à 5D illustrate the operation of a system 1 according to the invention in the case of a user descending a staircase 10.

[0068] The user's presence is initially detected on an upper step M3 ( figure 5A ).

[0069] When the user places his foot on this step M3 and begins to descend, the actuator 11 lowers this step M3 and the actuator 11 of the adjacent lower step M2 raises it to the same level ( figures 5B, 5C ).

[0070] Once the user has transferred his center of pressure to step M2, the operation is repeated with the following steps M2, M1 until reaching the lower floor Mi ( figure 4D ). The unused M3 step has returned to its lowest position.

[0071] With the system according to the invention, it is possible to detect potential fall situations of a user due to stumbling and to respond actively to them.

[0072] This detection can be done from the recognition of two strategies for regaining balance, which is characterized by protective steps of the user.

[0073] Thus, during a stumble, which is a situation where there is contact between one of the user's feet in flight and an obstacle, the user can adopt a first strategy called "elevation". In this situation, the foot, having come into contact with the obstacle, will perform a flight phase, in order to bypass the obstacle. Following this strategy, the user returns to a bipodal support phase on the same step.

[0074] The second strategy is called "low". When the take-off foot collides with the obstacle, the user brings their take-off foot back to the ground, in order to return to a bipodal support phase.

[0075] With the system according to the invention and from the measurement of the center of pressure, it is possible to distinguish the phases of unipodal support (on one foot) and bipodal support (on both feet). This is achieved by locating the center of pressure relative to the user's sagittal plane, and measuring the speed of movement of the center of pressure.

[0076] When detecting a unipodal then bipodal support phase on the same step, it is possible to detect the low strategy of protective step and therefore potential imbalance. This situation is shown in figure 6 .

[0077] When detecting a unipodal then bipodal phase on two successive steps, it is possible to detect the elevation strategy. This situation is shown in figure 7 .

[0078] Following one or other of the detections, the system can freeze the mechanism, i.e. not generate any lifting of the stair steps, so as not to disturb the user or to significantly reduce, for example by a factor of 10, the speed of movement of the stair steps.

[0079] The invention is not limited to the examples which have just been described; in particular, it is possible to combine characteristics of the examples illustrated within non-illustrated variants.

[0080] Other variations and improvements may be envisaged without departing from the scope of the invention.

[0081] For example, if in the illustrated example, the staircase 10 comprises three instrumented and motorized steps by means of a lifting actuator, any number of steps can be envisaged from a single instrumented and motorized step.

Claims

1. System (1) for assisted ascent or descent, comprising: a staircase (10) comprising at least one instrumented mobile step (M1, M2, M3), provided with at least one sensor (20) for measuring the centre of pressure of a user and at least one lifting actuator (11) capable of raising or lowering the step according to a vertical degree of freedom; a calculation unit (40) connected to the sensor for measuring the centre of pressure and the lifting actuator, the calculation unit being configured to calculate at least the position, the speed of movement and the acceleration of the user on the basis of the centre of pressure measured by the sensor and, as a function of the calculated values, control the lifting actuator.

2. Assistance system (1) according to Claim 1, wherein the staircase comprises a plurality of instrumented mobile steps adjacent to each other, the calculation unit being configured to control each lifting actuator independently of the others.

3. Assistance system (1) according to Claim 1 or 2, further comprising at least two fixed steps each instrumented with at least one sensor for measuring the centre of pressure of the user, each of the two fixed steps respectively defining the upper and lower storeys between which the staircase is arranged.

4. Assistance system (1) according to one of the preceding claims, wherein the sensor for measuring the centre of pressure is a so-called six-axis force sensor, capable of measuring forces on six axes (Fx, Fy, Fz, Mx, My, Mz).

5. Assistance system (1) according to one of the preceding claims, further comprising at least one sensor (30) for measuring the centre of mass connected to the calculation unit, said unit further being configured to compare the measurement of the centre of mass of the user to the measurement of the centre of pressure, deduce therefrom whether the user is imbalanced and, as a function of this comparison, control the lifting actuator.

6. Assistance system (1) according to Claim 5, wherein the sensor for measuring the centre of mass is arranged near the staircase.

7. Assistance system (1) according to Claim 6, wherein the sensor for measuring the centre of mass is a camera or a stereoscopic device.

8. Assistance system (1) according to one of the preceding claims, wherein the calculation unit incorporates a learning algorithm capable of acquiring the characteristics of a given user's gait from the measurements of the centre of pressure sensor, and if applicable of the sensor for measuring the centre of mass, recognizing the user and adjusting the control of each lifting actuator as a function of the recognition made.

9. Use of the assistance system according to one of the preceding claims to detect a fall of the user and in response to this detection, send an alert to a remote server connected to the system.

10. Use of the assistance system according to one of Claims 1 to 8 to detect a unipedal phase followed by a bipedal phase, corresponding to a potential fall of a user by tripping and, in response to the detection, immobilize the steps of the staircase or at the very least reduce their lifting speed.