EXOSKELETON, METHOD OF PROVIDING COUNTERACTING TRANSLATIONAL LINEAR FORCES BY EXOSKELETON KINEMATICS, AND USE OF AN EXOSKELETON

Abstract

 The invention relates to an exoskeleton configured for physical training of lower limbs of a user, exhibiting an upper part supported by the user's upper body (torso) and connected thereto via first coupling means, lower parts connected to the upper part and extending along the legs of the user, and an actuation system, wherein the lower parts each consist of at least one linear rail unit with a rotatably mounted pedal and a bottom plate, wherein the rail translationally guides the pedal and bottom plate, the pedal being connected to a foot of the user via second coupling means and configured to be translationally movable between a retracted position and an extended position by a force exerted by the user, and the bottom plate being configured to be translationally movable between the retracted position and an extended position by forces exerted by the actuation system, wherein the bottom plate is configured for translationally counteracting, via the forces exerted by the actuation system, the translational pressing force exerted by the lower limbs of the user, wherein the actuation system exerts a constant force and an inertial force.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates to the field of exoskeletons, in particular for physical training of lower limbs of a user, especially in the field of space programs.

BACKGROUND OF THE INVENTION

[0002] Exoskeletons are mostly used for medical purposes such as rehabilitation programs for patients with damage in the nervous system or in the lower limbs.

[0003] Different types of training devices are known to allow astronauts the training of their lower limbs in space.

GOAL OF THE INVENTION

[0004] It is the goal of this invention to provide an improved exoskeleton for physical training of lower limbs of a user, that can simulate behavior of gravitational and inertial forces and offers an increased flexibility. It is further a goal of the invention to provide a method of counteracting translational linear forces exerted by a user and to provide a use of an exoskeleton.

BRIEF DESCRIPTION OF THE INVENTION

[0005] According to the invention, the problem is solved with the exoskeleton according to claim 1. Advantageous embodiments of the exoskeleton result from sub claims 2 - 8. The second task is solved with the method according to claim 9. Advantageous embodiments of the method result from sub claims 10 and 11. The third problem is solved with the use according to claim 12.

[0006] The provided exoskeleton is configured for physical training of lower limbs of a user. The exoskeleton exhibits an upper part supported by the user's upper body (torso) and is connected thereto via first coupling means. The exoskeleton further exhibits lower parts and an actuation system, wherein the lower parts are connected to the upper part and extend along the legs of the user. The lower parts each consist of at least one linear rail unit with a rotatably mounted pedal and a bottom plate. The rail translationally guides the pedal and bottom plate. The pedal and bottom plate are preferably connected to the rail in such a manner, that they cannot surpass one another and are always in contact to the rail. The pedal is connected to a foot of the user via second coupling means and configured to be translationally movable between a retracted position and an extended position by a force exerted by the user. If the user moves his foot along the rail, the pedal connected to the foot via the second coupling means moves with it. The bottom plate is also configured to be translationally movable between the retracted position and an extended position. It is connected to the actuation system that exerts a force on it in opposite direction to the user. It is possible to use a plurality of parallel rails in one lower part, wherein the pedal is placed in a first rail and the bottom plate is placed in a separate rail. However, it must be ensured that the bottom plate cannot surpass the pedal, so the bottom plate is always below the pedal. This way, the bottom plate translationally counteracts the translational pressing force exerted by the lower limbs of the user. The actuation system is configured such that it exerts a constant force to simulate potential energy of the user and an inertial force to simulate kinetic energy of the user. This allows for accurate simulation of gravitational forces. If the user were to practice a jumping motion, he would have to press against the constant force exerted by the actuation system that is pressing from below against the pedal via the bottom plate. If the force exerted by the user is big enough, he accelerates the pedal and the bottom plate until the user reaches his extended position. The bottom plate keeps moving if the speed is high enough due to the inertial forces until all kinetic energy is converted to potential energy and stored via an energy storing mechanism such as a battery or a spring in the actuation system, and the bottom plate reaches its climax. After the bottom plate reached its climax, the potential energy is converted at least partly back to kinetic energy, wherein now the bottom plate is accelerated upwards towards the user to accurately simulate a landing on the ground. When the bottom plate hits the pedal from underneath, the user feels the constant force plus the inertial force.

[0007] It has been proven to be advantageous, if the constant force is exerted via at least one spring with a constant force mechanism connected thereto and if the inertial force is exerted via at least one flywheel, preferably two counter-rotating flywheels, wherein the flywheel or the flywheels exhibit a plurality of masses, that move radially outwards or inwards synchronously, thus changing the moment of inertia of the flywheel. The placement of the masses is preferably chosen in such a manner that the inertial force created by the rotation of the flywheel cooperates with the constant force that is exerted by the constant force mechanism. In other words, to simulate the user's kinetic energy E_kin,user = ½ m_user * v²_user with the flywheels, the radius on which the masses spin has to be chosen such that E_rot = ½ J * ω² is equal to it, wherein the moment of inertia J is J = m_flywheel * r², with r being the distance from the centre of each mass of the flywheel to the centre of the flywheel and m_flywheel being the sum of all masses of the flywheels. The masses can for example be mounted on lead screws, that can be driven by a central bevel gear, such that they move outwards or inwards, when the bevel gear is driven. The preferred counter-rotation of two flywheels allows the wheels to stay in place, when they are spun, since the reaction torque of both wheels cancel out. The constant force mechanism can be realized by basic spring-to-spring balancing or spring-to-mass counterweighting system mechanisms, as can be found e.g. in "Energy-free Systems; Theory, conception and design of statistically balanced spring mechanisms" by Herder from 2001. Using a mass or a plurality of springs allows for a creation of a precise force, that is exerted by the spring and independent of the extension of this spring. For example, the springs can be connected via a pulley block with steel cables to a lever, that is in turn connected via steel cables to the bottom plate. The user exerts a constant force F = m*g onto the bottom plate, which is held up via the spring. Depending on the placement of the spring and the lever arm, assuming they are placed length a apart, with the spring constant k, wherein the spring is attached to the lever at pivot point r, and the lever has a length of L, the two forces are held in equilibrium if m*g*L = r*k*a.

[0008] It has been proven to be beneficial if the constant force is exerted via at least one motor driven with constant torque, and/or wherein the inertial force is exerted via at least one motor. This can be especially useful, when the exoskeleton is used in an environment, where the power consumption and generation of heat is not critical. This can reduce the cost of the exoskeleton. The motor can for example be a permanent magnet synchronous machine, which in general has an excellent torque to weight ratio, driven for example via Direct Torque Control to apply a constant torque to the legs of the user.

[0009] According to a preferred embodiment, the moment of inertia of the flywheel and the constant force are adjustable via at least one motor, especially during operation of the exoskeleton, wherein a/the motor adjusts the inertial forces via driving at least one bevel gear and at least one differential, wherein the motor is decoupled from a spinning motion of the flywheel via the at least one differential such that a rotation of the motor moves the masses of the at least one flywheel radially outwards or inwards, independent of the spinning motion of the flywheel and/or wherein a/the motor with a gear drives a lead screw in the constant force mechanism to adjust the constant force exerted by the actuation system. It is especially preferred, that the motor/motors can adjust the moment of inertia of the flywheels and the constant force of the constant force mechanism during operation of the exoskeleton. With the exemplary relation m*g*L = r*k*a for the constant force mechanism, the constant force of the constant force mechanism can be tuned by the motor with gear driving the lead screw to for example drive a pulley and adjust the space a between the attachment point of the spring and the lever, until the constant force that is exerted corresponds to the weight force exerted by the user on earth or the environment that is to be simulated respectively. This way, a user can increase the simulated gravitational force to train for different circumstances or simply increase the intensity of his training, especially while the user is already wearing the exoskeleton, just by varying one parameter. This increases the flexibility of the exoskeleton as a training tool, and allows for a simulation of different gravitational forces, regardless of the G-forces the user is otherwise exposed to in his surroundings. This semi-passive system, wherein motors are only used to change the behaviour of the otherwise mechanic system, is especially useful in space applications, because of the little to energy demand which also reduces the amount of heat that is created because of the losses of the motor.

[0010] It has been proven to be advantageous, if the at least one spring with the constant force mechanism connected thereto is placed in the upper part of the exoskeleton and the flywheels are placed preferably in the lower part of the exoskeleton. This allows for an especially small form factor and reduces the weight of the exoskeleton. Alternatively, the flywheels could be stored in the upper part of the exoskeleton.

[0011] According to a preferred embodiment, the bottom plate of both lower parts can be interlocked such that they are translationally movable as one. This allows the user to execute a wide range of exercises, such as one leg hopping or squat jumps.

[0012] In any of the exoskeletons disclosed herein, the upper part supported by the user's upper body and a lower part connected thereto are connected to each other in an articulated manner on both sides of the user at the height of his/her centre of mass, especially by means of rotary joints which preferably can be locked in rotary position and/or wherein the first and second coupling means are arranged in such a manner that the load applied to/by/via the user's feet at the second coupling means is concentric to the first coupling means, especially irrespective of relative translational position, especially with a resulting force vector pointing to the second coupling means. By placing the rotary joints on both sides of the user at the height of his/her centre of mass, a particularly natural feeling is created. Furthermore, the locking of the rotary joints can enhance the user's perception of stability, especially during training.

[0013] According to a preferred embodiment of the invention, the exoskeleton exhibits at least one sensor from the following group: at least one sensor being arranged in or coupled to at least one linear rail unit and providing for position and/or velocity data; at least one force sensor being arranged in or coupled to the bottom plate; at least one rotary position sensor being arranged in or coupled to the rotary joint connecting the lower part and the upper part. Generating data can be beneficial when trying to evaluate the performance of the user and helps tracking the amount of repetitions and sets a user has performed.

[0014] According to another embodiment of the invention, a method of providing counteracting translational linear forces by exoskeleton kinematics for physical training of lower limbs of a user is provided, wherein the exoskeleton exhibits an upper part with first coupling means and the exoskeleton exhibits lower parts, each consisting of at least one linear rail unit with a pedal with second coupling means and a bottom plate, the rail unit extending along the user's legs and being configured to translationally guide the pedal and the bottom plate between a retracted position and extended positions, wherein an adjustable counteracting force is exerted in translational direction on the bottom plate by an actuation system of the exoskeleton when the user is exerting a translational pressing force with his lower limbs between first coupling means and second coupling means, wherein the counteracting force consists of a constant force and an inertial force. The combination of a constant force and inertial force allows the exoskeleton to accurately model the behaviour of a ground for the user via the bottom plate and therefore, model the mechanical potential energy and the kinetic energy of the user. The bottom plate and pedal can be separable such that a user can for example experience a jump wherein the force that is exerted via the bottom plate onto the user also depends on the speed at which the bottom plate is moving in relation to the user.

[0015] In a further advantageous embodiment of the method, the constant force is generated by means of dampable and/or adjustable spring elements with a constant force mechanism of the actuation system, wherein a force control is provided in a linearly displaced section exclusively in translational direction along the linear rail units, and/or wherein the inertial force is generated by means of at least one flywheel, preferably two counter-rotating flywheels, of the actuation system, wherein the flywheel or the flywheels exhibit a plurality of masses, that move radially outwards or inwards synchronously, thus changing the moment of inertia of the flywheel. The masses can for example be placed on lead screws and can be connected in the centre by a central bevel gear, such that an actuation of the bevel gear turns all screws simultaneously and the masses move either radially inwards or outwards depending of the direction in which the central bevel gear is actuated. This increases the flexibility of the exoskeleton. The use of spring elements with a constant force mechanism also allows to reduce the size and weight of the exoskeleton compared to using a motor for the constant force mechanism. The same is true for the inertial force mechanism, wherein the inertial force could also be modelled with a motor. The use of two counter-rotating flywheels enhances the stability of the exoskeleton since the reaction torque of both flywheels cancel out.

[0016] According to a preferred embodiment, the exoskeleton provides for force regulation of the translatory force via the actuation system in such a manner, that the amount of constant and inertial force can be provided independently of the path and/or position of translatory motion and independently of the knee angle of the user's legs, especially such that the user can experience different gravity constants in relation to the exoskeleton. This enables the training and preparation for the behaviour on different planets independent of the surrounding of the user. The user only experiences the force applied to him via the bottom plate, which is pressing upwards underneath his foot, allowing the exoskeleton to be used inside a space shuttle, as well as on earth.

[0017] According to another embodiment of the invention, a use of an exoskeleton for providing translational and/or rotational kinematics for exercising lower limbs of a user is provided by translational donning and doffing of the exoskeleton pedals along linear rail units, wherein a counteracting force is exerted by the exoskeleton on a bottom plate pushing against the pedals along the linear rail units, wherein the exoskeleton's translational and/or rotational kinematics preferably are used for controlling squat jump sequences, especially in absence of gravity. The translational and/or rotational kinematics are created by the actuation system that exerts a constant as well as an inertial force on the bottom plate, which results in a particularly natural perception of a ground. With the lower part being rotatably connected via the joints at the height of the user's centre of gravity, the user is enabled to execute a wide range of exercises, such as lunges, one leg hopping, squats, and squat jumps.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further advantages, special features and expedient further embodiments of the invention can be seen from the sub claims and the following illustration of preferred embodiments based on the figures.

[0019] From the illustrations shows

Fig. 1a

a front view of a user wearing an exoskeleton;

Fig. 1b

a side view of a user wearing an exoskeleton;

Fig. 2

a close-up view of a foot and second coupling means;

Fig. 3a

a foot mounted to a pedal;

Fig. 3b

an elevated pedal in relation to a bottom plate;

Fig. 3c

a foot leaning forward;

Fig. 3d

a foot leaning backward;

Fig. 4a

a slightly turned front view of an alternative exoskeleton;

Fig. 4b

a slightly turned side view of an alternative exoskeleton;

Fig. 4c

an alternative exoskeleton where guard plates have been removed;

Fig. 5a

a semi front view of an exoskeleton with telescopic rails;

Fig. 5b

a semi back view of an exoskeleton with telescopic rails;

Fig. 5c

an exoskeleton with telescopic rails where a backpack is transparent;

Fig. 6a

a perspective view of a constant force mechanism and springs;

Fig. 6b

a front view of a constant force mechanism and springs;

Fig. 7

a mechanically equivalent schematic for explanation;

Fig. 8

a front view of a constant force mechanism in a second state;

Fig. 9

a close-up view of two counter-rotating flywheels;

Fig. 10a

flywheels with a first moment of inertia;

Fig. 10b

flywheels with a second moment of inertia;

Fig. 10c

a counter-rotation mechanism for flywheels;

Fig. 11

a squat jump sequence;

Fig. 12

a lunge sequence;

Fig. 13

a user jumping on one leg.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Fig. 1a shows a front-view of a user (3) wearing a first exoskeleton (1). The exoskeleton (1) is configured for physical training of lower limbs (2) of a user (3) and exhibits an upper part (4) which is supported by the user's (3) upper body (5) and is connected thereto via first coupling means (6). The first coupling means (6) are formed by a torso harness. The exoskeleton (1) further exhibits two lower parts (7) and an actuation system (14) that is located inside the upper part (4) and/or the lower parts (7) and therefore not explicitly shown. The lower parts (7) are connected to the upper part (4) at his centre of gravity, which can be assumed to be approximately at the height of his belly button. The lower parts (7) and the upper part (4) are connected on both sides of the user (3) via rotary joints (15) which preferably can be locked in a rotary position by the user (3). The lower parts (7) extend along the legs (8) of the user (3), wherein each lower part (7) consists of at least one linear rail unit (9), a pedal (10), and a bottom plate (11). The exoskeleton of Fig. 1a and 1b shows a plurality of linear rail units (9) that are nested inside each other, allowing a telescopic motion. The pedals (10) are for example guided in translational direction via a glider or cogs on a rail (16) inside the rail units (9). In the exoskeleton shown in Fig. 1a and 1b, the bottom plate (11) forms part of the most inner linear rail unit (9) of the telescopically interlocked linear rail units (9). Therefore, both the pedals (10) and the bottom plates (11) are translationally guided and it is assured, that the bottom plate (11) can never surpass the pedal (10), as will be also evident from Fig. 2. The exertion of a force by the user (3) moves the pedal (10) up and down along the rails.

[0021] Fig. 2 shows a close-up view of a leg (8) of the user (3) and the lower end of a lower part (7). An inner rail (16), acting as a flight guide rail (16), when the user (3) is for example executing a jumping motion, is shown inside the lowest of the linear rail units (9). This ensures that the pedal (10) and the bottom plate (11) are always aligned and cannot surpass each other. The two orthogonal lines (18, 19) indicate the direction (19) of the translatory motion and axis of rotation (18) of the pedal (10). The pedal (10) is connected to the foot (12) of the user (3) via second coupling means (13), formed by lugs. In addition, the pedal (10) comprises a heel retainer (17) to prevent any accidental slipping out of the second coupling means (13).

[0022] Fig. 3a shows a leg (8) of a user (3) in an extended position. The foot (12) is connected to the pedal (10) and the bottom plate (11) is pressing upwards against the pedal (10) to create a feeling that the user (3) is standing on the ground. In Fig. 3b the user (3) has jumped and is in relation to the bottom plate (11) mid-air. The glider (20) that is connected to the pedal (10) and guided inside the flight guide rail (16) has moved up in relation to the bottom plate (11). Fig. 3c and 3d demonstrate how the pedal (10) is rotatably mounted. The user (3) can chose to stand on his heels or toes, allowing him to execute a wide variety of exercises, not only for training the legs (8) but for most parts of the lower limbs (2).

[0023] Fig. 4a shows a semi front view of a user (3) wearing a second embodiment of an exoskeleton (1) configured for physical training of lower limbs (2) of the user (3). The exoskeleton (1) also exhibits an upper part (4) connected to the torso (5) of the user (3) via first coupling means (6), that are not shown here for clarity reasons. They can be formed analogously to the torso harness in the first embodiment of the exoskeleton (1) in Fig. 1a. The exoskeleton (1) further exhibits two lower parts (7) connected to the upper part (4) on both sides of the user (3) at the height of the user's (3) centre of gravity and extending along his legs (8). The lower parts (7) consist of linear rail units (9), pedals (10), and bottom plates (11). In this configuration of an exoskeleton (1), the bottom plate (11) is part of a glider (20) that is translationally movable along the linear rail units (9) and exhibits its own flight guide rail (16) to which the pedal (10) is rotatably mounted. The glider (20) moves along the outer linear rail units (9), wherein the movement of the glider (20) can be dampable. The exoskeleton exhibits a mounting frame (21) at the upper part (4), so it can be statically fixed inside a training facility. Fig. 4b shows a side view of the exoskeleton (1) with the guard plates (22). Fig. 4c shows the same side view, wherein the guard plates (22) have been removed to show an actuation system (14). In all embodiments of the exoskeleton (1) the actuation system (14) is configured to exert a constant force and an inertial force on the bottom plate (11) translationally along the linear rail units (9) against the user. The resulting force vector points from the bottom plate (11) towards the rotary joints (15). The placement of the rotary joints (15) at the height of a user's (3) centre of gravity/centre of mass creates a particularly natural feeling for the user. The actuation system (14) consists of spring elements (23) with a constant force mechanism (24) to create the constant force, and flywheels (25) which are mounted in the upper end of the lower parts (7) in this configuration. The spring elements (23) and the constant force mechanism (24) exert a constant force on the bottom plate, such that independent of the position of the bottom plate (11) in the linear rail units (9) the magnitude and direction of the constant force stays the same. When the bottom plate (11) is moved by a force exerted by the user (3), the flywheels (25) are spun, simulating inertial forces for the user (3).

[0024] Fig. 5a shows a user (3) wearing an exoskeleton (1) with an upper part (4) and lower parts (7) connected thereto on both sides of the user (3). The exoskeleton (1) exhibits linear rail units (9) that are nested inside each other to allow telescopic movement of the linear rail units (9). The exoskeleton (1) shows an actuation system (14) that is entirely included in the upper part (4). The actuation system (14) consists of spring elements (23) connected to a constant force mechanism (24), and flywheels (25). The flywheels (25) could of course also be placed at the upper end of the lower parts (7), as shown in Fig. 4.

[0025] Fig. 6a shows a perspective view of a constant force mechanism (24). The mechanism is further explained with reference to Fig. 6b and Fig. 7, wherein the reference numbers show the relations between the schematic. Spring elements (23) at the top apply a restoring force proportional to their extension via a pulley block (26). The spring elements (23) apply their restoring force on the rail (28) at pivot points (33) of levers (36), wherein the rail (28) is connected via a steel cable (35) rolling over a pulley (34) to a bottom plate (11), to which a user (3) exerts his weight force F = mg via a pedal (10), wherein m is the user's (3) mass and g is the gravity constant. The weight force and spring force in Fig. 7 are in equilibrium for m*g*L = a*k*r, wherein L is the length (37) of the lever (36), a is the distance (31) between the anchor (27) of the lever (36) and the attachment point (30) of the spring (23), k is the spring constant, and r is the distance (32) at which the spring (23) is connected to the lever (36). This way, independent of the position of the rail (28), the force exerted by the spring (23) is always constant. To change the constant force, the distance (31) a, and/or the distance (32) r have to be changed. In Fig. 6b, the fixing point (27) of the levers (36) can be moved up or down via a motor and a bevel gear, thus changing distance (31) a and the preloading of the spring elements (23). This way, the constant force can be increased or decreased to adjust to different masses of users (3). A maximum displacement of the constant force mechanism (24) can be seen in Fig. 8.

[0026] Fig. 9 shows two flywheels (25), which are connected via a steel cable (35) that is guided over pulleys that are located between the two flywheels (25) to a bottom plate (11). The flywheels (25) are connected to the pulleys, such that when the steel cable (35) is moved, the flywheels (25) rotate in opposite direction. The flywheels exhibit three masses (37) that are each mounted on a lead screw (38), wherein the lead screws (38) are connected in the centre of the flywheels via a bevel gear (39). The flywheel's moment of inertia can be adjusted by driving the bevel gear (39), thus spinning the lead screws (38) and moving the masses (37) radially outwards or inwards. The moment of inertia of each flywheel (25) is calculated via J = mr². The bevel gear (39) can be driven manually or via a motor. The motor shaft (40) is for example connected to one or more differentials located between the flywheels (25), wherein the differential or the differentials are connected to the bevel gears (39). The decoupling of the motor shaft (40) from the flywheels (25) via the differential or via the differentials allows the motor to be static, when the wheels are spinning.

[0027] Fig. 10a shows a configuration of the flywheels (25), wherein the flywheels (25) exhibit the minimal moment of inertia, because the masses (37) of the flywheels (25) are located as close to the centre as possible. Fig. 10b shows flywheels (25) that have the maximal moment of inertia. Here, the circularly arranged pulleys (41), to which the steel cable (35) is connected, can be seen. Fig. 10c shows the pulley configuration (41) that causes the counter-rotation of the two flywheels (25). A differential (42) located at the centre between the two flywheels (25) is also depicted. The motor shaft (40) can be decoupled from the flywheels (39) via this differential (42).

[0028] Fig. 11 shows a user (3) wearing an exoskeleton (1) and executing a squat jump sequence. In a first position, the user (3) goes into a squat position, wherein the telescopic linear rail units (9) of the exoskeleton (1) are retracted. The user (3) then presses downwards into an extended position, where his legs (8) are completely straight. If the user (3) pushed strong enough, the inertial force exerted by the actuation system (14) of the exoskeleton (1) will make the bottom plate (11) keep moving and separate from the pedal (10), as if the user (3) was jumping on the ground. Because of the constant force vector pointing towards the user's (3) centre of gravity, the bottom plate (11) is accelerated towards the user (3). When the pedal (10) is brought into contact with the accelerated bottom plate (11), the user (3) experiences the constant force, simulating his gravitational force, and the inertial force from his movement, thus creating a natural sensation of ground for the user (3).

[0029] Fig. 12a and Fig. 12b show a user (3) wearing an exoskeleton (1) with telescopic linear rail units (9), executing a lunge. Therefore, the linear rail units (9) are aimed in different directions, which is possible because of the rotary joints (15). One leg (8) of the user (3) is in a retracted position, while the other leg (8) is extended.

[0030] Fig. 13 shows a user (3) wearing an exoskeleton (1) with telescopic linear rail units (9), hopping on one leg (8). The user's (3) right leg (8) is in a retracted position, while the user (3) pushed with his left leg (8) downwards, such that the bottom plate (11) is separated from the pedal (10), thus creating the sensation, that the user (3) is mid-air. The pedal (10) with second coupling means (13) connected to the foot (12) of the user (3) guides the user's (3) foot (12) back onto the bottom plate (11), therefore increasing the safety, while exercising complex movements, e.g. one leg hopping, and the like.

Claims

1. Exoskeleton configured for physical training of lower limbs of a user, exhibiting an upper part supported by the user's upper body (torso) and connected thereto via first coupling means, lower parts connected to the upper part and extending along the legs of the user, and an actuation system, wherein the lower parts each consist of at least one linear rail unit with a rotatably mounted pedal and a bottom plate, wherein the rail translationally guides the pedal and bottom plate, the pedal being connected to a foot of the user via second coupling means and configured to be translationally movable between a retracted position and an extended position by a force exerted by the user, and the bottom plate being configured to be translationally movable between the retracted position and an extended position by forces exerted by the actuation system, wherein the bottom plate is configured for translationally counteracting, via the forces exerted by the actuation system, the translational pressing force exerted by the lower limbs of the user, wherein the actuation system exerts a constant force and an inertial force.

2. Exoskeleton according to claim 1, wherein the constant force is exerted via at least one spring with a constant force mechanism connected thereto and the inertial force is exerted via at least one flywheel, preferably two counter-rotating flywheels, wherein the flywheel or flywheels exhibit a plurality of masses that can move radially outwards or inwards, preferably synchronously so that all masses show the same distance to the centre of the at least one flywheel, thus changing the moment of inertia of the at least one flywheel.

3. Exoskeleton according to claim 1, wherein the constant force is exerted via at least one motor driven with constant torque, and/or wherein the inertial force is exerted via at least one motor.

4. Exoskeleton according to claim 2, wherein the moment of inertia of the flywheel and the constant force are adjustable via at least one motor, especially during operation of the exoskeleton, wherein a/the motor adjusts the inertial forces via driving at least one bevel gear and at least one differential, wherein the motor is decoupled from a spinning motion of the flywheel via the at least one differential such that a rotation of the motor moves the masses of the at least one flywheel radially outwards or inwards, independent of the spinning motion of the flywheel and/or wherein a/the motor with a gear drives a lead screw in the constant force mechanism to adjust the constant force exerted by the actuation system.

5. Exoskeleton according to one of claims 2 or 4, wherein the at least one spring with the constant force mechanism connected thereto is placed in the upper part of the exoskeleton and the flywheels are placed preferably in the lower part of the exoskeleton.

6. Exoskeleton according to one of the preceding claims, wherein the bottom plate of both lower parts can be interlocked such that they are translationally movable as one.

7. Exoskeleton according to any of the preceding claims, wherein the upper part supported by the user's upper body and a lower part connected thereto are connected to each other in an articulated manner on both sides of the user at the height of his/her centre of mass, especially by means of rotary joints which preferably can be locked in rotary position and/or wherein the first and second coupling means are arranged in such a manner that the load applied to/by/via the user's feet at the second coupling means is concentric to the first coupling means, especially irrespective of relative translational position, especially with a resulting force vector pointing to the second coupling means.

8. Exoskeleton according to any of the preceding claims, wherein the exoskeleton exhibits at least one sensor from the following group: at least one sensor being arranged in or coupled to at least one linear rail unit and providing for position and/or velocity data; at least one force sensor being arranged in or coupled to the bottom plate; at least one rotary position sensor being arranged in or coupled to the rotary joint connecting the lower part and the upper part.

9. Method of providing counteracting translational linear forces by exoskeleton kinematics for physical training of lower limbs of a user, namely by an exoskeleton exhibiting an upper part with first coupling means and exhibiting lower parts, each consisting of at least one linear rail unit with a pedal with second coupling means and a bottom plate, the rail unit extending along the user's legs and being configured to translationally guide the pedal and the bottom plate between a retracted position and an extended position, wherein an adjustable counteracting force is exerted in translational direction on the bottom plate by an actuation system of the exoskeleton when the user is exerting a translational pressing force with his lower limbs between first coupling means and second coupling means, wherein the counteracting force consists of a constant force and an inertial force.

10. Method according to the preceding method claim, wherein the constant force is generated by means of spring elements with an adjustable constant force mechanism of the actuation system, wherein a force control is provided in a linearly displaced section exclusively in translational direction along the linear rail units, and/or wherein the inertial force is generated by means of at least one flywheel, preferably two counter-rotating flywheels, of the actuation system, wherein the flywheel or the flywheels exhibit a plurality of masses, that can move radially outwards or inwards synchronously, thus changing the moment of inertia of the flywheel.

11. Method according to any of the preceding method claims, wherein the exoskeleton provides for force regulation of the translatory force via the actuation system in such a manner, that the amount of constant and inertial force can be provided independently of the path and/or position of translatory motion and independently of the knee angle of the user's legs, especially such that the user can experience different gravity constants.

12. Use of an exoskeleton, especially use of an exoskeleton according to any of the preceding device claims, for providing translational and/or rotational kinematics for exercising lower limbs of a user by translational donning and doffing of the exoskeleton pedals along linear rail units, wherein a counteracting force is exerted by the exoskeleton on a bottom plate pushing against the pedals along the linear rail units, wherein the exoskeleton's translational and/or rotational kinematics preferably are used for controlling squat jump sequences, especially in absence of gravity.

Drawing