Load compensation device for exoskeletons, especially for gravity loads

Abstract

The present invention relates to a load compensation device (201, 301, 501, 601, 701, 901), comprising: an auxiliary joint (3; 302) configured to be constrained to a support structure (102, 104; 303; 702, 704); a main rod (304) comprising a proximal end (305) connected to the auxiliary joint (3; 302) and further comprising a distal end (306) configured to bear an applied load (11); an auxiliary rod (307) comprising a first end (308) and a second end (309), the first end (308) being hinged to the main rod (304) for relative movement of the auxiliary rod. The main rod (304) rotates the auxiliary rod (307), and the second end (309) can move in the plane where the applied load (11) is located; an elastic element (310, 910) is configured to provide an elastic force acting between the second end (309) of the auxiliary rod (307) and the distal end (306) of the main rod (304); an adjustment system (313; 613) is configured to adjust the distance between the second end (309) of the auxiliary rod (307) and the auxiliary joint (3; 302) to change the preload of the elastic element (310, 910). The elastic element (310, 910) is configured to provide the elastic force based on the kinematic configuration of the load compensation device (201, 301, 501, 601, 701, 901) so as to compensate the applied load (11) on its component transverse to the main rod (304). The invention also relates to an exoskeleton (100; 700) comprising at least a load compensation device (201, 301, 501, 601, 701, 901).

Description

Technical Field

[0001] The present invention relates to load compensation devices, in particular for compensating gravity loads. In a preferred and non-limiting application, the present invention also relates to an associated exoskeleton.

[0002] In general, the invention has non-limiting application in the field of transport devices and in the field of physical activity and rehabilitation exercise devices. Prior art

[0003] Over the past few years, a variety of applications of exoskeletons have been explored, mainly related to the biomedical and industrial fields.

[0004] In the biomedical field, exoskeletons are designed to enhance the physical and motor functions of an individual, further compensating for the effects of gravity, thereby reducing physical effort and individual fatigue. Specifically, in the biomedical field, exoskeletons are used in the fields of motor function recovery and assistance. Recovery is related to the rehabilitation of the patient, while "assistance" involves simple assistance situations in which the user's motor functions are irreversibly impaired.

[0005] In the industrial sector, exoskeletons are mainly used in manufacturing and construction, where operators must maintain uncomfortable postures or must move or lift heavy loads; they are also used to assist medical personnel. Typically, in this industrial sector, exoskeletons are designed to reduce the load on one or more body parts.

[0006] In exoskeletons, load compensation is performed through different technologies, which can be classified as "passive" or "active": "passive" compensation technologies use a set of one or more elastic elements that are loaded during movement and release deformation energy during the reverse movement; "active" compensation technologies, on the contrary, use motor-driven actuators, usually of the electric type; other types of actuators can provide piezoelectric actuators, SMA ("shape memory alloys"), pneumatic actuators or electroactive polymers.

[0007] The advantage of passive compensation technology is that it does not require an external power source, allowing to obtain a lighter and more compact exoskeleton, which also does not require an electronic power source. In practice, a passive compensation system usually consists of a kinematic chain of elastic elements that support the weight of the user by deforming.

[0008] However, there is only one equilibrium point at which an exoskeleton with passive compensation can fully compensate for the load, not for any position of the user. Furthermore, during the movement of the load, the user must generate a force to load the elastic element.

[0009] In contrast, active compensation techniques require external power supplies, electronics, and control logic. Disadvantageously, electric motors are bulky, making the exoskeleton heavier and less ergonomic than passive ones. Furthermore, with high energy consumption, the exoskeleton cannot be effectively powered by a light and compact battery system.

[0010] For these reasons, the most widespread exoskeletons in industry and biomedicine are of the passive compensation type.

[0011] Examples of active exoskeleton systems and gravity load compensation devices are provided in documents KR20160071661, EP3278938A1, WO2017161257 and WO2015106278, which describe solutions including actuators.

[0012] Examples of passive exoskeleton systems and gravity load compensation devices are provided in documents KR2012008221, WO2015147584, CA2952403, US20120184880, CA2544645, WO2018165399A1, and EP2861387, which include elastic elements of the same adjustable type recommended in user-wearable exoskeletons and devices.

[0013] Another example of a gravity load compensation device is provided in document EP3342390A1, which refers to a device for supporting a limb, comprising a passive element connected to a wearable element and supporting an active element actuated by a traction actuator of a cable driven by a motor. However, the device known in EP3342390A1, although realizing a hybrid structure between active and passive systems, has disadvantages and limitations of application. SUMMARY OF THE INVENTION

[0015] The object of the present invention is to solve the disadvantages of the prior art.

[0016] Another specific object of the invention is to provide a device which has reduced energy consumption and which can therefore be efficiently powered by a portable battery system.

[0017] Another specific object of the invention is to allow variable load compensation, in particular gravity load, for any position of the user.

[0018] Another specific object of the invention is to provide a device that is less bulky than a fully active device, so as to obtain a lighter and more ergonomic exoskeleton.

[0019] These and other objects are achieved by a load compensation device and an associated exoskeleton according to the features of the attached claims, which form an integral part of the present description.

[0020] The idea of ​​the present invention is to provide a load compensation device, which comprises:

[0021] - an auxiliary joint configured to be constrained to a supporting structure;

[0022] - a main rod comprising a proximal end connected to the auxiliary joint and further comprising a distal end configured to bear an applied load;

[0023] - an auxiliary rod comprising a first end and a second end, the first end being hinged to the main rod for rotating the auxiliary rod relative to the main rod, and the second end being movable in the plane of the applied load;

[0024] - an elastic element configured to provide an elastic force acting between the second end of the auxiliary rod and the distal end of the main rod;

[0025] - an adjustment system configured to adjust the distance between the second end of the auxiliary rod and the auxiliary joint in order to vary the preload of the elastic element;

[0026] Therein, the elastic element is configured to provide the elastic force based on the kinematic configuration of the load compensation device so as to compensate the applied load in its component transverse to the main rod.

[0027] In short, the load compensation device of the present invention is intended to fully recognize and compensate, with minimal energy consumption and volume, the effects of forces, such as those of gravity, acting on the main rod, which represents the connection point between the load compensation device and the system structure (such as an exoskeleton or a robotic arm) into which the device is inserted.

[0028] The load compensating device of the invention then comprises a mechanical structure provided with appropriate sensors and control logic, wherein the preloaded elastic element provides the necessary compensating force.

[0029] Advantageously, the invention allows to realize a load compensation device implementing a hybrid technology designed to apply a load compensation adapted to the movements of the user, while guaranteeing high compactness and low energy consumption.

[0030] Specifically, the load compensation device of the present invention allows the positive aspects of passive and active technologies to be merged into a unique device that can be expanded to any type of device or exoskeleton.

[0031] The load compensation device of the present invention can also be advantageously used in different fields, such as industrial robots and lifting or handling systems, to develop more compact and less energy-consuming equipment.

[0032] Preferably, the load compensation device comprises a movable adjustment element associated with the support structure. In particular, the movable adjustment element preferably provides an adjustment rod and linear actuator system, or a cable and motor driven pulley system.

[0033] Preferably, the elastic element is at least indirectly connected to the second end of the auxiliary rod. In particular, the load compensation device preferably comprises a compensation cable connecting the second end of the auxiliary rod to the elastic element having a pulley near the distal end of the main rod.

[0034] As an object of the present invention, load compensation devices can be applied to one or more joints of an exoskeleton or a robotic arm, allowing the solution to be applied to multiple degrees of freedom.

[0035] Thus, another idea of ​​the present invention is to provide an exoskeleton comprising one or more load compensating devices.

[0036] Further features and advantages will be apparent from the following detailed description of a preferred non-limiting embodiment of the invention and from the dependent claims outlining preferred and particularly advantageous embodiments of the invention.

[0037] BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The invention is illustrated, by way of non-limiting example, with reference to the following drawings, in which:

[0039] - Figure 1 An example of an upper limb holding an object that is subject to gravity-induced loads is shown.

[0040] - Figure 2 An exoskeleton coupled to an upper limb and including the load compensation device of the present invention is shown.

[0041] - Figure 3 A first embodiment of the load compensating device of the present invention is shown.

[0042] - Figure 4a and Figure 4b Exemplary performance of the load compensation device of the present invention is shown.

[0043] - Figure 5 A second embodiment of the load compensating device of the invention is shown.

[0044] - Figure 6 A third embodiment of the load compensating device of the present invention is shown.

[0045] - Figure 7 An exoskeleton involving the pelvis and lumbar spine and including the load compensation device of the present invention is shown.

[0046] - Figure 8 A fourth embodiment of the load compensating device of the present invention is shown.

[0047] - Fig. 9 A fifth embodiment of the load compensating device of the present invention is shown.

[0048] In different drawings, similar elements will be identified by similar reference numerals.

[0049] Details

[0050] In a preferred embodiment, the load compensation device of the present invention is used to compensate the effects of gravity loads in an exoskeleton or a robotic arm. In particular, the present invention relates to a robotic arm and an exoskeleton, which can be used for multiple joints of the human body, such as the shoulder, hip, especially the lumbar spine, and the knee. The present invention will refer to the non-limiting application of the load compensation device according to the present invention.

[0051] In this exemplary application, most of the force required to perform upper limb movements is used to overcome the effects of gravity, which can be identified by the torque acting on the arm itself. Accordingly, the shoulder is the joint that is primarily stressed. An exoskeleton is a device designed to reduce the burden on the user who wears it, which increases the strength capabilities exponentially. Specifically, the load compensation device of the present invention is designed to be integrated into the exoskeleton and applied to the joints of the upper or lower limbs of the user. Similar applications can be extended to robotic arms.

[0052] Figure 1 An example of an upper limb 1 is shown holding an object 11 which is subjected to a load caused by the gravitational acceleration "g".

[0053] The load "g" acting on the object 11 is particularly relevant for flexion and extension movements of the shoulder of the limb 1: this is the case with "pick and place" movements performed in many industrial fields, for example in large retailer logistics and manufacturing.

[0054] The limb 1 can be illustrated diagrammatically, consisting of rigid bodies 6 and 8, a load 11 and masses 7, 9, 10 and 11, respectively. The rods 6 and 8 are connected to each other by hinges 5 and are constrained to the ground by hinges 3. This system represents the solution of the user in the sagittal plane. Therefore, to compensate for the gravity effect acting on the system and caused by the gravitational acceleration "g", the compensation torque applied to the body 6 will depend on its position in the plane, which is determined by the angles 2 and 4, the geometric values ​​of the rods 6 and 8 and the corresponding masses 7, 9, 10 and 11. Therefore, the gravity effect can be understood as the torque generated on the rod 6 by the gravity acting on the center of gravity of the bodies 7, 9, 10 and 11.

[0055] Figure 2 An exoskeleton 100 is shown in combination with an upper limb 1 and comprising a load compensation device 201 of the present invention.

[0056] As previously mentioned, a non-limiting example of an application of the present invention is the compensation of the gravity load acting on the upper limb during shoulder flexion and extension movements, i.e., rotational movements of the shoulder in the sagittal plane, such as Figure 1As shown, arrow 2 represents the rotation of the shoulder and "g" represents the gravity vector. In this case, the exoskeleton 100 is configured to compensate for the gravity load on the user's shoulders.

[0057] The application of load compensation device 201 to exoskeleton 100 is exemplified to provide hybrid technology for exoskeletons used for upper limb and "pick and place" activities.

[0058] The load compensating device 201 is connected to the support structure 102 and releases forces onto the support structure 102. During the shoulder flexion and extension movement of the user about the hinge 3, the compensating forces are transferred from the device 201 to the limb via the arm rest 103. The belt 104 preferably contains the electronics and power supply batteries for all active components, while the strip 105 contains sensors for detecting the relative rotation between the arm and forearm.

[0059] Typically, in the exoskeleton 100, the load compensation device is associated with a battery to power a regulation system, which will be described further, and which has a plurality of sensors and at least one processor.

[0060] In other embodiments, the load compensation device may be applied to a robot or lifting device or load handling device having an auxiliary joint configured to be constrained to a support structure where the main pole is present in order to compensate for the lateral component of the load applied to the main pole.

[0061] Figure 3 A first embodiment of a load compensating device 301 of the present invention is shown.

[0062] The load compensation device 301 , which is specifically configured to compensate for gravity loads, comprises an auxiliary joint 302 configured to be constrained to a support structure 303 .

[0063] The load compensating device 301 further comprises a main rod 304 comprising a proximal end 305 connected to the auxiliary joint 302 and further comprising a distal end 306 configured to bear an applied load (such as the load 11 already described).

[0064] The load compensating device 301 further comprises an auxiliary rod 307, which comprises a first end 308 and a second end 309. The first end 308 is hinged to the main rod 304 for rotating the auxiliary rod 307 relative to the main rod 304. Conversely, the second end 309 is movable in a plane where the applied load 11 is located, and the load compensating device 301 is configured to compensate for the applied load 11.

[0065] Specifically, the auxiliary rod 307 extends out of the main rod 304 in a direction opposite to the main direction of the applied load 11. Figure 3In the exemplary configuration in, the main rod 304 is horizontal and the auxiliary rod 307 extends out of the main rod 304 in a substantially vertical and "upward" direction, and therefore on the side opposite to the main direction of the applied load 11, i.e., "downward".

[0066] Preferably, the first end 308 of the auxiliary rod 307 is hinged to the main rod 304 at an intermediate position between the proximal end 305 and the distal end 306 of the main rod 304 .

[0067] In particular, the distal end 306 of the main rod 304 corresponds exactly to the support of a movable structural element subjected to a variable load, such as the element 103 already described.

[0068] In general, the lengths of rods 304 and 307, the distances between constraints, and the general kinematic configuration of the load compensation device are determined based on the desired compensation performance and the energy and volume constraints of the overall system.

[0069] The load compensating device 301 further includes an elastic element 310 configured to provide an elastic force acting between the second end 309 of the auxiliary rod 307 and the distal end 306 of the main rod 304 .

[0070] In a preferred embodiment, the elastic element 310 comprises a traction or compression helical spring. In a variant, the elastic element may be a band made of rubber or an elastic material suitable for the purpose.

[0071] Preferably, the elastic element 310 is at least indirectly connected to the second end 309 of the auxiliary rod 307 .

[0072] In a preferred embodiment, Figure 3 As shown, the elastic element 310 is indirectly connected to the second end 309 of the auxiliary rod 307 . Specifically, a compensation cable 311 is provided, which directly connects the second end 309 of the auxiliary rod 307 to the elastic element 310 .

[0073] Preferably, the elastic element 310 is axially extended and substantially parallel to the main rod 304; thereby, the load compensation device can be more compact and a more rigid elastic element can be inserted. The load compensation device 301 also includes a pulley 312 near the distal end 306 of the main rod 304, wherein the compensation cable 311 is combined with the pulley 312.

[0074] In a variant, the elastic element 310 can be connected directly to the second end 309 of the auxiliary rod 307 without a compensating cable by connecting the distal end 306 directly to the second end 309 inserted therebetween, as described in reference Fig. 9 described.

[0075] The load compensating device 301 further comprises an adjustment system 313 configured to adjust the distance between the second end 309 of the auxiliary rod 307 and the auxiliary joint 302 to change the preload of the elastic element 310 .

[0076] The elastic element 310 is configured to provide an elastic force based on the kinematic configuration adopted by the load compensating device 301 in order to compensate the applied load 11 in its component transverse to the main rod.

[0077] In this sense, the adjustment system 313 is preferably configured to minimize the difference between the transverse component of the load 11 to be compensated and the opposing transverse component provided by the elastic force of the elastic element 310 .

[0078] The working principle implemented by the load compensation device 301 is as follows: in any position assumed by the user (exoskeleton or robotic arm), the appropriate control logic processes, through sensors and processors, the gravitational torque / force acting on the auxiliary joint 302. From this, they process the control actions to be sent to the regulation system 313 so that the regulation system 313 adjusts the preload of the elastic element 310 through the articulation system of the arms 304 and 307 so that the compensation force is equal to the gravitational effect.

[0079] Specifically, the load compensation device 301 further includes a plurality of sensors (not shown), which are configured to measure the absolute position of the main rod 304 and also measure or obtain the torque borne by the auxiliary joint 302 due to the applied load 11. In addition, the load compensation device 301 further includes at least a processor (not shown), which is operably connected to the plurality of sensors and the adjustment system 313, and the processor is configured to calculate the preload of the elastic element 310 to offset the torque borne by the auxiliary joint.

[0080] Preferably, the processor is further configured to adjust the elastic force provided by the elastic element 310 according to the dynamic trajectory measured by the plurality of sensors so as to support the movement desired by the exoskeleton user or required by the robot programming.

[0081] Examples of adjustment processes that can be performed in the sagittal plane at any position assumed by the user, such as those implemented by control logic and sensors, are provided to manage the duty cycle of the load compensation device 301 .

[0082] A single exemplary working cycle can be summarized by the following operational flow:

[0083] -The sensor provides position measurement and sends it to the control logic.

[0084] - The control logic calculates the position taken by the user and the corresponding gravity effect acting on it, expressed as a torque relative to the reference auxiliary joint 302. Furthermore, the control system preferably processes the kinematics and the type of trajectory executed.

[0085] - The processor calculates the deformation that must be applied to the elastic element 310 in order to obtain the torque that counteracts the effect of gravity.

[0086] The processor processes the control actions to be sent to the adjustment system 313 , which allows obtaining the desired deformation of the elastic element 310 by resolving the kinematics of the articulated system composed of the rods 304 and 307 .

[0087] Preferably, such control is designed to adjust the drive force according to the trajectory and dynamics performed by the user when performing an activity in order to support the user's intentions in the application of the exoskeleton 100.

[0088] As described above, the adjustment system 313 is configured to adjust the distance between the second end 309 of the auxiliary rod 307 and the auxiliary joint 302 to change the preload of the elastic element 310. Generally, the adjustment system 313 is also configured to change the relative angle between the main rod 304 and the auxiliary rod 307.

[0089] To this end, the adjustment system 313 comprises a movable adjustment element 314 associated with the support structure 303 .

[0090] Preferably, the adjustment system 313 further comprises an adjustment rod 320, which connects the movable adjustment element 314 to the second end 309 of the auxiliary rod 307. Preferably, the movable adjustment element 314 comprises a linear actuator 321 to which the adjustment rod 320 is hinged.

[0091] Preferably, the linear actuator 321 is movable along a ramp element 322 constrained to the support structure 303 .

[0092] Figure 4a and Figure 4b Exemplary performance of the load compensation device of the present invention is shown.

[0093] Specifically, Figure 4a A comparison is shown between the torque at the joint required by the user according to the rotation angle of the main rod 304 about the auxiliary joint without using the device of the present invention (line 400) and using the load compensation device 301 (line 401).

[0094] It can be noted that, in case of use of the device, the force required by the user is almost completely zero (line 401 , for any value of angle).

[0095] Specifically, Figure 4b Different situations are shown, where it is assumed that the exoskeleton 100 is equipped with a motor that controls the rotation of the auxiliary joint 302 by providing torque, instead of the user, without using the device of the invention (line 402) and with using the load compensation device 301 (line 403).

[0096] It can be noted how the total power (calculated by assuming a constant angular velocity) is almost zero along the entire work field when the exoskeleton 100 is provided with the load compensation device of the present invention (line 403), compared to the power in the case of using an active exoskeleton with motors but without the device of the present invention (line 402).

[0097] The exemplary performance shows that the load compensation device of the present invention is able to almost completely compensate for the effects of gravity in the entire work field with minimal energy consumption.

[0098] Thus, the load compensation arrangement of the present invention allows for the use of lighter, less energy consuming motors, thereby facilitating an overall lighter, more efficient system.

[0099] Figure 5 A second embodiment of a load compensating device 501 of the present invention is shown.

[0100] The load compensation device 501 basically comprises a Figure 3 Elements described in embodiment 301 are presented.

[0101] Compared to the embodiment 301 already described, the load compensating device 501 provides a different overall geometry, which means that slightly different kinematic characteristics allow for load compensation adapted to the specific application.

[0102] Furthermore, in contrast to the already described embodiment 301 , the load compensating device 501 provides a linear actuator 321 which moves on different ramp elements 522 which have different slopes and which are not directly connected to the auxiliary joint 302 , but which is always connected to the support structure 303 .

[0103] In other words, the load compensating device 501 provides an adjustment system 313, which always includes a movable adjustment element 314 relative to the support structure 303, and in which the linear actuator 321 can be moved along different ramp elements 522 constrained to the support structure, wherein the ramp elements 522 have a slope determined based on different desired kinematic characteristics of the load compensating device 501.

[0104] Figure 6 A third embodiment of a load compensating device 601 of the present invention is shown.

[0105] The load compensation device 601 basically comprises a Figure 3 Elements described in embodiment 301 are presented.

[0106] Thus, the load compensating device 601 employs the same operating principles as described with respect to the above embodiments 301 and 501, but uses a different regulation system 613 within the hybrid mechanical structure.

[0107] Specifically, the adjustment system 613 further includes a cable 620 that connects the movable adjustment element 614 to the second end 309 of the auxiliary rod 307 .

[0108] In this embodiment of the adjustment system 613, the movable adjustment element 614 includes a motor-driven pulley 621, and the cable 620 is suitable for winding or unwinding on the motor-driven pulley 621. Therefore, the adjustment system 613 is configured to adjust the distance between the second end 309 of the auxiliary rod 307 and the auxiliary joint 302 to change the preload of the elastic element 310. Generally, the adjustment system 613 is also configured to change the relative angle between the main rod 304 and the auxiliary rod 307.

[0109] Preferably, the motor driven pulley 621 is in a fixed position relative to the auxiliary joint 302 , and the second distance between the motor driven pulley 621 and the auxiliary joint 302 is determined based on the desired kinematic characteristics of the load compensating device 601 .

[0110] In other words, in this embodiment of the adjustment system 613, the linear actuator 321 is replaced by a rotary actuator or motor 621, and the adjustment rod 320 is replaced by a cable 620 that is wrapped around a pulley 621 controlled by the motor.

[0111] Figure 7 An exoskeleton 700 is shown incorporating 701 the pelvis and lumbar spine and including the load compensation device of the present invention.

[0112] In the present embodiment of the load compensating device 701, it is applied to an exoskeleton of the lumbar spine.

[0113] The load compensation device 701 is connected to the support structure 702 and releases forces to it. During the user's leg movements around the hinge 3, the compensation forces are transferred from the device 701 to the limb through the element 704. The element 704 itself preferably contains the electronics of all active components and the power supply battery, while there are sensors for detecting the relative rotation between 703 and 704.

[0114] Typically, a load compensation device is associated with a battery in the exoskeleton to supply power to the regulation system, the plurality of sensors and at least one processor.

[0115] Figure 8 A fourth embodiment of the load compensating device of the present invention is shown.

[0116] The load compensating device 701 is applied to the exoskeleton 700 to relieve the forces in the lumbar region. In this case, the auxiliary joint 302 is the one of the pelvis. The support structure to which the load compensating device 701 is fastened consists of two parts, one part fastening to the upper part of the leg and the other part fastening to the pelvis.

[0117] The load compensating device 701 follows the same implementation as the load compensating device 501 already described.

[0118] Fig. 9 A fifth embodiment of a load compensating device 901 of the present invention is shown.

[0119] The load compensation device 901 includes a Figure 3 and Figure 5 Certain elements described in embodiments 301 and 501 are presented.

[0120] Specifically, the load compensating device 901 includes an auxiliary joint 302 configured to be constrained to a support structure 303 .

[0121] The load compensating device 901 further includes a main rod 304 including a proximal end 305 connected to the auxiliary joint 302 , and a distal end 306 configured to bear the applied load 11 .

[0122] The load compensation device 901 further comprises an auxiliary rod 307, which comprises a first end 308 and a second end 309. The first end 308 is hinged to the main rod 304 for rotating the auxiliary rod 307 relative to the main rod 304. The second end 309 is movable in the plane where the applied load 11 is located.

[0123] The load compensating device 901 further includes an elastic element 910 configured to provide an elastic force acting between the second end 309 of the auxiliary rod 307 and the distal end 306 of the main rod 304 .

[0124] Specifically, the elastic element 910 is a tension spring directly connecting the second end 309 to the distal end 306. In a preferred embodiment, the elastic element 910 comprises a helical spring, but may also be a band made of rubber or an elastic material suitable for the purpose.

[0125] In a variation, the tension springs may connect the exterior of the rods 304 and 309 rather than directly connecting their ends.

[0126] The load compensating device 901 further includes an adjusting system 313 configured to adjust the distance between the second end 309 of the auxiliary rod 307 and the auxiliary joint 302 to change the preload of the elastic element 910 .

[0127] The regulation system 313 preferably corresponds to the Figure 5 An embodiment is described which has a linear actuator 321 moving on a ramp element 522 .

[0128] Typically, the elastic element 910 is configured to provide a spring force based on the kinematic configuration of the load compensating device 901 , which is determined by the positions of the primary rod 304 and the auxiliary rod 307 and the preload of the elastic element 910 .

[0129] Therein, the load compensation device 901 is able to compensate the applied load 11 at its component transverse to the main rod 304 .

[0130] Industrial Applicability

[0131] The invention allows loads, in particular gravity loads, to be effectively compensated.

[0132] The load compensation device of the invention can be integrated in exoskeletons designed in particular for industrial applications in which the user has to perform strenuous manual or generally physically tiring operations, and for rehabilitation and assisted biomedical applications.

[0133] In this sense, the load compensation device of the invention integrated in an exoskeleton allows load reduction in different joints such as shoulder, lumbar spine, knee, hip etc.

[0134] Furthermore, the load compensation device of the present invention can also be integrated into a robot arm.

[0135] In view of the description herein, a person skilled in the art will be able to envisage other modifications and variations to meet occasional and specific needs.

[0136] Therefore, the embodiments described herein are to be regarded as illustrative and non-limiting examples of the present invention.

Claims

1. A load compensation device (201, 301, 501, 601, 701, 901), comprising: - an auxiliary joint (3; 302) configured to be constrained to the supporting structure (102, 104; 303; 702，704)； - a main rod (304) comprising a proximal end (305) connected to said auxiliary joint (3; 302) and further comprising a distal end (306) configured to bear an applied load (11); - an auxiliary rod (307) comprising a first end (308) hinged to the main rod (304) for rotating the auxiliary rod (307) relative to the main rod (304) and a second end (309) movable in the plane of the applied load (11); - an elastic element (310, 910) configured to provide an elastic force acting between the second end (309) of the auxiliary rod (307) and the distal end (306) of the main rod (304); - an adjustment system (313; 613) configured to adjust the distance between the second end (309) of the auxiliary rod (307) and the auxiliary joint (3; 302) in order to vary the preload of the elastic element (310, 910); The elastic element (310, 910) is configured to provide the elastic force based on the kinematic configuration of the load compensation device (201, 301, 501, 601, 701, 901) so as to compensate the applied load (11) on its component transverse to the main rod (304).

2. A load compensation device according to claim 1, wherein the adjustment system (313; 613) comprises a movable adjustment element (314; 614) associated with the support structure (102, 104; 303; 702, 704).

3. A load compensation device as described in claim 2, wherein the adjustment system (313; 613) also includes an adjustment rod (320), which connects the movable adjustment element (314; 614) to the second end (309) of the auxiliary rod (307), and wherein the movable adjustment element (314; 614) includes a linear actuator (321) articulated to the adjustment rod (320).

4. A load compensating device as claimed in claim 3, wherein the linear actuator (321) is movable along a ramp element (322; 522), the ramp element (322; 522) being constrained to the support structure (102, 104; 303; 702, 704) and having a slope determined based on the desired kinematic characteristics of the load compensating device (201, 301, 501, 601, 701, 901).

5. A load compensation device as described in claim 2, wherein the adjustment system (313; 613) also includes a cable (620), which connects the movable adjustment element (314; 614) to the second end (309) of the auxiliary rod (307), and wherein the movable adjustment element (314; 614) includes a motor-driven pulley (621), and the cable (620) is suitable for winding or unwinding on the motor-driven pulley (621).

6. A load compensating device as claimed in claim 5, wherein the motor-driven pulley (621) is in a fixed position relative to the auxiliary joint (3, 302), and wherein the second distance between the motor-driven pulley (621) and the auxiliary joint (3, 302) is determined based on the desired kinematic characteristics of the load compensating device (201, 301, 501, 601, 701, 901).

7. The load compensation device according to any one of claims 1 to 6, wherein the adjustment system (313; 613) is further configured to change the relative angle between the main rod (304) and the auxiliary rod (307).

8. A load compensation device as described in any one of claims 1 to 6, wherein the adjustment system (313; 613) is also configured to minimize the difference between the component of the applied load (11) transverse to the main rod (304) and the opposite lateral component provided by the elastic force.

9. A load compensation device as described in any one of claims 1 to 6, further comprising a plurality of sensors configured to measure the absolute position of the main rod (304) and also to measure the torque borne by the auxiliary joint (3; 302) due to the applied load (11), and further comprising at least one processor operably connected to the plurality of sensors and the adjustment system (313; 613), the processor being configured to calculate the preload to offset the torque borne by the auxiliary joint (3; 302).

10. The load compensation device of claim 9, wherein the processor is further configured to adjust the spring force according to a dynamic trajectory measured by the plurality of sensors to support a desired movement.

11. The load compensating device according to any one of claims 1 to 6, wherein the elastic element (310, 910) is at least indirectly connected to the second end (309) of the auxiliary rod (307).

12. The load compensation device according to any one of claims 1 to 6, further comprising a compensation cable (311), wherein the compensation cable (311) connects the second end (309) of the auxiliary rod (307) to the elastic element (310, 910).

13. A load compensating device as described in claim 12, wherein the elastic element (310, 910) extends axially and substantially parallel to the main rod (304), and the load compensating device (201, 301, 501, 601, 701, 901) further includes a second pulley (312) near the distal end (306) of the main rod (304), and the compensating cable (311) is combined with the second pulley (312).

14. The load compensating device according to any one of claims 1 to 6, wherein the auxiliary rod (307) extends beyond the main rod (304) in a direction opposite to a main direction of the applied load (11).

15. The load compensation device according to claim 14, wherein the first end (308) of the auxiliary rod (307) is hinged to the main rod (304) at an intermediate position between the proximal end (305) and the distal end (306) of the main rod (304).

16. The load compensation device according to any one of claims 1 to 6, wherein the distal end (306) of the main rod (304) corresponds to a support of a movable structural element (103; 703) subjected to a variable load.

17. An exoskeleton (100; 700) comprising at least one load compensation device (201, 301, 501, 601, 701, 901) according to any one of claims 1 to 16.

18. An exoskeleton as claimed in claim 17, further comprising at least one battery to power the regulation system (313; 613), a plurality of sensors and at least one processor.

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