Method for controlling an exoskeleton to assist with walking

Abstract

One aspect of the invention relates to a method (100) for controlling a user's walking assistance exoskeleton, the method (100) comprising steps of: measuring (110): an acceleration and angular velocity of the user's lumbar region by the six-axis inertial measurement unit, and an angle and rotational velocity of hip actuators, determining (120), from the measurements: a phase of a walking activity cycle, a period of the walking activity, and a slope of the terrain on which the walking activity is performed, modulating (130) the intensity of the current supplied by the energy source as a function of the determined phase of the walking activity cycle, the determined period of the walking activity, and the determined slope of the terrain, and applying (140) the modulated current to the hip actuators. Figure to be published with the abbreviation: Figure 1

Description

Title of the invention: Method for controlling an exoskeleton to assist with walking activity. TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of exoskeletons for assistance with walking activity.

[0002] The present invention relates in particular to a method of controlling an exoskeleton for assistance with a walking activity. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] An exoskeleton is a device fixed to one or more limbs of a user's human body to restore their mobility or increase their physical capabilities.

[0004] Exoskeletons can assist a user in various tasks such as carrying heavy loads, walking, running, hiking, etc. Numerous applications are possible, including in the medical, industrial, sports, and military fields.

[0005] Depending on the intended applications, exoskeletons differ greatly. Thus, it is possible to divide exoskeletons into two main categories.

[0006] A first category concerns passive exoskeletons. Passive exoskeletons are not motorized. Passive exoskeletons incorporate materials and equipment that store and release energy during the user's movement. The term "user" refers to the person wearing the exoskeleton. This person can be a man or a woman of any age. Passive exoskeletons are often used for ergonomic purposes, to prevent repetitive strain injuries, or to assist in lifting tools or equipment. Thus, passive exoskeletons, such as the one disclosed in patent application WO2014109799A1, are primarily intended to assist able-bodied individuals in performing repetitive and / or traumatic tasks.These passive exoskeletons do not require the implementation of a control process since the forces exerted by the exoskeleton on the user are generated in response to the user's movements.

[0007] A second category of exoskeletons concerns active exoskeletons. Active exoskeletons rely on systems, called actuators, such as motors, hydraulic or pneumatic systems, capable of increasing human force or reducing the body's energy consumption during movement. An active exoskeleton consists of one or more actuators, which could be an electric motor, for example. The actuator actively increases the power of the human body. Active exoskeletons that assist with walking contribute to Specifically, they actively assist in the flexion and / or extension of the user's hip. These exoskeletons may, for example, include an actuator located near each of the user's hips, generating torque around the flexion / extension axis of each hip.

[0008] Active exoskeletons for assisting walking require the implementation of a control method, for example, to control the intensity of the assistance provided by the hip actuators, i.e., the intensity of the torque generated by each hip actuator around the flexion / extension axis of each of these hips. US patent application 2021401324A1 discloses, for example, a method for controlling an active exoskeleton for assisting walking based, in particular, on the recognition of a limb movement pattern by a machine learning method.

[0009] In this context, the need for an improved control method is necessary. In particular, improvements in comfort and better adaptation to the characteristics of the user and the terrain during the use of the exoskeleton controlled by the control method are of particular interest. Summary of the invention

[0010] The invention offers a solution to the problems mentioned above by adapting the assistance provided by the hip actuators according to three parameters: the period of the walking activity, the phase of a walking activity cycle, and the slope of the terrain on which the walking activity is performed. These three parameters are determined beforehand using measurements taken at the hip actuators of the exoskeleton as well as measurements taken by a six-axis inertial measurement unit intended to be placed in the user's lumbar region.

[0011] One aspect of the invention relates to a method for controlling a user's walking assistance exoskeleton, the exoskeleton comprising: • a suitable source of electrical energy to supply an electric current, • a first and second hip actuator adapted to assist a flexion and / or extension respectively of the user's first and second hips, with the level of assistance depending on the intensity of the electrical current applied to the first and second actuators. • a six-axis inertial measurement unit designed to be placed in the user's lumbar region and adapted to measure acceleration and angular velocity of the user's lumbar region, • a processor configured to implement the process,

[0012] the process comprising steps of: • measure : • of an acceleration and angular velocity of the user's lumbar region by the six-axis inertial measurement unit, and • of an angle and a rotational speed of the first and second actuators, the rotational speed of the first and second actuators being positive during hip flexion of the user, • determination, based on measurements: • of a phase of a walking activity cycle from among at least one set of phases of the walking activity cycle, the at least one walking activity cycle being defined for the user's first hip, • of a period of walking activity among: • the beginning of walking activity, • an environment conducive to pedestrian activity, and • the end of a walking activity, and • the slope of a piece of terrain on which the pedestrian activity takes place, the slope of the terrain being negative during a descent and positive during an ascent, • modulation of the current intensity supplied by the energy source according to the determined phase of the pedestrian activity cycle, the determined period of the pedestrian activity, and the determined slope of the terrain, and • application of modulated current to the first and second hip actuators.

[0013] The control method according to the invention thus makes it possible to adapt to the user's characteristics, particularly the characteristics of their walking activity. Furthermore, the control method allows for adjustment of the intensity of the assistance provided at the start and end of the walking activity. The control method according to the invention also makes it possible to adapt to the characteristics of the terrain on which the walking activity is performed, in particular by taking into account the slope of the terrain. Thus, the user comfort of the exoskeleton is improved thanks to the control method according to the invention.

[0014] In addition to the characteristics mentioned in the preceding paragraph, the method according to one aspect of the invention may have one or more additional characteristics from among the following, considered individually or in all technically possible combinations: • The modulation of the current intensity applied to the first and second hip actuators is further performed according to a level of assistance determined by the user, • Walking is one activity among: • a walk, • Nordic walking, • a hike, • a race, • a snowshoe hike, • a ski touring ski, and at least one cycle of pedestrian activity includes a generic cycle with all the phases of the generic cycle including: • a flexion phase beginning when flexion of the first hip begins and ending when extension of the first hip begins, • an extension phase beginning when the extension of the first hip begins and ending when the flexion of the first hip begins, and Determining the phase of the generic cycle from among all the phases of the pedestrian activity cycle includes: • detection of entry into the bending phase when the angular velocity of the first actuator is zero after having been negative, and • detection of an entry into the extension phase when the angular velocity of the first actuator is zero after having been positive, Walking is an activity that involves walking, and the slope of the terrain is zero or positive, and at least one cycle of pedestrian activity includes an initial walking cycle, with the initial walking cycle comprising a set of phases including: • an initial oscillation phase beginning when one foot of the first leg, including the first hip, is no longer in contact with the ground after having been in contact with the ground, and ending when the first leg and a second leg, including the second hip, cross in a sagittal plane of the user, • a mid-oscillation phase beginning when the first and second legs cross in the user's sagittal plane and ending when one knee of the first leg begins its descent towards the ground, • a final swing phase beginning when the knee of the first leg starts its descent towards the ground and ending with contact between the foot of the first leg and the ground, • a support phase beginning with contact between the foot of the first leg and the ground and ending when the first and second legs cross in the user's sagittal plane, • a mid-support phase beginning when the first and second legs cross in the user's sagittal plane and ending when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground, Determining the phase of the first gait cycle from among all the phases of the first gait cycle includes: • detection of an entry into the oscillation start phase when the angular velocity of the first actuator is zero after having been negative, • detection of an entry into the mid-oscillation phase when: • the angle of the first actuator is larger than the angle of the second actuator after having been smaller, and • the rotational speed of the first actuator is greater than a predetermined threshold rotational speed, • detection of an entry into the end-of-oscillation phase when the angular velocity of the first actuator is zero after having been positive, • detection of entry into the initial support phase when: • an impact with the terrain is detected, and • the duration since the detection of the entry into the end-of-oscillation phase is greater than a first predetermined duration, and • detection of an entry into the mid-support phase when the angle of the second actuator is greater than the angle of the first actuator after having been smaller, Walking is an activity that involves walking, and the slope of the terrain is negative, and at least one cycle of walking activity includes a second walking cycle, with the second walking cycle comprising a set of phases including: • a phase of initial downward oscillation beginning when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground and ending when the first leg and the second leg cross in the user's sagittal plane, • a downward oscillation phase beginning when the first and second legs cross in the user's sagittal plane and ending at the contact between the foot of the first leg and the ground, • a phase of initial support during descent, beginning at the contact between the foot of the first leg and the ground and ending when the first and second legs cross in the user's sagittal plane, • a downhill support phase beginning when the first and second legs cross in the user's sagittal plane and ending when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground, and Determining the phase of the second gait cycle from among all the phases of the second gait cycle includes: • detection of an entry into the onset phase of downward oscillation when: • an impact with the ground is detected for a lower limb including the second hip, and • the duration since the detection of the entry into the initial support phase is greater than a second predetermined duration, • detection of an entry into the downward oscillation phase when: • the angular velocity of the second actuator is zero after having been positive, and • the angular velocity of the first actuator is positive, • detection of entry into the initial downhill support phase when: • an impact with the ground is detected for a lower limb including the first hip, and • the duration since the detection of the entry into the onset phase of oscillation is greater than a third predetermined duration, and • detection of entry into the downhill support phase when: • the angular velocity of the first actuator is zero after having been positive, and • The angular velocity of the second actuator is positive; the determination of the terrain slope is carried out taking into account the angle of the first actuator when entering the initial support phase; the intensity modulation further includes an increase in the current intensity applied to the first and second actuators as the determined slope increases. The modulation of the current intensity applied to the first and second actuators according to the determined phase of the pedestrian activity cycle includes the modulation of the current intensity applied to the first and second actuators according to: • Determining the current pedestrian activity cycle from among: • the generic cycle, • the first walking cycle, • the second walking cycle, and • the determination of an entry into at least one phase of the detected cycle, Determining the period of pedestrian activity includes: • detection of entry into the period of onset of pedestrian activity when an acceleration data point measured by the six-axis inertial measurement unit is greater than a predetermined initial horizontal acceleration data point, • detection of entry into the mid-activity period when the duration since detection of entry into the early activity period exceeds a predetermined fourth duration, and • detection of entry into the end-of-pedestrian activity period when the calculated horizontal acceleration data is less than a second predetermined horizontal acceleration data point, The modulation of the current intensity applied to the first and second actuators according to the determined period of pedestrian activity includes: • when entry into the period of onset of pedestrian activity is detected, an increase in a regulatory factor of the modulated intensity of the current applied to the first and second actuators, the increase in the regulatory factor being carried out initially at a predetermined rate, starting at a value of zero and ending at a value equal to 1, • when entry into the period of mid-pedestrian activity is detected, the regulatory factor is maintained at a value of 1, and • when entry into the period of end of pedestrian activity is detected, a decrease in the regulation factor of the modulated intensity of the current applied to the first and second actuators, the decrease in the regulation factor being carried out in a second predetermined time and starting at the value equal to 1 and ending at the value zero.

[0015] Another aspect of the invention relates to an exoskeleton for assisting a user with a walking activity, comprising: • a suitable source of electrical energy to supply an electric current, • a first and second hip actuator adapted to assist a flexion and / or extension of the user's first and second hips, with the level of assistance dependent on the intensity of the electrical current applied to the first and second actuators. • a six-axis inertial measurement unit designed to be placed in the user's lumbar region and adapted to measure acceleration and angular velocity in the user's lumbar region, and • a processor configured to implement the method according to the invention.

[0016] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0017] The figures are presented for illustrative purposes only and are in no way limiting of the invention. • Fig. 1 is a synoptic diagram illustrating the steps of an example of the method for controlling an exoskeleton to a pedestrian activity according to the invention. • Figures 2, 5 and 12 are examples of finite state machines 200 compatible with the process according to the invention. • Figures 3 and 4 are synoptic diagrams illustrating the phases of example walking cycles compatible with the process according to the invention. • Figures 6 to 11 are examples of modulation of the intensity of the current applied to actuators compatible with the method according to the invention. DETAILED DESCRIPTION

[0018] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0019] Fig. 1 is a synoptic diagram illustrating the steps of an example of the process 100 according to the invention.

[0020] The method 100 can be implemented by a processor, a microprocessor, or a microcontroller. A microcontroller is a compact integrated circuit designed to manage a specific operation within an integrated system. A typical microcontroller includes a processor, memory, and input / output (I / O) peripherals on a single chip. For example, the method 100 can be implemented by a processor within a walking assistance exoskeleton. The exoskeleton comprises an electronic circuit (in one or more parts) equipped with at least one non-volatile memory and a processor for performing logic operations. It may also include one or more other memories, such as random access memory (RAM) or another type, such as Flash or microSD, and one or more other processors.The exoskeleton also includes an electrical power source, such as a battery, adapted to supply an electric current. This electric current is supplied to two hip actuators. The first and second hip actuators are adapted to assist flexion and / or extension of the user's first and second hips, respectively. In other words, the first hip actuator, for example, the left hip actuator, assists flexion and / or extension of the left hip, while the second hip actuator, for example, the right hip actuator, assists flexion and / or extension of the right hip. The level of assistance provided by each hip actuator depends on the intensity of the electric current applied to the first and second actuators.Thus, by modulating the intensity of the electrical current applied to the first and second actuators, the intensity of the assistance provided by the hip actuators is also modulated. The exoskeleton further includes a six-axis inertial measurement unit (IMU) designed to be placed in the user's lumbar region and adapted to measure the acceleration and angular velocity of the user's lumbar region. In this application, the term "lumbar region" refers to the area in the lower back of the user. This area corresponds to the five lumbar vertebrae and the surrounding muscle masses. The lumbar region is also commonly referred to as the lumbar area. Optionally, the exoskeleton may include two six-axis IMUs designed to be placed at each of the hip actuators. These two IMUs are adapted to measure [missing information]. acceleration and orientation of each of the user's hips. The term "hip" in this application refers to the hip joint. The hip, in this application, is therefore a ball-and-socket joint, or spheroid joint, structured around the round head of the femur and the acetabulum, which is part of the pelvis. The hip allows, in particular, flexion and extension movements. Hip flexion allows the femur to be raised towards the abdomen, or the torso to be brought towards the femur. Hip extension allows the femur to be moved away from the abdomen, or the torso to be moved away from the femur. In this application, the rotational speed of the hip actuators is positive during flexion of the user's hips and therefore negative during extension of the user's hips.

[0021] By "processor-implemented," it is meant that the steps, or virtually all of the steps, are executed by at least one processor or other similar system. Thus, some steps are carried out by the computer, possibly fully automatically or semi-automatically. In some examples, the triggering of at least some of the steps in the process can be achieved through user-computer interaction. The level of user-computer interaction required may depend on the intended level of automation and be balanced against the need to implement the user's requirements. In some examples, this level may be user-defined and / or predefined.

[0022] The method 100 is a method for controlling an exoskeleton to assist a user in a walking activity. The walking activity performed by the user can be one of the following: • a walk, • Nordic walking, i.e., walking with poles in nature, • a hike, • a race, • a snowshoe hike, • a ski touring ski,

[0023] The walking activity may, in particular, be carried out outdoors, on terrain comprising one or more slopes. The slope is the incline of the terrain and may correspond to a difference in height in meters, over a route, divided by the length of the route in meters. In the present application, the slope is negative when descending the route and positive when ascending the route.

[0024] A first step 110 of the process 100 includes the measurement of various data. In particular, step 110 makes it possible to obtain a measurement of the acceleration, along 3 axes and expressed in meters per second squared, and of the angular velocity, expressed in meters per second, of the user's lumbar region. These measurements are carried out by the An inertial measurement unit (IMU) is designed to be placed in the user's lumbar region. It should be noted that these measurements allow for the calculation of the user's lumbar region's orientation along three axes, expressed in a global coordinate system. When optional IMUs are used, these IMUs also measure the user's hip acceleration and orientation. It is also possible to measure the current applied to each actuator to ensure they are functioning correctly. Therefore, optionally, step 110 can also provide a measurement of the current applied to each actuator and / or a measurement of the angle and speed of rotation of each hip actuator.

[0025] All of these measurements can be carried out at a frequency between 100 and 1000 hertz, preferably between 800 and 850 hertz.

[0026] A second step 120 of the process 100 comprises determining several pieces of information concerning: • the ongoing walking activity, and • the terrain on which the walking activity takes place.

[0027] This information is determined from the measurements performed in step 110. This determined information can, for example, be used to implement a finite state machine to control the exoskeleton. Figure 2 is an example of a finite state machine 200 compatible with the process 100. This finite state machine comprises 7 states: • A state of alert 210, • A state 220 of soft start, • A state 230 of gradual cessation, • A 240 operating state, • A 250 transitional state between walking and downhill walking, • A state of 260 walking downhill, and • A 270 transitional state between walking downhill and walking.

[0028] The information determined in step 120 allows the transition from a first state to a second state. The possibility of transitioning from a first state to a second state is illustrated in [Fig. 2] by an arrow. The standby state 210 can be the initial state, that is, the state in which the exoskeleton is when it is switched on.

[0029] During this step 120, the phase of a walking activity cycle is determined. It should be noted that several sets of walking activity phases can be managed in parallel by process 100. For example, the different sets of phases in the walking activity cycle may depend on the type of walking activity or the characteristics of the terrain on which the walking activity is carried out. It should also be noted that this step can be used to determine a phase of a cycle for several sets of cycles. Thus, this step can consist of determining, in parallel, a first phase for a first set of cycle phases and a second phase for a second set of cycle phases. The phases of a walking activity cycle are determined for one lower limb of the user. In one example, the phases of a first walking activity cycle are determined for the user's first lower limb from measurements 110, and the phases of a second walking activity cycle are determined for the user's second lower limb also from measurements 110. In another example, the phases of a first walking activity cycle are determined for the user's first lower limb from measurements 110, and the phases of the second cycle are determined from the phases of the first walking activity cycle.Thus, process 100 allows us to determine 120 phases of a cycle of pedestrian activity for at least one lower limb or hip of the user, called the first hip.

[0030] In an example consistent with the preceding examples, a first walking activity cycle is a generic cycle. This walking activity cycle can be used for any type of walking activity. This generic cycle comprises two phases. The first phase of the generic cycle is a flexion phase. The flexion phase begins when the flexion of the first hip starts and ends when the flexion of the first hip ends, or equivalently, when the extension of the first hip begins. The detection of entry into the flexion phase can be performed using data measured by the first actuator. For example, it is possible to consider that the flexion phase begins when the angular velocity of the first actuator is zero or positive after having been negative. The second phase of the generic cycle is an extension phase.The extension phase begins when the extension of the first hip starts and ends when the extension of the first hip is complete, or equivalently, when flexion of the first hip begins. The entry into the extension phase can be detected using data measured by the first actuator. For example, the extension phase can be considered to begin when the angular velocity of the first actuator is zero or negative after having been positive.

[0031] In an example, compatible with the preceding examples, two other cycles of pedestrian activity can be used. These two cycles of pedestrian activity, called first and second walking cycles, are particularly suitable when the pedestrian activity is walking or hiking but can potentially also be adapted to other types of pedestrian activities.

[0032] A first walking cycle corresponds to walking on flat ground or uphill, that is, when the slope is zero or positive. An example of the first cycle of march is illustrated in [Fig.3] with a synoptic diagram comprising 5 phases noted 310 to 350 on [Fig.3].

[0033] A first phase 310 of the first gait cycle is a swing start phase. The swing start phase is considered the first phase of the first gait cycle. The swing start phase begins when a foot of the first leg, i.e., the leg including the first hip, is no longer in contact with the ground, more precisely the toe of the first leg, after having been in contact with the ground. The swing start phase ends when the first leg and a second leg, i.e., the leg including the second hip, cross in a sagittal plane of the user, after the first leg has been in front of the second leg in the user's sagittal plane. This event generally corresponds to the knee of the flying leg, i.e., in this case, the first leg, passing in front of the knee of the supporting leg, i.e., in this case, the second leg.Entry into the oscillation start phase is detected when the angular velocity of the first actuator is zero or positive after having been negative.

[0034] A second phase 320 of the first gait cycle is a mid-swing phase. The mid-swing phase begins when the first and second legs cross in the user's sagittal plane. The mid-swing phase ends when one knee of the first leg begins its descent toward the ground. Furthermore, when the gait cycle is disturbed by the terrain or modified by the user, it is sometimes possible for the mid-swing phase to end with the first leg's foot making contact with the ground. In this case, the end-swing phase is absent from the gait cycle. Entry into the mid-swing phase is detected when: • the angle of the first actuator is larger than the angle of the second actuator after having been smaller, and • the rotation speed of the first actuator is greater than a predetermined threshold rotation speed, for example greater than a rotation speed of 5 degrees per second.

[0035] A third phase 330 of the first walking cycle is a final swing phase. The final swing phase begins when the knee of the first leg starts its descent towards the ground. The final swing phase ends upon contact between the foot of the first leg and the ground. Entry into the final swing phase is detected when the angular velocity of the first actuator is zero or negative after having been positive.

[0036] A fourth phase 340 of the first gait cycle is a stance initiation phase. The stance initiation phase begins at the contact between the first foot leg and the ground. The initiation of the stance phase ends when the first and second legs cross in the user's sagittal plane, after the first leg has been behind the second leg in the user's sagittal plane. Entry into the initiation of the stance phase is detected when: • an impact with the ground, for example between the heel of the lower limb including the user's first hip and the ground, is detected, and • a duration since the detection of the entry into the end-of-oscillation phase is greater than a first predetermined duration, for example greater than a duration of 500 milliseconds.

[0037] It is worth noting that the impact with the ground can be detected during the final phase of oscillation, but also possibly during the mid-oscillation phase. Furthermore, alternatively, the second condition for entering the initial support phase can be a time elapsed since the detection of entry into the mid-oscillation phase, rather than the final phase.

[0038] A fifth phase 350 of the first gait cycle is a mid-stance phase. The mid-stance phase begins when the first and second legs cross in the user's sagittal plane, after the first leg has been behind the second leg in the user's sagittal plane. The mid-stance phase ends when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground. Entry into the mid-stance phase is detected when the angle of the second actuator is greater than the angle of the first actuator after having been smaller.

[0039] These five phases therefore follow one another to form the first walking cycle. In other words, when these five phases 310 to 350 are determined successively, a first complete walking cycle is determined.

[0040] The second walking cycle corresponds to walking downhill, that is, when the slope is negative. An example of the second walking cycle is illustrated in [Fig. 4] with a synoptic diagram comprising 4 phases labeled 410 to 440 on [Fig. 4].

[0041] A first phase 410 of the second gait cycle is a downhill oscillation initiation phase. The downhill oscillation initiation phase is considered the first phase of the second gait cycle. The downhill oscillation initiation phase begins when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground. The downhill oscillation initiation phase ends when the first and second legs cross in the user's sagittal plane, after the first leg has been in front of the second leg in the user's sagittal plane. Entry into the downhill oscillation initiation phase is detected when: • an impact with the ground is detected for a lower limb including the second hip, for example between the heel of the lower limb including the second hip and the ground, and • a duration since the detection of the entry into the start-of-support phase is greater than a second predetermined duration, for example greater than a duration of 100 milliseconds.

[0042] A second phase 420 of the second gait cycle is a downhill swing phase. The downhill swing phase begins when the first and second legs cross in the user's sagittal plane, after the first leg has been in front of the second leg in the user's sagittal plane. The downhill swing phase ends upon contact between the foot of the first leg and the ground. Entry into the downhill swing phase is detected when: • the angular velocity of the second actuator is zero or negative after having been positive, and • the angular velocity of the first actuator is positive.

[0043] A third phase 430 of the second gait cycle is a downhill stance initiation phase. The downhill stance initiation phase begins upon contact between the foot of the first leg and the ground. The downhill stance initiation phase ends when the first and second legs cross in the user's sagittal plane, after the first leg has been behind the second leg in the user's sagittal plane. Entry into the downhill stance initiation phase is detected when: • an impact with the ground is detected for a lower limb including the first hip, and • a duration since the detection of the entry into the onset of oscillation phase is greater than a third predetermined duration, for example greater than a duration of 100 milliseconds.

[0044] A fourth phase 440 of the second gait cycle is a stance initiation phase. The stance initiation phase begins when the first and second legs cross in the user's sagittal plane after the first leg has been behind the second leg in the user's sagittal plane. The stance initiation phase ends when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground. Entry into the stance initiation phase is detected when: • the angular velocity of the first actuator is zero or negative after having been positive, and • the angular velocity of the second actuator is positive.

[0045] These four phases therefore follow one another to form the second walking cycle. In other words, when these four phases 410 to 440 are determined successively, a complete second walking cycle is determined.

[0046] Step 2 120 of process 100 also includes determining a period of walking activity. In this application, the term "period of walking activity" refers to one of the following periods: • the beginning of walking activity, • an environment conducive to pedestrian activity, and • the end of a walking activity.

[0047] In an example, consistent with the preceding examples, the determination 120 The gait activity period includes the detection of entry into the gait onset period. Entry into the gait onset period can be detected when an acceleration value measured by the six-axis inertial measurement unit (IMU) exceeds a predetermined initial horizontal acceleration value, for example, a horizontal acceleration of 0.75 meters per second squared. Alternatively, for the first gait cycle, entry into the gait onset period can be detected when entries into the mid-swing and stance onset phases have been detected.

[0048] In an example consistent with the preceding examples, the determination 120 of the period of pedestrian activity includes the detection of entry into the mid-period of pedestrian activity. Entry into the mid-period of pedestrian activity can be detected when a duration since the detection of entry into the start period of pedestrian activity is greater than a fourth predetermined duration, for example, greater than a duration of 200 milliseconds.

[0049] In one example, consistent with the preceding examples, the determination 120 of the period of walking activity includes the detection of entry into the period of end of walking activity. Entry into the period of end of walking activity can be detected when the calculated horizontal acceleration data is less than a predetermined horizontal acceleration data point, for example, less than a horizontal acceleration of 0.75 meters per second squared.

[0050] The second step 120 of the process 100 finally includes determining the slope of a terrain on which the pedestrian activity is carried out.

[0051] In an example consistent with the preceding examples, the determination of the terrain slope is carried out by taking into account the angle of the first actuator upon entering the initial support phase. It is possible to consider, by convention, that the angle of the first actuator is minimal, i.e., close to zero degrees, for a full extension of the user's first hip, and that the angle of the first actuator is maximal, i.e., close to 180 degrees, for flexion complete of the user's first hip. By respecting this convention, it is possible, for example, to determine that: The slope of the terrain increases when the angle of the first actuator during the initial support phase increases. the slope of the terrain decreases when the angle of the first actuator during entry into the initial support phase decreases.

[0052] In an example, consistent with the preceding examples, the determination of the The slope of the terrain can also be determined by using the current operating cycle. Figure 5 illustrates an example of a finite state machine 500, allowing the determination of whether the current operating cycle is the first operating cycle, labeled 510 in Figure 5, or the second operating cycle, labeled 520 in Figure 5. The transition from state 510, corresponding to the first operating cycle, to state 520, corresponding to the second operating cycle, is permitted when: a second complete walking cycle is determined during a fifth predetermined duration, for example a duration of 1300 milliseconds, and the angle of the first and second hip actuators are greater than a predetermined angle, for example greater than 10 degrees respecting the convention described previously.

[0053] The transition from state 520, corresponding to the second operating cycle, to state 510, corresponding to the first operating cycle, may be permitted when: a second complete walking cycle is not determined during the fifth predetermined duration, for example a duration of 1300 milliseconds, and the angle of the first hip actuator is less than a predetermined angle, for example less than 10 degrees, respecting the convention described previously.

[0054] Referring back to [Fig. 2], the transition from state 210 to state 220 can be permitted when entry into the start of the walking activity period is detected. The transition from state 220 to state 230, from state 260 to state 230, and from state 240 to state 230 can be permitted when entry into the end of the walking activity period is detected. The transition from state 220 to state 240 can be permitted when entry into the middle of the walking activity period is detected. The transition from state 240 to state 250 can be permitted when the second walking cycle is the current walking activity cycle detected. The transition from state 250 to state 260 can be allowed when the duration in state 250 exceeds a predetermined duration, for example, 1.3 seconds. The transition from state 260 to state 270 can be allowed when the first walking cycle is the currently detected walking activity cycle.The transition from state 270 to state 240 may be allowed when a duration in state 250 is greater than . a predetermined duration, for example greater than 1000 and preferably 2500 milliseconds.

[0055] A third step 130 of the process 100 includes modulating the intensity of the current supplied by the energy source. In other words, step 130 involves modifying the intensity of the current applied to the hip actuators. The modulation is therefore performed according to the determined phase of the walking activity cycle, the determined period of the walking activity, and the determined slope of the terrain.

[0056] In an example, consistent with the preceding examples, the modulation 130 The intensity of the current applied to the actuators also depends on a user-defined assistance level. For example, the user can choose a light, moderate, or high assistance level before or during the walking activity.

[0057] In an example consistent with the preceding examples, the modulation 130 of the current intensity applied to the actuators, according to the determined phase of the walking activity cycle, is performed based on the determination of the current walking activity cycle from among: • the generic cycle, • the first walking cycle, and • the second walking cycle.

[0058] Furthermore, in this example, when the walking activity cycle is determined, the current intensity applied to the actuators can also be modulated based on the detection of an entry into at least one phase of the cycle. Figure 6 is a graph illustrating an example of modulating the current intensity applied to the actuators for the first walking cycle. The vertical axis represents the normalized intensity of the assistance provided by the hip actuator. The horizontal axis represents time, normalized as a function of the total time of the first walking cycle. The stance period is denoted 610 on Figure 6, with the peak of the stance period denoted 620. The swing period is denoted 630 on Figure 6, with the peak of the swing period denoted 640. Figure 7 is a graph illustrating an example of modulating the current intensity applied to the actuators for the second walking cycle.The vertical axis represents the normalized intensity of the assistance provided by the hip actuator. The horizontal axis represents time, normalized to the total time of the first gait cycle. The stance onset period is denoted 710 in [Fig. 7]. The stance period is denoted 720 in [Fig. 7], with the peak of the stance period denoted 730. The swing period is denoted 740 in [Fig. 7], with the peak of the swing period denoted 750. Modulating the current intensity applied to the actuators based on the detection of an input in at least one phase of the cycle can, for example, include time deformation. of a predefined modulation of the current intensity according to the timing of the detected events. For example, compared to [Fig.7], when the support period 720 is twice as long relative to the walking cycle as the support period 720 of the graph of [Fig.7], the transition from a current intensity equal to -1 to a current intensity of zero does not take place over a period equal to 10% of the walking cycle but over a period equal to 20% of the walking cycle.

[0059] In one example, consistent with the preceding examples, the modulation 130 of the current intensity applied to the actuators as a function of the determined slope further includes an increase in the current intensity as the determined slope increases. [Fig. 8] is a graph 800 illustrating five examples of a linear increase in the current intensity applied to the actuators, represented by the vertical axis and expressed in amperes, as a function of the hip angle at the beginning of the stance phase, represented by the horizontal axis and expressed in degrees. The choice between these five examples depends, for example, on the level of assistance determined by the user. [Fig. 9] is a graph 900 illustrating three examples of a non-linear increase in the current intensity applied to the actuators, represented by the vertical axis and expressed in amperes, as a function of the hip angle at the beginning of the stance phase, represented by the horizontal axis and expressed in degrees.The choice between these three examples may also depend on the level of assistance determined by the user.

[0060] In an example consistent with the preceding examples, the modulation 130 of the current intensity applied to the actuators as a function of the determined period of pedestrian activity includes an increase in a regulation factor of the modulated current intensity applied to the actuators when entry into the pedestrian activity start period is detected. The regulation factor is thus used as a factor of the modulated current intensity that is applied to the actuators. In other words, when the factor is zero, the current applied to the actuators is zero, and when the factor is equal to 1, the current applied to the actuators is the current modulated according to the other parameters. The increase in the regulation factor is, for example, carried out over a predetermined initial time, for example, equal to 2 seconds. The increase begins at a value of zero and ends at a value equal to 1. The [Fig.

[10] illustrates an example of a linear increase in the current intensity applied to the actuators, represented by the vertical axis and expressed in amperes, as a function of time, represented by the horizontal axis and expressed in seconds, from the detection of entry into the period of onset of pedestrian activity.

[0061] In this example, the modulation 130 of the current intensity applied to the actuators as a function of the determined period of pedestrian activity also includes maintaining the regulation factor at a value equal to 1 when entering the mid-period pedestrian activity is detected and for the entire duration of the mid-period pedestrian activity.

[0062] In this example, the modulation 130 of the current intensity applied to the actuators as a function of the determined period of pedestrian activity includes a decrease in the regulation factor of the modulated current intensity applied to the actuators when entry into the end-of-pedestrian activity period is detected, and for the entire duration of the middle-of-pedestrian activity period. The decrease in the regulation factor is carried out in a predetermined second time, for example, 0.5 seconds. The decrease in the regulation factor begins at a value of 1 and ends at a value of 0. Figure 1100 illustrates a linear decrease in the current intensity applied to the actuators, represented by the vertical axis and expressed in amperes, as a function of time, represented by the horizontal axis and expressed in seconds, from the detection of entry into the end-of-pedestrian activity period.

[0063] A fourth step 140 of the method 100 comprises applying the modulated current to the hip actuators. For example, a first electric current is modulated for the first actuator using the method 100, and a second electric current is modulated, in parallel, according to the modulation of the first actuator. In another example, two methods 100 are implemented in parallel to control an exoskeleton. Thus, a first electric current is modulated for the first actuator with the first implementation of the method 100, and a second electric current is modulated for the second actuator with the second implementation of the method 100.

[0064] Fig. 12 is an example of a finite state machine compatible with process 100. The state machine 1200 takes as input the measurements made in step 110 and provides as output a current intensity 1220 to be applied to the hip actuators. These measurements are provided to a module, designated 1230, comprising finite state machines 200, 300, and 400, and modifying the current intensity according to examples 600 and 700. This module modulates the current intensity applied to the actuators based on the phase of the detected pedestrian activity cycle. Subsequently, the measurements taken in step 110, the modulated current intensity, and the information determined by module 1230 are transmitted to module 1240, which modulates the current intensity applied to the actuators based on the detected period of pedestrian activity. This module 1240 modifies the current intensity according to examples 800 or 900.Finally, the measurements taken in step 110, the intensity of the modulated current as well as the information determined by modules 1230 and 1240 are transmitted to module 1250 which allows the intensity of the current applied to the actuators to be modulated according to the detected slope. This module 1240. includes in particular the finite state machine 500 and modifies the current intensity according to examples 1000 and 1100.

Claims

Demands

1. Method (100) of controlling a user's walking assistance exoskeleton, the exoskeleton comprising: - a suitable source of electrical energy to supply an electric current, - a first and a second hip actuator adapted to assist flexion and / or extension respectively of a first and a second hip of the user, the intensity of assistance being dependent on the intensity of the electrical current applied to the first and second actuators, - a six-axis inertial measurement unit designed to be placed in the user's lumbar region and adapted to measure the acceleration and angular velocity of the user's lumbar region, - a processor configured to implement the process (100), the process (100) comprising the steps of: - measurement (110): • of an acceleration and angular velocity of the user's lumbar region by the six-axis inertial measurement unit, and • of an angle and a rotational speed of the first and second actuators, the rotational speed of the first and second actuators being positive during hip flexion of the user, - determination (120), from the measurements (110): • of a phase of a walking activity cycle from among at least one set of phases of the walking activity cycle, the at least one walking activity cycle being defined for the user's first hip, • of a period of walking activity among: • the beginning of walking activity, • an environment conducive to pedestrian activity, and • the end of a walking activity, and • of a slope of land on which the activity The pedestrian route is constructed with the terrain slope being negative during a descent and positive during an ascent. - modulation (130) of the intensity of the current supplied by the energy source as a function of the determined phase of the pedestrian activity cycle, the determined period of the pedestrian activity, and the determined slope of the terrain, and - application (140) of the modulated current to the first and second hip actuators.

2. A method according to claim 1 wherein the modulation (130) of the intensity of the current applied to the first and second hip actuators is further carried out according to a level of assistance determined by the user.

3. A method according to claim 1 or 2 wherein: - Walking is one activity among: • a walk, • Nordic walking, • a hike, • a race, • a snowshoe hike, • a ski touring ski, and - at least one cycle of the walking activity includes a generic cycle with all the phases of the generic cycle including: • a flexion phase beginning when flexion of the first hip begins and ending when extension of the first hip begins, • an extension phase beginning when first hip extension begins and ending when first hip flexion begins, and - the determination (120) of the generic cycle phase The following are among the phases of the walking activity cycle: • detection of entry into the bending phase when the angular velocity of the first actuator is zero after having been negative, and

4. • detection of an entry into the extension phase when the angular velocity of the first actuator is zero after having been positive. A method according to any one of the preceding claims, wherein: - Walking is a form of walking, and - the slope of the terrain is zero or positive, and - at least one cycle of walking activity includes an initial walking cycle, with the initial walking cycle comprising a set of phases including: • an initial oscillation phase beginning when one foot of the first leg, including the first hip, is no longer in contact with the ground after having been in contact with the ground, and ending when the first leg and a second leg, including the second hip, cross in a sagittal plane of the user, • a mid-oscillation phase beginning when the first and second legs cross in the user's sagittal plane and ending when one knee of the first leg begins its descent towards the ground, • a final swing phase beginning when the knee of the first leg starts its descent towards the ground and ending with contact between the foot of the first leg and the ground, • a support phase beginning with contact between the foot of the first leg and the ground and ending when the first and second legs cross in the user's sagittal plane, • a mid-support phase beginning when the first and second legs cross in the user's sagittal plane and ending when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground, - the determination (120) of the phase of the first walking cycle among all the phases of the first walking cycle includes: • detection of an entry into the oscillation start phase when the angular velocity of the first actuator is zero after having been negative, • detection of an entry into the mid-oscillation phase when: • the angle of the first actuator is larger than the angle of the second actuator after having been smaller, and • the rotational speed of the first actuator is greater than a predetermined threshold rotational speed, • detection of an entry into the end-of-oscillation phase when the angular velocity of the first actuator is zero after having been positive, • detection of entry into the initial support phase when: • an impact with the terrain is detected, and • a duration since the detection of the entry into the end-of-oscillation phase is greater than a first predetermined duration, and • detection of an entry into the mid-support phase when the angle of the second actuator is greater than the angle of the first actuator after having been smaller.

5. A method according to any one of claims 1 to 3 in which : Walking is an activity that involves walking, and the slope of the terrain is negative, and at least one cycle of walking activity includes a second walking cycle, with the second walking cycle comprising a set of phases including: • a phase of initial downward oscillation beginning when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground and ending when the first leg and the second leg cross in the user's sagittal plane, • a downward oscillation phase beginning when the first and second legs cross in the user's sagittal plane and ending at the contact between the foot of the first leg and the ground, • a phase of initial support during descent, beginning at the contact between the foot of the first leg and the ground and ending when the first and second legs cross in the user's sagittal plane, • a downhill support phase beginning when the first and second legs cross in the user's sagittal plane and ending when the foot of the first leg is no longer in contact with the ground after having been in contact with the ground, and the determination (120) of the phase of the second walking cycle among all the phases of the second walking cycle includes: • detection of an entry into the onset phase of downward oscillation when: • an impact with the ground is detected for a lower limb including the second hip, and • the duration since the detection of the entry into the initial support phase is greater than a second predetermined duration, • detection of an entry into the downward oscillation phase when: • the angular velocity of the second actuator is zero after having been positive, and • the angular velocity of the first actuator is positive, • detection of an entry into the downhill support phase when: • an impact with the ground is detected for a lower limb including the first hip, and • a time since the detection of the entry into the downhill oscillation phase is greater than a third predetermined time, and • detection of an entry into the downhill support phase when: • the angular velocity of the first actuator is zero after having been positive, and • the angular velocity of the second actuator is positive.

6. Method according to claims 4 or 5 wherein the determination (120) of the slope of the ground is carried out taking into account the angle of the first actuator when entering the start-up phase of support.

7. Method according to the preceding claim wherein the intensity modulation (130) further comprises an increase in the current intensity applied to the first and second actuators when the determined slope increases.

8. A method according to any one of claims 4 to 7 wherein the modulation (130) of the intensity of the current applied to the first and second actuators as a function of the determined phase of the walking activity cycle comprises the modulation of the intensity of the current applied to the first and second actuators as a function of: - the determination of the current walking activity cycle among: • the generic cycle, • the first walking cycle, • the second walking cycle, and - the determination of an entry into at least one phase of the detected cycle.

9.

10. A method according to any one of the preceding claims, wherein the determination (120) of the period of pedestrian activity comprises: - detection of entry into the period of onset of pedestrian activity when an acceleration data measured by the six-axis inertial measurement unit is greater than a predetermined initial horizontal acceleration data, - detection of entry into the mid-activity period when the time elapsed since the detection of entry into the early activity period exceeds a predetermined fourth time period, and - detection of an entry into the period of end of pedestrian activity when the calculated horizontal acceleration data is less than a second predetermined horizontal acceleration data. A method according to the preceding claim, wherein the modulation (130) of the intensity of the current applied to the first and second actuators as a function of the determined period of pedestrian activity comprises: - when entry into the period of onset of pedestrian activity is detected, an increase in a regulation factor of the modulated intensity of the current applied to the first and second actuators, the increase in the regulation factor being carried out in a predetermined time and starting at a value of zero and ending at a value equal to 1, - when entry into the period of mid-pedestrian activity is detected, the regulatory factor is maintained at a value of 1, and - when entry into the period of end of pedestrian activity is detected, a decrease in the regulation factor of the modulated intensity of the current applied to the first and second actuators, the decrease in the regulation factor being carried out in a second predetermined time and starting at the value equal to 1 and ending at the value zero.

11. Exoskeleton to assist a user in a walking activity, comprising: - a suitable source of electrical energy to supply an electric current, - a first and a second hip actuator adapted to assist flexion and / or extension of the user's first and second hips, the intensity of assistance being dependent on the intensity of the electrical current applied to the first and second actuators, - a six-axis inertial measurement unit designed to be placed in the user's lumbar region and adapted to measure acceleration and angular velocity in that region, and - a processor configured to implement the method according to any one of the preceding claims.

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