Patent Description:
Various solutions exist for controlling lower-limb prosthetic and orthotic devices ("POD"). Typical solutions are limited by high cost of the components, the high level of integration required with the POD, and the reduction in performance due to various constraints associated with POD. These and other approaches inadequately deal with the asymmetry of acceleration spikes in transitioning from swing-to-stance versus stance-to-swing. This introduces complexity by relying heavily on advanced signal processing and interpretation. Therefore, improvements in controlling POD's based on ground contact detection are desirable.

<CIT> discloses a sensor device for a prosthesis, in particular for a leg prosthesis, that is provided for measuring forces acting on the prosthesis, having a ring-shaped outer member of closed construction and an inner member connecting two opposite inner sides of the outer member having a sensor element for measuring the force acting in the direction of the connecting axis. The outer member deforms under the action of a bending moment while the inner member feels only the axial force acting in the direction of its connecting axis. By this means measurement of the axial force unaffected by bending moments is possible. Furthermore, the sensor device is able to transmit loads.

<CIT> discloses a sensor assembly that is provided for measuring forces and/or torques which are transmitted by means of a rigid transmitter having a first part and a second part. The sensor assembly includes a first connection, a second connection, electromechanical sensor elements, a first flange, a second flange and a plurality of struts. The first and second connections are connectable to the first and second parts of the transmitter, respectively. The electromechanical sensor elements convert mechanical parameters into electrical parameters. The first flange surrounds the first connection and originates at the first connection. The second flange is aligned substantially parallel to the first flange. The second connection is arranged on the second flange and has a first surface and a second surface. The plurality of struts are substantially perpendicular to the first flange and connect the first flange to the second flange. A gap is formed between the first flange, the second flange and the struts, and is larger than a width of the struts. The electromechanical sensor elements are designed for determining strains or compressions and are arranged next to the plurality of struts on at least one of the first and second surfaces of the second flange.

<CIT> discloses prosthetic and/or orthotic devices (PODS), control systems for PODS and methods for controlling PODS. As part of the control system, an inference layer collects data regarding a vertical and horizontal displacement of the POD, as well as an angle of the POD with respect to gravity during a gait cycle of a user of the POD. A processor analyzes the data collected to determine a locomotion activity of the user and selects one or more control parameters based on the locomotion activity. The inference layer may be situated between a reactive layer control module and a learning layer control module of the control system architecture.

<CIT> discloses a prosthetic foot that can include an attachment member, at least one first brace, at least one first flexible member, an unpowered actuator, at least one second brace, and at least one second flexible member. The attachment member can include a connector configured to connect the attachment member to a user or another prosthetic device. The at least one first brace can mount to the attachment member and the at least one first flexible member can connect to the attachment member by the at least one first brace such that a force between the ground and the attachment member can be supported by the at least one first flexible member. The unpowered actuator can mount to the attachment member and the at least one second brace can be mounted to the actuator. The at least one second flexible member can connect to the attachment member by the at least one second brace such that a force between the ground and the attachment member can be supported by the at least one second flexible member.

The embodiments disclosed herein each have several aspects no single one of which is solely responsible for the disclosure's desirable attributes. Without limiting the scope of this disclosure, its more prominent features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description," one will understand how the features of the embodiments described herein provide advantages over existing systems, devices and methods for detecting ground contact to control a lower-limb prosthetic or orthotic device ("POD").

The following disclosure describes non-limiting examples of some embodiments. For instance, other embodiments of the disclosed systems and methods may or may not include the features described herein. Moreover, disclosed advantages and benefits can apply only to certain embodiments of the invention and should not be used to limit the disclosure.

Features for systems, devices and methods for detecting ground contact with a lower-limb POD are described. A sensor array for the lower-limb POD may include two or more sensors, which may be non-contact displacement sensors, that can determine a change in distance between a moving part and a non-moving part of the lower-limb POD. A moving part or a non-moving part of the POD may support the sensors. Ground contact with the lower-limb POD may cause the offset distance between the moving part and the non-moving part to change. For instance, the distance from each of the sensors to respective target portions of the other body, such as respective portions of the moving body, respective magnets, or other respective targets, may be detected by the sensors. The sensors detect the change in this offset distance and generate data indicative of the load applied to the prosthetic device, which may be used to determine control signals for the lower-limb POD. A control system having a processor and memory may be used to receive and analyze the data, and generate the control signals accordingly. Various control approaches for lower-limb POD's based on the use of an array of non-contact sensors are described.

Various aspects and embodiments thereof described herein include, among other things, the use of a sensor array in a ground contact sensor with a selectively compliant mechanical structure. Further, the sensors are positioned in locations within the array configuration so as to maximize ground contact sensing system sensitivity to the loads observed during typical amputee ambulation. Further, a subset of the sensors may be used for sensor signals fusion and integration. Further, the system includes the capacity to integrate redundant sensing and allow recovering in case of sensor failure.

The various aspects and embodiments thereof described herein have various advantages. For example, limitations arising from ground contact structure overload are removed or reduced. Further, sensor sensitivity around the zero-load point up to the physiologically relevant load points is maximized or otherwise increased. Further, discrimination between torque loads and axial loads is possible, for instance by showing reduced mechanical response to torque loads. Further, requirements for precision in positioning the prosthetic device components in assembly and installation is reduced, for example by producing data showing the same sensitivity level for all load cases. Further, detection and identification of load progression direction is possible. Various other advantages are described in further detail herein.

In one aspect, a ground-contact sensor array for a lower limb prosthetic device is described that comprises a first body, a second body, and a plurality of sensors. The first body is configured to attach to a distal portion of a shank of the lower limb prosthetic device and has a first portion configured to remain stationary relative to the shank, with the first body comprising a second portion configured to compress in response to a ground contact load applied to the lower limb prosthetic device. The second body is moveably attached to and located distally of the first body and comprises a distal connector configured to attach to a prosthetic foot or ankle, with the second body configured to translate and/or rotate relative to the first body in response to the ground contact load applied to the lower limb prosthetic device to cause the second portion of the first body to compress. The plurality of sensors is coupled with a proximal portion of the first body and is configured to generate data related to a plurality of distances from the plurality of sensors to respective target portions of the second body in response to translation and/or rotation of the second body relative to the first body and/or in response to compression of the second portion of the first body, where the data is indicative of location of the second body relative to the first body, which is indicative of ground contact by the lower limb prosthetic device. In some embodiments, the plurality of sensors comprises Hall effect sensors and the respective target portions of the second body comprise magnets.

In another aspect, a ground-contact sensor array for a lower limb prosthetic device is described. The ground-contact sensor array comprises a first body, a second body, and a plurality of sensors. The first body is configured to attach to a shank of the lower limb prosthetic device. The second body is moveably attached to the first body and comprises a distal connector configured to attach to a prosthetic foot or ankle. The plurality of sensors is coupled with the first or second body and configured to generate data related to a plurality of distances between the first and second body.

Various embodiments of the various aspects describe herein may be implemented. The plurality of sensors may be coupled with the first body. The plurality of sensors may comprise non-contact distance sensors coupled with the first or second body and configured to generate data related to a plurality of distances to respective portions of the other of the first or second body. The ground-contact sensor array may further comprise a plurality of magnets coupled with the first or second body, where the plurality of sensors comprises a plurality of Hall effect sensors coupled with the other of the first or second body, and where each Hall effect sensor is configured to generate data related to a respective distance to a respective magnet.

The data related to a plurality of distances may comprise first data related to a plurality of first distances and second data related to a plurality of second distances, where the first or second data are generated in response to a non-inertial load applied to the lower limb prosthetic device, and where the first and second data are indicative of at least one of the plurality of first distances being different than at least one of the plurality of second distances. The plurality of sensors may be arranged in a transverse plane. The first body may be configured to not move relative to the shank and the second body may be configured to move relative to the first body.

The first body may comprise a selectively compliant structure. The selectively compliant structure may comprise a first pair of beams and a second pair of beams. The first pair of beams may be located on a medial side of the first body and extend in an anterior-posterior direction, with each beam of the first pair of beams spaced axially apart from each other. The second pair of beams may be located on a lateral side of the first body and extend in the anterior-posterior direction, with each beam of the second pair of beams spaced axially apart from each other. The ground-contact sensor array may further comprise a first bridge axially connecting the first pair of beams and a second bridge axially connecting the second pair of beams.

The data related to a plurality of distances between the first and second body may be generated in response to a ground-contact load applied to the first or second body during a stance phase of a gait cycle. The plurality of sensors may be configured to generate data related to a predetermined plurality of axial distances between the first and second body when no load is exerted on the second body.

The first body and second body may define a plurality of gaps therebetween. The plurality of gaps may be located between anterior and posterior ends of the first and second bodies. The gaps may change in size in response to relative movement between the first and second body. The first body may be attached to a raised surface of the second body located between the plurality of gaps.

In another aspect, a ground-contact sensor array for a lower limb prosthetic device is described. The ground-contact sensor array comprises a first body, a second body, and a plurality of sensors. The first body is configured to attach to a first portion of a lower limb prosthetic device that is located proximally of the first body. The second body is moveably attached to the first body and is configured to attach to a second portion of the lower limb prosthetic device that is located distally of the second body. The plurality of sensors is attached to the first or second body, and each sensor is configured to detect a respective distance between the sensor and a respective target of the other of the first or second body.

Various embodiments of the various aspects describe herein may be implemented. The plurality of sensors may be attached to the first body and each sensor may be configured to detect a respective distance between the sensor and the respective target of the second body. The respective target may comprise a respective portion of the other of the first or second body. The plurality of sensors may comprise a plurality of Hall effect sensors and the respective target may comprise a respective magnet. The plurality of sensors may be configured to generate a first set of data based at least on location of the first body relative to the second body, where the plurality of sensors are positioned in an array such that the first set of data represent distances at different locations to the other of the first or second body, and where the first set of data is representative of amount of load applied to different locations of the moving body and thereby provide a load pattern across the second body.

In another aspect, a lower limb prosthetic device is described comprising any of the ground-contact sensor arrays herein. The lower limb prosthetic device having the ground-contact sensor array may further comprise a prosthetic hip portion, a prosthetic thigh portion, a prosthetic shank portion, a prosthetic ankle portion, and/or a prosthetic foot portion.

In another aspect, a method of detecting ground-contact by a lower limb prosthetic device is described. The method comprises detecting first data related to a plurality of first distances between each sensor of a plurality of sensors and a moving body of the lower limb prosthetic device, detecting second data related to a plurality of second distances between each sensor of the plurality of sensors and the moving body of the lower limb prosthetic device, and determining that the lower limb prosthetic device has contacted ground based on the first and second data.

Various embodiments of the various aspects describe herein may be implemented. The method may further comprise detecting, using each of the plurality of sensors, a magnetic field generated by a plurality of magnets, determining a magnitude of the magnetic field detected by each of the plurality of sensors, and calculating the plurality of second distances based at least on the magnitude of the magnetic field.

In another aspect, a non-transitory computer readable medium is described. The non-transitory computer readable medium has stored thereon a set of instructions that when executed by a processor performs a method for determining a load pattern of a load applied to a lower limb prosthetic device. The method may comprise the above methods or any of the other methods described herein. In some embodiments, the method comprises measuring a first set of data using a plurality of sensors, the plurality of sensors coupled to a non-moving body of the prosthetic device and axially spaced apart at a predetermined distance from a moving body of the prosthetic device, the first set of data representative of relative motion between the non-moving body and the moving body of the prosthetic device, the moving body and the non-moving body coupled via a connector comprising a selectively compliant structure configured to resiliently flex under a load applied to the moving body. The method further comprises determining a second set of data using the first set of data, the second set of data comprising a plurality of electronic signals from the plurality of sensors, each of the plurality of electronic signals corresponding to an amount of load applied to different areas of the moving body of the prosthetic device, thereby providing a load pattern across the moving body of the prosthetic device. When a load is applied to the moving body, the selectively compliant structure resiliently flexes to change the distance between the plurality of sensors and the moving body. The change in the distance between the plurality of sensors and the plurality of actuators is representative of the relative motion between the non-moving body and the moving body.

In some embodiments, the method performed by the processor comprises calculating a plurality of first distances between each sensor of a plurality of sensors and a moving body of the lower limb prosthetic device, the plurality of sensors coupled to a non-moving body of the lower limb prosthetic device. The method further comprises calculating a plurality of second distances between each of the sensors of the plurality of sensors and the moving body of the lower limb prosthetic device, determining differences between each of the plurality of first distances and each of the plurality of second distances, and analyzing data related to the differences between each of the plurality of first distances and each of the plurality of second distances. The method further comprises determining that the lower limb prosthetic device has contacted ground in response to analyzing the data related to the between each of the plurality of first distances and each of the plurality of second distances.

In another aspect, a non-transitory computer readable medium is described having stored thereon a set of instructions that, when executed by a processor, performs the methods described herein for determining a load pattern of a load applied to a lower limb prosthetic device. The method performed may comprise measuring a first set of data using a plurality of sensors, with the plurality of sensors coupled to a non-moving body of the prosthetic device and axially spaced apart at a predetermined distance a moving body of the prosthetic device, the first set of data representative of relative motion between the non-moving body and the moving body of the prosthetic device, and the moving body and the non-moving body coupled via a connector comprising a selectively compliant structure configured to resiliently flex under a load applied to the moving body. The method may further comprise determining a second set of data using the first set of data, the second set of data comprising a plurality of electronic signals from the plurality of sensors, each of the plurality of electronic signals corresponding to an amount of load applied to different areas of the moving body of the prosthetic device, thereby providing a load pattern across the moving body of the prosthetic device. When a load is applied to the moving body, the connector may resiliently flex to change the distance between the plurality of sensors and the moving body, and the change in the distance between the plurality of sensors and the moving body may be representative of the relative motion between the non-moving body and the moving body.

According to another aspect of the present disclosure, a sensor assembly for a prosthetic device is described. The sensor assembly for a prosthetic device can include a connector comprising a selectively compliant structure disposed between a moving body and a non-movable body of the prosthetic device. The selectively compliant structure can move relative to the non-moving body. The selective compliant structure can include a first pair of blades disposed on a medial side of the connector and extending in an anterior-posterior direction. The first pair of planar blades can be spaced apart from each other. The selectively compliant structure can further include a second pair of blades disposed on a lateral side of the connector and extending in an anterior-posterior direction. The second pair of planar blades can be spaced apart from each other. The blades may flex to provide the relative movement between the bodies. The sensor assembly can further include a plurality of sensors coupled to the non-moving body. The plurality of sensors can be positioned in an array and sense the relative movement between the moving body and the non-moving body. The sensor assembly can further include a plurality of magnets coupled to the moving body. The plurality of magnets can be positioned at a predetermined axial distance from the plurality of sensors of the non-moving body when no load is exerted on the moving body. The first and the second pair of blades can resiliently flex to allow a relative movement between the connector and the non-moving body when the moving body is under a load. Each of the plurality of sensors can generate a first set of data based at least of the relative movement. The plurality of sensors can be positioned in an array such that the plurality of sensors represent different locations of the moving body. The first set of data can represent amount of load applied to different locations of the moving body, thereby indicating a load pattern across the moving body.

According to another aspect of the present disclosure, a method of determining a load pattern of a load applied to a lower limb prosthetic device is described. The method can include measuring a first set of data using a plurality of sensors. The plurality of sensors can be coupled to a non-moving body of the prosthetic device and axially spaced apart at a predetermined distance from a moving body of the prosthetic device. The moving body of the prosthetic device can comprise a plurality of magnets. The first set of data can represent relative motion between the non-moving body and the moving body of the prosthetic device, where the moving body and the non-moving body can be coupled via a connector that can resiliently flex under a load applied to the moving body. The method can further include determining a second set of data using the first set of data. The second set of data can include a plurality of electronic signals from the plurality of sensors, where magnitude of each of the plurality of electronic signals can correspond to an amount of load applied to different areas of the moving body of the prosthetic device. The second set of data can thereby provide a load pattern across the moving body of the prosthetic device. When a load is applied to the moving body, the connector can resiliently flex to change the distance between the plurality of sensors and the plurality of magnets. The change in the distance between the plurality of sensors and the plurality of magnets can represent the relative motion between the non-moving body and the moving body.

The foregoing and other features of the present development will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the development and are not to be considered limiting of its scope, the development will be described with additional specificity and detail through use of the accompanying drawings. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the scope of the subject matter presented here. It will be readily understood that the aspects of the present development, as generally described herein, and illustrated in the drawings, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

The following detailed description is directed to certain specific embodiments of the development. In this description, reference is made to the drawings wherein like parts or steps may be designated with like numerals throughout for clarity. Reference in this specification to "one embodiment," "an embodiment," or "in some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrases "one embodiment," "an embodiment," or "in some embodiments" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. Similarly, various requirements are described which may be requirements for some embodiments but may not be requirements for other embodiments.

Features for systems, devices and methods for detecting ground contact with a lower-limb POD are described. The lower-limb POD may include a first body and a second body. A sensor array for the lower-limb POD may include two or more sensors, such as non-contact displacement or other type sensors, coupled to the first or second body. The first and second bodies may be offset from each other and configured for relative movement between the bodies. The first body may move relative to the second body of the supporting structure, or vice versa, to change the offset distance between the sensors and the other of the first or second body. The first or second body may include one or more target portions sensed by the sensors. In some embodiments, the sensors are Hall Effect sensors and the target portions are magnets. Load data may be generated for control of the POD, such as for stance phase control. Control signals are generated based on the load data. In some embodiments, control signals are generated based on a magnetic field generated by the magnets and detected by the Hall Effect Sensors. Various control approaches for lower-limb POD's based on the use of an array of non-contact sensors are described.

The ground contact sensing techniques described herein allow for robust and high performance control of lower-limb POD's. The POD's may implement stance phase control with data from the ground contact sensing. Swing phase control may also be more robust when based on the ground contact sensing. Aspects described herein present a ground contact sensor array wherein a selectively compliant mechanical structure may be used. This may, for example, minimize the impacts of swing phase inertial perturbation on the sensor output, such that swing and stance phases are properly detected in a robust and timely manner.

The systems, devices and methods described herein provide advantages over other systems for detecting ground contact, such as those described, for example, in <CIT>.

The systems, device and methods described herein may include ground contact sensing systems and methods that use a selectively compliant mechanical structure to allow discriminating inertial loads associated with phase from axial loads generated during stance phase. Using a plurality of, i.e. two or more, displacement sensors with the mechanically selective compliant structure allows for measuring occurrence of ground contact between the prosthetic limb and the ground, without having to deal with the dependencies of zero-load shift or overloading of the ground contact sensor assembly. Additionally, since the overload does not affect the sensor system itself, it is possible to control the maximum displacement of the flexible part of the mechanical structure, while maintaining the full sensor resolution around the zero-load point, effectively decoupling the two parameters.

In some embodiments, a load-cell may be used to measure the displacement of the flexible part of the mechanically selective compliant structure. The load-cell may be positioned substantially at the center of the assembly in the anterior-posterior direction. In some embodiments, the load cell may be positioned offset to one side in the coronal or frontal plane.

For a user's gait, vertical ground reaction force may not move in-line with the foot during stance phase, as foot rotation takes place during stance phase roll-over. Additionally, the amputee gait and foot alignment may seldom match what can be observed on non-amputated subjects. Furthermore, low proprioception and control over the residual limb may reduce the amputee capacity to apply sufficient loading to ensure that sufficient sensor output is generated in all use scenarios. The use of a plurality of non-contact sensors, as compared to a single non-contact sensor and other approaches, can address these and other issues. For example, use of a single non-contact sensor to average the ground contact reading with respect to the combined rotation and axial displacement of the assembly flexible part leads to decreased sensitivity on toe-load, and even further decreased sensitivity when a load cell with a single non-contact sensor is used and the load is applied on an opposite side from where the load cell is mounted. The array of non-contact sensors as further described herein overcome these and other drawbacks of existing approaches.

The features described herein have various advantages. Significant benefits and performance improvements are achieved when using a sensor array instead of, for example, a single sensor. For example, limitations arising from ground contact structure overload are removed or reduced. Further, sensor sensitivity around the zero-load point up to the physiologically relevant load points is maximized. Further, discrimination between torque loads and axial loads is possible, for instance by showing reduced sensitivity of torque loads. Further, dependency on the final details of the prosthetic device installation is reduced, for example by producing data showing the same sensitivity level for all load cases. Further, detection and identification of load progression direction is possible.

Other advantages include achieving repeatable measurements of loads applied to a lower-limb POD. The load applied to a lower-limb POD during a transition from swing phase to stance phase can be a small fraction of the total load registered when the user is standing still. In addition, in light of the shocks and overload possibility associated with the lower-limb POD, ensuring repeatable, accurate load measurements at a range of low and high loads is useful. The development described herein ensures both repeatable and accurate reading of small loads while still being capable of accurately registering high loads.

Additionally, the array improves capabilities related to "zero load" measurements and calibration-related issues. The development allows for stability of "zero load" measurements in view of perturbing influences, such as temperature changes, shocks, overload, electrical perturbations and exposure to humidity. The development allows for avoiding the complexities and impracticalities associated with taring to ensure zero-stability during use of the lower-limb POD. The development avoids the need for performing a calibration procedure or automating a zero-load calibration procedure, which can be cumbersome and prone to failure. This is useful since lower-limb POD's are submitted to various levels of load at almost all times during use.

Further, the array provides for reduced sensitivity to inertial loading through use of a selectively compliant mechanical structure, allowing at the same time sufficient compliance in the axial direction to properly measure occurrence of the foot strike event using a low-cost sensor.

Further, selective sensitivity may be achieved though the use of a selectively compliant mechanical structure with the sensor array. This may provide high stiffness to sagittal plane torque loading, e.g., foot generated inertial effects, while being highly compliant under axial loading.

Further, sensitivity for detecting specific types of loads applied to prosthetic devices can be increased. The foot-ground interaction can be properly characterized. The use of an array of sensors can minimize the impact or fully avoid any loss of sensitivity due to reduction of sensor and load line colinearity. These and other advantages, benefits, and uniquely desirable features will be apparent in the following detailed description.

Turning to the figures, <FIG> illustrates an embodiment of a prosthetic device <NUM> that includes an embodiment of a sensor assembly <NUM> therein. As further described herein, the sensor assembly <NUM> includes an array of sensors for detecting ground contact with the prosthetic device <NUM> and to control the device. The sensor assembly <NUM> is located at a distal end of the prosthetic device <NUM>. This specific embodiment of the prosthetic device <NUM> is provided as merely one example. The sensor assembly <NUM> may be located at the proximal end of the prosthetic device <NUM>, or in locations between the distal and proximal ends. Further, the features described herein may be applied to other embodiments, such as prosthetic feet, other lower limb prosthetics or orthotics, sensors for non-prosthetic or non-orthotic use, and other devices.

Anatomical reference directions for the anterior, posterior, lateral, and medial directions are indicated in <FIG> for the sake of description. The directions have their usual and ordinary meanings as known in the art. Anterior and posterior indicate directions in the sagittal or lateral plane toward the front and rear of the body, respectively. Medial and lateral indicate directions in the coronal or frontal plane generally toward the inner side and outer side of the body, respectively. As used herein, "anterior-posterior" indicates a direction along the sagittal plane, and "medial-lateral" indicates a direction along the coronal plane. The various terms may be used to indicate directions that are exactly along the corresponding planes, as well as directions that are angled relative to the planes but still at least partially in the direction.

The prosthetic device <NUM> illustrated in <FIG> implements a knee joint and may be connected to a user's residual limb, such as a thigh, through a socket (not shown) via the proximal connector <NUM> on its proximal end. The proximal connector <NUM> may be pyramidal in shape. The prosthetic device <NUM> is a lower-limb prosthetic device, shown as a shank. The proximal connector <NUM> may be coupled to an actuator <NUM>, which can rotate with respect to a body <NUM>. The actuator <NUM> may be motorized. Rotation of the actuator <NUM> may cause rotation of the proximal connector <NUM> with respect to the body <NUM>, and vice versa. In some aspects, the body <NUM> may be on or form a shank portion of the prosthetic device <NUM>. The body <NUM> may include electronic components, sensors, etc. (not shown) required for the prosthetic device <NUM> to operate, although in some aspects these components may be located elsewhere, such as on a peripheral device or within the components further described below. The prosthetic device <NUM> may be connected to a prosthetic or orthotic ankle or foot (not shown) via the distal connector <NUM> located on a distal portion of the prosthetic device <NUM>. The prosthetic device <NUM> may be connected with or include a prosthetic hip, prosthetic thigh, prosthetic foot and/or prosthetic ankle.

Ground contact sensing systems described herein may be used to control an operation of a device such as the prosthetic device <NUM>. The device <NUM> may incorporate various features and/or functions of other embodiments of lower-limb PODS's, and those various other POD's may be controlled with the system described herein, such as the lower-limb POD described in <CIT>.

<FIG> is an enlarged view of the distal portion of the prosthetic device <NUM> having the sensor assembly <NUM> therein. The sensor assembly <NUM> is located partially within the device <NUM> and is thus labelled with a dashed line. The distal connector <NUM> may include a base <NUM> (see <FIG>), a mating surface <NUM>, and/or a stud <NUM>. The mating surface <NUM> may be dome-shaped and may extend away from a distal end of the body <NUM>. In some embodiments, the mating surface <NUM> may be different shapes including, but not limited to, circular, rounded, square, hexagonal, other suitable shapes, or combinations thereof. The mating surface <NUM> may include an arcuate outer surface that may allow a smooth movement between the distal connector <NUM> and a prosthetic or orthotic foot or ankle coupled to the distal connector <NUM>. The mating surface <NUM> may be a mating section that may be coupled to a corresponding mating section of a prosthetic or orthotic ankle or foot.

The stud <NUM> may be a protrusion extending distally from the mating surface <NUM>. The stud <NUM> may be integrated with the mating surface <NUM> or separate from the mating surface <NUM>. The stud <NUM> may be removably coupled to the mating surface <NUM> to allow users to use different types of studs or protrusions having different dimensions or shapes. In this regard, users may couple the prosthetic device <NUM> with different prosthetic devices having different types of connectors. The stud <NUM> may be square in shape or triangular, circular, hexagonal, or other shapes that allow removeable coupling between the distal connector <NUM> and a prosthetic or orthotic foot or ankle. The stud <NUM> may be dimensioned and/or shaped to minimize accidental detachment between the prosthetic device <NUM> and a prosthetic or orthotic ankle or foot.

<FIG> shows the distal connector <NUM> with structural components of the body <NUM> shown transparently for clarity, for example to more clearly illustrate functional interactions between the structural components of the body <NUM>, the sensor assembly <NUM>, and the distal connector <NUM>. The base <NUM> of the distal connector <NUM> may be mounted near a distal end of the body <NUM>. In order to prevent ingress of solid parties or water, the connection between the base <NUM> of the distal connector <NUM> and the distal end of the body <NUM> may be sealed.

An annular recess <NUM> may be formed around an inner circumference of the distal end of the body <NUM>. A sealing element may be inserted into the groove <NUM> of the distal end and between the body <NUM> and the base <NUM> to create a seal. In some embodiments, the base <NUM> may include an annular recess <NUM>. The recess <NUM> may correspond to and couple with the recess <NUM> and sealing element located at the distal end of the body <NUM>. The recess <NUM> may be formed around the entire circumference of the base <NUM>. Alternatively, the recess <NUM> may be formed around a portion of the circumference of the base <NUM>. One or more sealing elements may removably couple to the recess <NUM>. A seal may be created between the distal end of the body <NUM> and the distal connector <NUM> by, for example, having a sealing element, such as an O-ring, removably coupled to the body <NUM> and the recess <NUM>. The seal between the body <NUM> and the recess <NUM> of the distal connector <NUM> may prevent ingress of solid particles or water, which could impair proper function of the prosthetic device <NUM>.

The distal connector <NUM> may be mounted near the distal end of the body <NUM> such that it is allowed to move axially in a proximal-distal direction, for example in a direction substantially parallel to the length of the body <NUM> of the prosthetic device <NUM>. Additionally, the distal connector <NUM> may be constrained radially and/or in other directions such that it may not move in directions at angle to a longitudinal axis (as labelled in <FIG>) or other than the proximal-distal direction. In this regard, the distal connector <NUM> may only move, for example be pushed due to ground contact or other loads, proximally in a direction towards the proximal connector <NUM> of the prosthetic device <NUM>, and/or move, for example be pulled due to gravity or inertial loads, distally in a direction away from the proximal connector <NUM>.

The sensor assembly <NUM> may be coupled proximally of the distal connector <NUM> as shown. The sensor assembly <NUM> may be attached to a proximal end of the base <NUM>, as further described herein. In some embodiments, the sensor assembly <NUM> may be located distally of the base <NUM>, or in a more proximal location such as at a proximal end of the shank. The sensor assembly <NUM> may be located entirely or partially within the body <NUM>, and thus the assembly <NUM> is labelled with dashed lines in <FIG> and <FIG>. The body <NUM> and/or the connector <NUM> may cover the sensor assembly <NUM>.

<FIG> are various views of the sensor assembly <NUM> attached to the distal connector <NUM>. <FIG> is a perspective view of the sensor assembly <NUM>. <FIG> is a side view of the sensor assembly <NUM>. <FIG> is a cross-section view of the sensor assembly <NUM> as taken along the line 3C-3C indicated in <FIG>. <FIG> is a perspective view of the sensor assembly <NUM> with certain parts removed for clarity.

With reference to <FIG>, the sensor assembly <NUM> may be coupled to the distal connector <NUM>. The sensor assembly <NUM> may be positioned adjacent to the base <NUM> opposite from the mating surface <NUM> and the stud <NUM>, as shown in <FIG>. In some aspects, the sensor assembly <NUM> may be positioned within a recess formed about the distal end of the body <NUM> of the prosthetic device <NUM>. The sensor assembly <NUM> or portions thereof may be fixedly coupled to the body <NUM> of the prosthetic device <NUM> such that some of the structure of the sensor assembly <NUM> remains stationary with respect to the body <NUM>. The sensor assembly <NUM> may not translate or rotate relative to the body <NUM>. A first portion of the sensor assembly <NUM> may not translate or rotate relative to the body <NUM>, while another portion of the sensor assembly <NUM> may rotate and/or translate relative to the body <NUM>, as further described herein.

The sensor assembly <NUM> includes a structural support <NUM>. The structural support <NUM> may include a frame <NUM> and beam structures <NUM> and <NUM>. The structural support <NUM> may include one or more first fasteners <NUM>, one or more backing plates 308A, 308B, and/or one or more second fasteners <NUM>. A portion of the structural support <NUM> is attached to a shank portion of the prosthetic device <NUM>, such as the body <NUM>, such that there is no relative movement between that portion of the structural support <NUM> and the shank portion, as further described. The frame <NUM> of the sensor assembly <NUM> may be affixed to the body <NUM> such that the frame <NUM>, for example a portion of the frame <NUM> attached to the body <NUM>, does not move with respect to the body <NUM> when a load is applied to the distal connector <NUM> in an axial direction. The frame <NUM> may include one or more apertures to accommodate for the fasteners <NUM> and fasteners <NUM>. The one or more apertures may be threaded or not threaded. The fasteners <NUM> may fasten a first portion of the structural support <NUM> to the shank, and the fasteners <NUM> may fasten a second portion of the structural support <NUM> to the base <NUM>, as further described.

The structural support <NUM> includes one or more beam structures. As shown, there is a first beam structure <NUM> located on a lateral side on the sensor assembly <NUM> and a second beam structure <NUM> located on a medial side of the sensor assembly <NUM> (for example for a left leg prosthetic). The second beam structure <NUM> is labelled in dashed line because it is not entirely visible as oriented in the figure. The beam structures <NUM>, <NUM> may be symmetric, for example about the sagittal plane. The beam structures <NUM>, <NUM> may include portions that extend in an anterior-posterior direction. Depending on the size of the beam structures <NUM>, <NUM> and the size of the sensor assembly <NUM>, one or more beam structures <NUM>, <NUM> may be positioned on the medial side and the lateral side of the sensor assembly <NUM>. The beam structures <NUM>, <NUM> may be symmetric with respect to the sagittal plane and/or the coronal plane. There may be three, four, five or more beam structures.

As shown in <FIG>, there may be one beam structure <NUM> on the lateral side and one beam structure <NUM> on the medial side of the sensor assembly <NUM>. In some embodiments, there may be two or more beam structures <NUM> on the lateral side and two or more beam structures <NUM> on the medial side of the sensor assembly <NUM>. Additionally and/or alternatively, the sensor assembly <NUM> may have beam structures <NUM>, <NUM> located on a posterior side and/or an anterior side, extending in a medial-lateral direction. As discussed above, there may be one beam structure on the posterior side and one beam structure on the anterior side. In some embodiments, there may be two or more beam structures on the posterior side and two or more beam structures on the anterior side. The number and/or locations of the beam structures <NUM>, <NUM> of the sensor assembly <NUM> may change the degree of flexibility of the beam structures <NUM>, <NUM> and thereby change responses of the beam structures <NUM>, <NUM> under different load conditions, for example, different load conditions applied to the distal connector <NUM> during stance phase of gait.

Each of the beam structures <NUM>, <NUM> may include two or more beams <NUM>, such as plates. The beams <NUM> may be located in the anatomical transverse plane, which may be parallel to the base <NUM> of the distal connector <NUM>. The beam structures <NUM>, <NUM> may each include two beams <NUM> as shown in <FIG>. The beams <NUM> extend in an anterior-posterior direction. The beams <NUM> may extend in a plane such that the beams are stiffer in one direction and less stiff in a second direction that is different from the first direction. The beams <NUM> may be stiffer about the longitudinal axis (that is, axis parallel to the sagittal plane and extending in anterior-posterior direction) as compared to about axes perpendicular to the longitudinal axis. The beams <NUM> may extend in a plane parallel to the anatomical transverse or horizontal plane. The beams <NUM> may have a length in the anterior-posterior direction that is longer than a length in the medial-lateral direction. The beams <NUM> may have a thickness in the axial direction that is less than either or both of the length(s) in the anterior-posterior direction and the medial-lateral direction. In some embodiments, the beam structures <NUM>, <NUM> may each include one, three, four, five, or more beams <NUM>. The number of beams <NUM> may vary the degree of flexibility or compliance of the beam structure <NUM> against different load conditions.

Axially opposing beams <NUM> of the beam structures <NUM> may be connected via a bridge <NUM>. The bridge <NUM> may extend axially (that is, in a proximal-distal direction) from about the middle portions of the anterior-posterior length of the opposing beams <NUM>. The bridge <NUM> may have an anterior-posterior thickness that is different from an axial thickness of the beams <NUM>. The anterior-posterior thickness of the bridge <NUM> may be greater than the axial thickness of the beams <NUM>, as shown in <FIG> and <FIG>. Alternatively, the anterior-posterior thickness of the bridge <NUM> may be equal to or less than the axial thickness of the beams <NUM>. The pair of axially opposing beams <NUM> may be offset in a medial-lateral direction from the other pair of axially opposing beams <NUM> to define a space there between in which the sensor assembly <NUM> or portions thereof is located, as further described.

The bridge <NUM> may have a depth in the medial-lateral direction that extends coextensively with the medial-lateral depth of the beam structure <NUM> or portion thereof, for example the beams <NUM>. Alternatively, the bridge <NUM> may have a depth that is greater than or less than the corresponding depth of the beam structure <NUM> or portion thereof. The depth of the bridges <NUM> may vary the flexibility and/or compliance of the beam structure <NUM> against different load conditions. The bridges <NUM> may be symmetrically positioned with respect to the sagittal plane and/or coronal plane.

The beams <NUM> of the beam structures <NUM> may be spaced axially apart from each other. The distance between the beams <NUM> may be sufficient to allow the beam structure <NUM> to be flexible and/or compliant against different load conditions, for example, during stance phase of a gait of the user. The distance between the beams <NUM> may be varied to vary stiffness of the beam structure <NUM> against torque loads. In some embodiments, the distance between the beams may not affect stiffness of the beam structure <NUM> against axial loads. As further described below, the compliance of the beam structure <NUM> of the sensor assembly <NUM> may allow accurate mapping of the load conditions applied on the prosthetic device <NUM>, for instance due to ground contact. The beams <NUM> may be compliant such that they flex or compress axially in response to a load applied to the prosthetic device, such as a non-inertial ground contact load. The beams <NUM> may be configured to not compress or flex in response to an inertial load. One, some or all of the beams <NUM> may flex in response to a load.

As discussed above, the dimensions, numbers, and/or positions of the various features of the beam structures <NUM>, <NUM>, such as the beams <NUM>, the bridges <NUM>, etc., of the sensor assembly <NUM> may determine how the sensor assembly <NUM> and/or the beam structures <NUM>, <NUM> respond to different load conditions. The beam structures <NUM>, <NUM> may be positioned adjacent to the base <NUM> of the distal connector <NUM>. In the example shown in <FIG>, the beam structures <NUM>, <NUM> may be positioned up against the base <NUM> of the distal connector <NUM>, on a side of the base <NUM> that is opposite from the mating surface <NUM> and the stud <NUM>. The fasteners <NUM> may be used to fasten the beam structures <NUM> with the base <NUM>.

Some portions of the beam structures <NUM>, <NUM> may not be in direct contact with the base <NUM>. In some embodiments, the portions at, toward and/or or near the center of the beam structures in the anterior-posterior direction <NUM>, <NUM> may be in direct contact with the base <NUM> while the ends of the beam structures <NUM>, <NUM> in the anterior-posterior direction are not in direct contact with the base <NUM>. As shown in <FIG>, gaps <NUM>, <NUM> may exist between distal portions of the anterior and posterior ends of the beam structures <NUM>, <NUM> (that is, not the center portion of the beam structure <NUM>) and a proximal side of the base <NUM>. The size of the gaps <NUM> and/or <NUM> may be from about <NUM> to about <NUM>, from about <NUM> to about <NUM>, from about <NUM> to about <NUM>. The size of the gaps <NUM> and/or <NUM> may be <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or more. The size of the gaps <NUM> and/or <NUM> may be between ranges of any two of the various aforementioned values. The gaps <NUM> and <NUM> may be the same or different in size. The gaps <NUM>, <NUM> may be measured axially between opposing portions of the support structure <NUM> and the base <NUM>.

The gaps <NUM>, <NUM> may be located such that the frame <NUM> and/or other portions of the support structure <NUM> may be able to move relative to the base <NUM> and/or mating surface <NUM>. The support structure <NUM>, for example the frame <NUM> that supports the PCB <NUM> and sensors <NUM> thereon, may thus not move relative to the shank or other proximal portion of the prosthetic device <NUM>. The base <NUM> may move relative to the support structure <NUM> that supports sensors <NUM>, as further described. Such movement may be due to ground contact and other loads during stance phase.

The frame <NUM> may be able to move by flexing and/or rotating about the anterior-posterior direction and/or about the medial-lateral direction. The beams <NUM> may flex, as described. The frame <NUM> or portions thereof may flex about a first raised portion <NUM> of the distal surface of the base <NUM>. The first raised portion <NUM> may extend along the surface of the base <NUM> and partially define one or more recesses <NUM>. The first raised portion <NUM> may extend in a medial-lateral direction. There may be a second raised portion <NUM> located on anterior and posterior sides of the first raised portion <NUM>. The second raised portion <NUM> defines surfaces that are located distally of, or lower than, the surface of the first raised portion <NUM>. The second raised surfaces partially define the recesses <NUM>. The higher first raised portion <NUM> allows for a level distal surface of the frame <NUM> to result in the gaps <NUM>, <NUM> when assembled with the base <NUM>. Other configurations may be implemented to result in the gaps <NUM>, <NUM>, such as a non-level distal surface of the frame <NUM>, the use of spacers or shims on either a proximal surface of the base <NUM> and/or a distal surface of the frame <NUM>, etc..

A top surface of the base <NUM>, such as the raised portion <NUM>, may define a first abutment surface and a bottom surface of the frame <NUM> facing the base <NUM> may define a second abutment surface. As discussed above, the first abutment surface of the base <NUM> can include one or more recesses <NUM> and raised portion <NUM>. Alternatively, the first abutment surface of the base <NUM> can be flat. The second abutment surface of the frame <NUM> can be level. The beam structures <NUM>, <NUM> can define at least a portion of the second abutment surface of the frame <NUM>. The non-moving body and the moving body of the device <NUM> can be coupled such that the first abutment surface of the base <NUM> and the second abutment surface of the frame <NUM> can be adjacent to each other.

A first or second body of the sensor assembly <NUM> may move relative to the other of the first or second body. As shown, the base <NUM> may translate and/or rotate relative to the structural support <NUM>. The base <NUM> may rotate about the raised surface <NUM>. The base <NUM> may translate axially. Such movements may change the size of the gaps <NUM>, <NUM>. The gaps <NUM>, <NUM> may change to zero distance such that the moving body has reached a maximum relative axial movement relative to the non-moving body and the two bodies abut each other in the locations of the gaps <NUM>, <NUM>. The various movements of the moving body relative to the non-moving body cause changes in the distances between the two bodies that the sensors <NUM> then detect to determine ground contact, as described herein.

In some embodiments, there may not be the gaps <NUM>, <NUM>. In some embodiments, the gaps <NUM>, <NUM> may be in different locations. The structures may have these gaps in a resting state where no external loads other than those due to the weight of the various structures are applied, i.e. without ground contact.

In some embodiments, the base <NUM> is suspended from the structural support <NUM>, such as from the beam structures <NUM>, <NUM>, of the sensor assembly <NUM>. Since the beam structures <NUM>, <NUM> may be compliant and thus flex when load is applied in the distal-proximal direction, additional structures may be provided to limit the effects of loads causing a distal pull on the base <NUM>. The backing plates <NUM> may attach to the shank of the prosthetic device <NUM> and to the base <NUM>. The backing plates <NUM> may be connected to the shank and/or base <NUM> via fasteners <NUM>. Connection of the base <NUM> with the shank may prevent or limit the sensor assembly <NUM> and the base <NUM> of the distal connector <NUM> from moving in a distal direction. The backing plates <NUM> may thus limit displacement of the base <NUM> under distal pull forces. The backing plates <NUM> may be rigidly connected to the base <NUM> and/or the shank via the fasteners <NUM>. The backing plates <NUM> may extend axially with an opening therethrough. The backing plates <NUM> may be separate from the base or integral therewith. The backing plates <NUM> may extend through the support structure <NUM>. The backing plates <NUM> may be located in between the two beam structures <NUM>, <NUM>. The backing plates <NUM> may be located on a medial side of the beam structure <NUM>, on a lateral side of the beam structure <NUM>, on a posterior side of the anterior portion of the frame <NUM>, and/or on an anterior side of the posterior portion of the frame <NUM>.

The backing plates 308A, 308B may connect the support structure <NUM> to the shank, as mentioned. The backing plates 308A, 308B and the corresponding fasteners <NUM> may be provided in the anterior and/or posterior areas of the sensor assembly <NUM>. Most of the load applied to the prosthetic device <NUM> may be applied to anterior and posterior section of the sensor assembly <NUM>. The backing plates 308A, 308B may therefore be located in the anterior and posterior sections, for example to limit movement of a moving part (e.g., the base <NUM>) of the prosthetic device <NUM>. The backing plates 308A, 308B may be fixed to the shank, such as the body <NUM>, via the fasteners <NUM>. Additionally and/or alternatively, the backing plates 308A, 308B and the corresponding fasteners <NUM> may be provided in the medial and/or lateral areas of the sensor assembly <NUM>. The backing plates 308A, 308B may be symmetrically positioned with respect to the sagittal plane and/or the frontal plane.

Various portions of the structural support <NUM> may move and other portions may not move in response to an applied load. A portion of the support <NUM> attached to the body <NUM> may not move. A portion of the support <NUM> attached to the distal connector <NUM> may move, for example flex. Further, the distal connector <NUM> or portions thereof may move relative to the support <NUM>. As further described herein, the base <NUM> or other portions may translate, rotate, or translate and rotate relative to the support <NUM>. Such movement may be detected by sensors to determine ground contact, as further described.

The sensor assembly <NUM> may include a plurality of sensors <NUM>. The sensors <NUM> may be non-contact or other type sensors that detect a distance from the sensor to another object without contacting that other object. The other object may be a target portion of an opposing structure, a magnet, or other object. The sensors <NUM> may be attached to the moving or non-moving portion of the structure. The sensors <NUM> may be attached to the non-moving portion, such as an upper part of the support <NUM> that does not move relative to the shank or other portion of the prosthetic body, and may detect a plurality of distances between each sensor and an opposing respective target, such as a respective portion or region of the moving body portion. In some embodiments, the sensors <NUM> are Hall effect sensors that detect a distance to an opposing respective magnet. In some embodiments, the sensors <NUM> may be contact sensors.

The sensors <NUM> may be coupled to a printed circuit board (PCB) <NUM>. The PCB <NUM> may be rigidly coupled to a portion of the frame <NUM> such that the PCB <NUM> does not move with respect to the frame <NUM> under different load conditions. The frame <NUM> in turn is rigidly connected to the shank or other portion of the prosthetic device <NUM> that is proximal of the base <NUM>. Thus the sensors <NUM> do not move relative to the shank or other portion. When a load is applied to the prosthetic device <NUM>, the beam structures (for example, beam structures <NUM>, <NUM>) of the sensor assembly <NUM> can flex to change the distance between the base <NUM> and the frame <NUM>. The sensors <NUM>, in turn, can detect changes in the distance between the base <NUM> and the frame <NUM>. The sensors <NUM> may be separate physical sensors, or separate areas of sensitivity of one larger sensor.

The sensors <NUM> may be any type of proximity or distance sensor. For example, the sensors <NUM> may be non-contact sensors, contact sensors, inductive sensors, capacitance sensors, photoelectric sensors, through-beam sensors, retro-reflective sensors, diffuse sensors, ultrasonic sensors, other suitable sensors, or a combination thereof. In some embodiments, other non-contact displacement sensors may be used. For example, the various sensors may be inductive displacement sensors, optical displacement sensors, time-of-flight sensors (laser, IR, ultrasound, etc.), other suitable sensors, or combinations thereof.

Additionally, the sensor assembly <NUM> may include one or more magnets <NUM> coupled to the base <NUM>. The magnets <NUM> are one example of targets that the sensors <NUM> may detect. Other targets may be used, such as respective regions or portions of the opposing structure, such as a top surface of the base <NUM>, that moves relative to the structure on which the sensors <NUM> are mounted. Thus any description of the magnets <NUM> herein may be applicable to other types of targets for the sensors <NUM>.

The magnets <NUM> may be oriented to face in the proximal direction, for example towards the proximal connector <NUM> of the prosthetic device <NUM>. The magnets <NUM> are capable of generating a magnetic field in surrounding areas. As shown, the sensors <NUM> are magnetic sensors that detect the magnetic field generated by a corresponding magnet <NUM>. The sensors <NUM> may generate an output indicative of the magnitude of the magnetic field of a respective magnet <NUM> that the sensor <NUM> is detecting. The sensors <NUM> may be Hall effect sensors. The sensors <NUM> may be transducers that vary an output voltage in response to the magnetic field from the actuators <NUM>, which output voltage may be directly proportional to the strength of the magnetic field through the sensor <NUM>.

As the base <NUM> with the magnets <NUM> moves relative to the frame <NUM>, the magnets <NUM> and sensors <NUM> correspondingly move relative to each other. The magnets <NUM> and the sensors <NUM> may be at a first offset distance from each other when no load is applied to the prosthetic device <NUM>. When a non-inertial load is applied to the prosthetic device <NUM>, the offset distance between the magnets <NUM> and the sensors <NUM> may change to a second offset distance. The difference between the first offset distance and the second offset distance can correspond to the amount of load applied to the prosthetic device <NUM>. Additionally, the magnets <NUM> and the sensors <NUM> may be arranged in an array (see <FIG>, <FIG>, and <FIG>). The sensors <NUM> may be arranged in an array. The sensors <NUM> may be arranged in the transverse plane, sometimes referred to as the horizontal plane. As used herein, "transverse plane" has its usual and customary meaning, and includes without limitation a plane perpendicular to the coronal and sagittal planes and which may divide the body into relative upper and lower portions. The arrangement of the sensors <NUM> and their target sensing portion, such as the magnets <NUM>, may advantageously allow the prosthetic device <NUM> to collect data representative of load applied to the prosthetic device <NUM> during a gait cycle and characteristics of that load, as further described below. The magnets <NUM> may be separate from each other as shown. In some embodiments, a single larger sensor with separate areas of sensitivity may be used and still fall under the scope of a "plurality" of sensors.

In some embodiments, at least a portion of the base <NUM> includes a magnetic element that can generate a magnetic field around the sensor assembly <NUM>. For example, a top surface of the base <NUM> facing the sensors <NUM> can be magnetic. In another example, at least a portion of the beam structures <NUM>, <NUM> or the mating surface <NUM> can be magnetic such that the sensors <NUM> can detect changes in the magnitude of a magnetic field generated by the beam structures <NUM>, <NUM> or the mating surface <NUM> under different load conditions.

The sensors <NUM> may be positioned such that they are an initial offset distance apart from the base <NUM> when no load is applied to the prosthetic leg by the ground. The initial distance between the base <NUM> and the sensors <NUM> may represent a zero-load condition. When a load due to ground contact is applied to the prosthetic device <NUM>, the load may cause relative movement between the base <NUM> and the frame <NUM> of the support structure <NUM> of the sensor assembly <NUM>, thereby changing the offset distance between the base <NUM> and the sensors <NUM>. As discussed above, the change in the distance between the base <NUM> and the sensors <NUM> may directly correspond to the amount of load applied to the prosthetic device <NUM>. The change in distance will produce a change in voltage generated by the non-contact sensors, which can be analyzed to determine ground contact, as further described.

Under different load conditions, the beam structures <NUM> and/or <NUM> of the sensor assembly <NUM> may be compressed at least in an axial direction to reduce the distance between the base <NUM> and the sensors <NUM>. In the example in which the base <NUM> includes the magnets <NUM>, the magnets <NUM> may move proximally. In this regard, the change in proximity of the magnets <NUM> and the sensors <NUM> may change the strength of the magnetic field surrounding the sensors <NUM>. For example, reduced distance between the magnets <NUM> and sensors <NUM> may increase the magnitude of the magnetic field detected by the sensors <NUM>. The increase in the magnitude of the magnetic field detected by the sensors <NUM> may represent the change in the distance between the magnets340 and the sensors <NUM>, which may represent the change in the distance between the sensor assembly <NUM> and the base <NUM>, which may be analyzed to determine the presence and/or characteristics of ground contact by the prosthetic device. The sensors <NUM> may generate signals corresponding to the change of the magnetic field. In some aspects, the sensors <NUM> may detect changes in the amount of current or voltage generated by the sensors <NUM> due to the magnetic field generated by the magnets <NUM>. The changes in distance detected by the sensors <NUM> may be caused by axial translation movement of the base <NUM> relative to the structure <NUM>, by transverse translational movement of the base <NUM> relative to the structure <NUM>, and/or by rotational movement of the base <NUM> relative to the structure <NUM> about any three orthogonal axes.

As discussed above, the beam structures <NUM>, <NUM> of the sensor assembly <NUM> may allow selective compliance under different load conditions. While the beam structure <NUM> may be compliant to an axial load (distal-proximal direction), it may be relatively more rigid or less compliant to loads in the anterior-posterior and/or medial-lateral directions. The degree of compliance of the beam structure <NUM> may be varied by changing various dimensions of the beam structure <NUM>.

The selective compliance of the support structure <NUM> and the array of the sensors <NUM> allow for more accurate detection of loads due to ground contact. The separation distance between axially opposing beams <NUM> provides rigidity in response to sagittal plane torque loads. Thus the sensors <NUM> are less likely to move or to move as much due to such loads, which may be applied due to influences other than ground contact, such as inertial loads during swing phase. Therefore axial loads during stance phase due to ground contact are better isolated and detected. This results in less complex signal processing as compared to other approaches, as discussed herein.

The configuration of the support structure <NUM> and base <NUM> allow for relative movement between the two structures. Since the support structure <NUM> may be rigidly attached to the shank or other portion of the prosthetic device <NUM>, movement of the base <NUM> as detected by the sensors <NUM> corresponds to relative movement between the base <NUM> and supports structure <NUM>. Thus the resulting voltage changes detected by the sensors <NUM> is indicative of the relative movement of the respective structures. The layout of multiple sensors <NUM> in an array with such structural configurations can result in robust and reliable output data.

<FIG> illustrates an example array <NUM> of the magnets <NUM>. As discussed above, the magnets <NUM> may be coupled to the base <NUM> of the distal connector <NUM>. There may be four magnets <NUM> coupled to the base <NUM> as shown in <FIG>. In some aspects, there may be less than four magnets <NUM> coupled to be base <NUM>. In other aspects, there may be more than four magnets <NUM> coupled to the base <NUM>. The magnets <NUM> may be arranged in symmetry with respect to the sagittal plane and/or coronal plane. The magnets <NUM> may be in symmetry with respect to any other planes. In some aspects the magnets <NUM> may be arranged in point symmetry with respect to a predetermined location of the sensor assembly <NUM> or the base <NUM>. The magnets <NUM> may be positioned equidistant from each other. The magnets <NUM> may be positioned in a square array (as shown in <FIG>), a rectangular array, a circular array, an oval array, a hexagonal array, and the like.

In some embodiments, the magnets <NUM> can be integrated with the base <NUM>. In other embodiments, as discussed above, the base <NUM> can be made out of magnetic material such that at least a portion of the base <NUM> is magnetic and generates a magnetic field around the sensor assembly <NUM>.

<FIG> illustrates an example array <NUM> of the sensors <NUM> coupled to the PCB <NUM>. The sensors 350F and <NUM> may be positioned in the anterior portion of the PCB while the sensors 350A and 350B may be positioned in the posterior portion of the PCB. The sensors 350C, 350D, and 350E may be positioned between the rest of the sensors (that is, sensors 350A, 350B, 350F, and <NUM>).

The array <NUM> of the sensors <NUM> on the PCB <NUM> may be symmetric in one or more ways. For example, the sensors 350C, 350D, and 350E may define an axis of symmetry for the sensors 350F and <NUM> the sensors 350A and 350B. In this regard, the distance between the axis of symmetry defined by the sensors 350C, 350D, and 350E and the sensors 350F and <NUM> may be the same as the distance between the axis of symmetry and the sensors 350A and 350B. In some aspects, the sensors 350C, 350D, and 350E may define the coronal plane that bisects the sensor assembly <NUM> into an anterior region and a posterior region.

The sensors may be in symmetry with respect to the sagittal plane that bisects the sensor assembly <NUM> into a medial side and a lateral side. In the example illustrated in <FIG>, the sagittal plane may extend between the front side and the rear side through the sensor 350D. In this regard, the sensor <NUM> and the sensor 350F may be in line symmetry with respect to the sagittal plane. Likewise, the sensors 350C and 350E, and the sensors 350A and 350B may be in line symmetry with respect to the sagittal plane. In some aspects, the sensors <NUM> may be in symmetry with respect to any other plane.

A point symmetry may exist between the sensors 350A-<NUM> of the sensor array <NUM> illustrated in <FIG>. The sensor 350A may be in point symmetry with the sensor <NUM> with respect to the sensor 350D. Similarly, the sensor 350B may be in point symmetry with the sensor 350F with respect to the sensor 350D. The sensor 350C may be in point symmetry with the sensor 350E with respect to the sensor 350D.

The symmetry between the sensors <NUM> may prevent reduction of sensor sensitivity during gait. Typical ground-foot interaction during level walking gait is characterized by an initial contact taking place on the lateral side of the heel and progressing towards the big toe during the stance phase roll-over. Center of pressure line then crosses over the foot during the stance phase roll-over. By having an array of sensors <NUM>, the sensors <NUM> may remain colinear with the force application points throughout the roll-over, thereby preventing reduction of sensor sensitivity. In other words, the sensors <NUM> together will not experience what is perceived by the control system as a reduction of load during the stance phase roll-over.

For right leg/foot amputees, the sensors 350B, 350E, and <NUM> may represent sensors <NUM> located on a medial side, while the sensors 350A, 350C, and 350F may represent sensors <NUM> located on a lateral side. On the other hand, for left leg/foot amputees, the sensors 350B, 350E, and <NUM> may represent sensors <NUM> located on a lateral side, while the sensors 350A, 350C, and 350F may represent sensors <NUM> located on a medial side.

The array <NUM> of the sensors <NUM> may include seven sensors <NUM> as illustrated in <FIG>. In some aspects, the array <NUM> may include less than or more than seven sensors <NUM>. The array <NUM> may include four sensors <NUM> as shown in <FIG>. The array <NUM> may include ten, fifteen, twenty, thirty, or more sensors. The sensors <NUM> may be positioned such that one or more line symmetry and/or point symmetry may exist. The sensors <NUM> may define the sagittal plane and/or coronal plane.

In some embodiments, as discussed above, the sensor assembly <NUM> can includes one or more magnets <NUM>. The number of magnets <NUM> and the sensors <NUM> used for detecting different load conditions may be the same or different. As shown in <FIG> and <FIG>, the sensor assembly <NUM> may include four magnets <NUM> and seven sensors <NUM>. Different combinations of numbers of magnets <NUM> and sensors <NUM> may be used to capture the relative motions of the base <NUM> of the distal connector <NUM> and the frame <NUM> of the sensor assembly <NUM>. In some embodiments, the magnets <NUM> may be coupled to a non-moving body of the POD while the sensors <NUM> may be coupled to a moving body of the POD.

The locations of the sensors <NUM> on the PCB <NUM> may represent different locations of the sensor assembly <NUM> or a load-bearing area of the prosthetic device <NUM>. For example, the load-bearing surface may be a bottom of a prosthetic or orthotic foot or an ankle. With respect to <FIG>, the sensors 350A and 350B, for example, may represent the posterior portion/area of a prosthetic or orthotic foot, while the sensors 350F and <NUM> may represent the anterior portion/area of the prosthetic or orthotic foot. More specifically, the sensors 350A and 350B may represent the heel of the prosthetic or orthotic foot, while the sensors 350F and <NUM> may represent the toes of the prosthetic or orthotic foot. The sensors 350C-350E may represent the mid-section of the prosthetic or orthotic foot. Likewise, the sensors 350B, 350E, and <NUM> may represent medial (or lateral) side of a prosthetic or orthotic foot, while the sensors 350A, 350C, and 350F may represent lateral (or medial) side. In this regard, for example, the sensor <NUM>, may represent a medial-anterior region of a load-bearing surface of a prosthetic foot.

<FIG> illustrate data 650A-<NUM> collected by the sensors 350A-<NUM> of the array <NUM>, respectively, during a stance phase of a gait cycle on a level surface by a right side amputee. In this example, the sensors 350A and 350B may represent the posterior area of a load-bearing surface of the prosthetic device <NUM>, the sensors 350F and <NUM> the anterior portion, the sensors 350B, 350E, and <NUM> medial portion, and the sensors 350A, 350C, and 350F lateral portion. It may be observed that sensors located on the same row (for example, sensors 350A and 350B, or sensors 350F and <NUM>) do not present the same response at the same point in time during the stance phase. <FIG> illustrates data collected by each row (that is, rear (posterior), middle, and front (anterior) rows as shown in <FIG>). <FIG> show progression of a load line through sensor rows and coronal plane alignment. With respect to <FIG>, data points 650A-<NUM> may represent the signal collected by the sensors 350A-<NUM> shown in <FIG>.

At initial contact, it may be observed that a posterior-medial sensor (that is, the sensor 350B) experiences a load that is greater than a load experienced by a rear-lateral sensor (e.g., the sensor 350A). In addition, it may be observed that the sensor 350B experiences higher load than the sensor 350A during the entire stance phase. <FIG> and <FIG> illustrate that middle and anterior row sensors also register load at the initial contact of the heel. This observation may arise from the array <NUM> of the sensor <NUM> and the position of the load. Since the hip is flexed at foot strike, the load line is in front of a posterior portion of the base <NUM>, and may cause displacement of the anterior sensors as well. As the roll over the foot progresses, the load line may move towards toes, which may result in reduced displacement of the posterior and middle sensors, as illustrated in <FIG>. Since the load line is at the front of the base <NUM>, posterior components of the sensor assembly <NUM> are undergoing a distal pull, which reduces the signal strength from posterior and middle row sensors (that is, 350A, 350B, 350C, 350D, and 350E). As the roll over progresses, medial-anterior loading amplitude (that is, signal from the sensor <NUM>) increases as late stance rotation on the big toe occurs.

Using the sensor array <NUM>, it is then possible to follow the load line progression (that is, the amplitude of the signals received from the sensors 350A-<NUM>) in the coronal and/or sagittal plane while avoiding area of low sensitivity, as seen on the lateral sensors of the posterior and middle rows in <FIG> and <FIG>.

The data and the results shown in <FIG> and discussed above do not limit the subject matter disclosed herein any way. For example, depending on the user of the prosthetic device <NUM>, it is possible that there may be a lateral side loading bias during a stance phase of a gait cycle. In some other examples, load may transfer from the posterior-medial portion to the anterior-lateral portion, or from the posterior-lateral portion to the anterior-medial portion. Different types of load patterns during a stance phase of a gait cycle may be analyzed and those load patterns may be used to detect ground contacts. Using an array to capture and analyze load patterns may be advantageous in recognizing different and/or abnormal gait characteristics and/or types for different users of prosthetic devices, and those load patterns may be used to provide specific actuator outputs to assist users with normal, different, or abnormal gait characteristics.

Similar results may be obtained using an array 500A shown in <FIG>, where sensors <NUM> (sensor 350AA, sensor 350BB, sensor 350CC, and sensor 350DD) are located in the corners. In this example, the sensors 350AA and 350BB may be located on the posterior portion of the sensor assembly <NUM> and may represent load applied to the posterior portion of a load-bearing surface/area of the prosthetic device <NUM>. Likewise, the sensors 350CC and 350DD may be located on the anterior portion of the sensor assembly <NUM> and may represent load applied to the anterior portion of the load-bearing surface/area.

<FIG> and <FIG> illustrate graphical illustration of data 750AA-750DD collected by the sensors 350AA-350DD as shown in <FIG>. Results from two different amputees using the same prosthetic device are compared, where <FIG> illustrates data collected from a left-side amputee, while <FIG> illustrates data collected from a right-side amputee. It may be observed from these plots that the dominant signal source between the two plots is inverted. For the left amputee, the sensor 350AA experienced load greater than the sensor 350BB, while for the right amputee, the sensor 350BB experienced load greater than the sensor 350AA. This indicates that the loading was biased towards the medial side of the heel, as per expected from gait biomechanics. In other words, the relative displacement between the sensor assembly <NUM> and the base <NUM> was greater in the medial side than in the lateral side. In both cases, the array 500A was able to properly record a load cycle, regardless of whether a user was an left amputee or a right amputee. Similar characteristic may be observed for the anterior sensors (that is, the sensors 350CC and 350DD) in the later portions of the stance phase of a gait cycle. Readings from the sensors 350CC and 350DD may be inverted in amplitude between the two amputees as the medial side sensor shows higher loading than the lateral sensor. For the left amputee, the sensor 750CC (that is, anterior-medial sensor) experienced load greater than load experienced by the sensor 750DD (that is, anterior-lateral sensor). Likewise, for the right amputee, the sensor 750DD (that is, anterior-medial sensor) experienced load greater than load experienced by the sensor 750CC (that is, anterior-lateral sensor).

It is to be noted that the difference in amplitude may be attributed to a difference in body weight between users or different gait characteristics or abnormalities.

Use of a sensor array pattern in-line with the nature of the loads and typical loading patterns observed during gait allows the sensors <NUM> to sense load applied during a stance phase of a gait cycle. In addition, using different sensor array patterns may allow the prosthetic device <NUM> to identify different foot-ground interactions, as discussed above. It is also possible to further strengthen the robustness of the ground contact sensor function by adding signal processing, either in hardware or in firmware. Since there is no a priori knowledge of the amputation side or the characteristic progression of the load line during ambulatory or non-ambulatory gait activities, there is a benefits in processing the raw signals, similar to the one shown in the figures above, such that prosthetic device performance is maintained in all use-cases.

One aspect of a software process merging the information provided by the individual sensors (for example, the sensors 350A-<NUM>) present in an array may include creating a contour plot from the individual sensor signals. In the context of a control system managing actuator behavior/operation by utilizing information regarding the interaction of a prosthetic device with the ground surface, a contour plot allows to sum contribution of all sensors. The contour plot may be generated by adding all the partial loading observed through the measurement points by all sensors. A contour plot of the data collected by an array of sensors may then present the total observed loading, which indicate a presence, or a lack of presence, of an interaction between the prosthetic foot and the ground. A simple hysteretic threshold process may then be used to determine whether the interaction is present or not. Additionally and/or alternatively, the contour plot may a pattern of the load applied to the prosthetic limb.

A simple contour plot may be created for a sensor assembly <NUM> implementing four sensors 350AA-350DD, such as shown in <FIG> and <FIG>, in real-time through a relation of the form: <MAT>
where At is the contour Amplitude at time t and Sx,t is sensor x signal amplitude at time t.

<FIG> shows an example contour plot <NUM> generated by using the data illustrated in <FIG>. Such process may increase the signal amplitude and preserve the general shape attributes over the stance phase load cycle. Use of contour plot processing may minimize impacts of signals characteristics that are not coherent across all sensors in the array, and in facts may be used as a weak majority voting scheme at the same time. Characteristics that are common across all signals will get amplified.

Another hardware or firmware based signal processing scheme that may be used to combine the information provided by multiple sensors present in an array is using a maximum filtering scheme. In the maximum filtering scheme, the sensor signal presenting the highest amplitude is considered as the only valid one. Such processing scheme may take the following form when implemented as a real-time process: <MAT>
where At is the maximum amplitude at time t and Sx,t is sensor x signal amplitude at time t.

<FIG> illustrates an example plot <NUM> after applying the above maximum filter to the data presented in <FIG> above. With reference to <FIG>, it may be observed that the plot <NUM> follows readings from the sensor 350AA (that is, a posterior-medial sensor) until mid-stance (after a few rapid transition during a heel strike) before switching to readings from the sensor 350CC (that is, an anterior-medial sensor) at the start of a rollover to the toes until loading is removed.

Additional and/or alternatively, other signal processing approaches may be used for firmware processing of the data streams, such as heuristic rule-based decisions or weighted average.

Additionally and/or alternatively, dependencies on the load line progression pattern could be extracted and use for either prosthetic device control, gait quality assessment or providing guidance on prosthetic foot alignment. For example, load line progression pattern may be analyze to detect different gait characteristics including, but not limited to, walking speed, cadence, stance time, swing time, double support time, step length, step width, walking angle, toe angle, and the like. In some aspects, different types of gait abnormalities including, but not limited to, hemiplegic gait, diplegic gait, neuropathic gait, myopathic gait, choreiform gait, ataxic gait, Parkinsonian gait, sensory gait, and the like by analyzing load line progression pattern.

Additionally and/or alternatively, load line progression pattern of a specific user may be collected using the sensor assembly described above and be used to generate a user-specific methodology and/or signal processing algorithms/approaches. Such methodologies and/or signal processing algorithms/approaches may be used to detect different phases (for example, a stance phase and a swing phase) of the user's gait cycle. In this regard, prosthetic devices may utilize a ground contact sensor assembly described above to accurately detect ground contacts for any user's gait cycle and, in turn, provide signals to operate its actuator to provide adequate stance phase control.

The graphical illustrates shown in figures above are for illustrative purposes only and does not limit the subject matter disclosed herein in any way.

Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith.

Furthermore, certain features that are described in this disclosure in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination may, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

Other operations that are not depicted or described may be incorporated in the example methods and processes. For example, one or more additional operations may be performed before, after, simultaneously, or between any of the described operations. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems may generally be integrated together in a single product or packaged into multiple products.

Conditional language, such as "may," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps.

Claim 1:
A ground-contact sensor array (<NUM>) for a lower limb prosthetic device (<NUM>), wherein the ground-contact sensor array (<NUM>) comprises:
a first body configured to attach to a shank of the lower limb prosthetic device (<NUM>);
a second body moveably attached to the first body and comprising a distal connector (<NUM>) configured to attach to a prosthetic foot or ankle; and
a plurality of sensors (<NUM>) coupled with the first or second body;
characterized in that the sensors (<NUM>) are
configured to generate data related to a plurality of distances between the first and second body.