Rehabilitation device

Abstract

An assistive device for supporting a limb of a user, the assistive device comprising a limb support member 1 and an articulated armature having plurality of arms 2, 5 extending in series between a bas

Description

The present invention relates to a rehabilitation device. More particularly, but not limited to, a system for assisting and monitoring upper limb movement during exercise with a mechanism for adjusting the level of support provided to counteract the weight of a person’s arm. Background of the invention We have years of experience providing arm supports for people with muscle weakness caused by conditions such as: muscular dystrophies, spinal injuries, stokes, motor neurone disease and multiple sclerosis. These arm supports assist people with daily living tasks such as self-feeding, grooming and using portable electronic devices. We and the therapists we work with, have noticed medical benefits to using our arm supports. The upper limb movement facilitated by the arm supports means that users have fewer joint contractures, a wider movement range and fewer lung problems; resulting in reduced hospital admissions and prolonged life-expectancy. This has led us to explore repurposing and developing versions of our arm supports primarily as rehabilitation and exercise tools. There is a growing body of evidence that intensive, frequent movement exercise with multiple repetitions results in more positive outcomes for people who have suffered a stroke or spinal cord injury. Robot controlled arm support equipment exists but is bulky and costs hundreds of thousands of pounds which is out of reach for individuals and for most rehabilitation centres particularly within the NHS. Repurposing and developing further the technologies used in our arm supports and in our robotic eating aid enables us to offer bespoke physiotherapy equipment at less than a tenth of the price of equivalent existing equipment. Our devices can also be used in a patient’s own home, monitored occasionally remotely by their therapists. This facilitates more effective physiotherapy with far more movement repetitions. It also facilitates more effective occupational therapy as people can perform real tasks at home. Should an individual user require the use of an arm support longer term, the use of such a device during their physical rehabilitation period will help facilitate effective use through familiarity. Statement of Invention The arrangement described herein provides a means for facilitating and encouraging exercise for physiotherapy and occupational therapy exercise. Typically, upper limb rehabilitation equipment is extremely bulky and expensive, unsuitable for use in patients’ homes, with no remote monitoring. The arrangement described herein is a development of a relatively compact mobile arm support with a proven track record of use by people in their own homes and elsewhere. It incorporates a robotic system based upon the operating system used in a robotic feeding aid also with a proven track record of use in people’s homes and when going out for a meal. The technologies are acceptable to people unlike other bulky equipment and can be produced for far less than alternative equipment, within a budget acceptable to far more rehabilitation departments. According to the invention, there is a rehabilitation device as defined in claim 1. According to a further aspect of the invention, there is provided an assistive device for supporting a limb of a user, the assistive device comprising the rehabilitation device of claim 1, wherein the controller receives the output of the one or more sensor so that the assistive device can be used to assess the physical capability of the user when moving the supported limb. The articulated armature may comprise one or more freely rotatable joint. An arm may be connected to the base by a freely rotatable joint. Said arm may be connected to an intermediate arm by a freely rotatable joint. Either or both of said joints may rotatable within a substantially horizontal plane. 18 06 24 The arms of the articulated armature may be connected end-to-end, e.g. with a joint between each adjacent arm. 5 The user’s arm may be held in a supportive sling or frame attached via a spring-loaded lifting arm to a freely moving articulated framework. The controller may be used to monitor the lifting arm and articulated framework joint positions so as to calculate the user’s limb / hand position in three-dimensional 10 space. The assistive device or system may comprise robotic sensor technology. A spring mechanism may counteract or partially counteract the weight of the user’s arm. This spring mechanism may be adjustable using an electric motor activated by the controller, e.g. the robotic control system. The controller and / or monitoring 15 system may automatically adjust the lifting force of the spring to pre-set or calculated values, e.g. reactive values which may be adjusted according to use of the device by the user. The robotic sensor control system may communicate with a computer, smart tablet 20 or phone, that may set the user targets and enable the playing of games through the system thus encouraging exercise. Additional sensors, including accelerometers and force sensors, may also communicate with the robotic system, detecting rotation of the user’s hand and grip. This can be the same hand as that supported by the sling or frame, or it can be the other hand; thus encouraging coordinated bilateral movements. The system may comprise a further device to be held by the user or worn by the user whilst using the device. The further device may comprise the one or more additional sensor. The operating system may include remote communication so that therapists can monitor progress of exercise and adjust difficulty of movement tasks, spring assistance or loading and other targets. According to a further aspect of the invention, there is provided a physiotherapy system comprising the assistive device of any preceding aspect and an operator / therapist interface device operatively connected to the controller for communication therewith. Any optional feature defined in relation to any one aspect of the invention may be applied to any further aspects of the invention wherever practicable. Detailed Description Practicable embodiments of the present invention will now be described, by way of example only, with reference to the accompanying Figures, in which: Figure 1 - Three-dimensional view of a rehabilitation device with an arm support frame attached via a spring-loaded lifting arm to a freely moving articulated framework mounted on a table-clamp base. Figure 2 - View from above of a rehabilitation device with an arm support frame attached via a spring-loaded lifting arm to a freely moving articulated framework mounted on a table-clamp base. Figure 3 - Section view from the side of a joint in the articulated framework. Figure 4 - Section view from the side of the table clamp base with the articulated framework in place. Figure 5 - Section view from the side of the table clamp base with the articulated framework removed. Figure 6 - Three-dimensional view of the spring-loaded arm lifting part of the rehabilitation device with a cover removed. Figure 7 - Section view from the side of the spring-loaded lifting arm part of the rehabilitation device. Figure 8 - Schematic of a rehabilitation system. Figures 1 and 2 show a rehabilitation device that is based upon a development of an assistive device that would be used for supporting a user’s arm. The device provides an arm / limb support frame 1. The support frame in this example is elongate in form, e.g. extending along a user’s limb in use. The support frame comprises a pair of side bars and one or more strap, sling or web extending therebetween. The arm support frame 1 is swivellably mounted onto a lifting arm 2, rotatable around an angled axis 3. The lifting arm is mounted to a spring-loaded mechanism 4 with a substantially horizontal axis. The spring-loaded mechanism is swivellably mounted onto the end of an articulated framework 5 with substantially vertical axis joints 6. The articulated framework is swivellably mounted to a table-clamp base 7 with a substantially vertical axis. A user can rest their arm in the arm support frame 1 and move their arm around freely in a substantially horizontal plane supported by the articulated framework 5 swivellably mounted in the table-clamp base 7 clamped to a table. The weight of the user’s arm is wholly or partially supported by the spring-loaded mechanism 4. In the specific embodiment of the invention shown, the rehabilitation device is fixed to a table. The invention applies equally to other mounting arrangements including wheelchair mounts, stands and adjustable height arrangements. In the specific embodiment of the invention described, the spring-loaded mechanism wholly or partially supports the weight of the user’s arm. The invention applies equally when the spring force is greater then the weight of the user’s arm so they have to apply downward force to lower their arm. The invention applies equally when additional weights are added so that the user has to apply extra upward force to raise their arm. The amount of force required can be varied by adjusting the spring-loading mechanism 4. The invention applies equally to right or left-handed arrangements or when both right and left-handed units are operated together. The invention applies equally to arrangements supporting lower limbs or other parts of the user’s body. Figure 3 shows a cross-section of a substantially vertical axis joint in an articulated framework of a rehabilitation device. A pin 8 is fixed in an upper arm assembly end 9. A magnet 10 is fixed in the end of the pin. A bearing assembly 11 is fixed to a lower arm assembly end 12. A sensor board 13 is fixed below the bearing assembly. As the upper arm moves relative to the lower arm, the magnet 9 rotates relative to the sensor board 13. Thus, movement of the arms can be detected and measured. In the specific embodiment of the invention shown, the movement sensors are hall effect or other magnetic sensors. The invention applies equally to if other sensor devices are employed and to other configurations. For example, an accelerometer, gyroscope, proximity sensor or other orientation sensor could be used to detect movement. Due to the swivelling mounting of the arms, a rotation sensor is in many ways preferred. A continuously variable sensor may be used to detect varying degrees and / or orientations of relative movement between the arms. Figure 4 shows a cross-section side view of a table-clamp base of a rehabilitation device with an articulated arm fitted. A tapered-end pin 14 is fixed in an arm assembly end 15. A magnet 16 is fixed in the end of the tapered-end pin. A bearing assembly 17 is fitted into a table-clamp base 18. A sensor board 19 is fixed below the bearing assembly. As the articulated arm moves relative to the table-clamp base, the magnet 16 rotates relative to the sensor board 19. Thus, movement of the arm can be detected and measured. In the specific embodiment of the invention described herein, all the joints including the spring-loaded mechanism have movement sensors. The outputs of each the movement sensors are sent to a controller, which monitors the movements. Geometrical calculations are used to calculate the position of the user’s hand in three dimensional space. Other arrangements are also possible, e.g. in which the movements are processed to determine a measure of the extent or nature of the movement of the user’s limb. Figure 5 shows a cross-section of a table-clamp base of a rehabilitation device with an articulated arm fitted lifted up. The articulated arm can be lifted out of the table-clamp base as the tapered-end pin 14 slides easily in and out of the bearing assembly 17. The magnetic sensor system works when the magnet is close enough to the sensor. There is no need for reconnection or realignment each time. This facilitates packing away and transportation, making the rehabilitation device portable. The invention applies equally to other arrangements. Figure 6 shows a spring-loaded arm lifting part of a rehabilitation device with a cover removed to show a toothed pulley train. A lifting arm 2 is fixed to a spring holder rotor 20. The spring holder rotor is swivellably mounted in a mounting block 21. A motor and gearbox assembly 22 is mounted in the mounting block. A toothed pulley train 23 connects the motor and gearbox assembly output shaft 24 to a worm screw shaft 25. Figure 7 - shows cross-section side view of a spring-loaded arm lifting part of a rehabilitation device. A worm screw 26 is fixed to a worm screw shaft 25. A worm gear 27 engages with the worm screw 26. An adjustable position stator shaft 28 is fixed in the worm gear 27. The adjustable position stator shaft has a slot to hold the inner leg of a torsion spring 29. The outer leg of the torsion spring is held in a slot in the spring holder rotor 20. Magnets 30 are fixed in the two ends of the adjustable position stator shaft. A sensor board 31 is fitted in a cap attached to the end of the mounting block 21. Another sensor board 32 is fitted in an end cap 33 fitted to the spring holder rotor 20. The motor and gearbox assembly 22 rotate the toothed pulley train 23 to rotate the worm screw 26. The worm screw drives the worm gear 27, turning the adjustable position stator shaft 28. This increases or decreases tension in the torsion spring 29 increasing or decreasing the torque it applies on the spring holder rotor 20 and thus the lifting force on the lifting arm 2. By this means the level of assistance to or loading on a user’s arm can be adjusted. The invention applies equally to alternative methods of providing and adjusting lifting forces or weighting to a person’s arm. The sensor board 31 in the end of the mounting block assembly is used to measure the adjustment of the torsion spring 28. The sensor board 32 in the end cap 33 of the spring holder rotor 20 measures the relative position of the adjustable position stator shaft 28 and the spring holder rotor 20. The two measurements from sensor boards 31 and 32 are compared to calculate the angle of rotation of the lifting arm 2 around the substantially horizontal axis of the spring loaded mechanism 4. The invention applies equally to alternative methods of measuring and comparing movements. In a specific embodiment of the invention, viscous grease is inserted between the spring holder rotor 20 and the mounting block 21 to smooth the movement. In a further embodiment of the invention this viscous damping is increased to provide a load for the user to work against. In a still further embodiment of the invention, friction is deliberately applied to this joint. In still further embodiments of the invention, viscous and / or friction damping is applied to any combinations of the joints of the rehabilitation device. In the specific embodiment of the invention described herein, the articulated arm has a specific number of joints and is free to move without constraints. The invention also applies if stops are applied to the articulated arm constraining its movement. It may be useful to limit movement when a user has a tendency to move in a particular direction for instance as a consequence of a having suffered a stroke. The invention applies equally to configurations with more and with fewer joints including with no articulated arm, the spring load mechanism being mounted directly to the base. In the specific embodiment of the invention described herein, the base is positioned substantially in front of the user, the invention applies equally when the base is substantially to the side of or behind the user. In the specific embodiment of the invention described herein, a motor is used to adjust the lifting spring tension. The invention applies equally to alternative arrangements such as manual adjustment through a knob or a fixed amount of lifting assistance. The invention applies equally to alternative lifting mechanisms including counter balance weights and active motor-powered lifting and lowering. The invention applies equally when forces are applied to other joints to assist or constrain movements. These forces can be applied by any combination of motors, spring or weights. Figure 8 shows a schematic of a rehabilitation system. A main arm unit 34 comprises an arm support frame attached via a motor adjustable spring-loaded lifting arm to a freely moving articulated framework. Sensors detect positions of all the joints. The main arm unit is mounted onto a base unit 35. A cable 36 combining wires from the main arm unit’s sensors and from the motor, plugs into the base unit. Thus, the main arm unit is easily attached to or detached from the base unit to aid portability. A cable 37 from the base unit plugs into a main circuit board 38. The cable 37 carries the data and connections required from cable 36 as well as data from the sensor in the base unit 35. The main circuit board thus acts as a controller for the device / system and receives all the sensor outputs, e.g. for logging movements and / or adjusting the spring-loaded mechanism. A tablet 39 is connected by Bluetooth (RTM) 40 or other suitable wired or wireless communication means to the main circuit board. Thus, the tablet can read the positions of sensors and can command the main circuit board to power the motor to adjust the spring-loading in the lifting arm. The tablet provides for output, reporting and / or control by an operator. The tablet 39 may be considered to provide a controller in common with the main circuit board 38 or could otherwise provide an input / output device for an operator. The tablet typically has a display as would be understood, e.g. a touchscreen display, to provide a interface for an operator. A handheld sensor 41 comprising a multi-axis accelerometer and a squeeze force sensor is also connected by Bluetooth (RTM) 42, or other suitable wired / wireless communication means, to the tablet. The tablet is connected by Wi-Fi (RTM) 43 to remote communications and the internet 44 in this example. The main circuit board can connect to other input control devices 45, if necessary. The tablet 39 detects movements of the main arm unit and signals from the handheld sensor. It uses these to control movement task software, such as games, installed on the tablet or accessible on-line. Settings for the movement tasks can be changed directly on the tablet or by remote communication to vary the movements and exercises required to perform tasks, achieve goals and play games. Thus, the user or patient can be incentivised to perform relevant exercises that meet their physiotherapeutic needs. The tablet or main circuit board (i.e. the controller) can control the motor to dynamically set the assistance of loading offered to user’s arm during tasks. In this way, the controller can receive the sensor outputs and determine one or more measure for assessing movements of the user. Based upon the determined measure, the controller can increase or decrease the assistance provided by the spring mechanism, e.g. automatically without the need for operator intervention. Tasks can be set that mimic activities of daily living such as reaching to grasp a cup, gripping it, lifting it and tilting it to take a drink. This offers a safe means of delivering occupational therapy. A camera on the tablet can be accessed for communications and assessment by remote therapists. Pose detection software can also be employed as a means to control task or play games or to ensure the patient has good enough posture when performing tasks. In the specific embodiment of the invention described herein, the different elements of the rehabilitation system communicate with each other by a specified combination of wired and wireless systems. The invention applies equally to any combination of any types of wired and wireless communications and to when any of the elements are combined into one or more other elements making a single element and to when some of the elements are not present. The handheld sensor 41 can be held in the same hand as the arm being supported in the main arm unit. Alternatively, it can be held in the opposite hand in order to encourage bilateral co-ordinated movements. By way of example, a game could be played whereby movements of the user’s arm move blocks on a screen, rotating the user’s other hand turns the bocks and squeezing their hand releases them. The invention applies equally to other types of sensor and when no handheld sensor is employed. The invention applies equally when used with any type of game and when no game is played. 18 06 24 In a further embodiment of the invention, the tablet’s microphone is used as part of the control system for instance to encourage speech. 5 In the specific embodiment of the invention described herein, a tablet is used to control the system and / or as an operator interface device. However, the invention applies equally to other computerised devices such as personal computers, smartphones or smartwatches and it will be appreciated that any suitable local or remote computing device could be used. 10 In a further embodiment of the invention other sensors within or connected to the computerised device are also employed to control the system for instance, heart monitoring in a smartwatch or other sensor. 15 In view of the foregoing description, it will be appreciated that an assistive device of simple construction for supporting a user’s limb can be modified to provide a physiotherapeutic device. Thus the user can be monitored to assess their physical capability and the level of resistance / support offered by the assistive device can be altered to provide improved response by the user and / or to encourage a 20 greater degree of physical activity. 05 09 24

Claims

1. An assistive device for supporting a limb of a user, the assistive device comprising:5 a limb support member;an articulated armature having plurality of arms extending in series between a base and the limb support member, comprising a proximal arm connected to the base, a distal arm connected to the limb support member and an intermediate arm connected between the proximal arm and the distal arm, wherein each arm is10 pivotably mounted to an adjacent arm at a swivel joint having a substantially vertical axis of rotation and wherein an adjustable support / resistance mechanism is mounted between the intermediate and distal arms in the articulated armature and the distal arm bearing the limb support member is further rotatable about a substantially horizontal axis to offer support for the weight of the user’s limb and to15 counteract loading on the limb support member by the user in use;one or more sensor for sensing movement of the articulated armature at the adjustable support / resistance mechanism;a controller for receiving an output of the one or more sensor;an adjustment mechanism for varying the resistance of the adjustable20 support / resistance mechanism so that the assistive device can be used for tailored physiotherapy of the user, wherein the adjustable support / resistance mechanism comprises a passive or un-powered support / resistance mechanism; and,wherein the adjustment mechanism is powered and under the control of the controller.

252. An assistive device according to claim 1, wherein the articulated armature further comprises one or more freely rotatable joint.

3. An assistive device according to claim 2, wherein the base is connected to 30 the articulated armature by a freely rotatable joint and / or wherein the freelyrotatable joint is provided between adjacent arms of the articulated armature.

4. An assistive device according to any preceding claim, wherein the resistance mechanism comprises a spring.05 09 245. An assistive device according to any preceding claim, wherein a controller is programmed to adjust the resistance of the adjustable support / resistance5 mechanism based on the output of the one or more sensor.

6. An assistive device according to any preceding claim, wherein the adjustment mechanism comprises a motor.10 7. An assistive device according to any preceding claim, wherein theadjustment mechanism comprises a rotational adjustment mechanism, such as a worm gear.15 8. An assistive device according to any preceding claim, wherein the one ormore sensor comprises a rotational sensor arranged to sense rotation of one or more joint between the arms of the articulated armature.

9. An assistive device according to claim 8, comprising a plurality of the20 sensors wherein one or more sensor is located at each of a plurality of joints between arms of the articulated armature.

10. An assistive device according to claim 9, wherein one sensor is provided between the base and the proximal arm and a further sensor is provided between 25 arms of the articulated armature.

11. An assistive device according to claim 9 or 10, wherein the controller determines a total movement of the user’s limb or the limb support member based on a combination of outputs of the plurality of sensors..3012. An assistive device according to any preceding claim, wherein the one or more sensor comprises a Hall effect sensor.05 09 2413. An assistive device according to any preceding claim, wherein the adjustable support / resistance mechanism comprises a rotational resistance mechanism and the one or more sensor comprises a pair of sensors at opposing sides of the rotational resistance mechanism.

514. An assistive device according to any preceding claim, wherein the limb support member comprises a limb support frame extending in a direction of the limb of the user.10 15. A physiotherapy system comprising the assistive device of any precedingclaim and an operator interface device operatively connected to the controller, the operator interface device arranged to output information on user movement derived from the one or more sensor.15 16. A physiotherapy system according to claim 15, wherein the operatorinterface device comprises one or more operator control for adjusting the resistance of the adjustable support / resistance mechanism via the controller.

17. A physiotherapy system according to claim 15 or 16, wherein the operator 20 interface device allows setting of user movement targets or games to be implemented using the device.

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