WO2009150417A2

WO2009150417A2 - Motor skills measuring systems

Info

Publication number: WO2009150417A2
Application number: PCT/GB2009/001449
Authority: WO
Inventors: Roger Gassert; Ludovic Dovat; Olivier Lambercy; Etienne Burdet
Original assignee: Imperial Innovations Limited
Priority date: 2008-06-11
Filing date: 2009-06-11
Publication date: 2009-12-17
Also published as: WO2009150417A3; GB0810637D0; WO2009150417A4

Abstract

A motor skills measurement system comprising a sensor unit including a sensor arranged to generate a sensor signal indicative of an action of a user, feedback means arranged to provide feedback to a user, and control means arranged to receive the sensor signal, and control the feedback means, wherein the sensor unit further comprises mounting means arranged to mount the sensor unit removably on support means.

Description

Motor Skills Measuring Systems

Field of the Invention

The present invention relates to measuring systems for measuring motor skills of a subject. It can be used for subjects who are patients, for example during rehabilitation after a stroke or other illness, or for healthy subjects, for example in athletic training, and has application in diagnostic, training and assessment systems for such cases. It can also be used to promote patient activity monitoring, tele-medicine and tele- rehabilitation.

Background to the Invention

Stroke is one of the leading causes of adult disability in the world, with more than 15 million cases every year. Most stroke survivors suffer from hemiparesis, a paralysis of one side of the body, resulting in a severe decrease in their ability to perform typical activities of daily living (eating, manipulating objects, handwriting, typing, etc.) . Rehabilitation centres will typically focus on regaining the ability to walk, as well as on shoulder and elbow function, often having only limited time to work on the hand and fingers. Additionally, physiotherapy sessions are limited by costs and the amount of available personnel. In the long-term, patients will tend to use their unaffected hand to grab and manipulate objects, eat and write, or compensate with body movements, due to a lack of performances in the affected limb or a lack of confidence in these performances [MC Cristea and MF Levin. Compensatory strategies for reaching in stroke. Brain, 123: 940-53, 2000] .

Robotic rehabilitation systems offer increased therapy under well- controlled conditions and with on-line feedback and assessment of the patient's motor function. In addition, exercises can be embedded in motivating games, allowing a variety of exercises with a given device. Current robotic rehabilitation systems are often large, complex and costly devices such as arm exoskeletons, requiring technical assistance and making them unsuited for decentralised use, e.g. at home. Passive objects generally used in rehabilitation such as balls, pegs, cups, etc. , in contrast, provide no feedback and little motivation.

Kahn et al. [L. Kahn, P. Lum, W. Rymer, D. Reinkensmeyer. Robot- assissted movement training for the stroke-impaired arm: Does it matter what the robot does? Journal of Rehabilitation Research & Development, 43:5, 619-630, 2006] found that isometric training using robotic devices can significantly improve force generation capabilities and motor function of stroke survivors. This system was used to train arm movements. Kamper et al [D. Kamper, H. Fischer, E. Cruz, W. Rymer. Weakness is the primary contributor to finger impairment in chronic stroke. Arch Phys Med Rehabil, 87, 1262-1269, 2006] studied the impairment of fingers after stroke, and found that muscle weakness is the primary contributor to finger impairment. Strengthening finger muscles must therefore be the primary focus of hand rehabilitation, and using isometric exercises is a simple and promising approach. Adamovich et al. [S. Adamovich, A. Merians, R. Boian, J. Lewis, M. Tremaine, G. Burdea, M. Recce, H. Poizner. A virtual reality-based exercise system for hand rehabilitation post-stroke. Presence 14:2, 161-174, 2005] developed a robotic glove for hand rehabilitation to train finger movement in a virtual environment using simple games. The addition of the visual feedback increased the motivation and concentration of subjects. However, this system only offers a limited number of possible exercises and does not provide the flexibility and simplicity of our system. L. Dovat et al. [L. Dovat, O. Lambercy, V. Johnson, B. Salman, S. Wong, R. Gassert, E. Burdet, CL. Teo, T. Milner. A Cable Driven Robotic System to Train Finger Function After Stroke. Proc. IEEE International Conference on Robotic Rehabilitation (ICORR), 2007] developed a cable driven haptic interface for rehabilitation of finger function, which also allows isometric training when used in a blocked mode. Again, this system is more complex and does not provide as much flexibility.

Summary of the Invention

The present invention provides a motor skills measuring system comprising a sensor unit including a sensor arranged to generate a force sensor signal indicative of an action of a user, feedback means arranged to provide feedback to a user, and control means arranged to receive the sensor signal, and control the feedback means, wherein the sensor unit further comprises mounting means arranged to mount the sensor unit removably on support means.

The sensor or sensors may be, for example, force sensors, position sensors such as potentiometers or optical encoders, accelerometers or tilt sensors.

The feedback means may be, for example, discrete and computer- controllable components such vibrators for tactile stimulation and light emitting diodes (LEDs) , to generate timing, spatial or dynamic cues.

The system may include a plurality of sensor units, which can be removably mounted on a variety of differently shaped supports to train different motor skills. For example the supports may take the form of simple boxes or cups, or small objects such as keys. This may provide a simple way of achieving an ergonomic configuration adapted to the specific biomechanics of each user.

The sensor units may be arranged so that they can be used as at least part of a modular computer keyboard to train typing. The sensor/cueing/feedback units may have removable or replaceable contact pads so that the can be adapted for different uses. They may be placed on everyday objects.

Some embodiments of the present invention can provide a safe, simple and cost-effective therapy to regain and maintain motor function of various body parts (e.g. fingers, wrist, arm, leg, foot) for patients suffering e.g. from stroke, Parkinson's disease, spinal cord injury, cerebral palsy, brain injury or other motor dysfunctions. They can also be used to train healthy people, for example in sports training or educational environments. The system may consist of force and/or pressure transducers with, e.g. , a magnetic base, allowing simple adaptation to various functional tasks and shapes of body parts (e.g. hand shapes), as well as simple vibrotactile stimulators. The transducers and stimulators may be connected to a PC over a data acquisition system and can be fixed to various surfaces or objects in the case of the force transducers, or to pneumatic bellows of various shapes in the case of the pressure transducers. The PC may be arranged to assist the user in setting up the equipment, and gives access to a wide variety of motivating game-like exercises with visual and auditory feedback. The system can serve as well for training as for assessment, and can allow remote monitoring. Assessments can be used to automatically adapt the difficulty of exercises to the state of the patient.

The present invention further provides a method of measuring a user's motor skills comprising: providing a motor skills measuring system comprising a sensor unit including a sensor arranged to generate a sensor signal indicative of an action of the user, feedback means arranged to provide feedback to a user, and control means arranged to receive the sensor signal, and control the feedback means; mounting the sensor unit removably on an object, sensing an action of the user on the sensor unit, and providing feedback via the feedback means.

The feedback may be to the user whose motor skills are being measured, i.e. the subject of the measurement, or to another person, such as a clinician, who may be with the user, or may be remote from the user.

The measuring system may be used for assessment, diagnosis or training of the user.

Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings.

Brief Description of the Drawings Figure 1 is a diagram of a system according to the invention;

Figure 2 is a perspective view of a set of force sensor units forming part of the system of Figure 1 ;

Figure 3 shows a bellows unit forming part of the system of Figure 1;

Figure 4 shows a contoured support forming part of the system of Figure l;

Figure 5 shows a spring lever mounting for one of the force sensor units of the system of Figure 1 ;

Figure 6 shows a flexible beam mounting for one of the force sensor units of the system of Figure 1 ; Figures 7 and 8 show the use of a box-shaped support forming part of the system of Figure 1 ;

Figure 9 shows the use of a cup-shaped support forming part of the system of Figure 1 ;

Figure 10 shows the use of a key-shaped support forming part of the system of Figure 1 ;

Figures 11 and 12 show forms of visual feedback provided by the system of Figure 1 ;

Figures 13 to 15 show various exercises that can be provided by the system of Figure 1.

Detailed Description of the Preferred Embodiments

Referring to Figure 1, a rehabilitation system comprises a processor in the form of a PC 10, a set of force sensor units 12 connected to the PC 10 so that the PC can receive signals from the sensor units 12 and a display in the form of a screen 14 which is connected to the PC 10 so that the PC can control the display to give feedback to a user of the system, which may be the patient or a physiotherapist. A vibrator 15 is also connected to the PC 10 and can be configured to provide vibratory tactile feedback to a user. A speaker 17 is also connected to the PC 10 and can be controlled by the PC to provide auditory feedback to the user. An indicator 19 in the form of an LED is also connected to the PC and can be controlled by the PC to provide a prompt or cue to a user to perform a certain action.

Referring also to Figure 2, each of the pressure sensor units 12 comprises a thick film force sensor 16 mounted on a magnetic base 18. An exchangeable contact pad or finger knob 20 is removably mounted on top of the force sensor 16. This enables the sensor units to be adapted for different users or different uses. Other shapes of contact pad may be provided as alternatives, for example concave pads may be provided with a force sensor located at the bottom of a recess. This can help a user to place their finger in the correct location. The force sensor 16 is connected to the PC 10 by means of a power and signal cable 22 which supplies power to the force sensor unit 12 and transmits signals from the force sensor 16 back to the PC 10 which are indicative of the force applied to the sensor unit 12. A soft iron support plate 24 is provided with a smooth surface on which the force sensor units 12 can be mounted in any desired positions. In this embodiment there are five sensor units 12 which are specifically designed for measuring the forces applied by the fingers of one hand of the patient. The sensor units 12 can easily be moved into other configurations, for example to train the left hand rather than the right hand. Furthermore it will be appreciated that different sizes, numbers, and shapes of sensor units can be used in systems for training other parts of the patient's body.

The indicator 19 is also mounted on a magnetic base so that it can be removably mounted on various surfaces. Further similar indicators can also be connected to the PC so that an array of indicators can provide different prompts, cues, or indeed feedback, to the user.

Referring to Figure 3, the system further comprises a pneumatic bellow 30 designed to be gripped in the hand of a patient, and connected to a flexible tube 32. A pressure sensor 34 is arranged to fit into the end of the tube 32 in a sealed airtight manner to sense the air pressure within the bellows 30. The pressure sensor 34 can be connected to the PC 10 in place of, or as well as, the sensor units 12. The bellow and pressure sensor combination can be used to measure the ability of the patient to grip or squeeze the bellow. Referring to Figure 4, the system further comprises a shaped iron support plate 40 on which the sensor units 12 can be mounted instead of on the flat support plate 24. This allows the sensor units to be located in, for example, a non-planar array. This provides further variety in the positioning of the sensor units, and therefore further variety in the types of movement that the system can be used to train. Different shaped supports can be provided as required to provide different layouts and relative positions of the sensor units 12.

Referring to Figure 5, the system further comprises a flexible support on which one of the sensor units 12 can be mounted. The support comprises a base 50 with a support member 52 pivotably mounted on the base 50 by means of a hinge 54. A spring 56 acts between the base and the support member 52 to urge the support member towards a raised position as shown in Figure 5, so that the sensor unit 12 can be pressed to depress the support member 52. It will be appreciated that the force on the sensor unit 12 will increase as the support member 52 is depressed further, and therefore the force on the force sensor is indicative of the position of the support member 52, as well as the force being applied to it. This arrangement can therefore be used as a passive system to test movement of a finger 60 as well as the forces which it applies .

Referring to Figure 6, an alternative design of support comprises a resilient flexible beam 62 on which the force sensor unit 12 can be mounted. Again the flexible beam 62 allows for movement of the sensor unit 12 which is dependent on the amount of force applied to it.

Referring to Figures 7 to 10, the system further comprises a number of sample objects, in this case made of iron or steel, to which the sensor units can be attached. This allows the function of the hand in grasping various objects to be tested. Specifically these include a rectilinear box 70 as shown in Figures 7 and 8, a cup 90 as shown in Figure 9 which can be loaded with weights to vary its weight, and a key 100 as shown in Figure 10 which can be used to train pinching movements.

One particular test which can be performed for example with the box of Figure 8 or the cup of Figure 9, is to attach one of the sensor units 12 to the underside of the box or cup, so that its signal gives an indication of the weight of the object when it is resting on a surface, and two of them to opposite sides of the box or cup. The PC 10 can then measure the gripping force applied to the object by a subject when the subject is asked to pick the object up. This can allow comparison between the weight of the object and the gripping force applied to it to lift it. For example the gripping force applied can be compared with a gripping force, for example a minimum gripping force, which is necessary to pick the object up. It has been shown that healthy subjects can quite accurately adapt the gripping force they apply to an object according to their estimation of the weight of the object, whereas stroke patients tend to apply more gripping force than is needed to prevent the object from slipping out of their hand. This ability can be tested using this system. The PC 10 can be arranged to simply store the values of the forces measured by the force sensors, for analysis by the clinician, or it may be arranged to provide a display indicating the relationship between the weight of the object and the gripping force applied, or the magnitude of the gripping force compared to a reference magnitude.

The system described above provides a passive device for rehabilitation of motor function in the fingers, but can also be arranged for various other body parts (e.g. wrist, elbow, arm, foot leg, etc.) by using different sizes and shapes of sensor units and supports. The system can be used, for example, after stroke, spinal cord injury, cerebral palsy and other motor dysfunctions, as well as to maintain finger function in the elderly (e.g. to maintain range of motion, coordination and independence of fingers) . Instead of using expensive motors requiring power electronics and a mechanical structure, this embodiment consists of several simple force sensors, which can include integrated electronics (amplification and filtering) connected to a data acquisition card in the PC, making the system safe, cost-efficient and thus allowing it to target a large population. The sensors can easily be arranged on various surfaces (e.g. the flat support, curved objects, metal cups, etc. of Figures 3 and 8 to 10) to allow training of adequate force patterns in activities of daily living. The ability for the sensors to be connected to passive resilient mechanical structures incorporating springs to combine force and motion control, allows the testing of movement of the fingers or limbs .

In addition to the supports and objects described above, the sensor units 12 can also be attached to various known devices and systems which are arranged to assess patients' motor skills. These may be other passive devices, or may be at least partially active, for example taking the form of robots which are arranged to move either in response to the user's input, or to monitor the user's response to movement.

An indication of forces applied to the sensor units 12 is fed back to the user over the visual display 14 in a game-like manner to provide motivating exercises. This feedback is arranged to make the user aware of the force exerted by each finger, and can be used for efficient learning. Placing the sensors on various objects, such as flat and curved surfaces, boxes, cups, etc. , the user can train finger coordination and independence, reaction time and muscle strength. Many stroke survivors would also like to improve their keyboard typing skills, which can also be practised and assessed with this system. For example, referring to Figure 11, one type of display is arranged for use with the box-shaped test object of Figures 7 and 8. The display includes five separate indicators 110 each of which indicates the magnitude of the force applied with one of the five fingers of one hand (the thumb, and index, middle, ring and little fingers). A further indicator 112 is provided which shows a target force so that the patient can compare the force they are applying with each finger to the target force, and adjust the force they are applying to try to match it to the target. Separate target force indicators 114 can also be used to show different target forces for each finger.

Visual feedback is used to embed the functional exercises in motivating, game-like virtual environments. In the simplest case, as shown in Figure 11 , feedback is provided as a force bar, the length of which can be used to represent the measured force by multiplying the measured force by a gain (alpha) to obtain a bar length (height or width) (y) :

y= a/ (D

Particular dependencies of the form

can be used to define relationships between the forces {f, , i = 1, ... n]

of the n involved limbs, where A is a suitable (possibly nonlinear) function of the forces. For example, referring to Figure 12, to train finger independence, the parasite forces / applied by the fingers not to be trained (i ≠ k) can be multiplied by a gain (betai) and subtracted from the force of the finger (Jc) to be trained:

i≠k (2)

The force bar is therefore arranged to vary in length depending on both the force of the finger being trained and the parasitic force from the other fingers. Again a target force can be set and indicated as a target marker or bar length on the display. The system therefore measures and provides feedback on coordination of the patient. It will be appreciated that other functions can be defined and used to drive the feedback, varying in different ways with the various measured forces to test coordination in different ways. In some cases other variables can be measured and used to provide the feedback. These may be other variables which measure the actions of the subject, such as position measured by position sensors, or they may be other variables which can be used in combination with force or position, such as temperature as measured by a temperature sensor.

For some exercises, the user's reaction times can be measured, and these can then be used to drive the feedback displayed to the user. For example, the indicator unit 19, which can be attached to a suitable surface, can be operated as a cue, and a required response defined, such as a single input to one of the sensor units 12. The PC 10 is then arranged to measure the time between operation of the indicator and the user's response, and suitable feedback provided. The feedback can be visual or auditory for example. Where several indicator units are provided these can be located adjacent to respective sensor units, and lit up in a random sequence. The ability of the user to follow the sequence by pressing the sensor unit associated with the correct indicator, and the speed of their response, can be measured. Alternatively the indicator units 19 and sensor units 12 can be mounted on different objects or just in different positions, and the patient's skill in moving, for example, one finger between the sensor units as indicated by the indicator units, measured.

In more complex displays, in which objects in a virtual world are moved by the patient, a virtual admittance controller takes the force applied by the user as the input and outputs a displacement of an object in the virtual world. This gives the objects moved around on the screen virtual dynamics (inertia and damping in addition to a stiffness), which require the user not only to control force, but also to predict the evolution of the object trajectory and adapt the force accordingly.

Motion of the virtual object on the screen is governed by a differential equation, e.g. the second order linear equation: n f ≡ Y f_k = Mx + Dx + Kx fc= l (3)

where / is the sum of the forces f_k applied on the object, x is the linear displacement of the object, and M, D and K are constants. By applying the Laplace transform L we obtain the transfer function of the (virtual admittance) controller:

1

G(s) ≡ ^C{ώ)

£(/) Ms + D + K

(4)

Acceleration, velocity and position of the virtual object on the screen can then be determined from this differential equation and used to update the visual feedback. The simple case of equation (1) is obtained if virtual mass (M) and damping (D) are set to zero. This scheme allows simulation of real-world objects, thereby giving the possibility of training adequate muscle activation patterns for activities of daily living with realistic dynamics. Imaginary dynamics can also be implemented to train specific functions, e.g. assistance or resistance with a tuneable parameter. Again, measured parameters other than force can be used to control the visual feedback, in a linear or non-linear manner, such as a combination of position and temperature.

Referring to Figure 13 in one embodiment the force sensor unit 12 is mounted on a spring-lever mechanism of Figure 6 or on a flexible beam as shown in Figure 7. The measured force can be used to estimate the displacement of the force sensor, or the flexion angle of the beam, allowing a visual feedback of, and training for, displacement instead of force. The visual interface, in this embodiment in the form of a touch sensitive screen on the display 14, also allows the subject to adjust simple values influencing the practice according to his desire, such as the force amplitude to be trained, or the success force range around this desired amplitude, both adjusted over a simple slider control. For example as shown in Figure 13, a game of virtual squash is played by the patient moving the racquet 130 by applying forces to the sensor units 12 mounted on opposite sides of a flexible beam 132. The relationship between the movement of the beam 132 and the movement of the racquet 130 can be chosen as required. For example the speed of movement of the racquet 130 may be proportional to the displacement of the beam 132.

Referring to Figure 14, the system can be arranged to provide a typing exercise, where subjects have to press ,,keys" formed by the force sensor units 12, in the right order to spell a word. The display 14 shows a letter key 140 associated with each of the sensor units 12, from which the user has to determine the required order of pressing. The force level for each sensor unit to be considered as pressed, and the difficulty of the test, can be adjusted using adjustment icons 142, 144. Subjects can either be requested to type the word as fast as possible or receive visual, auditory or tactile cues for timing. In a modification to this arrangement, the force sensor units 12 can be integrated into a full keyboard so that full typing skills can be assessed.

Referring to Figure 15, the system can also be arranged to provide an exercise to train force sequences/patterns, by flashing LED's 150 corresponding to the force transducers in a certain order, with regular or varying time steps, which the user must follow by pressing the sensor units 12. The force sensors can be placed on different objects, and arranged for use with different parts of the patient's body. The system can therefore be used to test the patient's reaction time, by simply timing their response to a stimulus. It can also be used to test their reaction time during bilateral tasks, such as pushing buttons with fingers of both hands or with both feet. Another use is in assessment of spatiotemporal planning and execution, for example giving a stimulus indicating a number of sensors that need to be pressed and analysing the time taken for the patient to press them all, and the order in which they are pressed.

Referring back to Figure 1, in any of the arrangements described above, feedback may be complemented with the vibrator 15 to train a patient in interaction with objects which involves the application of force by the patient, and tactile feedback from the system via the vibrator. Alternatively, a pneumatic switch and pressure sensor may be used to train control of grip force using the device of Figure 3. The user interface focuses on usability and accessibility, and can include online video tutorials, which guide the user through installation, configuration and the various exercises. The system can be set up so that the user simply selects an exercise and chooses the force magnitude to train (from fine force control to muscle strengthening) and the feedback (visual or tactile) as desired. Several motivating game-like exercises with visual and auditory rewards can be implemented. Scores and force data can be made available for continuous assessment over the internet. The catalogue of exercises for each patient can be determined after an initial assessment with the device, taking into account the exercises patients find most motivating.

Again, referring back to Figure 1, the speaker 17 can be used to provide auditory feedback to assist in timing (e.g. to practice reaction time or to perform a task at a certain frequency) , to promote motivation (applause or phrases like ,,good job" or ,,keep it up") upon successful task completion or reward such as a nice music or encouraging statements such as ,,you can do it" if improvement is possible. Like with the vibrotactile feedback, realistic (e.g. hitting a surface) or hyper-realistic auditory feedback can also inform the subject about task performance (e.g. that he/she has entered the desired force range) .

Simple programs to assess motor function of the patient can be implemented on the system described. The force sensors allow assessing maximum voluntary contraction (MVC) of fingers in both flexion/extension as well as adduction/abduction, due to the flexibility in mounting them on various surfaces. Other factors such as performance scores in the various games, evolution in finger independence/fractionation and reaction time measurements can be logged and transmitted over the internet for remote assessment and adaptation of exercise parameters. The system can also easily assess the evolution of sensory sensitivity, e.g. the just noticeable difference (JND) in force changes of the patient. This continuous assessment of the patient's motor performance can be used to adjust experimental parameters to maximise motivation, avoiding both exercises which are too simple or too complex for the patient. The system can be set up as part of a network, for example over a LAN or over the internet or a GSM network. This allows the system including the PC to be located locally with the user, and to communicate over the network with a remote station which can be arranged simply to analyse or report on the results of the tests, or to allow a remote user, such as a physiotherapist or other clinician, to interact with the patient or other subject of the tests to supervise and assist them or compete in a game.

Another advantage of the system described is that it can be made portable, and can therefore be used as a portable diagnostics tool, for example for the school pedagogic service or for general medical practitioners, for example for diagnosing transient ischemic attacks.

It will be appreciated that some embodiments of the invention may have one or more of the following advantages:

1. The system is safe and does not require a physiotherapist to be physically present for supervision of the training.

2. The patient can train independently at his or her own pace and whenever he or she is motivated to train (i.e. not at predetermined hours) 3. Training does not require physical effort from a physiotherapist.

4. The system is modular, allowing connection of several force and pressure transducers or vibrotactile stimulators and their mounting on various objects.

5. The magnetic, or other detachable, base of the sensor units allows simple rearrangement and fixation to various surfaces.

6. The system allows for tele-monitoring of subject performance over internet communication.

7. Visual, audio (applause, encouraging comments, etc.) and tactile feedback modalities are provided. 8. Training of muscle strength and control of fine forces is possible. The measuring range of the sensors may be adjustable, and may be adapted to appropriate levels to match the body part to be trained, giving the system greater flexibility.

9. Stimulation of tactile senses is possible.

10. Training to improve finger coordination, fractionation and independence as well as reaction time can be provided.

11. Training to improve coordination between different body parts, e.g. hand opening/closing and wrist pronation/supination, or coordination between the two arms or the two legs.

12. Continuous online assessment of performance can be provided, including the grip/load force (weight) relationship indicating a patient's ability to assess and generate a level of grip force appropriate for a particular object.

13. Motivating games can be provided to train for functional tasks.

14. A virtual admittance controller gives objects dynamics and allows the user to practice control in a predictive manner. This can help to stimulate the many neural circuits involved in the planning and execution of motor tasks. For example it can help the user to (re) learn internal models of tasks dynamics based on suitable sensorimotor loops by providing tactile and visual feedback relating to exerted force, pressure, position etc. 15. Having the sensors mounted on simple objects makes them easier to use than, for example, a glove, in cases where the mobility of the user's hand is seriously affected. This is particularly relevant where the user may be testing himself remotely from the clinician.

Various modifications to the embodiments described can of course be made. For example, the detachable mounting method for the sensor units can take forms other than magnetic, such as adhesive tape or Velcro™. Alternatively the mounting method may include a combination of mechanisms, such as magnetic and mechanical, for example using a magnet and a pin or socket device. Also the size and shape and number of the sensor units can be varied so that the system can be used for other body parts. For example larger sensor units can be provided which can be removably mounted on a wall, or a suitable stand or support, for example by suitable mounting brackets, for training of the patient's arms and legs.

Different types of sensor may be used. As well as force sensors, which may be, for example, force sensitive resistors, other sensors such as position sensors, vibration sensors and accelerometers can be used. Similarly the indicator units, instead of LED devices, can be vibratory or auditory units, or stimulators to provide electrical or thermal stimulation of nociceptors, or olfactory or gustatory stimulation. Clearly auditory stimulation can be very simple sounds, or more complex or specific commands optionally combined with a timing cue.

Rather than wired connection between the sensor units and the PC, in some cases a wireless connection may be suitable, in which case the sensor signals will be transmitted wirelessly. The sensor units can also each be provided with their own local embedded power source, which avoids the need for a power connection to the sensor units. This gives greater flexibility in the location of the sensor units.

Claims

1. A motor skills measurement system comprising a sensor unit including a sensor arranged to generate a sensor signal indicative of an action of a user, feedback means arranged to provide feedback to a user, and control means arranged to receive the sensor signal, and control the feedback means, wherein the sensor unit further comprises mounting means arranged to mount the sensor unit removably on support means.

2. A system according to claim 1 further comprising at least one further sensor unit so that there are a plurality of sensor units each comprising mounting means arranged to mount it removably on support means .

3. A system according to claim 1 or claim 2 wherein the mounting means is magnetic.

4. A system according to any foregoing claim further comprising mounting means on which the sensor unit or units can be removably mounted.

5. A system according to claim 4 wherein the support means is contoured so that the orientation of the sensor unit or units can each be varied by moving its position on the support means.

6. A system according to claim 4 or claim 5 comprising a plurality of mounting means of different shapes on each of which the sensor unit or units can be removably mounted.

7. A system according to any foregoing claim wherein the feedback means is arranged to vary in a predetermined way in response to changes in the sensor signal.

8. A system according to claim 7 when dependent on claim 2, wherein the feedback means is arranged to vary in a predetermined way in response to changes in a function which is arranged to vary with sensor signals generated by each of the sensors.

9. A system according to claim 8 wherein the function is arranged to increase in response to an action on one of the sensors, and decrease in response to an equivalent action on another of the sensors.

10. A system according to any foregoing claim wherein the feedback means is arranged to provide feedback including an image of a moving object.

11. A system according to claim 10 wherein the control means is arranged to vary at least one of the position, speed and acceleration of the object in a manner which depends on the sensor signal.

12. A system according to any foregoing claim wherein the oreach sensor is a force sensor.

13. A system according to any foregoing claim further comprising a bellows and a pressure sensor arranged to generate a pressure signal indicative of the air pressure in the bellows, the pressure sensor being connected to the control means and the control means being arranged to control the feedback in response to the pressure signal.

14. A system according to any foregoing claim wherein the feedback means comprises a vibrator.

15. A system according to any foregoing claim wherein the feedback means is arranged to generate auditory feedback.

16. A system according to any foregoing claim further comprising an indicator arranged to provide an indication to a user to which the use can respond.

17. A system according to claim 16 wherein the indicator forms part of an indicator unit which further comprises mounting means arranged to mount the indicator unit removably on support means.

18. A method of measuring a user's motor skills comprising: providing a motor skills measuring system comprising a sensor unit including a sensor arranged to generate a sensor signal indicative of an action of the user, feedback means arranged to provide feedback to the user, and control means arranged to receive the sensor signal, and control the feedback means; mounting the sensor unit removably on an object, sensing an action of the user on the sensor unit, and providing feedback via the feedback means.

19. A method according to claim 18 wherein the system comprises a plurality of sensor units and the sensor units.

20. A method according to claim 19 wherein the sensor units are mounted on different objects.

21. A method according to claim 19 wherein the sensor units are mounted on the same object.

22. A method according to claim 21 wherein the feedback means is arranged to provide feedback based on the relationship between the forces measured by the sensor units.

23. A method according to any of claims 19, 21 or 22 wherein at least one of the sensor units is attached to the underside of an object so as to measure its weight, and at least one of the sensor units is attached to a side of the object to measure a gripping force applied to the object.

24. A method according to any of claims 18 to 23 further comprising providing a stimulus to the user and timing the user's response.