WO2008100133A1

WO2008100133A1 - System, method and gripping element for giving tactile feedback

Info

Publication number: WO2008100133A1
Application number: PCT/NL2008/000037
Authority: WO
Inventors: Hendrikus Petronella Johanna Van Der Zanden
Original assignee: Van Der Zanden Hendrikus Petro
Priority date: 2007-02-12
Filing date: 2008-02-07
Publication date: 2008-08-21
Also published as: NL1033372C2

Abstract

As a means for treating or preventing muscle problems caused by stress, a system is provided for giving tactile feedback, comprising a grip element (101, 201-202, 301a, 301b, 301d), measuring means (102-103, 203, 210, 302a, 303, 304) for measuring a gripping force being applied on the grip element, an actuator (105, 107, 108, 207-209, 302b, 302c, 304) for providing tactile feedback, detection means (104, 109, 205, 206) for detecting a gripping force level as measured by the measuring means, wherein the detection means are arranged for activating the actuator in dependence on the gripping force measured by the measuring means, wherein the actuator is connected to the grip element in such a manner that said tactile feedback takes place in the grip element at the location where the force is being applied.

Description

System, method and gripping element for giving tactile feedback

DESCRIPTION

The invention relates to a system, a method and a grip element for giving tactile feedback.

Increased muscle tension in humans is a common problem. Increased muscle tension may lead to stress and RSI (Repetitive Strain Injury). In many cases this problem can be solved by relaxation, by therapy or by relaxation- oriented special training. In a number of cases, however, this is not sufficient and devices must be used to achieve the desired effect.

A special category of devices is arranged for giving a patient muscle tension feedback, for example by delivering an audio signal or a visual signal when an applied force or pressure, or a muscle activity, exceeds a specified value.

An example of this is to be found in Dutch patent publication NL 9402147, which measures the squeezing force on a writing device, for example a pen. When the squeezing force exceeds a predetermined value, a visual signal is produced by means of an LED. The user of the pen can then check his or her muscle tension and reduce it, if necessary.

A second example is to be found in US patent publication US 5,662,123, which discloses a biofeedback sensor and various methods for giving feedback. One method of giving feedback employs tactile means. A user is given a tactile stimulus to reduce his muscle tension. An advantage of this is that the outside world, or persons other than the user, are not informed about or involved in the use of the device. A problem with known devices or methods for giving feedback is that the feedback is provided at a different place and/or in a different form than that in which the stimulus associated with the applying of the force is given, rendering a long feedback loop.

It is an object of the invention to provide tactile feedback with a short feedback loop.

According to a first aspect of the invention, this object is accomplished by means of a system for providing tactile feedback, which system may comprise a grip element provided with at least one carrying part for providing carrying capacity, measuring means for measuring a gripping force being applied on the grip element, an actuator for providing tactile feedback, detection means for detecting a gripping force level as measured by the measuring means, wherein the detection means are arranged for activating the actuator in dependence on the gripping force measured by the measuring means, wherein the actuator is connected to the grip element in such a manner that said tactile feedback takes place in the grip element at the location where the force is being applied.

The invention is based on the insight that a user who applies a gripping force onto a grip element according to the invention is provided with tactile feedback where the gripping force is applied depending on the measured gripping force.

The advantage of feedback by tactile means in the region where the force is applied is that a user can immediately adjust the force he or she is applying without having to think about it. Another advantage of this form of tactile feedback is that it enhances the natural sensation of gripping or applying a force. This is very advantageous for users who suffer from increased muscle tension caused by a reduced tactile sense. Consequently, this form of tactile feedback will be experienced as a natural, stimulus to reduce the applied force.

The grip element may form part of or be connected to an object, for example an implement or a piece of sports equipment. In that case the grip element forms the part by which a user engages the object.

In one embodiment of the first aspect of the invention, the actuator and the measuring means may be integral with the grip element. The advantage of this is that this combination can be used as a handle or a grip element as a single unit. In another embodiment of the first aspect of the invention, the actuator uses vibration. Vibration is easily experienced as alarming and enhances the natural tactile feedback that is already provided by the reaction force of the gripping action.

In another embodiment of the first aspect of the invention, the measuring means may comprise a low-conductivity, compressible layer and at least, two electrodes, which said low-conductivity, compressible layer is arranged around the grip element, wherein said low-conductivity, compressible layer is made of a conductive material whose resistivity varies with the force being applied on the layer, and wherein said at least two electrodes are disposed between the grip element and said low-conductivity, compressible layer, so that said at least two electrodes make contact with said low-conductivity, compressible layer.

In this way the strength of the grip element is retained, the grip element can have a simple tubular shape and can be easily combined with an implement. The low-conductivity, compressible layer may also form a "grip" by which the grip element can be comfortably held. A grip element of this kind is equally sensitive for measuring applied force in any axial direction with respect to the tubular shape.

In another embodiment of the first aspect of the invention, the grip element comprises at least two parts split in longitudinal direction, which are movably disposed with respect to each other, which at least two parts are resiliently connected to each other.

In another embodiment of the first aspect of the invention, the measuring means measure the gripping force by measuring the force between the at least two parts of the grip element. The advantage of this is that the measuring means are situated in or between the parts of the grip element, which makes the measuring means less vulnerable. This way sensing of an applied force to the grip element is performed in the direction of the relative movement of the two parts.

In another embodiment of the first aspect of the invention, in which the actuator provides tactile feedback by engaging between said at least two parts of the grip element and setting them vibrating relative to each other, a comparatively strong vibratory stimulus can be generated because the parts of the grip element actually move with respect to each other.

In another embodiment of the first aspect of the invention, in which the actuator provides tactile feedback by engaging between parts of the grip element other than those between which said at least one gripping force is measured, the measurement of the gripping force is mechanically disconnected from the tactile feedback.

In another embodiment of the first aspect of the invention, the actuator comprises an electric motor provided with a mounting bracket and an eccentrically disposed mass connected to the drive shaft, which mounting bracket engages the grip element, wherein the actuator can be concealed in the grip element, so that it will be free from the environmental influences, such as moisture and dirt. In a basic embodiment of the first aspect of the invention, the detection means are arranged to have the actuator operate at a first strength level when the gripping force measured by the measuring means exceeds a preset first threshold value. In another embodiment of the first aspect of the invention, the detection means are arranged to have the actuator operate at a second strength level when the gripping force measured by the measuring means exceeds a preset second threshold value, wherein the second strength level of the actuator operation is higher than the first strength level and wherein the second threshold value for the measured gripping force is higher than the first threshold value. In this way a user can be given a second, stronger warning when he ignores the first warning.

In another embodiment of the first aspect of the invention, the actuator can operate at a multiple of strength levels, and the detection means are arranged for having the actuator operate at a strength level that increases proportionally with the measured gripping force. In another embodiment, the actuator operates proportionally with the applied force from a specified threshold value for the applied force.

In another embodiment of the first aspect of the invention, the system may comprise setting means for setting at least one of said first and said second threshold values.

When the invention as described above is used in the treatment of patients, there may be a need during a therapeutic session to be able to set the threshold values at which the detection means activate the actuator, for example in order to train a patient with varying threshold values. In another embodiment of the first aspect of the invention, the sensor may be formed by at least one piezo-electrical element, which is mounted in a staggered position between the two parts of the grip element via connecting pieces.

The application of a pressure on the two parts of the grip element will cause said at least one piezo-electrical element to bend and generate a voltage that is proportional to the force being applied.

In another embodiment of the first aspect of the invention, the actuator may be formed by at least one piezo-electrical element, which is mounted in a staggered position between the two parts of the grip element via connecting pieces.

The application of a voltage to the at least one piezo-electrical element will cause said element to bend and apply a force on the parts to which it is connected. The advantage of using piezo-electrical element is that it makes it possible to configure the grip element as a very flat element. This is for example the case when the parts to which the piezo-electrical elements are attached are essentially flat.

In another embodiment of the first aspect of the invention, said at least one piezo-electrical element is used alternately in time as a measuring means and as an actuator, wherein the detection means connected to the piezo-electrical element are arranged for alternately measuring and activating.

The advantage of this is that it makes it possible to reduce the amount of wiring used for connecting the piezo-electrical element to the detection means to an absolute minimum.

Besides making manual use of a grip element, wherein a force being applied is measured, and wherein the tactile feedback is given at the location where said force is being applied, it is also possible to use such a grip element in the (therapeutic) treatment of undesirable, involuntary nocturnal teeth grinding. For some patients involuntary nocturnal teeth grinding is a major problem. Also other forms of gripping or clamping force are conceivable.

The invention may thus be used for measuring a force applied between a person's jaws. A grip element can be placed between the person's jaws in that case. When the jaws tense up while the person is asleep, the grip element according to the invention provides tactile feedback to the jaws.

According to a second aspect of the invention, the aforesaid object is also accomplished by means of a method for giving tactile feedback, which method may comprise the steps of measuring a gripping force applied onto a grip element, detecting a gripping force level, providing tactile feedback to the grip element in dependence on the detected gripping force level, wherein said provision of tactile feedback takes place in the grip element at the location where the gripping force is being applied.

In an embodiment of the second aspect of the invention, the step of measuring of a gripping force applied on a grip element comprises the measuring of the resistance in a low-conductivity, compressible layer by means of at least two electrodes, wherein said low-conductivity, compressible layer is arranged around the grip element, and wherein said low-conductivity, compressible layer is made of a conductive material whose resistance varies with the force being applied on the layer, and wherein said at least two electrodes are arranged between the grip element and said low-conductivity, compressible layer, so that said at least two electrodes make contact with said low-conductivity, compressible layer.

In another embodiment of the second aspect of the invention, the grip element is made up of at least two parts split substantially in longitudinal direction, which are movably disposed with respect to each other, wherein said at least two parts are resiliently or elastically connected to each other, and wherein the step of measuring a gripping force comprises measuring the force between the at least two parts of the grip element.

In another embodiment of the second aspect of the invention, the step of providing tactile feedback comprises transferring said tactile feedback to said at least two parts of the grip element and setting said parts vibrating with respect to each other.

In another embodiment of the second aspect of the invention, the step of providing tactile feedback comprises transferring said tactile feedback to at least two parts of the grip element other than those between which said at least one gripping force is measured.

In another embodiment of the second aspect of the invention, the step of providing tactile feedback in dependence on the detected gripping force comprises providing tactile feedback at a first strength when the measured gripping force exceeds a preset first threshold value.

In another embodiment of the second aspect of the invention, the step of providing tactile feedback in dependence on the detected gripping force comprises providing tactile feedback at a second strength when the measured gripping force exceeds a preset second threshold value, wherein the second strength level of the tactile feedback is higher than the first strength level and wherein the second threshold value for the measured gripping force is higher than the first threshold value.

In another embodiment of the second aspect of the invention, the step of providing tactile feedback in dependence on the detected gripping force comprises providing tactile feedback at a strength which increases proportionally with the measured gripping force.

In another embodiment of the second aspect of the invention, the method may comprise the step of setting at least one of said first and said second threshold values.

According to a third aspect of the invention, the aforesaid object is also accomplished by means of a grip element for use in a system for providing tactile feedback, which grip element may comprise: at least one carrying part for providing carrying capacity, measuring means for measuring a gripping force being applied on the grip element, an actuator for providing tactile feedback, wherein said measuring means and said actuator can be connected to detection means for detecting a gripping force level measured by the measuring means, wherein the detection means are arranged for activating the actuator in dependence on the gripping force measured by the measuring means, wherein the actuator is connected to the grip element in such a manner that the tactile feedback takes place in the grip element at the location where the force is being applied.

The grip element has the advantage that it can be integrated in or mechanically attached to as a single unit in objects such as implements, utensils and sports equipment. The embodiments and advantages of the first and the second aspect of the invention also apply with regard to the grip element according to the third aspect of the invention.

Figure 1 is a schematical cross-sectional view in longitudinal direction of a preferred embodiment of the invention. Figure 2 is a schematical cross-sectional view in longitudinal direction of an alternative embodiment of the invention.

Figure 3 is a schematical cross-sectional view in longitudinal direction of another alternative embodiment of the invention.

The system according to the first aspects of the invention comprises a grip element, measuring means, detection means and an actuator. The measuring means are connected to the detection means. The detection means are arranged for activating the actuator. The grip element comprises a region where it is engaged by a user for handling an object to which the grip element is attached or of which the grip element forms part. The grip element may be a handle, for example. The user may be human, but also an animal may be considered.

As shown in figure 1 , in a preferred embodiment the carrying portion of the grip element is formed by a sleeve 101 , which sleeve 101 may have any cross-sectional shape, but which is preferably round. The measuring means comprise a layer of a compressible material

102 applied to the outer side of the sleeve wall, which comprises an electrically conductive filling, and at least one pair of electrodes 103. The electrodes 103 may be positioned between the sleeve 101 and the layer of compressible, low- conductivity material 102, or within said layer of compressible, low-conductivity material. The electrodes may be isolated from the sleeve, if necessary, if the sleeve is made of a conductive material. The electrodes 103 and the compressible, low- conductivity material thus jointly form a force or pressure sensor, for example according to German patent publication DE 19750671. In such a sensor the measured resistance between the electrodes decreases as the pressure being applied on the sensor increases.

The layer of compressible, low-conductivity material 102 may be configured as a thimble and forms a "grip" round the sleeve 101, as it were, furthermore making the grip element comfortable to the user's touch.

The electrodes 103 are connected to the detection means via connecting wires 111. The detection means are made up of a detection circuit 104 and a power supply 109. The detection circuit 104 is arranged for measuring the resistance between the electrodes 103. The detection circuit 104 is also arranged for activating an electrical output when the measured resistance between the electrodes 103 falls below a specified value. The detection circuit 104 may comprise a power source that sends a current through the electrodes 103, wherein the voltage drop across the electrodes 103 is measured as a measure of the resistance between the electrodes 103. The measured voltage can be compared with a threshold value for the voltage drop measured between the electrodes by a comparator, wherein an output of the comparator becomes active when the measured voltage across the electrodes 103 falls below the threshold value. This corresponds to the applied force exceeding the threshold value in force, corresponding to the voltage drop falling below the voltage threshold value.

The output of the comparator becomes inactive again when the voltage drop measured between the electrodes exceeds the threshold value, whether or not with a specified hysteresis. This corresponds to the applied force falling below the threshold value corresponding to the voltage drop.

The detection circuit 104 may comprise two or more comparators having different threshold values, wherein the actuator can be driven more strongly when the gripping force exceeds a higher threshold value in force, i.e. when the voltage drop across the electrodes 103 falls below a lower threshold value voltage.

The detection circuit 104 may furthermore comprises a circuit by means of which it can be arranged that when the gripping force exceeds a threshold value, the strength with which the actuator will vibrate will be proportional to the force being applied or, in other words, proportional to the reversed voltage drop across the electrodes 103.

The output of the comparator may control a control circuit or a buffer, which control circuit is suitable for driving an actuator. The threshold value is selected to correspond to a voltage drop across the electrodes 103 associated with an excessive force being applied on the compressible, low-conductivity layer 102.

The detection circuit 104 may also comprise a difference amplifier circuit, which, in the situation in which the voltage drop across the electrodes 104 falls below a threshold value, arranges for the actuator to be driven with a strength corresponding to the difference between the threshold value and the voltage drop across the electrodes 104.

This achieves that proportional tactile feedback is given when the force being applied exceeds a threshold value.

The actuator may be formed by an electric motor 105 mounted within the sleeve 101 , which is connected to the output of the detection circuit 104 by means of connecting wires 110. The motor 105 is rigidly connected to the sleeve

101 by means of a connecting piece 106. The motor 105 comprises a driven shaft

107, to the end of which a mass 108 is eccentrically attached. The connecting piece

106 is connected to the sleeve 101 at the location where the grip element is gripped.

In figure 1 this is the location where the compressible, low-conductivity material 102 is provided. This way the actuator provides tactile feedback in the region where the grip element is engaged by a user.

The power supply 109 may be the mains, but preferably it is a battery power supply, for example comprising rechargeable batteries, which is advantageous especially in the case of portable applications of the system according to the invention.

The operation of the preferred embodiment of the above-described system according to the invention is as follows:

- a user grips the grip element at the location where the layer of compressible, lower-conductivity material 102 is provided;

- the resistance between the electrodes 103 is measured as function of the force applied on the layer of compressible, low-conductivity material 102;

- if said resistance is lower than a preset threshold value, the detection circuit 104 will activate the output; - the activated output of the detection circuit 104 drives the motor 105, which starts to run;

- the mass 108 that is eccentrically attached to the drive shaft 107 causes vibration, which is transmitted to the sleeve by the motor 105 and the connecting piece 106;

- when the applied force falls below the threshold value again, taking into account, or not, a specified hysteresis, the motor 105 is turned off again.

In this way the object of the invention is accomplished and the user's attention is drawn to the fact that a specified pressure or force on the grip element has been exceeded at the location where said pressure of force is being applied. Besides using a low-conductivity, compressible layer 102, wherein a varying resistance is measured when the pressure on the layer 102 changes, also other measuring methods may be used. Thus the layer 102 might be an insulating layer, for example, with a first electrode being provided over the inner surface of the layer and a second electrode being provided on the outer surface thereof. Compressing the layer 102 causes the electrical capacitance measured between the first and the second electrode to vary. In the case of an increasing pressure the electrodes will be positioned closer together, as a result of which the capacitance will increase. The detection circuit 104 might in that case be arranged for measuring the capacitance. If the capacitance exceeds a specified reference value, the detection circuit 104 may activate an output.

Further variations as regards the forming of a pressure sensor as known from the prior art will be clear to those skilled in the art.

The detection means 111 , 104, 109 and 109 may be mounted in the sleeve 101 as one unit. The advantage of this is that in this way the system can be used as an independent unit in objects, such as implements and pieces of sports equipment.

An example of this is shown in figure 2, in which the grip element may be integrated in the shaft of a golf club. Another example is a pen, in which case the grip element also functions as the carrier of a nib and an ink reservoir.

The grip element may be provided with a coupling piece, which, if the sleeve 101 of the grip element has a circular cross-section, may be provided with screw thread at the end of the section. The screw thread may be internally or externally provided. The screw thread corresponds to screw thread formed on an implement, so that the grip element can be screwed to the implement.

Said coupling piece may be so configured that it can be "snap fitted" on or in a corresponding coupling piece of an implement.

In an alternative embodiment of the invention, as shown in figure 2, the grip element may comprise at least two longitudinally split parts 201 , 202, which parts are movable with respect to each other. The parts 201 , 202 move together upon applying of a pressure or a gripping force. The parts 201 , 202 may be formed by splitting a sleeve lengthways, for example. A pressure sensor 203 known from the prior art may be mounted between the parts 201 , 202 via connecting pieces. The parts 201, 202 may optionally be resiliently mounted relative to each other, in which case a displacement sensor 203 can measure the spring compression when the grip element is gripped and a pressure or a force is being applied, thus forming a pressure sensor. A wide range of displacement sensors is available in the art.

By comparing the measured pressure with a preset reference value in a detection circuit 205 fed by a power supply 206, an output of the detection circuit 205 can be activated upon transgression of the reference value, which output can activate an actuator.

The actuator may be an electromagnet 207 having a fixed yoke 208 and a movable yoke 209 to be provided between the parts that are movable with respect to each other, wherein the electromagnet 207 is attached to one carrying part 202 via the fixed yoke 208, whilst the movable yoke 209 is attached to a second carrying part 201. By energizing the electromagnet 208 in a pulsating manner by the detection circuit 205, the first carrying part 202 and the second carrying part 201 are set vibrating by the force applied on the movable yoke 209 by the electromagnet 207 in combination with the fixed yoke 208. The points of attachment of the pressure sensor 203 and the actuator 207, 208, 209 must be spaced close together to obtain the effect of tactile feedback. To that end the points of attachment must not be spaced apart by more than a handbreadth. To prevent the vibration generated by the actuator from influencing the measurement, the grip element may be divided into more than two parts, with the pressure sensor 203 engaging parts other than the actuator. To achieve this, the detection circuit 205 may also be arranged for filtering out the pressure variations caused by the actuator, such that only the slow pressure variations are compared with a reference value.

In an alternative embodiment of the invention as shown in figure 3, a grip element is built up of two parts 301a, 301b. The parts 301a, 301 b may be beams disposed opposite each other or flat plate elements, which may or may not be elongated in shape, wherein piezo-electrical elements 302a, 302b and 302c are arranged between the plates, which piezo-electrical elements 302a, 302b and 302c are connected to the parts 301a, 301b by means of connecting pieces 304. If necessary, the space between the parts 301a, 301b is filled with a resilient or yielding filling 308.

The piezo-electrical elements 302a, 302b and 302c are provided with control electrodes 303, by means of which said elements can be controlled, but they may also be used as sensors. When the piezo-electrical elements are bent by applying a force on the opposite parts 301a, 301b, the voltage generated on the electrodes 303 can be measured.

By way of example, the electrodes of the piezo-electrical elements 302a are connected to the input 306 of a detection circuit 305 by means of connecting wires. The electrodes 303 of the piezo-electrical elements 302b and 302c are electrically connected in parallel to the output 307 of the detection circuit by means of the connecting wires 309 and 310.

The applying of a pressure on the grip element, with the parts 301a, 301b moving relative to each other in a direction towards each other, causes the piezo-electrical elements 302a, 302b and 302c to bend. The voltage generated on the electrodes 303 of the piezo-electrical element 302a is a measure of the force being applied on the parts 301a, 301b. This voltage is measured by the detection circuit 305. When the measured voltage exceeds a threshold value, the detection circuit 305 can generate a control voltage, which is supplied to the piezo-electrical elements 302b and 302c via the output 307 and the connecting wires 310 and 309, setting said elements in motion via their electrodes 303, which movement is preferably a vibrating movement. Such a grip element can be designed to be very flat, because the piezo-electrical elements 302a, 302b and 302c can be designed to have a thickness in the order of tenths of millimetres to millimetres.

The above-described embodiment of the invention makes it possible to connect the actuators, being the piezo-electrical elements 302a, 302b and 302c, in parallel with their electrodes, wherein said parallel-connected actuators can be connected both to the input 306 and to the output 307 of a detection circuit. The detection circuit may in that case be arranged for measuring the voltage on the input 306 and subsequently applying a control signal to the output 307, by means of which control signal the piezo-electrical elements 302a, 302b and 302c can be set in motion. This process may be cyclically repeated in time. A grip element according to the above-described embodiment of the invention may for example be adapted for use in a treatment method for nocturnal teeth grinding, in which case the grip element may be provided with a liner on the parts 301a, 301b, and be dimensioned to enable placement thereof between the teeth of the user's jaws, wherein, when the user clamps his jaws together, tactile feedback can be given if said clamping force exceeds a preset value.

The grip element may be so configured that the parts 301a, 301 b provided with a liner, the piezo-electrical elements 302a, 302b and 302c, the fixing parts 304 and the resilient filling 308 together form the grip element, wherein the wires 309 and 311 electrically connect the parts 301a, 301b and exit at a specific point of the assembly, being connected to the detection circuit 305 via a lead. The detection circuit 305 may in that case furthermore comprise setting means for setting the threshold values for the measured voltage at which the detection circuit can set the actuators, being the piezo-electrical elements 302a, 302b and 302c, vibrating. It is also possible to mount the wires 309, 310 between the parts 301a, 301 b together with the detection circuit 305 as a single unit, in which case the detection circuit is also provided with an energy source 312, for example a battery.

The use of a grip element or system according to the invention, preferably according to the embodiment shown in figure 3, in the treatment of nocturnal teeth grinding requires that the grip element is adapted for placement in a user's teeth, between the jaws. To that end the grip element may be very flat and be provided with a liner on the outside so as to prevent damage to the teeth.

The detection circuits 104, 205 and 305 may be arranged for comparing the measured resistance, or the force, with more than one reference value, wherein, each time the force increases, a next threshold value is reached at which the actuator is driven correspondingly more strongly. When a small force is applied, the user will not experience any tactile feedback, therefore, a medium- strong force will result in some degree of tactile feedback and a large force will result in strong tactile feedback. The detection circuits 104, 205 and 305 might furthermore be arranged so that the strength of the tactile feedback is proportional to the force that is applied, which can be realised by amplifying the measuring signal proportionally and modulate it, if necessary, in cases in which the actuator does not generate the vibration itself, and presenting it to the actuator for proportional tactile feedback. The detection circuits 104, 205 and 305 may furthermore be arranged so that measuring the force is alternated with driving the actuator.

Setting means for setting one or more threshold values of the detection means may be in the form of an adjustable potentiometer, for example, by means of which it is possible to directly set a threshold value at which the comparator of the detection circuit can operate. It is also possible to provide the detection means with a processor or microcontroller and with communication means, so that threshold values can be set via an interface. Insofar as the threshold values and any other setting parameters of the detection circuit can be set, said setting may take place wirelessly, for example via a BlueTooth or a WLAN connection, but also via a wire connection, using a control element disposed near the user.

Initially a high threshold value may be used in the treatment of patients, which threshold value is decreased further and further as a patient responds more quickly to the treatment. Also the reverse is possible, initially a low threshold value is used, but as the treatment progresses said threshold value is increased further and further.

It will be apparent to those skilled in the art that the above description, in conjunction with the figures, merely describes examples and that variations to said examples are possible without departing from the scope of the following claims.

Claims

1. A system for providing tactile feedback, comprising

- a grip element (101 , 201-202, 301a, 301 b, 308) for applying onto an external gripping force; the grip element comprising

- measuring means (102-103, 203, 210, 302a, 303, 304) for measuring the gripping force being applied on the grip element (101 , 201-202, 301a, 301b, 308); - an actuator (105, 107, 108, 207-209, 302b, 302c, 304) for providing tactile feedback; the system further comprising

- detection means (104, 109, 205, 206) for detecting a gripping force level as measured by the measuring means (102-103, 203, 210, 302a, 303, 304), the detection means (104, 109, 205, 206) being arranged for activating the actuator (105, 107, 108, 207-209, 302b, 302c, 304) in dependence of the gripping force measured by the measuring means; characterised in that the actuator (105, 107, 108, 207-209, 302b, 302c, 304) engages the grip element (101 , 201-202, 301a, 301 b, 308) such that in use said tactile feedback is performed at the location where the gripping force is being applied.

2. The system according to claim 2, wherein the detection means (104, 109, 205, 206) and the actuator (105, 107, 108, 207-209, 302b, 302c, 304) are integrated in the grip element (101 , 201 -202, 301 a, 301 b, 308).

3. The system according to either one of the claims 1 - 2, wherein the actuator (105, 107, 108, 207-209, 302b, 302c, 304) uses vibration.

4. The system according to any one of the claims 1 - 3, wherein the measuring means (102-103, 203, 210, 302a, 303, 304) comprise a low- conductivity, compressible layer and at least two electrodes, which said low- conductivity, compressible layer is arranged around the grip element (101 , 201-

202, 301a, 301 b, 308), wherein said low-conductivity, compressible layer is made of a conductive material whose resistivity varies with the force being applied on the layer, and wherein said at least two electrodes are disposed between the grip element (101 , 201-202, 301a, 301b, 308) and said low-conductivity, compressible layer, so that said at least two electrodes are electrically connected to said low- conductivity, compressible layer.

5. The system according to any one of the preceding claims, wherein the actuator (105, 107, 108, 207-209, 302b, 302c, 304) comprises an electric motor provided with a motor mounting bracket and an eccentrically disposed mass connected to the drive shaft, wherein the mounting bracket of the electric motor engages the grip element (101 , 201-202, 301 a, 301 b, 308).

6. The system according to any one of the claims 1 - 3, wherein the grip element (101 , 201-202, 301a, 301 b, 308) comprises at least two parts split in the longitudinal direction, which are movably disposed with respect to each other, which at least two parts are resiliently or elastically connected to each other, wherein the measuring means (102-103, 203, 210, 302a, 303, 304) measure the gripping force by measuring the force between said at least two parts of the grip element (101 , 201-202, 301a, 301 b, 308).

7. The system according to claim 6, wherein the actuator (105, 107,

108, 207-209, 302b, 302c, 304) engages between said at least two parts (201 , 202) of the grip element (101 , 201-202, 301a, 301b, 308) and is arranged for vibrating said parts relative to each other

8. The system according to claim 7, wherein the actuator (105, 107, 108, 207-209, 302b, 302c, 304) provides tactile feedback by engaging between parts of the grip element (101 , 201-202, 301a, 301 b, 308) other than those between which said at least one gripping force is measured.

9. The system according to any one of the claims 6 - 8, wherein at least one piezo-electrical element is mounted between said at least two longitudinally split parts by means of connecting pieces, wherein at least one piezo-electrical element is provided with electrodes.

10. The system according to claim 9, wherein said at least one piezo- electrical element is controllable by the detection means as an actuator.

11. The system according to claim 9, wherein at least one piezo- electrical element is connected to the detection means as a measuring element.

12. The system according to claim 10 or 11 , wherein said at least one piezo-electrical element is both connected to the detection means as a sensor element and capable of being controlled as an actuator, wherein the detection

■ means are arranged for alternately having said at least one piezo-electrical element operate as a measuring element and having said at least one piezo- electrical element operate as an actuator.

13. The system according to any one of the preceding claims, wherein the detection means (104, 109, 205, 206) are arranged to have the actuator (105, 107, 108, 207-209, 302b, 302c, 304) operate at a first strength level when the gripping force measured by the measuring means (102-103, 203, 210, 302a, 303, 304) exceeds a preset first threshold value.

14. The system according to claim 13, wherein the detection means (104, 109, 205, 206) are arranged to have the actuator (105, 107, 108, 207-209, 302b, 302c, 304) operate at a second strength level when the gripping force measured by the measuring means (102-103, 203, 210, 302a, 303, 304) exceeds a preset second threshold value, wherein the second strength level of the actuator (105, 107, 108, 207-209, 302b, 302c, 304) operation is higher than the first strength level and wherein the second threshold value for the measured gripping force is higher than the first threshold value.

15. The system according to any one of the claims 1 - 12, wherein the actuator (105, 107, 108, 207-209, 302b, 302c, 304) is arranged for operating at multiple strength levels, and the detection means (104, 109, 205, 206) are arranged for having the actuator (105, 107, 108, 207-209, 302b, 302c, 304) operate at a strength level that increases proportionally with the measured gripping force.

16. The system according to claim 13 or 14, wherein the detection means are provided with setting means for setting at least one of said first and said second threshold values.

17. The system according to any one of the preceding claims, wherein the grip element (101 , 201-202, 301a, 301 b, 308) is provided with a connecting piece for connecting the grip element (101 , 201-202, 301a, 301b, 308) to an implement provided with a corresponding connecting piece.

18. A method for giving tactile feedback, comprising the steps of - measuring a gripping force applied on a grip element (101 , 201-

202, 301a, 301b, 308);

- detecting a gripping force level,

- providing tactile feedback in dependence on the detected gripping force level; characterised in that said provision of tactile feedback engages in the grip element (101 , 201 -202, 301 a, 301 b, 308) at the location where the force is being applied.

19. The method according to claim 18, wherein the step of measuring of a gripping force applied to a grip element (101 , 201-202, 301a, 301b, 308) comprises measuring of resistance in a low-conductivity compressible layer by means of at least two electrodes, wherein said low-conductivity compressible layer is arranged around the grip element (101 , 201-202, 301a, 301b, 308), and wherein said low-conductivity compressible layer is made of a conductive material of which resistance varies with the force being applied on the layer, and wherein said at least two electrodes are arranged between the grip element (101 , 201- 202, 301a, 301b, 308) and said low-conductivity, compressible layer, such that said at least two electrodes are connected electrically with said low-conductivity compressible layer.

20. The method according to claim 18 or 19, wherein the grip element (101 , 201-202, 301a, 301b, 308) comprises at least two parts split substantially in longitudinal direction, which are movably disposed with respect to each other, wherein said at least two parts are resiliently or elastically connected to each other, and wherein the step of measuring a gripping force comprises measuring the force between the at least two parts of the grip element (101 , 201-

202, 301a, 301b, 308).

21. The method according to any one of the claims 18 - 20, wherein the step of providing tactile feedback comprises transferring said tactile feedback to said at least two parts of the grip element (101 , 201-202, 301 a, 301b, 308) and vibrating said parts with respect to each other.

22. The method according to claim 21 , wherein the step of providing tactile feedback comprises transferring said tactile feedback to at least two parts of the grip element (101 , 201-202, 301a, 301b, 308) other than those between which said at least one gripping force is measured.

23. The method according to any one of the preceding claims 18 -

22, wherein the step of providing tactile feedback in dependence on the detected gripping force comprises providing tactile feedback at a first strength when the measured gripping force exceeds a preset first threshold value.

24. The method according to claim 23, wherein the step of providing tactile feedback in dependence on the detected gripping force comprises providing tactile feedback at a second strength when the measured gripping force exceeds a preset second threshold value, wherein the second strength level of the tactile feedback is higher than the first strength level and wherein the second threshold value for the measured gripping force is higher than the first threshold value.

25. The method according to any one of the claims 18 - 22, wherein the step of providing tactile feedback in dependence on the detected gripping force comprises providing tactile feedback at a strength which increases proportionally with the measured gripping force.

26. The method according to either one of the claims 23 - 24, further comprising the step of setting at least one of said first and said second threshold values.

27. A grip element (101 , 201-202, 301a, 301 b, 308) for use in a system for giving tactile feedback according to any one of the claims 1 - 17 or in a method for giving tactile feedback according to any one of the claims 18 - 26 comprising: at least one carrying part (101 , 201 -202, 301 a, 301 b)for providing carrying capacity, measuring means (102-103, 203, 210, 302a, 303, 304) for measuring a gripping force being applied on the grip element (101, 201-202,

301a, 301b, 308), an actuator (105, 107, 108, 207-209, 302b, 302c, 304) for providing tactile feedback, wherein said measuring means (102-103, 203, 210, 302a, 303, 304) and said actuator (105, 107, 108, 207-209, 302b, 302c, 304) being connected to detection means (104, 109, 205, 206) for detecting a gripping force level measured by the measuring means (102-103, 203, 210, 302a, 303,

304), wherein said detection means (104, 109, 205, 206) is arranged for activating the actuator (105, 107, 108, 207-209, 302b, 302c, 304) in dependence on the gripping force measured by the measuring means, wherein the actuator engages the grip element such that in use said tactile feedback is performed at the location where the gripping force is being applied.