Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
  • G06F3/045—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Definitions

• the present invention relates to tactile sensor apparatus and methods for operating them.
• the basic principle of a tactile sensor also called a touch sensor, is to measure a contact between an object and a touch area, which is the sensory surface of the tactile sensor.
• a sensor signal which is directly proportional to the applied force is not required. Rather, the emphasis is generally on cost-effective coverage of a large or oddly- shaped area.
• the touch area corresponds to a fixed plate suspended movably at a number of points, with the result that switching contacts are actuated in the event of force being applied. Neither an intensity nor a location of the pressure can be measured, and if the touch area is large it is not possible to achieve a high degree of sensitivity for the sensor.
• the touch area is covered with an elastic and air-permeable material situated in an airtight sleeve, and air pressure sensors are fitted within the airtight sleeve. This approach does not allow spatial resolution of the force loading.
• a pressure-sensitive membrane is stretched across the touch area according to a capacitive or piezoelectric principle. With this approach, it is generally possible only to detect a change in the force loading.
• a conductive plastic material is applied to an interdigital structure, with an increasing pressure on the touch area resulting in a decreasing resistance between the two electrode combs. It is also possible to use further layers, for example for coverage and insulation.
• a membrane-type pressure sensor is comparatively costly to produce.
• a still further example of a prior approach is found in a catalog from MicroTouch Systems describing a writing panel which operates according to the resistive sensor principle.
• a thin lower polyester layer is fixed on a rigid support, and a thin upper polyester layer is clamped above it.
• the upper polyester layer is under a tensile stress and is separated from the lower polyester layer by a gap.
• the mutually opposite surfaces of the two polyester layers are coated with a conductive material. In the event of pressure loading on the upper polyester layer, the latter is pressed onto the lower polyester layer and an electrical contact is closed, the position of which can be determined.
• An object of the present invention is to provide a versatile and cost-effective tactile sensor having a simple structure. This object is achieved by means of a tactile sensor and by means of methods for operating it, in accordance with specific embodiments of the present invention.
• the tactile sensor has at least two conductive workpieces which lie one on top of the other at a common bearing area. The workpieces are thus in mechanical contact with one another at the bearing area.
• at least one workpiece is composed of conductive elastomer material (called an elastomer piece).
• the elastomer piece is both elastic and conductive. In the event of loading of a force F on the elastomer piece, with the result that the latter is pressed against the other workpiece, there is a change in the contact resistance or the surface transition conductance at that part (called the contact area) of the bearing area that is exposed to pressure.
• the contact resistance is generally dependent on the contact area and on the applied pressure, while the electric conductance in the internal volume of the elastomer piece is only slightly dependent on the mechanical load. Typically, the contact resistance decreases, the larger the contact area is and the greater the pressure is.
• the tactile sensor of the present invention requires just one, additionally extended, bearing area between two workpieces.
• the workpiece of the present invention does not have to be mechanically clamped.
• the mechanical bearing of the workpieces means that there is also no need to perform complicated setting of a distance.
• the bearing area of the present tactile sensor is not restricted to a planar form.
• the need to structure the bearing area is obviated in the case of the tactile sensor.
• the workpieces and the bearing area may also have cutouts. It is sufficient if one of the workpieces is produced from elastomer material, for some embodiments.
• the other material may be made for example of metal, e.g., a metal sheet or a foil. However, such an arrangement affords a limited spatial resolution and flexibility.
• an application of force can be measured for example by means of measuring a current flow through the contact area or a resistance value that takes account of the contact resistance.
• the workpieces may, for example, be equipped with electrodes.
• a voltage loading and/or measurement of a contact resistance can be done for example by means of electrodes connected to the workpieces, e.g., electrodes incorporated in the elastomer, or by other means for electrical contact with the workpieces.
• the means for electrical contact is referred to below as electrode, in a manner that does not constitute a restriction.
• a sum of resistances is measured, inter alia a transition resistance from the electrode to the workpiece a series resistance along or through the workpiece, and a contact resistance between one workpiece and the other.
• the composition of the resistance values for a given contact situation is known for every mechanical arrangement, with the result that the contact resistance sought can be calculated.
• FIG. 1 shows a tactile sensor T, in accordance with a specific embodiment of the present invention.
• FIG. 2 shows a simplified equivalent circuit diagram of the tactile sensor T from FIG. 1.
• FIG. 3 shows a further tactile sensor T, in accordance with another specific embodiment of the present invention.
• FIG. 4 shows a simplified equivalent circuit diagram of the tactile sensor T from FIG. 3.
• FIGs. 5a-5c show a tactile sensor of a specific embodiment of the invention having a conventional interdigital structure I.
• FIG. 6 shows the pressure at the A/D port 6 against the force F loading the tactile sensor T, in accordance with specific embodiments of the present invention.
• FIGs. 7 to 10 show differently formed embodiments of the tactile sensor T, in accordance with various specific embodiments of the present invention.
• FIG. 11 shows a simplified tactile sensor T ofFIG. 1 coupled to a microcontroller for determining various parameters, in accordance with a specific embodiment of the present invention.
• FIG. 12 shows a simplified equivalent circuit diagram of the tactile sensor T useful for determining the various parameters as shown in the configuration ofFIG. 11.
• the tactile sensor of the present invention has the advantage that it is constructed in a very simple manner and can thus be produced cost-effectively. Moreover, it is durable, impact-resistant and readily deformable. It is advantageous if at least two workpieces lying one on top of the other are composed of elastomer material, because, in this way, a comparatively low force loading leads to a readily measurable change in the contact resistance. This allows good sensitivity and spatial resolution of the sensor signal. Moreover, such a sensor is flexible, light and inexpensive.
• a tactile sensor is preferred in which the elastomer material is a foam, in particular a closed- cell and conductive foam, in particular EV AZOTE® foam belonging to the ZOATEFOAMS product family.
• a tactile sensor constructed from a foam, in particular Evazote foam is that its surface affords impact protection. As a result, by way of example, persons who collide with the tactile surface already impart a large part of the impact energy to the soft sensor material. Injuries are therefore less severe.
• the Evazote foam material also has other advantages.
• Evazote foam is inert and light, and also has greater stiffness and tearing strength than the known polyurethane foams that are often used. Further, this foam absorbs energy to a high degree, and its temperature, chemical and water resistance are also favorable. Well known methods can be used to fabricate it, and it can also be easily thermoformed. Metals are not corroded by Evazote foam, and the foam exhibits high ultraviolet (UN) stability.
• Evazote foam has a low electrical internal resistance of approximately 100 ⁇ /cm. The surface resistance, on the other hand, is very high in the pressure-free state, corresponding to a high impedance. In the event of pressure loading, it may be reduced to down to a few kilo-ohms. Consequently, Evazote foam does not have to be coated in a costly manner.
• the elastomer material for example Evazote foam
• Evazote foam is often available in the form of plates of different thickness.
• further geometries are also possible, e.g., half shell-shaped, triangular or box-shaped.
• Perforated workpieces can also be used, for example having cutouts or slots.
• the thickness of the material and the size of the bearing area of a tactile sensor have an influence on the measurement accuracy and the signal sensitivity.
• the response characteristic can be adjusted by way of the dimensioning of the elastomer pieces and the type of electrical circuitry in a manner adapted within wide limits.
• an intermediate layer is introduced between two workpieces, e.g., an electrically insulating, perforated layer for keeping a distance between the two workpieces.
• each elastomer piece has at least one electrode which is pressed onto the respective elastomer piece.
• the contact pressure minimizes an interfering transition resistance between electrode and elastomer piece.
• the contact pressure can be applied externally, e.g., by clips, screws and clamps, or internally by the electrodes being inserted into the elastomer piece and fixed, e.g., welded or bonded, under pressure.
• each parallelepipedal workpiece electrodes are fitted parallel to the bearing area, in particular over the entire length of the side areas ("edge electrodes").
• the electrodes of the two parallelepipeds can be arranged either parallel to one another or in such a way that each pair of electrodes is offset by an angle relative to one another, in particular by 90° between the first pair of electrodes and the second pair of electrodes.
• the side area is provided by one of the surfaces with a z-component, for example in the (x, z) plane or the (y, z) plane.
• that area of the workpiece, which is opposite to the bearing area could be used as the touch area.
• any conductive material which does not corrode is suitable as the material for the electrodes, in particular for use as edge electrodes. It is advantageous, however, if the electrode material is flexible in the active, i.e. deformable, region of the tactile sensor. Spirally wound wires, for example, are preferred in this region because they endure deformation without any problems and also tolerate a length change within wide limits, without an excessively high tensile force occurring.
• a wire mesh is particularly well suited, this usually being used as a contact material on radiofrequency-proof doors. Said wire mesh exhibits elasticity with regard to pressure transversely with respect to its diameter and along the wire. Also conceivable are plastics that have been rendered conductive (rubber cords, etc.), in the case of which, however, an additionally occurring electrical resistance generally has to be taken into account.
• the edge electrodes should be performed carefully, in order to keep the transition resistance with respect to the elastomer material as small as possible.
• the electrode is preferably pressed against the elastomer material, a transition resistance thereby being minimized.
• an apparatus is preferred which can be moved along the side area of the elastomer parallelepiped. It has a guide, so that it slides accurately over the edge of the elastomer. A blade sits in the center of this guide and cuts open the foam to a depth of a few millimeters. The respective electrode is inserted into the slot that has been produced in this way. For this purpose, a guide from which the electrode material emerges is fitted behind the blade.
• the effect of the guide for example a small tube, is that the electrode can be inserted to a maximum extent into the slot.
• the lateral guide of the tool narrows, thereby producing a lateral pressure which is necessary in order to achieve a low transition resistance between electrode and elastomer material.
• a welding unit is also situated in the region of the constriction. It may comprise for example an infrared radiator or a hot roller and welds the slot introduced by the blade.
• the constriction of the lateral guide is designed to be long enough that it maintains the constriction even during significant cooling of the elastomer material.
• the elastomer material which is welded under a pressure, effects a continuous pressure on the electrode material and, consequently, a constant and low transition resistance.
• the position and form of the electrodes are not restricted. For example, two point electrodes in opposite corners of each workpiece are possible. However, it is expedient for at least two electrodes to be fitted to each workpiece on opposite sides, in particular along the side areas laterally adjoining the bearing area.
• the tactile sensor it may be expedient to connect a plurality of electrodes and thereby obtain electrical combination of the resistance values.
• the tactile sensor is designed in such a way that the transition resistance is very much smaller than the series resistance, which should in turn be very much smaller than the contact resistance Rs.
• the first workpiece and the second workpiece are connected to different voltages.
• both workpieces have an opposite pair of electrodes, and if an operating voltage is applied to the electrode pair of the first workpiece, and the electrode pair of the other workpiece is connected to ground. It is also possible for one pair of electrodes to be connected to a positive operating voltage and the other pair of electrodes to a negative operating voltage.
• a voltage difference can be applied at least to the first workpiece, and the second workpiece is connected to an A/D port.
• a voltage difference is applied to an elastomer piece, in particular a foam parallelepiped.
• the elastomer piece acts as a voltage divider, resulting in the advantage of a simple structure and the possibility of determining the position of the applied force in at least one direction.
• one electrode of a pair of electrodes of one elastomer piece is connected to a voltage, while the other electrode of this pair of electrodes is not connected; at the same time, the pair of electrodes of the other elastomer piece is connected up in the same way as for the measurement of the intensity of the contact resistance, e.g., to ground via a resistor and an A/D converter.
• the way in which the electrodes of said one elastomer piece are connected up is interchanged, and a measurement is made again. The two measured values of the total resistance are compared, that electrode which has the lower resistance value being nearer the contact location.
• connection changeover can also be carried out for the respective other elastomer piece. If, by way of example, two elastomer pieces are used whose electrode pairs are rotated through 90°, then it is possible to achieve a resolution in the x- and y-direction of the force application.
• the current is measured in the case of a voltage difference within an elastomer piece, for example in addition to the position of the pressure loading (see above).
• the current through the elastomer piece across which the voltage is present rises as the applied force rises, because its resistance between the electrodes decreases as a result of the other elastomer piece being connected in parallel to a greater extent.
• This current change is measured, for example by measuring voltage across a resistor.
• Typical measurement ranges of a tactile sensor made of two foam parallelepipeds made of Evazote foam are in the range of from 0.04 N (identification limit) to 5 N (saturation limit) and, e.g., in a different case, from 0.5 N (identification limit) to 50 N (saturation limit).
• a combined measurement range can be achieved for example by combining the two tactile sensors, for example by placing them one above the other.
• a tactile sensor with the size (0.75 m x 1 m) has a typical measurement accuracy of better than about ⁇ 1% in the case of position determination, with the accuracy capable of being improved by filtering and noise reduction.
• Combined circuit arrangements can also be used.
• approximately a point contact whose resistance decreases in the event of pressure loading. If, in the event of a pressure loading, additional contact points occur or the contact area is enlarged, then an average value of the contact resistance Rs is formed, which represents the centroid of the whole contact. In this case, not only the area centroid but also the pressure at the individual contact points or the finite contact areas influences the result.
• it is possible to make a statement about the position of the contact area in particular in the case of parallelepipedal workpieces, in particular made of foam. Due to the different averaging algorithms of the mentioned position measuring methods and variations thereof, as will be discussed below, it is possible to derive further information about the contact shape from the combination of these measurements.
• An electronic circuit is preferred for evaluating the sensor data.
• Said electronic circuit can be constructed very small and, in particular, be incorporated in the elastomer material of the sensor. Driving of the electrodes, for example voltage loading, is possible by means of a microcontroller.
• the evaluation of the sensor data for example the measurement of the position of the force loading and of the shunt resistance in one or more directions, can likewise be performed by means of a microcontroller.
• the microcontroller can be used to connect a current measurement via the contact resistance Rs via a resistor.
• FIG. 1 shows a tactile sensor T in an oblique view.
• the tactile sensor comprises a first workpiece 1 and a second workpiece 2, each in the form of a parallelepipedal foam plate made of Evazote material.
• the two plates 1, 2 are not touching one another in this figure, but in a real tactile sensor T said plates bear on one another at a bearing area.
• an electrode 3 is in each case fitted parallel to the bearing area over the entire length of the respective side area.
• a pair of electrodes 4 is fitted in a parallel fashion on side areas (in the (z, x) plane) of the second foam plate 2. This pair of electrodes 4 is rotated through 90° about the z-axis with respect to the other pair of electrodes 3. .
• the touch area that can have a force F applied to it corresponds to that side of the first foam plate 1 which is remote from the bearing area.
• the electrodes 3 of the first foam plate 1 are both at a voltage U of 5 V.
• an analog/digital port 6 is connected to the electrodes 4 and, in turn, may be connected to an A/D converter input.
• the current may, e.g., via the A/D converter, for example be connected to a microcontroller, or be measured by means of a voltage measuring device at the resistor 5.
• the current intensity is primarily determined by the contact resistance between the foam plates 1, 2.
• the two foam plates 1, 2 are pressed against one another and the contact resistance Rs is thus changed, as a rule decreased.
• the current flow increases, so that a contact can be identified.
• FIG. 2 shows a simplifying equivalent circuit diagram of the tactile sensor T from FIG. 1.
• the two chains Wl, W2 of resistances are connected to one another via a resistance Rs, which corresponds to the contact resistance.
• the resistance Rs is dependent on the applied force.
• this equivalent circuit diagram represents the case of just a point contact.
• Rs is the largest resistance, so that the total resistance of the circuit arrangement is determined principally by Rs.
• the internal resistances Rfl,...,Rf4 result in a measurement error which can be compensated for if the contact location is known.
• FIG. 3 shows a tactile sensor T whose circuitry for determining the position of the force loading differs from that for FIG. 1.
• the contact resistance between the two foam plates 1, 2 is reduced.
• the second foam plate 2 assumes the potential of the first foam plate 1 at the contact point. If a plurality of contact points and/or a larger contact area occur, then an average value of the contact resistance is formed, which represents the centroid of the whole contact. In this case, not only the area centroid but also the pressure at the individual contact points influences the result.
• FIG. 4 shows a simplifying equivalent circuit diagram of the tactile sensor T from FIG. 3 with two contact points represented by the two pressure- dependent resistances Rs.
• said total resistance is 2 -Re + Rfl + Rf2 + Rf3 + Rf2/(2-Rs + Rf5/(Rf4 + Rf6 + 2-Re)), and is thus significantly smaller than in the case of just one contact point.
• a two-dimensional measurement of the contact area is likewise possible, for example by producing a voltage drop in the other direction (e.g., using the further foam plate 2, whose electrodes 4 are arranged rotated through 90° in the (x, y) plane).
• a tactile sensor uses a conductive foam layer S disposed on a circuit board C, such as seen in FIG. 5a.
• the circuit board C On the side facing the foam material S, the circuit board C has printed on it an interdigital structure I in the form of two intermeshing comb structures. With an increasing force F on the foam material S, an electrical resistance between the two comb structures decreases.
• FIG. 5b shows, in plan view, the circuit board C with the interdigital structure I and the electrodes E.
• FIG. 5c shows an equivalent circuit diagram relating to the tactile sensor from FIG. 5a, which comprises a force- or pressure-dependent resistor R.
• FIG. 6 shows a sensor signal of a tactile sensor T according to FIG. 1 with foam plates 1, 2 made of Evazote foam in the case of variation in the material properties of the workpieces 1, 2.
• the thickness (in the z-direction in FIGs. 1 and 3) of the two foam plates 1, 2 (3 mm, 6 mm, 20 mm) is varied, and so is the foam (45 CN and 85 CN, where the number denotes a density and "CN" denotes an electrically conductive design).
• This 8-bit signal is plotted on the ordinate.
• the abscissa shows the external force F in N applied to the touch area of the tactile sensor T.
• FIG. 11 shows a simplified tactile sensor T ofFIG. 1 coupled to a microcontroller 100 for determining various parameters as shown in Table 1 below, in accordance with a specific embodiment of the present invention.
• FIG. 12 shows a simplified equivalent circuit diagram (150 for a single contact made, 155 for double contact made) of the tactile sensor T useful for determining the various parameters as shown in Table 1 for the configuration ofFIG. 11.
• Table 1 assumes a tactile sensor T having two foam layers each having two electrodes thereon (for example, for rectangular tactile sensor). Each electrode is connected to an electronic driver that can measure the electrode voltage, apply 0V or 5 V (or other predetermined supply voltage) or high impedance, or apply 0V or 5 V through a known resistor to the electrode. This is implemented by using two multi-purpose pins of microcontroller 100. Each of these microcontroller pins can either output High or Low or High Impedance. If the port is on high impedance, it can serve as analog input as well.
• AN Connecting one of these ports (called port O in the following) through a resistor to the other port (called AN in the following (only this port needs A/D-converter functionality)) and connecting the port AN to the electrode of the sensor results in the necessary electronic circuitry.
• Table 1 is merely an illustration for a specific embodiment of the types of information that can be measured and various parameters accordingly determined. Similar analysis can be provided for other embodiments (such as oddly-shaped tactile sensors that might be used for toys, etc.) besides a rectangular tactile sensor.
• the tactile sensor can comprise a continuous metal area and a conductive elastomer piece.
• a metal area can also be used simultaneously for a plurality of sensors (without insulation).
• the metal areas may be a vehicle ground.
• the elastomer pieces in particular, can also be used or produced as tliree-dimensional shaped parts.
• each elastomer piece can be sawn from a larger block, for example by means of a cutting wire installation.
• the at least two elastomer pieces can be produced simultaneously, which reduces the waste from cutting
• each elastomer piece can be welded together from a plurality of plates, as a result of which conductive connections are produced.
• the tactile sensor may then have, e.g., a rounded or edged form, with the sensor principle also remaining functional over this edge.
• each elastomer piece can be introduced into a specially produced mold, e.g., by pouring or foaming. An extremely high degree of freedom in terms of shaping can thus be realized.
• the tactile sensor can be bonded together with various other sensors, e.g., a further tactile sensor.
• Commercially available double-sided adhesive tapes are suitable for this purpose, and ensure a firm connection. Bonding using a hot-melt adhesive is equally possible, but afterward it is difficult to detach nondestructively. If a plurality of sensors are connected, care should also be taken to ensure that they are electrically insulated from one another. It is also recommended that an electrically insulating plastic layer, e.g., a foam layer, be applied to the surface, which layer may additionally have a decorative or wear- reducing function.
• FIG. 7a shows, in an oblique view, a tactile sensor T which can be fitted to a side area of, for example, a cleaning robot.
• the contour or the tactile sensor T is matched to the area of the application object, namely the cleaning robot.
• a nonconductive, regularly perforated intermediate layer 7 e.g., a net or bonding points
• the detection threshold is increased by the membrane.
• Tactile sensor T additionally has a cutout 8. Cutouts like this may be needed depending on the specific embodiment (in this case, for example, the cuteout may be used for a recharging comiector to a battery of a robot and for "windows" for sonar sensors).
• FIG. 7b shows, in side view, the first workpiece 1, (on the left) and the second workpiece 2 (on the right) of the tactile sensor T from FIG. 7a with the corresponding electrodes 3, 4. Since a voltage drop across the side areas of the two workpieces 1, 2 is no longer homogeneous, it may be advantageous to correct the position measurement, e.g., by means of calibration. For embodiments such as a cleaning robot, however, the accuracy of the position measurement is sufficient even without correction.
• FIG. 8a shows, in an oblique view, a tactile sensor T with a triangular shape.
• FIG. 8b shows, in side view, the first workpiece 1 (on the left) and the second workpiece 2 (on the right) of the tactile sensor T from FIG. 8a with the corresponding electrodes 3, 4. It can be seen that the electrodes 4 of the second workpiece 2 do not cover the whole side.
• FIG. 9 shows, in an oblique view, an example of a three-dimensionally acting tactile sensor T for enclosing a member such as a robot arm, in accordance with a further specific embodiment.
• the second electrode 3 of the first, outer workpiece 1 is fitted on the other end area in an analogous manner to the electrode 3 that is illustrated here.
• the entire perimeter of the arm is thus covered by just one tactile sensor T.
• FIG. 10a shows, in an oblique view, a half shell-shaped tactile sensor T.
• the two workpieces 1, 2 are not bearing on one another.
• FIG. 10b shows, in plan view, the first, outer workpiece 1 (on the left) and the second, inner workpiece 2 (on the right) of the tactile sensor T from FIG. 10a with the respective electrodes 3, 4.
• the first workpiece 1 has three electrodes 3 which are arranged rotationally symmetrically.
• the second workpiece 2 contains an annular electrode 41 and a point electrode 42 in its apex.
• This tactile sensor T can be operated in such a way that a voltage difference ⁇ U is applied between the electrodes 41, 42 of the second workpiece 2, the intensity of which voltage difference represents the spacing of the spherical apex, the location of the point electrode 42.
• An angle ⁇ between a contact point (designated by "x" here) and a zero mark is determined as the second coordinate. Since an unambiguous result cannot be achieved with the use of just two electrodes 3 in the case of the angle measurement, three electrodes 3 are used in the first workpiece 1. To that end, it can be expedient to connect in each case two of the electrodes 3 to one operating voltage and the third electrode 3 to another operating voltage. After a first measurement, the other operating voltage is assigned to another electrode 3, e.g., by cyclic interchanging, and another measurement is carried out. This increases the accuracy of a determination of the location of the contact point.
• the tactile sensor of the present invention can be used to determine touch information in various contexts, such as for identifying seat occupancy in a motor vehicle; for triggering an airbag; as a sensor for electronic percussion; as an input element for apparatus control; for use in conformable, wearable control devices; for identifying occupancy on conveyor belts; for collision identification on a cleaning robot; or for training assistance for sportsmen and sportswomen and for use in fitness equipment, e.g., for measuring a takeoff point in the high jump, etc.
• the tactile sensor of the present invention can also be particularly useful for investigating ergonomics, such as of automobile seats or shoes or office furniture.
• deformable foam sensors in accordance with the present invention can be embedded in furniture, such as an office chair, and be configured to provide ergonomic warnings and feedback of incorrect posture or other ergonomically incorrect or harmful positioning to a user of the furniture.
• the tactile sensor can also be used to monitor the progress of patients undergoing physical therapy by monitoring how exercises are being performed and moreover to help treat balance problems.
• the tactile sensor of the present invention also can be used to determine touch information for flexible keyboards for use with a computer terminal; a flexible keyboard or keypad for use with a personal digital assistant (PDA) device; or a touchpad for controlling a cursor or other positioning element in a user interface to a computer or other device (as a specific example, a large touch pad could be built into a portable computer carrying bag).
• PDA personal digital assistant
• the tactile sensor may be used as a mousepad that provides an input interface to a computer based on inputs based on a contacting object's (such as a finger) location determined using the tactile sensor.
• the tactile sensor of the present invention can further be used for touch and position sensors for toys such as dolls, cars, etc. such that contacts made to specific areas of the touch sensor can be configured to cause particular reactions (e.g., audio or other output, motion initiation, etc.) by the toy. For such applications, sensitivity and resolution might be different across the sensing surface.
• safety requirements can be imposed on the tactile sensor.
• the requirement of identifying a defect may be imposed. Identification of defects can be implemented in a simple manner, as discussed below. Providing information useful for defect identification can be valuable for automated quality control and after-production self tests.
• a defect can be identified if there is a break in a connecting line. When such a break exists, an infinite resistance is produced when a voltage is applied within an elastomer piece, where such infinite resistance does not occur during normal operation.
• Other defects can be identified if there is a short circuit of an electrode connected to a voltage. When such a short circuit exists, voltages which are very near the operating voltages (e.g., the terminal voltages at the electrodes of 0 V and 5 V) do not occur in a normal mode. When there is a short circuit of the electrodes to a value other than an operating voltage (e.g. 0 V and 5V), the defect can be identified in two cases.
• this condition can be identified, for example by fuzzy logic. Another possibility is to analyze the frequencies that occur. If a signal change occurs which is too fast for a change in the tactile contact, but can still be perceived by the measurement system, then a defect can be inferred from this.
• vandalism e.g. insertion of a blade
• Insertion of a blade would, for example, initially (for as long as the blade is inserted) be indicated as an intensive tactile contact (exception: ceramic blade or plastic blade). If the blade is removed, then the sensor resumes its functioning. In this case, however, the entire behavior is changed, which can also be identified by suitable comparison with its normal functioning.
• Removal of part of the tactile sensor for example in the event of vandalism by being torn out or cut out, can also be identified by virtue of the fact that the total resistance of the tactile sensor increases. If the tactile sensor is completely removed from its place, then this cannot be detected if the connecting wires are undamaged.
• One antidote to this is the possibility of mounting the terminal electrodes in each case on both sides fixedly on a housing of the installation which is equipped with the tactile sensor.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Human Computer Interaction (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (2)

Family

ID=24005292

Family Applications (1)

Country Status (4)

Cited By (1)

Citations (5)

Family Cites Families (6)

• 2001
  • 2001-02-15 JP JP2001560942A patent/JP2003523584A/ja active Pending
  • 2001-02-15 AU AU2001239772A patent/AU2001239772A1/en not_active Abandoned
  • 2001-02-15 WO PCT/US2001/004837 patent/WO2001061634A2/en active Application Filing
  • 2001-02-15 EP EP01914378A patent/EP1256089A2/en not_active Withdrawn

Patent Citations (5)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events