DE10060061C2 - Force feedback device - Google Patents

Description

The invention relates to a device for representing the rigidity of materials, with whose help displays physical measurements at a location remote from the measurement location and can be mapped tactile.

The properties of soft, elastic materials, especially biological tissues can u. a. with the help of new measuring instruments. With biological Fabrics are u. a. the arthroscopic and endoscopic stiffness measurements known. In the medical field, these methods allow damaged areas of distinguish intact. In addition, these procedures are used here to To evaluate the quality of healing tissue postoperatively. Ultimately, the The quality of the tissue changed by illness, trauma or care does not change differ significantly from the surrounding intact tissue.

So far, the measurement results have been given to the user as numerical values. Here is the Specifying the stiffness using numerical values is helpful for a quantitative comparison different measurement results. Alternatively, a graphic preparation can also be carried out The pressure-deformation diagram is output.

The "palpation" of the. Which is only partially available due to minimally invasive operation biological tissue is however neither by the representation as numerical value nor as Replaceable diagram.  

DE 43 32 580 A1 simulates the sense of touch on a surgical instrument described. For this purpose, a sensor and actuator array that is sensitive to force, pressure or displacement is attached to the Instrument arranged.

In DE 42 13 584 C2, the device enables the simulation of a spatial structure to perform a palpation on inaccessible body cavities. The 3D Geometry and the elasticity of a region using a complex elastic element being represented. Because the size and elasticity of the described Device influence each other and the spatial arrangement is limited only a very rough representation of the available input variables can be represented, as with the Palpation common (textures like soft, hard, gnarled or rough). It is not possible to convey relative differences in stiffness in order to e.g. B. small quantitative differences in to experience the stiffness of the tissues also tactile.

In DE 41 33 000 A1 the implementation of tactile information is carried out by Piezo-hydraulic module for displaying the geometric information.

In DE 42 33 323 A1, the input variables are represented by pneumatic or hydraulically operated piston directly on the fingertip.

In US 3 742 935 A, the input variable is represented using a Combination of loudspeaker membrane and corresponding cover.

DE 26 12 898 A1 describes a model for palpation using defined test specimens described.

All known devices are not sufficiently capable of measuring results To conduct rigidity of materials for a tactile, comparative evaluation. The object of the invention is therefore to evaluate measurement results in physical Measured values for an evaluating person can be felt in comparison to a reference value do. The area to be displayed should range from highly elastic to hard include.

An inventive solution to this problem is specified in claim 1. Further developments of the invention are characterized in the subclaims.

In the representation part, the device contains at least one touch surface or one Tactile pad or a tactile pillow (hereinafter referred to as tactile pillow), in which the Touch and the degree of deformation allowed a relative comparison of the stiffness  lets win. The input variables are available numerically and tactile on the display part Available. The rigidity of the tactile pads is controlled by an adjustable pressure chamber, which sets the back pressure to be displayed. The size of the touch pad allows the Rest of at least one or two fingers.

According to the concept of the invention, a force feedback device was developed which gives the user or surgeon a comparative feeling of the mechanical Stiffness value enabled. It controls, for example, for medical Applications stiffness value measured arthroscopically or endoscopically preferred via a measuring electronics outputting the measuring field Voltage U is the pressure P that prevails under an external large probe pad. To this Way, the stiffness of the pillow represents an equivalent of the measured stiffness of the material to be evaluated or the biological sample.

The tactile sensing pad is part of the stiffness transmitter, which means Input converter, control circuit and amplifier as a closed, regulated pressure system with Pump, pressure vessel and sensing pad is executed.

The input voltage U is input from the input converter via a controllable amplifier converts a pressure P equivalent to the voltage magnitude.

This pressure P is then a tactile measure of the tactile stiffness on the tactile pad and can be output in parallel via a digital display.

In the minimal variant, the display part has a tactile pad for feeling the Rigidities. Possible designs with additional tactile cushions serve the convenience of the Device z. B. to ensure the comparability of different stored Values. The essential functions are not affected.

Further details, features and advantages of the invention result from the following description of an embodiment with reference to the associated drawing. Show it

Fig. 1 shows the functional diagram of the transmitter stiffness,

Fig. 2 shows the overall view of a device version.

Fig. 1 illustrates the basic function of the force feedback device. An electrical voltage is used as the input variable for the stiffness transmitter, which represents the physical measured variable to be displayed. Using input transducer 3 and control circuit 4 with amplifier, a pressure P is generated in a closed pressure system and made available to a touch pad 2 for tactile evaluation of the current stiffness pressure.

The regulated, closed pressure system includes pump, pressure vessel and Tastpolster.

The standard version of the device has two buttons 2 , see. Fig. 2. In order to enable the comparative representation of several measuring points (memory function), additional tactile areas can be provided on the stiffness transmitter, the arrangement of which is arbitrary and is solely subject to functional aspects. The number of touch pads 2 is particularly limited by the complexity of the control systems, which must be provided separately for each touch surface.

The touch surfaces 2 are designed as pads or membranes. Silicone or a comparable material can be used as the material. The size of the tactile surface is at least 30 mm × 30 mm for rectangular geometry or 30 mm diameter for circular design.

Fig. 2 illustrates an exemplary device implementation. The stiffness transmitter 1 is integrated in a housing which is set up within the reach of the user. It has supply cables for power supply and feeding of the measurement and control signals. The buttons 2 , the associated digital displays with LED 5 and switch 6 for storing / deleting the current value are arranged on the front of the device. The device is put into operation via a power switch 7 . Switch 8 is used to amplify or switch over the measuring range to selectively display the palpable stiffness with different amplification factors. The digital displays with LED 5 also serve to indicate the activation of the button surface.

After the stiffness transmitter has been put into operation, the input voltage U is converted into a stiffness pressure value and made palpable by means of the first touch surface 2 . This button activation is indicated by the lighting of the assigned LED 5 .

The change in voltage U is continuously converted into a palpable change in the stiffness value of the touch surface 2 and is shown by the digital display 5 . Pressing the memory button 6 saves the current stiffness value, the LED goes out and the button is blocked for further changes. This blocking is ended by resetting the memory switch.

When setting up the device with several buttons 2 , the next unlocked button becomes active after saving on the first button. This is also indicated by LED 5 lighting up. If all buttons are in save mode and are therefore locked, a button must be activated.

The pulse for storage can also take place via an external control signal, so that the Users z. B. can focus on the current measurement.

For medical applications, the system is designed to be completely sterilizable and can be used directly on the operating table within easy reach of the surgeon. In this case, the last and penultimate measured value of the arthroscopic or endoscopic stiffness measurement is transferred to the two sensing pads 2 according to FIG. 2. A direct comparison of the two last data values is thus possible for the surgeon by palpation.

LIST OF REFERENCES

1

rigidity transmitter

2

Touch surface, touch pad, touch cushion

3

input transducer

4

loop

5

Digital display

6

Value storage switch

7

power switch

8th

Measuring range switch

Claims (5)

1. Force feedback device for displaying and recording the stiffness of materials, with the aid of which physical measured values can be displayed at a location distant from the measuring location and, above all, can be mapped tactilely, ie based on the sense of touch, consisting of a recording part for recording the Stiffness of materials and a representation part for representing the stiffness at a location distant from the measuring location, the measured stiffness value using pressure to control the stiffness of tactile surfaces, characterized in that

• a) there is measuring electronics in the detection part for evaluating the measuring field, which outputs a voltage U to the external display part and
• b) in the external representation part, the voltage U forms the input variable for a stiffness transmitter ( 1 ), which is designed by means of an input converter ( 3 ) and control circuit ( 4 ) with amplifier as a closed, regulated pressure system with a pump, pressure vessel and tactile surfaces ( 2 ), whereby the Voltage U equivalent pressure P of this pressure system can be evaluated comparably via the rigidity of at least one tactile tactile surface ( 2 ).

2. Force feedback device according to claim 1, characterized in that the tactile surfaces ( 2 ) are designed as tactile tactile pads or tactile cushions or as a tactile membrane and a separate control system is available for each tactile surface. 3. Force feedback device according to claim 1 or 2, characterized in that silicone or a comparable material is used as the material for the touch surfaces or membranes ( 2 ). 4. Force feedback device according to one of claims 1 to 3, characterized in that the size of the tactile surfaces ( 2 ) is at least 30 mm × 30 mm in a rectangular version and has a diameter of at least 30 mm in a circular version. 5. Force feedback device according to one of claims 2 to 4, characterized in that the pressure P provided by the control circuit ( 4 ) on a tactile surface ( 2 ) is output in parallel via a digital display ( 5 ).