EP3345068A1

EP3345068A1 - Device and method for determining the position of a force-absorbing element in three axes

Info

Publication number: EP3345068A1
Application number: EP16760038.6A
Authority: EP
Inventors: Christian Baumgartner
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-08-31
Filing date: 2016-08-30
Publication date: 2018-07-11
Also published as: WO2017037048A1; AT517676A1; AT517676B1

Abstract

A device for determining the position of a force-absorbing element (2) in three axes comprises a high-resolution image sensor (6), a movement support (4) which is arranged opposite the image sensor and is connected to the force-absorbing element (2), a projection device (3) which is connected to the movement support (4) and projects, onto the image sensor, a predefined geometric shape (10) which is positioned and distorted according to an x/y/z inclination of the movement support. A computing device (7) derives, from the position and distortion of the geometric shape (10), high-resolution x/y/z coordinates for further processing.

Description

Device and method for three-axis position determination of a force receiving element

The invention relates to a sensor device with an optical, teachable three-axis sensor, and a method for determining the position of a force receiving element

(at least) with respect to three axes.

Multi-axis sensors in general, and among other things

Two-axis sensors (joysticks, etc.) are used in all private and industrial sectors. These sensor systems are also used in the fields of automotive technology, aerospace, shipping and medical technology

used, because several functions can be controlled almost intuitively at the same time. Depending on the requirement, there is a certain precision (resolution), a certain force for deflection as well as a specific stroke for coping with the necessary paths fixed or in a slightly variable frame

predetermined.

Problems arise especially where it is not possible, with a constant force and lifting effort such

Sensor system to use or use. Too weak designed sensor systems are destroyed at too high power and lifting effort. Very robust designed sensor systems do not react at very low power and lifting effort or only to a non-usable extent. Conventional mechanical

Sensor systems are also subject to wear. Furthermore, commercial sensor systems, e.g. equipped with a rubber bellows around the axle to prevent the ingress of foreign and pollutants into the mechanics. This creates an additional problem with regard to any necessary cleaning or disinfection, especially in

medical field, as a bellows or other

Protective rubbers are difficult to clean or disinfect. For example, EP 1 696 300 AI and GB 2 334 573 A sensor systems (joysticks) are known which their position based on

Detect light sensors, which are in turn illuminated by a light source attached to the axis accordingly. The lines or matrices described there are depending on

Density of the light sensors used limited in their resolution. Also, there is a predefined stroke and a predefined force needed to bring the spring mechanism to the desired position. In addition, see these

Sensor systems only two axes in front (X and Y axis).

Object of the present invention is therefore, a

Three-axis sensor or to provide a method for determining the position of a motion carrier, which avoids the disadvantages mentioned. In addition, it should be possible to adapt the sensor to the desired input forces and the desired movement stroke.

This object is achieved by the device according to claim 1 and by the method according to claim 6. Advantageous developments of the invention are in the

dependent claims.

The invention provides an optical, learning or

adaptable three-axis sensors, which at any time by the user to the desired input forces and the

desired movement stroke can be adjusted. A

Projection unit projects a defined geometric shape onto an image sensor. If forces are applied to the force absorption, the inclination and / or the distance of the force changes

Movement carrier to the image sensor. Depending on the inclination and the pressure, the projection unit firmly connected to the movement carrier projects various distorted geometric shapes on the image sensor, from which an image analysis software computes corresponding X, Y and Z coordinates. The projection unit is associated with a light source (eg LED or laser); For example, the

Projection unit itself the light source. The light source may be advantageously followed by an optic (e.g., plano-convex lens, collimator lens, and / or template)

Creation of a geometric figure), which on the

Image sensor projects a corresponding geometric shape. This light figure or projection can be any

assume geometric shape, but also consist of points. If a laser is used as a light source, can on a

Shaping template are omitted, since as a light figure naturally a circular disk (filled circle) is formed.

The individual adaptation of the input forces can

be preprogrammed or by means of a learning process

take place, in which the user actuates all directions once and thus tells the image analysis, which maxima were reached. All then recognized coordinates are converted by successive approximation into suitable output signals for the downstream system. Both analog and digital signals and bus protocols as output signal are possible. By interpolation of the distorted geometric shapes, the resolution of the detected coordinates can be increased by a factor of 100, depending on the quality of the image sensor used.

The invention will be further elucidated below with reference to non-limiting exemplary embodiments, which are shown schematically in the attached drawings.

Fig.l shows a three-axis sensor according to a first

Embodiment in a sectional view along the

Center axis of the sensor. 2 shows a three-axis sensor according to a second

Embodiment in a sectional view along the

Center axis of the sensor.

3 shows the projected image of a geometric shape i rest position and the image of a distorted geometric shape when force is applied to the force on the

Movement carrier in the X direction.

4 shows the projected image of a geometric shape i rest position and the image of a distorted geometric shape when force on the force on the

Movement carrier in one direction diagonal to the X and Y direction.

5 shows the projected image of a geometrical shape i rest position and the image of a distorted geometric shape when force is applied to the force absorption on the

Movement carrier in the Z direction.

Fig. 6 shows four examples of light figures.

Fig. 7a shows a variant of the sensor device of Fig. 1 with horizontally layered material of the carrier holder.

Fig. 7b shows another variant of the sensor device with vertically layered material of the carrier holder.

Fig. 8 shows a further embodiment of the invention, with a spherical bearing for movable mounting in the

Power receiving element and the projection device.

Fig. 9 shows a further embodiment with a

Reflection surface for generating the light figure.

According to the invention, a three-axis sensor

proposed, comprising an image sensor, a projection device attached to the movement carrier or Reflection surface and a downstream of the image sensor arithmetic unit with image analysis software.

Referring to Fig. 1, a triaxial sensor according to a first embodiment comprises a force receiving member 2, e.g. may have the shape of a key or a stick. A carrier (moving carrier) 4 carries e.g. on the outside, the force receiving element 2 and is here as a rigid plate

educated. The movement carrier 4 is e.g. in one

layered material 9 stored, which has side panels

(Spacer) 5 is connected to a bottom part 8, here e.g. is formed by a board, which is also equipped with the already mentioned computing unit 7 (for example a microcontroller). The arithmetic unit can also be provided separately from the sensor device in a variant. The triaxial sensor further comprises a projection device 3 held by the carrier 4, and an image sensor 6 (e.g., a CMOS, CCD, or 3D chip) positioned on the bottom part 8. Via a supply line 1, e.g. in the form of a flexible cable, the projection unit 3 is electrically powered.

During operation, the projection device 3 is rigidly connected to the force receiving element 2 and thus follows the movements of the latter. The layer material 9 can

for example, a polymer, e.g. additioncrosslinked silicone. By the layering of different polymers with different density and / or strength

(Young's modulus) and / or viscosity, the layered material may have a large input force spectrum, e.g. 0.01N to 50N. Here, at low forces, which act on the force absorption 2, initially only the soft polymer is compressed and with increasing forces, the further harder layers. The forces acting on the force absorption 2 generate a reverse exponential deflection of the

projected image 11 (FIGS. 3-5) on the image sensor 6. 2 shows a second embodiment of the schematic section of the three-axis sensor with a movement carrier 4, which is fixedly connected to the image sensor unit 6 via side parts 5 and the bottom part 8. In this embodiment, the carrier 4 is flexible, preferably elastically deformable;

for example, it is made of a deformable material

made, e.g. polymer, plastic, CFRP, GRP or metal (e.g., a metal foil). The choice of material depends on the desired field of application. If, for example, a maximum force of 30N on the force transducer 2 is desired, a spring steel is used. To accommodate lower forces up to 5N, for example, a CFK or plastic moving member 4 is installed.

The three-axis sensor according to the invention can additionally be accommodated in a housing 12, as can be seen in the example of FIG. 1. The housing is shown in Figs. 2 and 7-9 of

for clarity, not shown.

The layering of the material may be horizontal, as shown in Fig. 7a, or vertical, as in Fig. 7b. According to the field of application can be dispensed with a layering of the material and only a material can be introduced. This reduces the difference between the applied force values for the minimum and maximum strokes.

As illustrated in FIGS. 3 to 5, FIGS

Projection device 3 or reflection surface (see Fig. 9) generates a defined geometric shape 10 (eg square, circle, arranged in any geometric shape points, see the four shown in Fig. 6 examples), which on the image sensor 6, depending on the movement or deflection of the motion carrier a correspondingly distorted and new

positioned image 11 projected. This allows the

Image analysis software of the arithmetic unit 7 from this distortion and position of the projection 11, opposite to the original shape 10, which derive X, Y and Z coordinates of the projection 11. Fig. 3 shows by way of example a distortion / displacement due to movement or deflection in the X direction, and Fig. 4 in a diagonal deflection. In the case of the Z axis, the image 11 changes visually, as shown by way of example in FIG. 5, for example, the image 11 decreases in size because of the

Moving support 4 in this case approaches the image sensor 6. After the complete analysis of the individual images, signals or protocols are created and output for the subsequent system.

The sampling rate of the image sensor is performed at a speed adapted to the downstream system (fps, frames per second). To a safety-relevant successor system

A high sample rate (at least 40 fps) is required to drive (e.g., medical, aircraft, car). If the sensor is used in the consumer sector (for example, computer games), the sampling rate can be lowered to 10-20 fps.

The image sensor 6 is preferably a high resolution

Sensor. Due to the high density of the individual points on the image sensor 6, only a barely detectable by the human and very low inclination of the moving member 4 is necessary to a corresponding change 11 of the projection on the

Image sensor 6 to produce. By software interpolation, the resolution of the detected coordinates can also be increased, for example by a factor of at least 100. Since the storage or the material properties of the

Moving carrier 4 preferably require an exponential force required to tilt and / or press the movement carrier 4 accordingly, a wide range of application is made possible with respect to the input forces to be applied. The extent to which this high resolution is actually required depends on the intended use and can be individually adapted by the software. The three-axis sensor described can be recalibrated at any time or individually adapted to the user or the purpose of use (see below for image analysis adaptation).

In particular, persons who actuate the sensor due to illness with different forces in each direction (e.g.

Muscular dystrophy, muscle atrophy, quadriplegia) or whose power is subject to a temperature or disease-related permanent or temporary change, will be able to perform permanent control tasks with the three-axis sensor described here (wheelchair, PC, environment, etc.).

Expensive, individual adjustments are thus eliminated.

The learning ability of the optical sensor will be explained below with reference to an example, in which case only one deflection direction is described, which behaves analogously to the other directions.

Starting from an X, Y coordinate system, the center point of the geometrical shape 6 found by the arithmetic unit is at the position (0,0) at rest (in the middle of the sensor). For example, if the image sensor has a maximum resolution of 5000x5000 pixels, 2500 pixels are available for each direction (starting from the center)

Available. For example, if the user reaches a maximum of 500 pixels to the right during the learning process,

multiplies the arithmetic unit in normal operation with the

Factor 5 to achieve a full output signal with maximum possible deflection by the user (5x500 = 2500). The remaining directions are calculated analogously, whereby any unequal input forces are always converted into an optimized output signal.

Further applications are for example in the areas

Aviation and automotive conceivable. Here stands the

Noise immunity in the foreground. Since EMI and RFI have no influence on the projection described here, such would be one System predestined for control. In addition, the aspect of wear is eliminated.

Even in geophysical areas, the optical sensor can be used due to its high resolution (for example, according to the current state of the art 19,580 x 12,600 pixels). This could detect the slightest relative movements of the earth's crust. At the above resolution and one

Image sensor diagonal of 1 inch corresponds to 1mm deflection of the projection 11 already about 770 pixels. If a lever system is used, the deflection (measured in pixels) increases as desired. In addition, the resolution increases by interpolation of the found geometric shape. In this application can be dispensed with the layered material 9 and the projection unit directly via a

Spherical bearings are driven, as shown in Fig. 8. In this embodiment, the force receiving element 2, e.g. formed as a button, and the projection device 3 is connected by an axis 13 which is guided by a pivot bearing 14. Upon application of force to the button (indicated by the double arrow in FIG. 8), the axis 13 is tilted in the pivot bearing 14, whereby the projection device 3 is deflected and, as already described, generates a change in the light figure 10, 11.

In other embodiments of the invention, the

Projection device as an optical device, eg. A mirror or other optically active element,

be formed, which directs a light image generated by a source as a light figure on the sensor.

Fig. 9 shows an embodiment with an optical

Device, in the case shown, a mirror 31, with which the movement carrier 4 is firmly connected. A light source 30, for example, on the bottom part 8 next to the sensor. 6

can be arranged, generates a light beam L (eg. Laser beam), and illuminated via this mirror 31 the

Sensor 6. In this way, the predefined geometric shape is indirectly projected onto the image sensor (6) via the reflection surface, on the basis of which the further evaluation of the light pattern takes place as described above.

Another possible material for some or all components of the device according to the invention is silicone rubber with sufficient material stiffness, which is vulcanized in suitable metal molds, for example in one

Molding process; suitable molding techniques are well known in the art.

In contrast to previously used sensor techniques

(capacitive, inductive and resistive), the optical sensor offers high accuracy, very good positional reproducibility and is subject to no wear at high interference immunity.

Due to the very low inclination of the movement carrier, due to the modulus of elasticity of the movement carrier 4, the counterforce of the three-axis sensor increases proportionally to

Force of the user. An otherwise only difficult and costly to implement force feedback (force feedback) is thus realized without further mechanics. If a stroke is desired by the user, this can be achieved, for example, by a tension spring fastened on the force receiver 2

(Buckling element) are simulated. This bends depending on the force and thus simulates a movement stroke. The

Possibilities of cleaning and disinfection (for example, use in operating theaters, or clean room technology) are also

optimized, since a complete encapsulation by the

layered material 9, or the movement carrier 4 together with the side parts 5 and a housing 12 is present. The operation of the Dreiachsensensik in liquids thus represents no problem

Triaxial sensor, the production is cost-effective. With The present prototype can be an input spectrum of

0.01 N to 250 N are covered.

Below are exemplary sequences of the

Image processing and the configuration of the device according to the invention shown.

Normal operation:

1. Loading a single image into the main memory.

2. Conversion of the image into a binary image based on a defined black / white threshold.

3. Locate the geometric shape in the binary image.

4. Comparison of the recognized geometric shape and position 11 with the original form 10 (at rest).

5. From the degree of the detected position and distortion 11 to the original shape 10, the values of the current X / Y / Z coordinates are calculated.

6. Adjustment of the calculated X / Y / Z values to the desired input format of the connected terminal, or the

Device for further processing of the data. Both analog values and digital values can be used here

Bus logs are generated.

First and one-time initialization process:

1. actuation of the movement carrier 4 with a maximum allowable force in each axial direction. 2. Image capture as in normal operation with storage of the maximum positions and distortions of the detected

geometric shape 11.

3. If the previously stored maximum position or the maximum distortion of the geometric shape 11 is exceeded in normal operation, a digital output is activated, for example, to stop an electric wheelchair.

Any often feasible learning or adaptation process by the user:

1. actuation of the movement carrier 4 with the desired

Effort in every direction.

2. Image acquisition as in normal operation with storage of the maximum individual position and distortion of the detected geometric shape 11 for each axis, according to the forces applied by the user.

3. The now possibly very different

Forces acting on the movement carrier 4 by the user in the different directions, is by software

successive approximation, as well as by multiplication with a factor calculated according to the input signal in

converted uniform output signals. The user is then able, despite different input forces (eg 0.03N to the right, 0, IN to the left, IN to the top, 0, 5N down) a subsequent system (eg electric wheelchair) in any direction at the same speed respectively.

To control the rotational speed. Thus, the

Triaxial sensor can be adapted to the user at any time.

Claims

claims

1. A device for three-axis position determination of a force receiving element (2), comprising an image sensor (6), a image sensor arranged opposite the movement carrier

(4), which is connected to the force receiving element (2), a with the movement carrier (4) connected projection device

(3) which projects a predefined geometric shape (10) onto the image sensor, which is positioned and distorted according to the X / Y / Z inclination of the motion carrier

(11), and a computing device (7), which

is set up, out of position and distortion of

geometric shape (10) X / Y / Z coordinates to further

Derive processing.

2. Apparatus according to claim 1, characterized in that the movement carrier (4) at the outer edge fixed to the

Image sensor unit (5,6,7,8) is connected and consists of a flexible material, which in force on the force receiving element (2) in terms of their

Tilt angle and its distance to the image sensor (6) deformed.

3. A device according to claim 1, characterized in that the movement carrier (4) is embedded in a layered material (9), which layer has different density and / or hardness (Shore) and upon application of force to the force receiving element (2) with respect to their inclination angle and their distance from the image sensor (6) is deformable.

4. Device according to one of claims 1 to 3, characterized in that the projection device (3) with the movement carrier (4) is firmly connected and the predefined geometric shape (10) directly to the image sensor (6)

projected.

5. Device according to one of claims 1 to 3, characterized in that the movement carrier (4) is fixedly connected to a reflection surface designed as a projection device (31), via which the predefined geometric shape indirectly on the image sensor (6) projects.

6. Method for Three-Axis Positioning of a

Power receiving element (2) in a device according to claim 1, characterized in that from a user to the

Force absorption element (2) applied forces, optionally with different force amplitudes in different directions, are converted by the arithmetic unit into uniform output signals, suitable for the connected terminal.

7. The method according to claim 6, characterized in that it allows the user to recalibrate at any time the three-axis sensor with the currently desired force on the force receiving element (2).

8. The method according to claim 6, characterized in that the computing device (7) by an image analysis software in real time, the predefined geometric shape (10,11) searches in each captured image of the image sensor whose shape

with regard to position and distortion (11), and from this the corresponding inclination and the change of the

Moving carrier (4) to the image sensor (6) derived.

9. The method according to claim 8, characterized in that before the first use of the three-axis sensor a

Initialization takes place in which all possible directions of the movement carrier (4) X / Y / Z at least once with a predetermined maximum allowable force on the force receiving element (2) are actuated, whereby the

Image analysis software the maximum allowable position and

Distortions of the predefined geometric shape (11) are shown.

10. The method according to claim 9, characterized in that the image analysis software in real time the predefined

searches geometric shape (10, 11) in each captured image of the image sensor and analyzes its shape with respect to position and distortions (11), and by means of this a

Plausibility check performs to what extent the recognized form (11) the maximum allowable positions and distortions

corresponds.

11. The method according to any one of claims 9 and 10, characterized in that the image analysis software in real time at detected impermissible positions or distortions (11) generates a digital signal to downstream systems before

To protect malfunctions.

12. The method according to claim 8, characterized in that the image analysis software in real time by interpolation of the detected geometric shape (11) specifies the resulting X / Y / Z coordinates.

A device according to claim 1, characterized in that the movement carrier (4) is designed as a hermetic seal to the interior of the device, thereby enabling operation in liquids.

14. The device according to claim 1, characterized in that the position determination of the movement carrier (4) to two

Axes (X / Y coordinates) is limited.

15. The device according to claim 1, characterized in that the position determination of the movement carrier (4) on an axis (X or Y or Z coordinate) can be limited.

16. The device according to claim 1, characterized in that the projection unit is mounted on a joint bearing (14) and can be acted upon directly with a force.

17. The device according to claim 1, characterized in that a laser diode is provided as a light source, which is associated with the movement carrier (4) connected to the projection device (3, 31), wherein the laser diode via a

Plano-convex lens projected a circle on the image sensor (6).