DE29515312U1 - Joysticks - Google Patents

Description

Dipl.-Ing. Gerhard Wergen, 90513 Zirndorf, Parkstr. 1

Joystick

The invention relates to a joystick.

Such a joystick is known as a joystick for computer inputs (also as a mouse replacement) or as an actuator for controlling the movement of mobile or stationary devices (such as self-driving lifts for the disabled, work tables, patient chairs or machine platforms). In commercially available versions, depending on the deflection, i.e. depending on the current swiveling into an inclined position of the handle, the taps on two potentiometers oriented perpendicular to each other are simultaneously moved using a fairly complex kinematic system. This is a solution that is very expensive to manufacture and is sensitive to mechanical interference, particularly impact stress. Because such joysticks have to be swivelled at a large angle relative to the normal to the housing for a large signal stroke, i.e. because the end on the operating side has to cover a relatively large distance, conventional joystick joysticks are particularly unsuitable for use by disabled people with such severe impairments of their motor organs that they are no longer able to apply a controlled force for such deflections over a larger range of motion. Their remaining functions, due to advanced muscle weakness, for example, are often just enough to use their fingers, feet or toes or head (e.g. the back of the head, chin or using a

mouthpiece) in a somewhat controlled manner with minimal travel to produce low pressure in a defined direction. And for blind people it would be particularly important to always find an operating handle in the same place and in the same position if possible.

The present invention is intended to create a joystick that is characterized by a low-cost, extremely simple and small-scale but still functionally reliable structure; and which is particularly designed to be able to be operated with minimal effort and with practically no movement, so that it can also be used by people with severe motor disabilities, and opens up further development in the direction of such complex control specifications that the disabled person can even use it to realize, for example, the multi-axis control of an extremity prosthesis or a small handling robot, in order to be able to use this aid to regain and use handling and movement options that have already been physically lost.

With regard to the inventive solution to these requirements, reference is made to the main claim together with the subclaims and to the following description of the drawing as well as its summary at the end.

The core of this solution is a mechanically and equilibrium-stable, structurally simple but precise ball joint suspension of a small, enclosed pressure element on a transverse pressure handle protruding from the hermetically sealed housing; with pressure direction-dependent mechanical stress on pressure sensors arranged orthogonally to each other between the pressure element and the housing. The force transmission from the pressure element, which can only be pivoted minimally, to the influencing surface of the respective sensor is expediently evened out by means of slightly elastically compressible support bodies. Mechanical overloading of the sensors is then practically impossible.

closed. It may be useful to also provide that the force is overcome by separately used return springs during pressure transmission. These are then clamped between the pressure element and the housing in order to ensure that the handle returns to the normal position when it is not operated, without any special adjustment effort being required when assembling the joystick to maintain the non-engaging neutral position. An axial pressure component of the handle (which in itself can only be loaded transversely) has no effect on the force introduction into the sensors because of the support on the ball profile. Due to the low weight of the pressure element, which is elastically supported against the housing together with its handle, the pressure stresses on the sensors are completely independent of the spatial operating position of the joystick housing. This joystick is therefore particularly suitable for industrial use under harsh environmental conditions; as well as for actuation through even slightly controlled, regardless of whether powerful or weak, minimally expansive body movements, with which disabled people can then control motor aids in everyday life or surgeons during operations.

The response pressure to be generated when the handle is operated can be specified structurally using the lever ratios (with regard to the partial lengths of the handle on both sides of the ball suspension) as well as the elastic constants and preloads of the support bodies and the return springs, and finally also the response sensitivity of the continuously or binary sensors. The current pressure loads of the sensors can be queried individually or in pairs in a differential circuit by a signal processing device inside or outside the housing. This device can also implement a signal stroke depending on the duration or intensity of the current transverse load on the handle.

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Because pressure components in the longitudinal direction of the rod-shaped handle have no effect on the stress on the sensors, i.e. on the signal from the joystick, the handle can be equipped with a finger engagement ring oriented transversely to the handle on the side or at the free front end for its transverse stress and/or with a fingertip engagement shell oriented parallel to the axis or coaxially to the handle in order to facilitate the application of the manual transverse force in changing directions without changing the position of the attacking extremity (especially the front finger joint) or to enable pulling in the first place. A fingertip shell that is open on the front side has the particular advantage of being able to arrange several of the small housings close together and then operate them simultaneously with the different fingers of one hand. In this way, three or four fingertips of one hand can engage in assigned shells arranged along a flat circular arc and possibly at a slightly offset height from one another, support themselves axially in them and transfer individual pressure directions to the individual handles. The ability to carry out spreading movements with the fingers is usually poorly developed, but this is not a problem here, as it is only a matter of exerting pressure with practically no travel. In this way, two independent control processes can be determined simultaneously with each fingertip - for example, with the index finger, on the one hand, the start-up and on the other, the sensitivity setting, and with the middle finger, the deflection of a handling robot in the two axes of the plane and finally, overlapping with this, with the ring finger, on the one hand, the lifting and lowering movement and on the other hand, the closing and opening movement of a gripper on the robot. Even a severely disabled person, for example due to advanced multiple sclerosis, is able to pick up an object that has fallen next to his wheelchair or to get a cup with its teat from the table to his mouth using a simple handling robot installed on the wheelchair, i.e. without the help of helpers.

This obviously opens up a whole new quality of life for such people.

The compact design and the practically path-free operation not only enable the described arrangement of several such joysticks next to each other, but also open up the advantageous further possibility of accommodating at least two such systems coaxially. The housings are then arranged one below the other or one inside the other, and the handle of the smaller one extends through a tubular handle of the housing above. At the free front end, the inner handle protrudes from the outer one, so that the two handles can be loaded laterally independently of each other by pushing them between the lips to different depths one after the other or by using two adjacent fingers at the same time in order to carry out two-axis control for each system. To operate four systems, i.e. for the eight axes of movement of an already quite sophisticated handling robot, with four fingers of one hand, the same coaxial joystick pair can be mounted again in the opposite orientation, i.e. coaxially on the front side, so that the two inner joysticks end directly butt-on in front of each other and the two outer ones are each slightly offset axially.

The pressure exerted on the sensors can be axial or radial with respect to the housing. In the first case, the sensors are arranged inside the top or bottom wall of the housing and are loaded by means of a pressure element in the form of a plate which is oriented approximately parallel to the housing plate, namely transverse to the longitudinal axis of the housing and thus transverse to the longitudinal extension of the handle and is rigidly attached to it (or formed as one piece with it). In the other case, the sensors are arranged between the side walls of the housing and the pressure element which, as an extension of the handle, is rod-shaped and is formed into a hollow cylindrical

housing, which allows an even more radially compact construction.

The drawing shows an enlarged view of the above explanations

Fig.l shows a known two-coordinate joystick that can be used as a direction indicator or so-called joystick with an axially non-scale representation of the inventive interior fittings of its housing for axially parallel sensor loading in an axial longitudinal section,

Fig.2 the coaxial arrangement of two pairs of such joysticks built into each other in a scaled housing representation but without further details on the sensor equipment according to Fig.l,

Fig.3 a joystick with radial sensor stress in an enlarged view in axial longitudinal section and

Fig.4 the joystick according to Fig.3 in cross section through the plane of its sensor arrangement.

The rod-shaped handle 12 of the joystick 11 extends vertically, with minimal pivoting, through an opening 13 in the cover wall 16 of its housing 14. In the housing 14, the handle 12 is equipped with a pressure element 15 that is rigid in movement, which in this axial design preferably has the shape of a circular disk that is screwed to it, for example. In its rest position (shown in the drawing), this lies parallel below the cover wall 16 within the side walls 17 of the pot-shaped housing 14.

The handle 12 (together with its pressure element 15) is supported at the entrance to the housing 14 by a ball profile 18. This is attached to the handle 12 or directly on its outer

surface in such a way that this profile 18 projects radially beyond the handle 12 in the area where it passes through the opening 13 in the housing cover wall 16. This raised ball profile 18 rests with as little play as possible in a flat hollow spherical section-shaped shell 19 with the handle 12 passing through into the interior of the housing 14 through a central hole 21. The shell 19 is pressed into the outer surface 20 of the housing cover wall 16, i.e. into its opening 13. This ball suspension of the handle 12 is the main reason for the high reproducibility and sensitivity of the pressure applied to the sensors 25, with optimal adjustment options for the external force introduction requirements via the lever ratios on both sides of the ball suspension - especially compared with the corresponding properties with an unstable tip bearing of the lower end of the handle 12 against the base 23 in the housing 14.

To ensure a consistently defined fit, the balanced, stable suspension of the handle 12 by means of the ball profile 18 in the cover wall 16 is not only achieved by the weight of the handle 12 including the pressure element 15, but in this axial structure also by compression springs 22 such as slim coil springs or rubber prisms, which are inserted between the pressure element 15 and the housing 14. With such an orientation parallel to the pressure direction against the sensors 25, these spring blocks 22 also determine the rest position of the manually non-operated pressure element 15 relative to the housing 14. The interior of the latter can be hermetically sealed by a base cover 23 held by the side walls 17.

In the case of an axially parallel effect, two pairs of diametrically opposed pressure sensors 25 are mounted between the housing 14 and the plate-shaped pressure element 15, preferably as shown opposite the circumferential plate edge 24, orthogonally offset from one another, e.g. under the cover wall 16. Each such sensor 25 can, for example, be a semiconductor

ter, a piezo, a magnetostriction, an optical fiber element or any other pressure sensor that operates practically without displacement. The use of a simple flat conductive rubber body as a sensor 25, the volume resistance of which varies between typically 1,000,000 ohms and 1,000 ohms depending on a current minimum compression load, i.e. when force is introduced, not only has the advantage of being inexpensively available and easy to handle, but, as has been shown in connection with the present invention, above all also has the advantageous property of being able to adjust the change in resistance (i.e. the sensor signal dynamics) for a specific pressure load via the pressure transmission area. This is because if the compression of the conductive rubber extends over a larger area for the same pressure load, the volume resistance is smaller overall compared to the same compression of only a small cross-sectional area.

A stiff, elastic, flat support body 26 bridges the axially parallel distance from the pressure element 15 to the sensor 25. The contact surface of the body 26 serves as a pressure introduction surface into the sensor 25 (and thus the specification of the sensor sensitivity both due to its stiffness and due to the aforementioned stress cross-section when force is introduced into the sensor 25). In addition, the stiff, elastic support body 26 causes a uniform pressure distribution over the surface when a sensor 25 is stressed, and it can simultaneously support or completely take over the reset function of one of the springs 22.

If the elastic blocks 22 and 26 are not attached to the pressure plate 15, but rather under the housing cover wall 16 or under the sensors 25 attached thereto, turning the inclined plate 15 using the handling rod 12 has no influence on the current pressure introduction into the sensors 25, so that the current information from the control stick 11 is not affected by this. This is also

achieved if the block-shaped structures 22/26 in cross section according to Fig.l of the drawing are actually concentric elastic rings fastened to the plate 15.

In any case, depending on the direction of the transverse stress on the handle 12, a sensor 25 or even two peripherally adjacent sensors 25 are subjected to more or less severe compression stress by the plate edge 24 of the pressure element 15, while at the same time the diametrically opposite sensor 25 is relieved. The mechanical pressure increase is converted, for example in the case of a conductive rubber sensor 25, into a reduction in its current electrical resistance. This can be easily measured in an evaluation device (operated inside or outside the housing 14) (symbolically indicated in Fig. 1 of the drawing) and output in a manner known as such as an electrical control coordinate for further processing or for direct control of servo motors for two-coordinate adjustment movements, for example. If no measurement-technically isolated detection of only the individual sensors 25 is planned, but rather of a pair of two diametrically opposed sensors 25, then the electrical evaluation can take into account that even a minimal tilting of the plate 15 as a result of manual pressure must always be accompanied by a drop in resistance in one sensor 25 and an increase in resistance in the other sensor 25. In this way, all electrical signal pairs that do not show this opposite tendency can be eliminated. This ensures that thermal expansion effects or mechanical vibrations and similar disturbances that act in the same direction on both sensors 25 of a diametrically opposed pair have no influence on the measurement result.

Due to the positive axial support of the rigid structure consisting of the handle 12 and the pressure element 15 in the ball-shell pairing 18/19 when the handle 12 enters the housing 14, the pressure exerted on the sensors 25 is not

influenced by axial mechanical stresses on the rod-shaped handle 12 and thus the electrical control value currently specified by manual transverse pressure is not distorted in an unreproducible manner. This is because the axial pressure components are absorbed by the stable housing cover wall 16 and therefore do not lead to a displacement of the pressure element 15 that relieves the sensors 25. In order to be able to absorb tensile forces on the handle 12 from the housing 14, the ball profile 18 is expediently clamped in a form-fitting manner between semi-hollow spherical shells 19 in both longitudinal directions of the handle 12, as shown in Fig. 1. The shells 19 do not have to be formed directly in a (possibly divided) cover wall 16. It is more practical to provide only one force-fit receptacle 27 for a divided cage in the form of the two ball shells 19-19 facing each other in the cover wall 16. In the case of an undivided double shell 19-19, its central hole 21 can be widened by temporarily heating in order to accommodate the ball profile 18 in the form of a bearing bush, such as is found in rod ends for axle suspensions in model making.

A particularly inexpensive but nevertheless functionally reliable construction of this control stick 11 is achieved when the ball profile 18, which is not integral with the handle 12, is pushed forward along a central bore 28 up to a stop, for example against a spacer sleeve 29 in front of the plate-shaped pressure element 15, on the handle 12 and is secured to the rear by means of a nut 30 which is screwed onto the external thread of a screw bolt that also engages in the pressure element 15 as the handle 12. In this way, a handle-pressure element unit consisting of only five inexpensive standard parts is quickly and rigidly assembled. A radial projection of the nut 30 over the ball profile 18 is not a problem because the operation of the handle 12 takes place practically motionless (without travel).

This joystick 11 can therefore be manufactured easily and inexpensively in a reliable design, and is resistant to environmental influences due to the housing encapsulation of the sensors 25. And in terms of operation, it is characterized by an extremely good distribution of force when the handle 12 is stressed due to the ball suspension of its handle 12. This facilitates operation because a fingertip does not rest freely on the side of the handle 12 for exerting pressure, but engages in a ring 31 or a shell 32 with which the handle 12 can be equipped, as already described in more detail at the beginning.

In the design according to Fig. 2, two housings 14, 14 are mounted coaxially one above the other. The handle 12 of the lower, smaller one runs with radial play through a tubular handle 12 of the upper housing 14 and is equipped with a cap 33 at the front exit, which has at least approximately the same outer diameter as the outer handle 12. Preferably, each handle 12 is equipped with a finger joint engagement ring 31 in order to be able to introduce pressure and tensile forces into the respective handle 12 without the need to re-grip. In this way, two adjacent fingers of one hand, which grip laterally on both sides of the separation point between the outer handle 12 and the cap 33, can operate two joysticks 11, 11 simultaneously, i.e. control four axes. This operating option is easily doubled in a tandem arrangement if, as indicated in Fig. 2 above, the same system of two control sticks 11/11 nested inside each other is mounted coaxially in front of the front in the opposite orientation (i.e. the caps 33-33 next to each other) and can thus be operated with two additional spread fingers of the same hand. Overall, this results in an eight-axis control that can be implemented with a single hand.

In order to use the inner and outer handles 12,12 of a double system according to Fig.2 with different effective axial

In order to achieve the same response sensitivity for the length of the handles 12,12, the longer handle 12 in the housing 14 can be assigned a shorter radial axis distance of the sensors 25 (for example by means of a smaller pressure element plate 15; not taken into account in the drawing).

This advantage of the axially parallel pressure transmission reversal using a plate-shaped pressure element 15 is no longer present if, instead, a radial pressure effect on the sensors 25 is implemented in the interest of an even more compact radial structure according to Fig.3/4. For this purpose, the handle 12 is again concentrically equipped with an approximately plate-shaped pressure element 15 within the housing 14, which is now not round but approximately square in cross-section, preferably with a somewhat star-shaped profile through concave side surfaces as shown in Fig.4. The 2*2 pressure sensors 25 are arranged in the same cross-sectional plane between the pressure element 15 and the hollow cylindrical housing side wall 17, preferably glued against the inner surface. The radial star-shaped bulges 34, which are inserted for example to fit, then lie directly radially against the sensors 25; or indirectly, as shown, namely via elastic support bodies 26, now in the form of a circumferential O-ring or thick rubber band (see Fig. 4), which also has a centering effect. The peripheral rounding radii of the radial bulges 34 on the now star-shaped pressure element 15 can again be used to constructively influence the pressure application surfaces on the sensors 25 and thus their signal dynamics.

To center the pressure element 15, a disk-shaped rubber block compression spring 22 can also be held inside the housing side wall 17 from the protruding area of the handle 12 in order to be able to adjust its axial position in the housing 14 and thus the lever ratio with respect to the pressure element 15, i.e. the restoring effect, independently of the optimization of the sensor loading. The protruding

The length itself is determined by the axial position of the ball profile 18 along the handle 12, which is fixed in an adjustable position with respect to the lever lengths on both sides of the housing cover wall 16 by means of two flat nuts 30. This radial structure of the control stick 11 can also be realized (analogously to the solution according to Fig. 2) several times telescopically into one another, as well as in a tandem arrangement, front to front.

Claims (11)

Expectations 1. Control stick (11), characterized in that that its handle (12) is suspended by means of a ball profile (18) in one of the walls (16) of a housing (14) and is equipped in the housing (14) with a plate- or disk-shaped pressure element (15) which can be slightly pivoted relative to the latter, between which and the housing (14) pressure sensors (25) are arranged. 2. Control stick according to claim 1, characterized in that the pressure element (15) loads at least one sensor (25) axially parallel to the handle (12). 3. Control stick according to claim 1, characterized in that the pressure element (15) loads at least one sensor (25) transversely to the axis of the handle (12). 4. Control stick according to one of the preceding claims, characterized in that compression springs (22) are clamped between the pressure plate (15) and the housing (14) in the direction of the mechanical sensor stress. 5. Control stick according to one of claims 1 or 2, characterized marked, that the sensors (25) have rigid elastic support bodies (26) can be pressurised. 6. Control stick according to one of the preceding claims, characterized in that the ball profile (18) of the handle (12) is in a Housing wall (16, 17, 23) is guided in two oppositely arranged shells (19-19). 7. Control stick according to one of the preceding claims, characterized in da3 its handle (12) carries a ball profile (18) which is fixed by means of a nut guided on the handle (12) (30) is clamped. 8. Control stick according to one of the preceding claims, characterized in that its handle (12) is provided with a finger engagement ring (31) and/or is equipped with a finger grip shell (32). 9. Control stick according to one of the preceding claims, characterized in that it is designed as a multi-axis control, especially for motion drives as in a handling robot, multiple inside each other for independent operation by multiple fingers. 10. Control stick according to claim 9, characterized in that in the case of housings (14) mounted coaxially one above the other, the handle (12) of the lower housing extends with radial play through a tubular handle (12) of the housing (14) located above it. 11. Control stick according to claim 9 or 10, characterized in , that an internally extending handle (12) is equipped with a cap (33) at the exit from the surrounding handle (12) which has approximately the outer diameter of the surrounding handle (12).