NL1003979C2 - Mechanical hand comprising thumb and four fingers fixed to base - Google Patents

Abstract

The thumb (3) has at least one first part (6) connected to the base and a second part (7) connected to the first. The first and second parts are hinged in their fixture and controlled in the sense of gripping with one another. The first part is hinged to the base, whereby the hinge and associated controls are such that a hinge movement in at least two directions is possible. The thumb has three hinged connected parts (6-8). The fingers each have at least two parts, a first part (9) connected with the base and a second part (10) connected to the first. The hinges between the different parts of the fingers and thumb incorporatea spring (16), whereby the control devices are fitted eccentrically in relation to the spring.

Description

Mechanical limbs.

The present invention relates to a mechanical hand comprising a thumb and four fingers attached to a base, the thumb and four fingers being hinged relative to that base and provided with control means to perform that movement. Such a mechanical hand is well known in the art and is used when used in robots and as an aid for the disabled. When used for robots, a distinction must be made between situations in which such robots perform purely mechanical work, i.e. moving objects from one position to the next, and situations in which the shape or movement of the human hand, in particular expressions, is simulated.

Mechanical hands are familiar with a wide range of degrees of freedom. Versions up to twenty-three degrees of freedom are known, and it will be understood that performing these twenty-three independent control movements requires particularly complex mechanisms. In addition, it will be understood that efforts are constantly made to limit this number of degrees of freedom without thereby also limiting the function of the hand.

It is the object of the invention in such a reduction of degrees of freedom of movement of both the base part and the fingers, respectively. thumb, wherein the construction can be simplified such that it can be properly built into the forearm part of a prosthesis or in a small space if the arm is used as a robot.

This object is achieved in a mechanical shirt described above in that the thumb comprises at least a first part connected to the base and a second part connected to the first part, the first and second parts being hinged and controlled in the sense of gripping are attached to each other and the first part is hinged to the base, the hinge and the associated control being designed in such a way that a hinge movement is possible in at least two directions. It has been found that for simulating. It is not so much the gripping function that is important to the movement of a human hand that it is the ability to make gestures by hand. The thumb is particularly important in this. With the aid of the above-mentioned construction it is possible to obtain a very natural movement of the mechanical thumb with the aid of three individually controllable degrees of freedom.

The thumb is preferably provided with three mutually hingedly connected parts. The same applies to the fingers, which may consist of two mutually hingedly connected parts and preferably of three hingedly connected parts.

The hinge between the different parts of the fingers preferably consists of a spring and more particularly of a screw spring. This creates a flexibility comparable to that of the human hand. This means that if the finger parts hit something, no damage will occur and, furthermore, nobody can be injured if such a mechanical hand makes an unexpected movement. By designing the spring as a continuous spring and sliding the finger parts over it, an accurate aiming and simulation of the human hand can be obtained. By fitting the point of engagement of the control means on the different parts of the fingers, a hinge movement which is not in one plane can be obtained. According to a further advantageous embodiment, the base is connected via a bi-directional hinge to a forearm part and the control means comprise cables which meet at a common point near the hinge, are guided through the center of the hinge and into the forearm part are connected to operating means. The hinge simulates the wrist that can move in two directions: bending / stretching and side-25 up / down. These movements and their results are similar to those of the human wrist. Operation of this hinge can, just like the control means for the fingers resp. thumb through cables corresponding to tendons of the human body. These cables can be connected to air-operated operating means, which can all be designed in the same manner. Moreover, they can be bundled in a compact manner, side by side, in the forearm part.

Although air is preferably used to drive the operating means, it will be understood that any other device known in the prior art can be used for this purpose, such as electric. Coils, etc. Air operation preferably includes operation with vacuum, i.e. the construction is vacuum controlled. Preferably, the operating means consist of bellows which become shorter and longer and which are arranged in an envelope which functions as a guide.

1003979 3

Preferably, means are also present for spreading at least three fingers. These are the little finger, ring finger and index finger.

In this way a mechanical hand is obtained, which includes 5 wrist joints and 10 degrees of freedom. By operating the cables described above, operation of the different parts is caused against the action of spring pressure. The construction discussed here can be applied completely hidden from view and may have a striking resemblance to the human hand. It goes without saying that all kinds of sensors can be present to check whether desired steering movements have been or are being carried out. These can be connected to electronic processing units, which in turn can control the operating means and resp. master steering means.

The invention also relates to a mechanical base. In contrast to constructions known in the prior art in which the pivoting movement between the foot and the lower leg part is effected by an operating means which is switched between them, according to the invention such a control takes place by connecting the operating means between the upper leg and the foot.

The invention will be explained in more detail below with reference to illustrative embodiments shown in the drawing. Show:

Fig. 1 is a perspective view of the mechanical hand according to a preferred embodiment of the invention;

Fig. 2a and b show a detail of the spreading mechanism of the fingers 25 shown in Fig. 1 in respectively. not spread and spread position;

Fig. 3 is a detail of the hinge mechanism of the fingers of the mechanical hand of FIG. 1;

Fig. ^ a detail of the operating means of the construction according to fig. 1; FIG. 5 schematically shows the different hinge possibilities of the mechanical hand according to FIG. 1;

Fig. 6 schematically in side view a mechanical base according to the invention; and

Fig. 7 operating means for such a mechanical foot.

. The mechanical hand according to the invention is indicated in its entirety by 1 in Fig. 1. This consists of a relatively stiff base 2 to which a thumb 3 and fingers 4 are hinged. Both thumb 3 and fingers k consist of a first, second 1003973 4 and third part. For the thumb, these parts are indicated by the reference numbers 6, 7 and 8, while for the fingers the first part is indicated by 9, the second part by 10 and the third part by 11. These are hinged with respect to each other and control thereof 5 takes place with the aid of cables 5 · The thumb has a pin hole hinge, which is indicated by 12, while the fingers 16 use springs. The hinged connection between thumb and base plate consists of two angled hinges 17 and 18. These are also operated by cables 5 and a starting position is provided by means of stops (not shown) and spring 13. The position the parts 6, 7 and 8 are mutually determined by springs 14, 15 which are present in those parts. Because the spring is placed eccentrically with respect to the cables 5 in both the thumb and the fingers, the cables will warp when the tensile force is applied.

All this is illustrated for the fingers in fig. 3. The spring 16 is shown as a part inserted in parts 9 and 10. It is to be understood that the spring 16 can also be one long continuous part over which the parts 9 and 10 are slidably arranged so as to provide adjustment of those parts. Due to the presence of guide brackets 24, the curved movement shown in Fig. 3 is obtained by applying a tensile force on cable 5.

Hinging of the thumb takes place in a corresponding manner, although the hinges do not yield, so that greater force can be exerted with the thumb.

Fig. 1 also indicates what the effect of such a hinge movement can be for the index finger.

By arranging the brackets 24 slightly at an angle to the drawing plane in Fig. 1, the fingers can exert a slightly curved movement during the bending.

In addition to this movement, it is also possible for the mechanical little finger, index finger and ring finger to perform a spreading movement. Details of the mechanism required for this purpose, which is incorporated in the construction according to Fig. 1, appear from Figs. 2a and b. A cable 5 Is connected to. 35 a sliding piece 31 which is movable downwards against the movement of a spring 30. Couplings 32 are attached to sliding piece 31 via hinges 33, which in turn are just connected via hinges 33 to the above-mentioned fingers. These fingers are themselves connected to the base plate 2 via hinges 34.

If sliding piece 31 is moved downwards by action of cable 5, coupling pieces 32 will also move downwards, so that the fingers in question are spread when moving around hinge 5 34.

Base plate 2 is connected to forearm part 21 via block 22 which provides hinges 19 and 20. Cables 5 come together at the heart of block 22 and pass through opening 23 and in forearm part 21 are connected to operating means 25 · These consist of a number of inner sleeves 29 includes bellows 26 which, as can be seen from Fig. 4, are connected to a connection 27 to which a vacuum is applied. Stationary guide baffles are provided around each of the bellows 26. By applying negative pressure to connection 27, cable 25 will be drawn in and thus the hinge concerned will be operated.

Fig. 5 schematically shows the various hinges discussed above. The hinge shafts are given the same reference numerals as the hinges described above. It has been found that with the construction shown here ten degrees of freedom are possible and with such a number of degrees of freedom all the usual gripping movements can be carried out, while the most common characteristic gestures realized by the human hand can be realized with such a device.

The invention also and independently of the above relates to a mechanical base. This is discussed with reference to Figs. 6 and 7 and consists of the actual foot 35 which is connected by means of a hinge 36 to a mechanical lower leg 38 which in turn is connected via a hinge 37 to an upper leg 40. In in general, this upper leg will be the human upper leg, but, as indicated earlier, it can also be the upper leg of a human simulating robot. Movement of foot 35 is caused by operating means 39, details of which can be seen from Fig. 7. In this figure it is indicated that these operating means consist of a hose 4l built up of spirally wound wires which, when increasing the air pressure, allow the hose to expand in a controlled manner, whereby the. 35 length decreases. Compressed air is supplied via connection 42.

It will be understood that operating means 39 can also be designed in another manner known in the art. The system described above 1003979 6 differs from prior art constructions in which operating means are present between lower leg 38 and foot 35. With the construction shown above, a more precise distribution of forces is possible and a foot can be displaced efficiently, whereby the movements are smoother and more precise. Human walking behavior is approached better with such a construction.

Although the invention has been described above with reference to preferred embodiments, it will be understood that numerous modifications can be made thereto without going beyond the scope of the present application as claimed in the appended claims.

1003979

Claims (8)

A mechanical hand (1) comprising a thumb (3) and four fingers (4) attached to a base (2), the thumb (3) and the four fingers (4) being hinged relative to that base and 5 provided with control means (5) to carry out that movement, characterized. that the thumb comprises at least a first part (6) connected to the base and a second part (7) connected to the first part, wherein the first and second parts are hinged and steered in the sense of gripping and wherein the first part (6) 10 is hinged to the base, said hinge and associated control being so designed that hinge movement is possible in at least two directions. The mechanical hand of claim 1, wherein the thumb comprises three hingedly connected parts (6-8). 15 Mechanical hand according to any of the preceding claims, wherein the fingers each comprise at least two parts, a first part (9) connected to the base and a second part (10) connected to said first part. Mechanical hand according to one of the preceding claims, wherein the hinges between the different parts of the fingers resp. thumb comprises a spring (16), the control means being arranged eccentrically with respect to said spring. Mechanical hand according to any of the preceding claims, wherein the base is connected to a forearm part (21) by a bi-directional hinge (22) and the control means comprise cables (5). which meet near that hinge at an approximately common point, are guided through the center (23) of the hinge and are connected in the forearm part with operating means. Mechanical hand according to claim 5, wherein the actuating parts are air-controlled. Mechanical hand according to claim 5 or 6, wherein said operating means are bundled side by side. Mechanical hand according to any of the preceding claims, comprising means for spreading at least three fingers. , * ##### «« 1003979