Coded data generation or conversion – Bodily actuated code generator – Including keyboard or keypad
Reexamination Certificate
1999-02-26
2001-02-13
Horabik, Michael (Department: 2735)
Coded data generation or conversion
Bodily actuated code generator
Including keyboard or keypad
C033S123000, C073S628000, C073S652000, C338S099000
Reexamination Certificate
active
06188331
ABSTRACT:
The invention relates to a tactile sensor comprising a base plate provided at a first side with a plurality of electrically conducting wires forming a row, and provided at a second side opposite to the first side of the base plate with a plurality of electrically conducting wires forming a column, each of these wires forming cross points with the electrically conducting row wires, wherein each of the column wires forms an electrical contact with the row wires near each cross point, which electrical contacts are located at the first side of the base plate, and the first side of the base plate is provided with a covering having a pressure-dependent electrical resistance and which, together with the electrical contacts of the column wires and the row wires, is suitable to form one or more current paths.
Such a tactile sensor is known from the journal “De Ingenieur”, volume 108, No. 5, Mar. 20, 1996, pages 28-31. The base plate of the tactile sensor of the prior art is a so-called printed circuit board. Both sides of the print are provided with this printed circuit. The printed circuit consists of 16 equidistant strips of conductive material on a first side of the print and 16 equidistant strips of electrically conducting material on the other side of the print arranged orthogonally to the fist strips. At the cross points, a metal connection from the one side to the other side is provided for the strips on the first side only, but in such a manner that these electric interconnections form islands at the cross points within the strips of conductive material on the other side of the print. The latter side is also provided with a covering of an electrically conductive rubber which has a pressure-dependent electric resistance. By applying a load to the sensor on the side of the covering, it is possible to measure both the position and the force of the applied load.
It is the objective of the invention to improve this known sensor such that this sensor can also measure tangential or shear forces and to enable the sensor to measure the start and progression of slip more accurately and continuously.
To this end the tactile sensor according to the invention is characterized, in that the covering is divided into segments, each segment covering at least two adjacent cross points. This makes it possible to measure a difference in load ensuing from shear forces at adjacent cross points because, in contrast with the prior art, the segmentation now admits varying normal forces at these adjacent cross points.
The invention also embodies a method for the determination of a shear force when a load is applied on a tactile sensor as discussed above. According to the invention this method is characterized in that the resistance values of current paths formed between the connection points of each of the electrically conductive row wires and of each of the electrically conductive column wires is determined, that for each current path these resistance values are converted to numerical values which are a measure for the load at the cross points of the row and column wires, and that the difference between the numerical values of adjacent cross points is determined, as being a measure of the shear force exerted on the sensor.
If the tactile sensor is made such that each segment covers four adjacent cross points forming the corners of a square, it is possible to measure the shear forces occurring in the plane of the covering in any arbitrary orientation by resolving the measured forces in combining orthogonal directions determined by these four adjacent cross points.
A possible embodiment of the tactile sensor in accordance with the invention is one in which the covering is composed of separate segments which are not interconnected. However, a preferred embodiment of the tactile sensor according to the invention is provided with a covering comprising an undivided base surface resting on the first side of the base plate, while the base surface is provided with separate projections forming the segments. The manufacture of this tactile sensor is particularly simple. This covering can be particularly easily provided if it is formed from an electrically conducting rubber having a pressure-dependent electrical resistance, due to the fact that the rubber is incised crosswise, with the segments being located between the incisions.
As mentioned above, the tactile sensor according to the invention is particularly suitable for the measurement of shear forces. In addition, the invention provides a tactile sensor possessing an increased sensitivity for the determination of slip occurring while the tactile sensor is loaded. To this effect this sensor according to the invention is applied such that resistance values are determined of current paths formed between the connection points of each of the electrically conducting row wires and of each of the electrically conducting column wires, that these resistance values are converted for each current path to numerical values constituting a measure for the load at the cross points of the row and column wires, that these values are totalized to produce a principal value, and that from a series of these principal values a frequency spectrum is determined and the occurrence of predetermined frequency characteristics is detected as an indication of the slip.
REFERENCES:
patent: 4208648 (1980-06-01), Naumann
patent: 4483076 (1984-11-01), Brooks
patent: 5553500 (1996-09-01), Grahn et al.
patent: 5604314 (1997-02-01), Grahn
patent: 0 595 532 (1994-05-01), None
patent: 0 658 753 (1995-06-01), None
patent: WO 96/13704 (1996-05-01), None
De Ingenieur, vol. 108, No. 5, Mar. 20, 1996, Netherlands, pp. 28-31, EP000614607, W. Jongkind: “Robothand krijgt mens”.
Proceedings of the Instrument and Measurement Technology Conference, Orvine, CA., May 18-20, 1993, May 18, 1993, Institute of Electrical and Electronics Engineers, pp. 579-583, XP000400239, McMath W S et al: High Sampling Resolution Tactile Sensor For Object Recognition.
Holweg Eduwardus Gerardus Maria
Jongkind Willem
Regtien Paulus Petrus Leonardus
Zee Fulco
Akerman & Senterfitt
Fokker Space BV
Horabik Michael
Wong Albert K.
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