Electricity: measuring and testing – Magnetic – Displacement
Patent
1991-03-25
1992-12-01
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Displacement
33 1M, 73779, 74471XY, 32420720, 32420722, 340709, 901 2, 901 15, 901 46, G01B 730, G01B 714, G05G 900, G09G 100
Patent
active
051682214
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to position sensors and more particularly to magnetic tactile sensors used in robotic manipulation and pointing devices for computer work-stations.
BACKGROUND OF THE INVENTION
The need for performant tactile sensors in robotics has grown in the past ten years with the emergence of very sophisticated robots and prehension devices. Experience has shown that tactile sensors sensitive to forces exerted thereupon such as pressure forces, torque or shear forces have many pitfalls and do not perform satisfactorily in most applications.
Position sensors used as pointing devices for pointing objects on a screen of a computer are also increasingly found in the computer industry in particular in connection with personal computers (desktop or laptop computers). The pointing devices heretofore known come in numerous forms and perform satisfactorily in most cases. Yet, they also have undesirable features inherent to the physical principles underlying their functioning.
Magnetic tactile sensors have been known to the robotics industry and are based on sensing variations of a magnetic field generated by the sensor or the object to be sensed. In particular, a shear-sensitive magnetoresistive tactile sensor has recently been disclosed in the article published in "IEEE TRANSACTIONS ON MAGNETIC", vol. Mag-22, No. 5, September 1986, entitled "Shear-sensitive Magnetoresistive Robotic Tactile Sensor", by T. J. Nelson et al.
As set forth in the above-referenced article, there is disclosed a tactile sensor consisting of a small magnetized rod, constrained to pivot about its attachment to a thin elastic sheet. Magnetoresistive detectors that produce differential outputs proportional to the x and y displacements of the end of the rod are arrayed underneath the sheet. The rod can pivot about its axis in response to shear forces on the active surface. The difference in resistance of opposite pairs of detectors indicates the angular displacement and thus the shear. This arrangement seems to be performant for determining the shear components of a force but is hardly versatile as an all-function tactile sensor. In particular, the tactile sensor disclosed in the aforementioned article does not appear adequately adapted to sense pressure or torque forces.
More tactile sensors are described in an article by Leon Harmon, published in Recent Advances in Robotics, edited by Beni and Hackwood, 1985 p. 389-424. Because of the unusual characteristics of tactile sensing and the difficult problems encountered in the realization of robust multiple-sensors, the state of the art has developed slowly and seems primitive despite the immense progress in electronics and information processing. The concept of compliance in particular is an important component of tactile sensing. It is also essential that a tactile sensor be proprioceptive, i.e., be able to generate a feedback proportional to the force exerted by the grip of the mechanical arm or wrist.
The instantaneous kinematic and static characteristics of robotic wrist joints are also analyzed in an article entitled "Kinematic and Static Characterization of Wrist Joints and Their Optimal Design", published in IEEE, International Conference on Robotics and Automation, P. 244-250, by H. Asada et al. It is demonstrated in this article that if wrist joints are required to rotate in all directions, the mobility is therefore considered to be optimal in isotropic kinematics.
As to pointing devices, they are now well known in the computer industry and they all serve the same purpose: pointing an object on the CRT terminal of a computer with the maximum accuracy, speed and the least fatigue by the user of the pointing device. A review of the pointing device currently used in the computer industry can be found in an article by Cary Lu, published in "High Technology", January 1984, pages 61 to 65, entitled "Computer Pointing Devices: Living with Mice". Very briefly summarized, the following pointing devices are presently found in the market:
cursor keys: moving the
REFERENCES:
patent: 3194990 (1965-07-01), Kendall
patent: 3611220 (1971-10-01), Hoffman
patent: 3849724 (1974-11-01), Ghibu et al.
patent: 4282484 (1981-08-01), Morrow
patent: 4517514 (1985-05-01), Howell
patent: 4628755 (1986-12-01), Hawley
patent: 4639668 (1987-01-01), Petit et al.
patent: 4691185 (1987-09-01), Loubier et al.
patent: 4853630 (1989-08-01), Houston
LandOfFree
Pivotal magnetic coupling and position sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pivotal magnetic coupling and position sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pivotal magnetic coupling and position sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-504704