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Tactile sensor unit, robot including the tactile sensor unit, and load calculation method

Foreign code F120007029
Posted date Nov 19, 2012
Country United States of America
Application number 201013201318
Gazette No. 20110301876
Gazette No. 8725431
Date of filing Feb 12, 2010
Gazette Date Dec 8, 2011
Gazette Date May 13, 2014
International application number JP2010052100
International publication number WO2010095573
Date of international filing Feb 12, 2010
Date of international publication Aug 26, 2010
Priority data
  • P2009-035903 (Feb 18, 2009) JP
  • 2010WO-JP52100 (Feb 12, 2010) WO
Title Tactile sensor unit, robot including the tactile sensor unit, and load calculation method
Abstract (US8725431)
A tactile sensor unit is provided, which includes a substrate; a coat formed on the substrate; and a cantilever beam structure having one end fixed to the substrate and curved to rise in such a direction that the other end of the cantilever beam structure is farther from the substrate than the one end.
The tactile sensor unit detects a load applied to the coat.
The cantilever beam structure is capable of resonating at a first resonant frequency and a second resonant frequency which is different from the first resonant frequency.
The tactile sensor unit further includes a computation section for calculating a directional component of the load based on a change ratio of the first resonant frequency obtained in accordance with a change in the load and a change ratio of the second resonant frequency obtained in accordance with the change in the load.
Scope of claims [claim1]
1. A tactile sensor unit, comprising: a substrate;
a coat formed on the substrate; and
a cantilever beam structure having one end fixed to the substrate and curved to rise in such a direction that the other end of the cantilever beam structure is farther from the substrate than the one end;
the tactile sensor unit detecting a load applied to the coat;
wherein:
the cantilever beam structure is capable of resonating at a first resonant frequency and a second resonant frequency which is different from the first resonant frequency; and
the tactile sensor unit further comprising a computation section for calculating a directional component of the load based on a change ratio of the first resonant frequency obtained in accordance with a change in the load and a change ratio of the second resonant frequency obtained in accordance with the change in the load;
the first resonant frequency is a frequency in a first resonance mode;
the second resonant frequency is a frequency in a second resonance mode which is different from the first resonance mode; and
the computation means includes: voltage application means for applying AC voltages of a plurality of different frequencies to a piezoelectric layer included in the cantilever beam structure to resonate the cantilever beam structure in the first resonance mode and the second resonance mode;
resonant frequency detection means for detecting the first resonant frequency and the second resonant frequency; and
load calculation means for, where a load-free state is a state in which no load is applied to the coat, calculating a directional component of the load in a direction normal to the coat and another directional component of the load in a shear direction based on a first change ratio with respect to the load-free state, which is a change ratio of the first resonant frequency obtained in accordance with the change in the load, and also based on a second change ratio with respect to the load-free state, which is a change ratio of the second resonant frequency obtained in accordance with the change in the load.
[claim2]
2. A tactile sensor unit according to claim 1, wherein: the voltage application means applies an AC voltage of a still different frequency to the piezoelectric layer to further resonate the cantilever beam structure in a third resonance mode;
the resonant frequency detection means further detects a third resonant frequency, which is a frequency in the third resonance mode, of the cantilever beam structure; and
the load calculation means calculates a directional component of the load in the direction normal to the coat and directional components of the load in two shear directions based on a third change ratio with respect to the load-free state, which is a change ratio of the third resonant frequency obtained in accordance with the change in the load, the components of the load in the two shear directions being perpendicular to each other.
[claim3]
3. A tactile sensor unit according to any one of claims 1 or 2, wherein: the cantilever beam structure is asymmetric with respect to each of the directional components of the load; and
the cantilever beam structure includes a plurality of electrodes insulated from each other.
[claim4]
4. A robot including a tactile sensor unit according to claim 1, wherein the substrate, the coat and the cantilever beam structure are provided in a portion of the robot which is contactable with an object which is to contact the robot.
[claim5]
5. A load calculation method for calculating a load applied to a coat of a tactile sensor unit which includes a substrate, the coat formed on the substrate, a computation section, and a cantilever beam structure; wherein the cantilever beam structure has one end fixed to the substrate and is curved to rise in such a direction that the other end of the cantilever beam structure is farther from the substrate than the one end, and is capable of resonating at a first resonant frequency and a second resonant frequency which is different from the first resonant frequency;
the load calculation method performed in the computation section comprising:
a change ratio calculation step of calculating a change ratio of the first resonant frequency obtained in accordance with a change in the load and a change ratio of the second resonant frequency obtained in accordance with the change in the load;
a directional component calculation step of calculating a directional component of the load based on the change ratio of the first resonant frequency obtained in accordance with the change in the load and the change ratio of the second resonant frequency obtained in accordance with the change in the load;
a step of dividing a calculation area into a plurality of quadrants in accordance with whether a normal load and a shear load, among the loads applied to the coat, are each positive or negative; and
a correction step of correcting an error on each of the loads at a point, among points in each of the plurality of quadrants, at which an absolute value of the normal load and an absolute value of the shear load are both maximum.
  • Inventor, and Inventor/Applicant
  • YAMASHITA KAORU
  • KYOTO INSTITUTE OF TECHNOLOGY
IPC(International Patent Classification)
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