Patent ID: 11940650
Assignee: TEMPLE UNIVERSITY-OF THE COMMONWEALTH SYSTEM OF HIGHER EDUCATION
Field: Measurement (Instruments)
Classification: CPC G  A  H | IPC A  G  H

Claim 18:
19. A method of determining a risk index for an object based on a surface or subsurface size of the object and a softness index of the object using a mobile-platform imaging device that uses compression of a target region to generate an image of the object, the mobile imaging device comprising:
a tactile sensor comprising an optical waveguide comprising at least a first layer that is flexible and transparent, the tactile sensor further comprising at least one light source configured to direct light into the optical waveguide, wherein the optical waveguide is configured so that at least some of the light directed into the optical waveguide is scattered out of the first layer when the first layer is deformed, and wherein the first layer is deformed by the tactile sensor being pressed against the target region;
a force sensor that detects a force being applied to press the tactile sensor against the target region and outputs corresponding force information, the force sensor mounted so as to permit calculation of an applied force in a direction normal to the front surface of the optical waveguide;
a first communication unit connected to receive the force information from the force sensor; and
a receptacle for holding a mobile device having a second communication unit and an imager so positioned that the imager can generate image information using at least some of the light scattered out of the first layer;
wherein the first communication unit is configured to communicate with the second communication unit and the mobile device is configured to communicate with an external network;
the method comprising the steps of:
obtaining the image information and corresponding force information at the second communication unit;
calculating the applied force in a direction normal to the front surface of the optical waveguide from the respective force information associated with the corresponding image information;
determining a number of pixels in the image of the object corresponding to the image information associated with the calculated normal applied force;
estimating the size of the object using 3D interpolation based on the number of pixels in the image of the object and the calculated normal applied force associated with the image of the object;
determining a contact area of the applied force associated with the image information that is generated for each image by the imager from light scattered out of the first layer due to each applied force;
determining stress for each image (k) from the contact area of the tactile sensor and the force information in accordance with the following equation:, σ
    z
   
   (
   k
   )
  
  =
  
   
    
     F
     ⁡
     (
     k
     )
    
    -
    
     F
     
      r
      ⁢
      e
      ⁢
      f
     
    
   
   
    A
    C
   
  
 

where F(k) is the applied force in the z direction, Fref is the force value taken at a reference point, and Ac is the contact area:
determining a deformation ratio for each image (k) in accordance with the following equation:, d
    z
   
   (
   k
   )
  
  =
  
   
    
     ❘
     "\[LeftBracketingBar]"
    
    
     
      I
      ⁡
      (
      k
      )
     
     -
     
      I
      
       r
       ⁢
       e
       ⁢
       f
      
     
    
    
     ❘
     "\[RightBracketingBar]"
    
   
   
    I
    
     r
     ⁢
     e
     ⁢
     f
    
   
  
 

where I(k) is the sum of intensities on the k-th compression image, and Iref is the sum of intensities on the image corresponding to the reference force Fref;
determining a softness index of the object based on the deformation ratio for for each image (k) associated with the applied force F(k) and the determined stress σz(k) for each image (k) in accordance with the following equation:, S
    CISS
   
   =
   
    
     
      σ
      z
     
     (
     k
     )
    
    
     
      d
      z
     
     (
     k
     )
    
   
  
  ,
 

where νz(k) is the stress calculated in the normal direction for each image (k), and dz(k) is the deformation ratio for each image (k); and
determining a risk index for the object based on the estimated size of the object and the softness index of the object.