Haptic force-feedback for computing interfaces

Abstract

Methods, systems, and apparatuses, including computer programs encoded on computer-readable media, for receiving, from an accelerometer, angle information of a device. A calibration position is measured based upon the angle information of the device when the device is at rest. A current position is constantly measured based upon the angle information of the device. A current pressure is calculated based upon the current position and the calibration position. The current pressure can be used to augment an audio signal and/or used to augment an audio instruction.

What is claimed is: 
     
         1 . A case for holding a mobile computing device comprising:
 a housing configured to receive the mobile computing device;   an elastic string affixed at a first portion to the case at a first location and having a tactile connection with a screen of the mobile computing device; and   a play mode location on the case for removably receiving a second portion of the string;   wherein the string extends over the mobile computing device when affixed to the first location and removably received at the play mode location, and   wherein the elastic string has an initial displacement and a pluck displacement, the initial displacement being the elastic string at rest, the pluck displacement being the displacement of the elastic string in response to a pluck displacement by a user, and   wherein the elastic string is released from the pluck displacement and returns to the initial displacement at a pluck velocity, the pluck velocity dependent on the tactile connection, initial displacement, and pluck displacement, and   wherein data within the mobile computing device is augmented based upon the pluck velocity.   
     
     
         2 . The case of  claim 1 , further comprising:
 a notch configured to receive a node; and   a retractable elastic band including the node.   
     
     
         3 . The case of  claim 1 , wherein the string is electroactive polymer. 
     
     
         4 . The case of  claim 1 , wherein the string is conductive. 
     
     
         5 . The case of  claim 1 , further comprising resistive material affixed to the house configured to compress when pressure is applied to the computing device, wherein pressure can be measured by the computing device based upon the compressed resistive material, and wherein data within the mobile computing device is augmented based upon the pressure. 
     
     
         6 . The case of  claim 1 , further comprising a rest mode location for removably receiving the string wherein the wherein the string does not cover the mobile computing device when affixed to the first location and removably received at the play mode location. 
     
     
         7 . The case of  claim 1 , wherein the pluck velocity is determined by an equation of 
       
         
           
             
               v 
               = 
               
                 
                   d 
                   t 
                 
                 = 
                 
                   
                     
                       x 
                       1 
                     
                     - 
                     
                       x 
                       0 
                     
                   
                   
                     
                       t 
                       1 
                     
                     - 
                     
                       t 
                       0 
                     
                   
                 
               
             
           
         
       
       wherein “v” is the pluck velocity, “d” is a distance, “t” is a time, “x1-x0” is a distance displaced, and t1-t0″ is a duration of the pluck displacement.