pressure sensor array touchpad user interface (u.s. patent 6,570,078)
- The geometric center of the pressure image determines two independent, readily controllable coordinates.
- The rough elliptical form of the pressure image produces a measurable angular orientation as suggested by the figure. From a user's perspective, this orientation can be readily and controllably varied by slight motion of the wrist as the finger pivots around its point of contact with the sensor surface. A moment's experimentation shows the three parameters thus far (ellipse orientation and "x" and "y" coordinates of the geometric center of the image) are quite easy to control independently of one another.
- It is additionally possible to independently control two coordinates of the finger's "tilt," i.e., the degree to which pressure is concentrated with respect to left-right and front-back axes. Thus far there are five continuous parameters which it is easy for the human finger to control independently over a reasonable operating range.
- With a little practice, a user can easily learn to keep all these parameters relatively constant while varying the average or total pressure exerted, giving a sixth independent parameter.
Pressure Sensor Array Touchpad User Interface
Demonstration 1: Six Parameters Controlled by Touch of a Fingertip
Assume the tip or end-joint of a single finger makes isolated contact with a pressure sensor array touchpad in a manner such as that depicted below.
The contact produces a spatially distributed pressure profile which is measured as a collection of small pressure measurements,
forming a pressure image comprising pixels of pressure values. A number of controllable parameters maybe be calculated from
the pressure image, each responsive to different aspects of where and how the pressure sensor array touchpad is touched.
For example:
The figure below summaries the variations in a single finger's touch as described thus far. In this example, the controller technology enables a single finger to simultaneously control six independent parameters in a way that is very easy to learn. Technologies relating to these ideas and many extensions of them are covered in U. S. Patent 6,570,078 [1] , and a wide range of applications and implementation considerations are presented in a family of associated whitepapers [2]-[5] and covered in other pending NRI patents [6]-[7]. Simplified versions involving two spatial parameters for musical instrument keys were explored earlier by Moog [8] and Snell [9], while issued and pending applications [1] and [6] cover a simplified cases and applications involving only three parameters.
The animation below shows an exemplary pressure image emulating a finger trajectory over a pressure sensor array. Each pixel registers local contact pressure in integer-valued steps between 0 and 10: pixels with a pressure value of zero are displayed in black, while the colors ranging from blues to cyans to greens to yellows to oranges to reds to magenta depict increasing values of pressure range of 1 to 10. The six parameters of geometric column center, geometric row center, angle of rotation, tilt column center, tilt row center, and average pressure are numerically calculated from the pixel data employing mathematical techniques adapted from simple classical mechanics as described in [5]. The values of the six parameters are plotted as they evolve over time. As discussed in the next demonstration page, increase of the pixel density (spatial resolution) and/or decrease measurement value step size (value quantization) increase the stability of the calculated parameters as the pressure image spatially evolves, while decreasing the spatial resolution and/or increasing value quantization decreases the stability of the calculated parameters.
REFERENCES
[1] U.S. Patent 6,570,078, "Tactile, visual, and array controllers for real-time control of music signal processing, mixing, video, and lighting," May 27, 2003
[2] NRI Whitepaper "Rich Multi-Parameter Touchpad User Interface: Overview: Background, Capabilities, and Application, 2004
[3] NRI Whitepaper "Rich Multi-Parameter Touchpad User Interface: Computer Pointing Devices, 2004
[4] NRI Whitepaper "Rich Multi-Parameter Touchpad User Interface: Technology and Examplary Implementation," 2004
[5] NRI Whitepaper "Rich Multi-Parameter Touchpad User Interface: Music Applications," 2004
[6] U.S. Pre-Grant Patent Application 2004/0074379, "Functional extensions of traditional music keyboards," April 22, 2004
[7] U.S. Pre-Grant Patent Application 2004/0099131, "Transcending extensions of classical South Asian musical instruments," May 27, 2004
[8] Moog, Robert A. "The Human Finger - A Versatile Electronic Music Instrument Component", Audio Engineering Society Preprint, 1977, New York.
[9] Snell, John M. "Sensors for Playing Computer Music with Expression,"Proceedings of the Intl. Computer Music Conference at Eastman, 1983.