Finger touch sensors and virtual switch panels

Details Finger touch sensors and virtual switch panels Finger touch sensors and virtual switch panels

1999-02-19

2001-05-22

Evans, F. L. (Department: 2877)

Radiant energy

Photocells; circuits and apparatus

Optical or pre-photocell system

Reexamination Certificate

active

06236037

ABSTRACT:

TECHNICAL FIELD
The present invention relates generally to sensory feedback devices and, more particularly, the invention relates to sensors for detecting human touch.
BACKGROUND
Data gloves have been extensively studied in the past decade in the robotics and virtual reality communities. There are many ways of providing force feedback to a human from a virtual environment or from sensors on a robot, and many data gloves now make use of such force feedback. However, few data gloves collect touch-force data from the human fingers as the human interacts with the environment. To measure the forces acting at the fingers, for example, sensor pads comprising conductive rubber, capacitive sensors, and/or optical detectors can be placed between the fingers and the environment surface. These sensor pads, however, inevitably deteriorate the human haptic sense since the fingers cannot directly touch the environment surface. Moreover, sensor pads may deteriorate or wear out due to mechanical contacts.
Data glove based input has also been used increasingly in the last decade for teleoperation and other forms of human-machine interaction. Postural gesture recognition has been applied to the teleoperation of robots and the teaching of robots by demonstration and guiding. Some systems have been developed for teaching and guiding by inferring human intentions by tactile gestures, which were measured by force sensors on the robots. However, such a system is not very flexible, as it requires modification of the hardware on the robot.
SUMMARY
In accordance with one aspect of the invention, a device for detecting contact pressure applied to a finger, the finger having a fingernail illuminated by light, comprises at least one photodetector for measuring a change in light reflected by an area of the finger beneath the fingernail in response to the contact pressure applied to the finger and providing a signal corresponding to the change and a processor for receiving the signal and determining whether the change corresponds to a specified condition. In a preferred embodiment, the photodetector is an array of photodetectors, the array of photodetectors having a spectral range. The spectral range may include visible and infrared wavelengths.
In another embodiment, the device further includes at least one light source, coupled to the photodetector, the light source for emitting light into the fingernail. In a preferred embodiment, the device further includes a set of light sources coupled to the photodetector, the set of light sources having varying wavelengths and for emitting light into the fingernail. In a further embodiment, the device further includes a housing, enclosing the photodetector and a coupling element, connected to the housing, the coupling element for coupling the housing to the fingernail. In a preferred embodiment, the coupling element is a transparent adhesive material. In yet another embodiment, the device further includes a surface for providing contact pressure to the finger, the surface having indicia and a position locator in signal communication with the processor and coupled to the finger, the position locator for identifying the position of the finger in relation to the surface.
In accordance with another aspect of the invention, a method for detecting contact pressure applied to a finger, the finger having a fingernail illuminated by light, comprises providing at least one photodetector, measuring a change in light reflected by an area of the finger beneath the fingernail in response to the contact pressure applied to the finger, providing a signal corresponding to the change and comparing the change and a specified condition. In a preferred embodiment, the method further includes illuminating the fingernail with light from a light source. In an alternative embodiment, the method further includes enclosing the photodetector and the light source in a housing and coupling the housing to the fingernail.


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