First Innovation in Robotic Sensors in 3 years!
Terry Fritz, a Colorado based engineer and creator of award winning robots, has designed the first new sensor to come on the market for robotics in several years.
Mr. Fritz calls the sensor: ThereminVision in honor of Leon Thermin who invented and patented a musical instrument in 1919, which is played by moving hands near a pair of antennas.
The advantage of Thereminvison II over current technology , infrared sensors, is that, with properly places antennas, you can have a full 360 degree detection zone.
The principle of the sensor is based upon the fact that there is a very weak electromagnetic field which surrounds an antenna. When a conductor enters the electromagnetic field, it changes the field's capacity in a measurable way. This conductor can be a hand or a metal object such as a robot. Almost all objects have some detectable capacitance which changes the electromagnetic field.
ThereminVision II is an inexpensive kit, which when assembled (requires soldering) allows experimenters and robotics enthusiasts to detect when objects approach. The output from the kit is wired to a microprocessor, which is not supplied with the kit. The kit consists of four(4) sensor boards and a processor board. The sensor boards, when placed at the 4 corners of a robot and connected to antennas, form an electromagnetic field around the robot which is a zone of detection for objects that approach.
A microprocessor connects to the kit's processor board and polls the sensors. As an object approaches the sensor's antenna, the sensor will send smaller and smaller numbers to the microprocessor until the object touches the antenna and then the output is one's and zeros. The antenna is NOT included since the kit builder needs to incorporate it into his design. The antenna could consist of a single wire(for testing only) extending upwards from the sensor or a metal tube which has a larger detection range. Design guidelines are in the manual noting that the antenna should be rigid. Sample programs are also included in the manual.
Features of the kit include:**Four sensors, Each sensor weighs 3.7 grams, draws far less than 1mA at 5 volts, and is less than 1 x 1.25 inches.
**The processor, a separate board, weighing 10.7 grams, at less than 1mA at5 volts, and is 1.3 x 2.4 inches.
**There are two digital control lines and one output signal line connected to a microprocessor which measures pulse width. An optional control line turns the sensors off.**Power can easily be drawn off the +5volts of most microprocessor supplies.
**Detection range is proportional to the antenna and object surface area. See manual for details. For example, a small robot with ½ inch x 3-inch rigid copper strips as an antennas, the detection range could be 12 - 15 inches. Programming could randomly move the robot until an object is detected.** Manual is downloaded and not sent with kit. Complete schematics are supplied noting that the printed circuit board layouts are copyrighted. Needs wire and electrical solder to assemble, also not supplied with kit.
A demonstration robot and a kit can be seen at:
Kit is price at $50. U.S. (plus S&H)
Mr. Fritz has a site devoted this subject which is also an excellent subject resource at:
There is a discussion group devoted to Thereminvision II kit at:
Kits can be purchased at: