HiTechnic NXT Color Sensor V2
4 stars based on
50 reviews
I have a long standing interest in color sensors I am lucky this year: The other is HiTechnic color sensor V2. You'll find below a comparison between these sensors. The sensors are based on different principles. Reflected light is collected by a light sensor sensitive to all wavelength. HiTechnic one has a white LED, and a specialized color sensitive chip. This chip has three sensitive areas covered by red, green and blue filters.
An added advantage of HiTechnic method is that it can detect the color of light sent on it in passive mode, with the white LED shut off. This test was performed with the setup pictured above. Six colored plates are mounted on a NXT motor. They are successively shown to the color sensor, and the color read is recorded.
In order to test reliability, this cycle is repeated 10 times at each distance. The triangle shaped support allows to change the angle between the plates and the sensor. Note that the NXT-G block provided with HiTechnic color sensor is able to directly discriminate 18 different colors and access color components. Here is a color sensor nxt robot lights with the color numbers provided by the sensors: Dark room, color sensor perpendicular to the plates.
The first test was performed in a dark room, with the color sensor perpendicular color sensor nxt robot lights the plates. Test distance between base of the sensor and the plates is 1, 2, 3, 5 and 8 studs.
At 3 studs distance, green is seen as black. At 5 and 8 studs, all colors are seen as black. With this setup, HiTechnic sensor returns rather weird data, with - for example - black seen as white! When measuring the color of a target surface, light from the sensor's internal light source can reflect from the target and interfere with readings.
To minimize problems caused by reflections, place the color sensor at a slight angle so it is not positioned exactly perpendicular to the target surface.
Dark room, color sensor slightly tilted. But this time HiTechnic sensor works perfectly at a distance of up to 5 studs, and color sensor nxt robot lights identify all colors except green seen as black at a 8 studs distance. Lit room, color sensor slightly tilted.
The next experiment check ambient light immunity. The previous setup is used, but this color sensor nxt robot lights a low voltage, 35W halogen lamp was placed about 55 cm away color sensor nxt robot lights the plates. HiTechnic sensor is not affected at all by this ambient light level, the result are the same as those obtained in a dark room. Day light, color sensor slightly tilted. Now I placed the test setup behind a window, with fine weather with some white, reflecting clouds.
HiTechnic remains completely immune to ambient light level! Impressed by the quality of ambient light cancellation of HiTechnic sensor, I even tried it under direct sunlight. But there it was not able to provide reliable readings. I then tried to characterize the sensor detection speed. Knowing the diameter of the propeller, width of blade and rotation speed, it's easy to derive the time during which the blade is in front of the sensor.
The NXT-G program used counts color sensor nxt robot lights number of cycles during which yellow and red are detected. This number is compared to the number of turns done by the propeller.
Motor speed is increased just below the point where color detection becomes unreliable. Here the LEGO sensor wins hands down, needing only 2. HiTechnic sensor needs 17 milliseconds for a reliable detection. Part color sensor nxt robot lights the explanation probably lies in the different choice of sensor interface: Each sensor has strong points and will be best suited in different situations. LEGO color sensor will perform best in situation where speed is important, such as color line following.
HiTechnic sensor will make wonder when it is difficult to color sensor nxt robot lights shield the sensor or when discrimination between more color shades is needed. Color Sensors Showdown I have a long standing interest in color sensors Detection range This color sensor nxt robot lights was performed with the setup pictured above.
Access to color components with the LEGO sensor is possible using other languages, or with a NXT-G block created by Steve Hassenplug soon to be available here Here is a table with the color numbers provided by the sensors:
