Very fast long distance 90° or 180°-IR-"Bumper" for Robotics with direction detection
This IR-Reflex "bumper" can trigger on obstracles in an adjustable range of about 10cm to 1.5m on a radius of 180° or 90°, and discriminate the direction by 26° respectively 13° or better (half step). One scan is performed in about 1ms. Using the 90° variant allows the use of LEDs with narrower angle and thus up to 3m distance radius.
This IR-Reflex "bumper" can trigger on obstracles in an adjustable range of about 10cm to 1.5m on a radius of 180° or 90°, and discriminate the direction by 26° respectively 13° or better (half step). One scan is performed in about 1ms. Using the 90° variant allows the use of LEDs with narrower angle and thus up to 3m distance radius. As this is rather a low cost approach, the circuit is easy, using one AVR2313, 8 Transistors, 9 High Speed IR-LEDs and two TSOP7000, plus some red LEDs and very little electronics. The sensitivity is in part software controlable and thus adaptable to the parcour or environment an additional poti alows additional adjustment.
As this bumper is working as reflex coupler, it is not suitable for extreme black materials but "normal" black can be detected thanks to the extraordinary sensitivity of the TSOP7000 at reduced distance. The actual output is RS-232 @19.2 or 34.4 kBd, but using a bigger ATmega controller would allow I²C and 360°-view.. Photos and sheet coming soon, if there is interest. sigo
Discussion (3 comments)
sigo 10 years ago
I realized repeated scan-rates of well below 1ms, depending on software comfort in BASCOM it can rise to about 2ms.
I single scan - shot can be as fast as about 100µs, because I send out a 10bit RS-232 Word and receive it with the very short delay time of the TSOP7000 right into the RS-232 input, that gives an interrupt on receive.
The rest ist reading it out and printing to RS-232. This could be done in Assember as well.
Ralf
sigo 10 years ago
Hi Clemens,
yes, it have to be high speed IR-Diodes (TSHF5410/TSFF5410 or TSHF5210/TSFF5210 or similar) with rise times in the 25..100ns range or little more. Normal speed IR-LEDs with typical 0.5µs or so rise time is not enough, but works at lower distance range. (About 1/4 to 1/3 or less that far)
The TSOP works at a modulation frequency of 455kHz or 2.2µs for full periode, this tells why high speed IR-LEDs are needed.
Using high Speed LEDs, you can easilly transmit RS-232 over 15-25m !
I am using BASCOM with a little in line assember code for sending the 455kHz modulated signal. The rest is BASCOM.
One complete sent out scan takes as short as sending one Byte via RS-232 @ 19.2 or 34.4kBit/s.
This is about 1/19200*15 seconds = 78µs. (times 15 because of 10bit for sending the data und 5 idle bus time needed for recovery of the TSOP's AGC-Amplifier.
But the Basic program needs longer. I realized times of about 0,3 to 1ms for a complete cycle including user interface via RS-232 and so on, writing the result to the RS232 output at the same speed as the transmitter. It depends on the programmed features. If it is only up to pass an interrupt or event to another controller you can go faster to about 100 to 200µs.
BTW: I am simply sending out an RS-232 object, with 8N1 coding. Echoed singnals appear on the RS-232 Rx input, so that BASIC can receive the receive the result without stress.
And the RS-232 can still be used as user - interface.
sigo
ClemensValens 10 years ago
How fast is your system? And does it need special high-speed infrared LEDs for it? I mean, all LEDs are pretty high speed.
Regards,
Clemens
sigo 10 years ago