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Sun, 23 Nov 2008
Laser pointer ranging function added to SRV-1 firmware

We now have a laser_range() function which uses the laser pointers and onboard camera in combination to estimate distance to the nearest obstacle. The function is accessed by console with 'R' or 'r' commands, the C interpreter via "range()", or the Lisp interpreter with "(range)". The 'r' console command dumps lots of diagnostic data, in case you want to see what the laser_range() function is thinking.

Here is a sample program for the C interpreter using the range() function:
main()
{
    int x;
    char ch;

    ch = 0;
    while (ch == 0) {
        x = range(); /* user laser pointer ranging */
        print("range = " x);
        if (x < 30) {
            motors(-50 , 50);
        } else {
            motors(50, 50);
        }
        delay(500);
        ch = input(); /* continue until any console input */
    }
    motors(0, 0);
}

A version of code for the new Lisp interpreter looks like this:
(define (stop) (robot 5))
(define (left) (robot 4))
(define (right) (robot 6))
(define (forward)
    (begin
        (robot 8)
        (delay 500)
        (robot 5)
    )
)
(define (back)
    (begin
        (robot 2)
        (delay 500)
        (robot 5)
    )
)

(define (branch)
    (begin
        (set! x (range))
        (print x)
        (if (< x 30) (right) (forward))
    )
)

(while (not (signal))
    (branch)
)

Note that while the Lisp version is longer, most of the code is creating some library functions such as stop, left, right ... that can easily be used later. A detailed discussion of the new firmware version is found here on the Surveyor Robotics Forum.

Posted Sun, 23 Nov 2008 18:08 | HTML Link | see additional stories ...