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I had no idea the Stingray was so fast! — Parallax Forums

I had no idea the Stingray was so fast!

MicrocontrolledMicrocontrolled Posts: 2,461
edited 2011-02-23 19:47 in Propeller 1
I've had lots of robots, and the one thing they all had in common: No real motors. All of my bots have been servo powered and VERY slow. The main problem was that I always wanted more speed. Well, now I have a Stingray, and I didn't expect to spend 5 minutes chasing it down after I set it loose with a PING sensor.
Some things I've learned:

(1: Use PWM, not full speed
(2: I now know what the purpose of a "PING protector" is.
(3: This thing can dent a wall or desk
(4: Don't leave the USB cable connected when you turn on the motors
(5: This hurts if it runs into your foot
(6: This is without a doubt the coolest robot I've ever owned. :-)

Comments

  • RavenkallenRavenkallen Posts: 1,057
    edited 2011-02-23 09:28
    I know what you mean. All of the robots i have are really slow to:)
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-02-23 14:01
    I think this is the best promotional material I've read about the Stingray. You make me want to get one.

    Can you quantify the speed? How long does it take to go 30 feet?
  • doggiedocdoggiedoc Posts: 2,245
    edited 2011-02-23 14:08
    Micro - make sure you use ramping routines to ramp up and ramp down to full speed - those little motors are stout but they can break from sudden full power of stops. I flipped mine a few times before I figured that out!
  • MicrocontrolledMicrocontrolled Posts: 2,461
    edited 2011-02-23 17:29
    I've stopped running mine at full speed, half speed (PWM @ 128) seems to do be perfect for indoor use.
    I'm also ramping them as advised above.
    @Duane Degn: It's hard to judge speed. If you start them off at full speed, the robot jerks and takes off, but it goes about 5 feet before it ramps up to pure full speed, but even before that, it's fast enough to be hard to chase. I know it was able to reach the other end of a long room (25-30ft.) in about 2.5 seconds.
    I've almost got autopilot with a single ping working smoothly, but I have to run it at half speed for reaction times to be fast enough.
  • Tony B.Tony B. Posts: 356
    edited 2011-02-23 19:47
    I had a similar experience with my homemade Stingray called Banshee here is the post link http://forums.parallax.com/showthread.php?119580-My-Stingray-Look-a-Like-Plywood-Robotics-Platform-Update-7-Banshee-meets-his. It uses the same motors/wheels and board as the Stingray

    Here is my first experience as recorded in that post "First run was very enlightening! Using the motor test run code (in Board manual) to run both motors at the same time I downloaded the code to the board thinking in BOE-BOT speed that a 2 second motor run wouldn't take the robot too far. Man was I wrong!!! I set the robot down it raced across the floor near the speed of light right for my computer desk and Linux server box. I knew a crash was imminent and began chasing it. After hitting the desk and server, moving it about six inches, it began running the second half of the code, running the motors in reverse for 2 seconds. We met each other half way and when it slammed into my foot it felt like it broke my big toe! First run observation: Man this thing is fast and wear your steel toed work boots for the next test!"

    I also have a Stingray that I never run at full speed. I guess I can be taught.

    Tony
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