software software software

FIRST General Forum
#1

Posted by Anton Abaya at 2/6/2001 12:27 AM EST

Coach on team #419, Rambots, from UMass Boston / BC High and NONE AT THE MOMENT! :(.

for those of you guys who have extremely fast robots, i’m sure you’ve had the problem of being over sensitive when turning the bot (tank driven).

so i was wondering if anyone has tried this via software… the concept goes…

“push a trigger button, then limit the min and max of the joystick yaxis to 70-200. push it again and default of 0-254 is returned.”

what this does is allows the driver more joystick room for a more accurate turn.

just wondering if anyone has tried it or might want to do it.

-antoninny

#2

Posted by Matt Leese at 2/6/2001 9:27 AM EST

Other on team #73, Tigerbolt, from Edison Technical HS and Alstom & Rochester Institute of Technology.

In Reply to: software software software
Posted by Anton Abaya on 2/6/2001 12:27 AM EST:

We sort of tried that. I think last year we had one of the joystick buttons set to take the speed of the robot to one quarter normal speed. It worked fairly well and it gave teh drivers a bit more control over the robot.

Matt

#3

Posted by Joe Johnson at 2/6/2001 1:37 PM EST

Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

In Reply to: Re: software software software
Posted by Matt Leese on 2/6/2001 9:27 AM EST:

We often use the wheel on the joystick as a variable throttle for the driver joystick(s).

This allows us to have a “training” speed and a competition speed.

The code is not difficult, something along the lines of:
if y1>127 then aaa
pwm1 = 127 - ((127-y1) / NCD (wheel1 + 1) Max 127)
goto bbb
aaa:
pwm1 = 127 + ((y1-127) / NCD (wheel1 + 1)) Max 254
bbb:

As a side benefit, we can dial down the throttle when we go for a show where a bunch of 3rd graders are going to be driving our robot.

Joe J.

P.S. I just wrote that code from memory on the spot, it may not be exactly correct though I believe the concept is substantially correct. JJ

#4

Posted by Chris Orimoto at 2/6/2001 11:30 PM EST

Student on team #368, Kika Mana, from McKinley High School and Nasa Ames/Hawaiian Electric/Weinberg Foundation.

In Reply to: use the wheel as a throttle
Posted by Joe Johnson on 2/6/2001 1:37 PM EST:

Last year, we also used the wheel on the joystick to
regulate speed. I don’t completely remember the code,
but it allowed the position of the wheel (0-254) to
equal the maximum speed the robot could travel when the
y-axis of the driver’s joystick was in full forward.
To this, we also added a button function that
automatically set the variable to 254…kind of like a
“warp to hyperspeed” button (although we were NOT fast
at all to begin with).

Just my personal thoughts…

Chr

#5

Posted by Chris Orimoto at 2/6/2001 11:36 PM EST

Student on team #368, Kika Mana, from McKinley High School and Nasa Ames/Hawaiian Electric/Weinberg Foundation.

In Reply to: use the wheel as a throttle
Posted by Joe Johnson on 2/6/2001 1:37 PM EST:

Last year, we also used the wheel on the joystick to
regulate speed. I don’t completely remember the code,
but it allowed the position of the wheel (0-254) to
equal the maximum speed the robot could travel when the
y-axis of the driver’s joystick was in full forward.
To this, we also added a button function that
automatically set the variable to 254…kind of like a
“warp to hyperspeed” button (although we were NOT fast
at all to begin with).

Just my personal thoughts…

Chr

#6

Posted by Khalid at 2/7/2001 11:48 PM EST

Student on team #486, The Positronic Panthers, from Strath Haven High School.

In Reply to: software software software
Posted by Anton Abaya on 2/6/2001 12:27 AM EST:

Last year, our rookie year, we had a very bad gearing on our drive wheels. Okay, I confess, we direct drove the drive wheels from the drill motors. This is a mistake we will never make again. We noticed that last year so we cut the voltage with software.

In the program we made a series of sloped lines that gave us proportional control of the output to the PWMs. All we did was have the lines with slopes of 1/4, 1/2 , 1, and 2. After plotting these lines, it almost looked like a curve. Now that I look at it I coud have used some kind of exponential equation instead of so many plotted lines.

Using this we were able to gain considerable amount of control ( much better than before, let me tell ya.) For the turning, we never went past 64 bits to either side of 127, agian using the different sloped lines.

: for those of you guys who have extremely fast robots, i’m sure you’ve had the problem of being over sensitive when turning the bot (tank driven).

: so i was wondering if anyone has tried this via software… the concept goes…

: “push a trigger button, then limit the min and max of the joystick yaxis to 70-200. push it again and default of 0-254 is returned.”

: what this does is allows the driver more joystick room for a more accurate turn.

: just wondering if anyone has tried it or might want to do it.

: -antoninny

#7