Help with Ramping Code for Boe-Bot

Felix79

Hi, I'm new to the Parallaxe message boards and I've recently just gotten my Boe-Bot robot kit last month.· I've done most of the activities in the activity book that came with the kit.· Chapter 4 has a really short section on ramping up / down for the servos on the Boe-Bot...· I was wondering if there was a way to incorporate that code into the other example programs in the book.· One being the one for Roaming with Whiskers or Roaming with irDetection.· Here is the code that I'm tryin to modify..

' Robotics with the Boe-Bot - RoamingWithIrDetectionAndRamping.bs2
' Boe-Bot uses·irDetection to detect objects, and navigates around them.
' {$STAMP BS2}
' {$PBASIC 2.5}
DEBUG "Program running"
irDetectLeft·· VAR····· Bit
irDetectRight· VAR····· Bit
pulseCount···· VAR····· Byte

FREQOUT 4, 2000, 3000
DO
· FREQOUT 8, 1, 38500
· irDetectLeft = IN9
· FREQOUT 2, 1, 38500
· irDetectRight = IN0
· IF (irDetectLeft = 0) AND (irDetectRight = 0) THEN
··· HIGH 10
··· HIGH 1
··· GOSUB Ramp_down
··· GOSUB Back_Up
··· GOSUB Turn_Left
··· GOSUB Turn_Left
· ELSEIF (irDetectLeft = 0) THEN
··· HIGH 10
··· GOSUB Ramp_Down
··· GOSUB Back_Up
··· GOSUB Turn_Right
· ELSEIF (irDetectRight = 0) THEN
··· HIGH 1
··· GOSUB Ramp_down
··· GOSUB Back_Up
··· GOSUB Turn_Left
· ELSE
··· LOW 10
··· LOW 1
··· GOSUB Ramp_Up
··· GOSUB Forward_Pulse
· ENDIF
LOOP
Ramp_Up:
· FOR pulseCount = 0 TO 60
··· PULSOUT 13, 750 + pulseCount
··· PULSOUT 12, 750 - pulseCount
··· PAUSE 20
· next
· RETURN
Forward_Pulse:
· PULSOUT 13, 850
· PULSOUT 12, 650
· PAUSE 20
· RETURN
Turn_Left:
· FOR pulseCount = 0 TO 45
··· PULSOUT 13, 750 - pulseCount
··· PULSOUT 12, 750 - pulseCount
··· PAUSE 20
· NEXT
· RETURN
Turn_Right:
· FOR pulseCount = 0 TO 45
··· PULSOUT 13, 750 + pulseCount
··· PULSOUT 12, 750 + pulseCount
··· PAUSE 20
· NEXT
· RETURN
Ramp_Down:
····FOR pulseCount = 0 TO 60
····· PULSOUT 13, 750 - pulseCount
····· PULSOUT 12, 750 + pulseCount
····· PAUSE 20
··· NEXT
··· RETURN
Back_Up:
· FOR pulseCount = 0 TO 40
··· PULSOUT 13, 650
··· PULSOUT 12, 850
··· PAUSE 20
· NEXT
· RETURN

When I try to run this program - My Boe-Bot seems to get stuck on this bit of code ( Ramp_Up ), and it repeats that over and over.· Is there a way to program the servos to gradually accelerate without having to go in a set/determined programmed length of area?· I want my Boe-Bot to move more fluidly around instead of having the jerks whenever it changes into a new direction.·

Thanks.

Zoot

Rather than a subroutine per se, you might think about just adding/subtracting a set value from the motor speed(s) each time through the loop. For example, on one of my Boe-bots, when the bot has to avoid using IR, rather than just setting turn speeds, I do something akin to this:

IF irLeft = Detected THEN
   motorLeft = motorLeft + 5 MAX 255 ' in my case I map motor speeds of 0-128-255 to 650-750-850 pulsewidths;
   motoRight = motorRight MIN 5 - 5    ' it's  a convenience that saves var space, but is technically unneccesary
ELSEIF irRight = Detected THEN
   motorLeft = motorLeft MIN 5 - 5
   motorRight = motorRight + 5 MAX 255
ELSE ' straighten out but do it more quicky
   motorLeft = motorLeft + 10 MAX 255
   motorRight = motorRight + 10 MAX 255
ENDIF

The only trap here is if you are doing any kind of subsumption based program (like many of the examples for the Boe floating around the forum). Many of those routines effectively "destroy" the previously sent motor speed, so you need to either preserve the last "sent" speed, or you need to code your subsumption state machines so they do not destroy the previous motor speed if they are not actually subsuming.

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When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php

Felix79

Cool.. Thanks for the Reply there Zoot - but I'm not exactly sure what you are trying to tell me here.· Hmm, though I will try and see if I can put in values beside the PULSOUT 750 code bit... Maybe something like your post - PULSOUT 13, 750 + 5 MAX 100 for my Boe-Bot.· I'll re-post here again if I can figure something out.

Felix79

Nope, that didnt work.. Hmm - starting to wonder if it is not possible for there to be any gradual acceleration of servo motors without giving them a set number of pulses to do ( FOR pulseCount = 1 TO 100 )...

One other question.. Why is there not a Sticky Boe-Bot thread? Like for the ones Penguin robot and Squibbler Robot?

Zoot

It is absolutely possible. Sorry -- the code fragment I provided is probably not enough info for you.

The basic idea is that you have a subroutine, or a single place in your code, where the motor speeds are actually "dumped" and output to the servos. That way you can have your main loop keep tweaking and changing the motor speeds, and when the loop is done, THEN the final "set" speeds are actually sent. This might show it better. I'm using Words for servo speeds for simplicity, but words are a real waste of var space for these speeds (if your servo speed range is 650-850 that's a range of only 200, far less than a byte):

servoLeft PIN 12  ' change if necessary
servoRight PIN 13 ' change if necessary
motorLeft VAR Word ' left servo speed
motorRight VAR Word ' right servo speed


Main:

  
Obstacle_Check:
IF irLeft = Detected THEN
   motorLeft = motorLeft + 5 MAX 850 ' turn right gradually
   motorRight = motorRight - 5 MIN 650
ELSEIF irRight = Detected THEN
   motorLeft = motorLeft - 5 MIN 650 ' turn left gradually
   motorRight = motorRight + 5 MAX 850
ELSE ' straighten out but do it more quicky
   motorLeft = motorLeft + 10 MAX 850
   motorRight = motorRight + 10 MAX 850
ENDIF

Output_Servos:
  PULSOUT ServoLeft, 1500 - motorLeft ' note that the motorspeed vars are "normal" -- 850 is forward for both;
                                                        ' only during output is the "backwards" motor value switched around
  PULSOUT ServoRight, motorRight
  PAUSE 5 ' this pause may need to be adjusted up or down (or eliminated) depending on how long it takes to run through the whole loop
                '  -- the goal is for all the code + the pause to add up to about 20ms

Main_Loop_Done:
  GOTO Main

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php