BRAT walking in circles

akdabaous · July 16, 2011, 4:27pm

Hi, my brat (and I) are having problems. It’s the autonomous one with the basic atom pro chip and I have set it up properly; by this, I mean that I have programmed it and adjusted it so the offsets are 0 and when it is powered up, it stand up straight with the angles between the legs and the other parts as they should be (corresponding to the images in the assembly guide).

The problem is that when I programmed it to follow a sequence of commands (I used the source code given and just changed the command numbers so that it would only walk in a straight line). However, it seems to take one step forwards, then turn right, take another step forwards and turn right again, etc.

Could someone please help me out, I can’t find the problem anywhere. Thank You!

robotdude · July 18, 2011, 2:26pm

We need much more information… viewtopic.php?f=32&t=6286

akdabaous · July 18, 2011, 2:35pm

Ok, let’s see now … I’m using a 32-bit laptop and a USB-Serial converter for programming (but I don’t think there is anything wrong with the code because the servos move fine when they are disconnected from the body - I took them out and then powered then from the board).

The kit I am using is the Biped BRAT Autonomous and I am having the problem with the first project (making it walk following the sequence of commands - e.g. walk, walk, walk, kick - something along those lines). The problem is the same as before. The assembly was fine (however, I did have to remove the servo horns of the servos and then put them back again - like in the tutorial for setting up the servo horn).

robotdude · July 18, 2011, 3:36pm

Please enlighten us… Show the code.

akdabaous · July 21, 2011, 7:48am

Sorry for not replying straight away:

[code];Program written for Bot Board II, Basic Atom Pro 28, IDE Ver. 8.0.1.7
;Written by Nathan Scherdin, modified by Jim and James Frye
;System variables
righthip con p10
rightknee con p8
rightankle con p7
lefthip con p6
leftknee con p5
leftankle con p4

NUMSERVOS con 6
aServoOffsets var sword(NUMSERVOS)
ServoTable bytetable RightHip,rightknee, rightankle,lefthip, leftknee, leftankle

TRUE con 1
FALSE con 0

;calibrate steps per degree.
stepsperdegree fcon 166.6

;You must calibrate the servos to “zero”. Each robot will be different!
;When homed in and servos are at 0 degrees the robot should be standing
;straight with the AtomPro chip pointing backward. If you know the number
;of degrees the servo is off, you can calculate the value. 166.6 steps
;per degree. The values for our test robot were found by running the
;program bratosf.bas written by James Frye.

;Interrupt init
ENABLEHSERVO
;==============================================================================
; Complete initialization
;==============================================================================
aServoOffsets = rep 0\NUMSERVOS ; Use the rep so if size changes we should properly init

; try to retrieve the offsets from EEPROM:

; see how well my pointers work
gosub ReadServoOffsets

;Init positions
;Note, movement subroutine arguments are Rightankle,Rightknee,Righthip,Leftankle,Leftknee,Lefthip,speed
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
;low 1
;low 2
pause 1000

command var byte
xx var byte
bat var word

;main
;---------------------------------------;
;--------Command Quick Reference--------;
;---------------------------------------;
;- Command 1 = Walk Forward -;
;- Command 2 = Walk Backward -;
;- Command 3 = Long Stride Forward -;
;- Command 4 = Long Stride Backward -;
;- Command 5 = Kick -;
;- Command 6 = Headbutt -;
;- Command 7 = Get up from Front -;
;- Command 8 = Get up from Back -;
;- Command 9 = Rest Position -;
;- Command 0 = Home Position -;
;- Command 11= Turn Left -;
;---------------------------------------;

     sound 9,[50\4400] 
     pause 50 
     sound 9,[50\3960] 
     pause 50 
     sound 9,[50\3400]

command = 0
gosub move
pause 2500

main

adin 16, bat

if (bat < 270) then;the battery is getting low
sound 9,[50\5000,25\4400,50\5000]
endif

command = 1
for xx = 1 to 5
gosub move
next

command = 1
for xx = 1 to 2
gosub move
next

command = 1
for xx = 1 to 3
gosub move
next

command = 1
gosub move

command = 1
for xx = 1 to 2
gosub move
next

command = 1
for xx = 1 to 4
gosub move
next

command = 1
gosub move

end

move:
if(command = 1) then ; Walk Forward
gosub movement 7.0,-20.0,-20.0, -7.0, 20.0, 20.0, 500.0]
gosub movement -7.0,-20.0,-20.0, 7.0, 20.0, 20.0, 500.0]
gosub movement -7.0, 20.0, 20.0, 7.0,-20.0,-20.0, 500.0]
gosub movement 7.0, 20.0, 20.0, -7.0,-20.0,-20.0, 500.0]
elseif(command = 2) ; Walk Backwards
gosub movement -7.0,-20.0,-20.0, 7.0, 20.0, 20.0, 500.0]
gosub movement 7.0,-20.0,-20.0, -7.0, 20.0, 20.0, 500.0]
gosub movement 7.0, 20.0, 20.0, -7.0,-20.0,-20.0, 500.0]
gosub movement -7.0, 20.0, 20.0, 7.0,-20.0,-20.0, 500.0]
elseif(command = 3) ; Long Stride Forward
gosub movement 12.0,-45.0,-45.0,-12.0, 45.0, 45.0, 750.0]
gosub movement -12.0,-45.0,-45.0, 12.0, 45.0, 45.0, 750.0]
gosub movement -12.0, 45.0, 45.0, 12.0,-45.0,-45.0, 750.0]
gosub movement 12.0, 45.0, 45.0,-12.0,-45.0,-45.0, 750.0]
elseif(command = 4) ; Long Stride Backward
gosub movement -12.0,-45.0,-45.0, 12.0, 45.0, 45.0, 750.0]
gosub movement 12.0,-45.0,-45.0,-12.0, 45.0, 45.0, 750.0]
gosub movement 12.0, 45.0, 45.0,-12.0,-45.0,-45.0, 750.0]
gosub movement -12.0, 45.0, 45.0, 12.0,-45.0,-45.0, 750.0]
elseif(command = 5) ; Kick
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 500.0]
gosub movement 42.0, 0.0, 0.0,-14.0, 0.0, 0.0, 500.0]
gosub movement 0.0,-32.0, 41.0,-23.0, 0.0, 0.0, 500.0]
gosub movement 0.0, 24.0,-20.0,-23.0, 0.0, 0.0, 250.0]
gosub movement 0.0, 0.0, 0.0,-18.0, 0.0, 0.0, 500.0]
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 500.0]
sound 9,[50\3960]
pause 50
sound 9,[50\4400]
pause 50
sound 9,[50\3960]
elseif(command = 7) ; Get up from front
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 500.0]
gosub movement 0.0, 90.0, 45.0, 0.0, 90.0, 45.0, 500.0]
gosub movement 40.0, 90.0,-37.0, 0.0, 90.0, 45.0, 500.0]
gosub movement 0.0, 90.0,-65.0, 0.0, 90.0,-65.0, 500.0]
pause 500 ; Then Bow
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 750.0]
sound 9,[50\4400]
pause 50
sound 9,[50\4400]
pause 50
sound 9,[50\3960]
elseif(command = 8) ; Get up from back
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,1000.0]
gosub movement 0.0,-90.0, 5.0, 0.0,-90.0, 5.0,1000.0]
gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,1000.0]
pause 1000
;gosub movement 0.0, 22.0,-80.0, 0.0, 22.0,-80.0,1000.0]
;gosub movement 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,1000.0]
sound 9,[50\3960]
pause 50
sound 9,[50\3960]
pause 50
sound 9,[50\4400]

   elseif(command = 0)							; Home Position 
     gosub movement   0.0,  0.0,  0.0,  0.0,  0.0,  0.0, 500.0] 
     sound 9,[50\4400] 
     pause 50 
     sound 9,[50\4400] 
     pause 50 
     sound 9,[50\4400] 
  elseif(command = 6)							; Headbutt 
     gosub movement   0.0,  0.0,  0.0,  0.0,  0.0,  0.0, 500.0] 
     gosub movement   0.0,-50.0,-90.0,  0.0,-50.0,-90.0, 500.0] 
     gosub movement   0.0, 32.0,-58.0,  0.0, 32.0,-58.0, 400.0] 
     pause 200 
     ;gosub movement   0.0,-11.0,  7.0,  0.0,-11.0,  7.0, 500.0] 
     gosub movement   0.0,  0.0,  0.0,  0.0,  0.0,  0.0, 500.0] 
     sound 9,[50\4400] 
     pause 50 
     sound 9,[50\3960] 
     pause 50 
     sound 9,[50\3960] 
  elseif(command = 11)							; Turn 
     gosub movement   0.0,-35.0,-40.0,  0.0, 35.0, 37.0,500.0] 
     gosub movement   0.0, 35.0, 37.0,  0.0,-35.0,-40.0,500.0] 
     gosub movement -14.0, 35.0, 37.0, 20.0,-35.0,-40.0,500.0] 
     gosub movement -14.0, 35.0, 37.0, 20.0, 35.0, 37.0,500.0] 
     gosub movement  20.0, 35.0, 37.0,-14.0, 35.0, 37.0,500.0] 
     gosub movement  20.0,-35.0,-40.0,-14.0, 35.0, 37.0,500.0] 

     ;gosub movement   0.0,-35.0,-70.0,  0.0, 35.0,  7.0,500.0] 
     ;gosub movement   0.0, 35.0,  7.0,  0.0,-35.0,-70.0,500.0] 
     ;gosub movement -14.0, 35.0,  7.0, 20.0,-35.0,-70.0,500.0] 
     ;gosub movement -14.0, 35.0,  7.0, 20.0, 35.0,  7.0,500.0] 
     ;gosub movement  20.0, 35.0,  7.0,-14.0, 35.0,  7.0,500.0] 
     ;gosub movement  20.0,-35.0,-70.0,-14.0, 35.0,  7.0,500.0] 



  elseif(command = 9)							; Rest Position 
     gosub movement   0.0, 45.0, 45.0,  0.0, 45.0, 45.0, 500.0] 
  endif

return

;Should never need to edit anything below this line. Add user subroutines above this and below main.
lefthippos var float
leftkneepos var float
leftanklepos var float
righthippos var float
rightkneepos var float
rightanklepos var float
last_lefthippos var float
last_leftkneepos var float
last_leftanklepos var float
last_righthippos var float
last_rightkneepos var float
last_rightanklepos var float
lhspeed var float
lkspeed var float
laspeed var float
rhspeed var float
rkspeed var float
raspeed var float
speed var float
longestmove var float

; variables passed to gethservo
idle var byte
finished var byte
junk var word

movement [rightanklepos,rightkneepos,righthippos,leftanklepos,leftkneepos,lefthippos,speed]
if(speed<>0.0)then
gosub getlongest[lefthippos-last_lefthippos, |
leftkneepos-last_leftkneepos, |
leftanklepos-last_leftanklepos, |
righthippos-last_righthippos, |
rightkneepos-last_rightkneepos, |
rightanklepos-last_rightanklepos],longestmove
speed = ((longestmovestepsperdegree)/(speed/20.0))
gosub getspeed[lefthippos,last_lefthippos,longestmove,speed],lhspeed
gosub getspeed[leftkneepos,last_leftkneepos,longestmove,speed],lkspeed
gosub getspeed[leftanklepos,last_leftanklepos,longestmove,speed],laspeed
gosub getspeed[righthippos,last_righthippos,longestmove,speed],rhspeed
gosub getspeed[rightkneepos,last_rightkneepos,longestmove,speed],rkspeed
gosub getspeed[rightanklepos,last_rightanklepos,longestmove,speed],raspeed
else
lhspeed=0.0;
lkspeed=0.0;
laspeed=0.0;
rhspeed=0.0;
rkspeed=0.0;
raspeed=0.0;
endif
hservo [lefthip\TOINT (-lefthipposstepsperdegree) + aServoOffsets(3)\TOINT lhspeed, |
righthip\TOINT (righthipposstepsperdegree) + aServoOffsets(0)\TOINT rhspeed, |
leftknee\TOINT (-leftkneeposstepsperdegree) + aServoOffsets(4)\TOINT lkspeed, |
rightknee\TOINT (rightkneeposstepsperdegree) + aServoOffsets(1)\TOINT rkspeed, |
leftankle\TOINT (-leftankleposstepsperdegree) + aServoOffsets(5)\TOINT laspeed, |
rightankle\TOINT (rightanklepos*stepsperdegree) + aServoOffsets(2)\TOINT raspeed]
;hservowait [lefthip,righthip,leftknee,rightknee,leftankle,rightankle]

; Simple loop to check the status of all of servos.  This loop will
; terminate when all of the servos say that they are idle.  I.E.
; they reached their new destination.   
do 
	finished = hservoidle(lefthip) and hservoidle(righthip) and hservoidle(leftknee) and hservoidle(rightknee) 	and hservoidle (leftankle) and hservoidle(rightankle)
	
	; ??? - we say not to edit, yet???
	;add sensor handling code here
	;adin 0,ir
	;if (ir > 210) then 
	;  detect = true
	;endif	
	
while (NOT finished)

last_lefthippos = lefthippos
last_leftkneepos = leftkneepos
last_leftanklepos = leftanklepos
last_righthippos = righthippos
last_rightkneepos = rightkneepos
last_rightanklepos = rightanklepos
return

one var float
two var float
three var float
four var float
five var float
six var float
getlongest[one,two,three,four,five,six]
if(one<0.0)then
one=-1.0one
endif
if(two<0.0)then
two=-1.0two
endif
if(three<0.0)then
three=-1.0three
endif
if(four<0.0)then
four=-1.0four
endif
if(five<0.0)then
five=-1.0five
endif
if(six<0.0)then
six=-1.0six
endif
if(one<two)then
one=two
endif
if(one<three)then
one=three
endif
if(one<four)then
one=four
endif
if(one<five)then
one=five
endif
if(one<six)then
one=six
endif
return one

newpos var float
oldpos var float
longest var float
maxval var float
getspeed[newpos,oldpos,longest,maxval]
if(newpos>oldpos)then
return ((newpos-oldpos)/longest)*maxval
endif
return ((oldpos-newpos)/longest)*maxval

;==============================================================================
; Subroutine: ReadServoOffsets
; Will read in the zero points that wer last saved for the different servos
; that are part of this robot.
;
;==============================================================================
pT var pointer ; try using a pointer variable
cSOffsets var byte ; number of
bCSIn var byte
bCSCalc var byte ; calculated checksum
b var byte ;
i var byte

ReadServoOffsets:
readdm 0, [cSOffsets, bCSIn]
;serout s_out, i9600, “RSO: cnt:”, dec cSOffsets, " CS in:", hex bcsIn];

if (cSOffsets > 0) and (cSOffsets <= NUMSERVOS) then 		; offset data is bad so go to error location

	; OK now lets read in the array of data
	readdm 2, [str aServoOffsets\csOffsets*2]
	
	;... calculate checksum...
	bCSCalc = 0

	for i = 0 to NUMSERVOS-1
		bCSCalc = AServoOffsets(i).lowbyte + AServoOffsets(i).highbyte

; serout s_out, i9600, " “, sdec aServoOffsets(i),”:", hex aServoOffsets(i)]
next

; serout s_out, i9600, " CS Calc:", hex bCSCalc]

	if bCSCalc <> bCSIn then 
		aServoOffsets = rep 0\NUMSERVOS
	endif
endif

; serout s_out, i9600, [13]
return[/code]

kurte · July 21, 2011, 1:54pm

OK, this looks like some of the standard brat code that you simply loop calling the move function something like 18 times with command = 1.

If it is not walking straight but instead turning, it may be that servo zero points is not correct and you need to rerun the program and make sure. Or maybe the servos are not all acting the same and you may need to tweak the numbers for what angles of the servos needs to make it walk straight. That is if you look in the Move: function at where it tests for command=1 and gosubs to movement 4 times. You will see that it is passing angles for the servos, like the first one: (7, -20, -20, 7, 20, 20). Which goes for Ankle, knee, hip… So you might try changing one of these angles, like shorten one of the hips from 20 to 19 or lengthen it to 21… And see if you find a combination that makes your brat walk straight.

Kurt

sn96 · July 21, 2011, 6:55pm

Got a youtube video of it walking? This can help us understand what might be going on.

robotdude · July 21, 2011, 6:58pm

The way I read it, he said it’s taking forward steps and then taking a turning step. So we are not looking at a minor adjustment of the step positions. He said that he modified the original code. I do not know if the code he posted is the stock program or his modified program. But after reading it again I can see how it could be read either way. Yes, video would be a big help.

akdabaous · July 22, 2011, 2:12pm

I changed the angles slightly as advised and it is now walking straight. Thank you everyone for your help, I really appreciate it a lot. :mrgreen: