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accurate on spot breaking

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mokvlcc

New Member
hi guys,
i am making an autonomous robot that should stop at exact positions.....i hv avoided the problem of 90 degree turns by using four roller wheels in perpendicular directions(along the sides of the square robot)
nw my question is...
what's the best method for accurate breaking???
i hv noticed tht there are different types of roller or omni directional wheels...which one is better??(three rollers,four rollers...or more)

is it ok to use four different motors or is it better to use two motors with two shafts???

i need the motors to move in two opposite directions what is the best way to accomplish that???
is it better to use a DC motor or a stepper motor???
are there any other types of motors tht u recommend??
my personal idea at the moment is to use four DC motors and the three rollers omni-directional wheel....and alternating the direction through inverting the input to the motor......n still haven't figured out a way for one spot breaking
 

Krumlink

New Member
Drive both sides of the H bridge Low OR high to stop it immedately.

You should probably stick to regular robot drive wheels and have encoders on them for accurate movements.
 

Krumlink

New Member
Use a DC motor for ease of interface, or a stepper motor for very precise motions (harder interface). Use a motor per wheel.
 

duffy

Well-Known Member
Drive both sides of the H bridge Low OR high to stop it immedately.
DON'T DO THIS!!!! This will short out the power supply and blow out drive transistors! Turn on both the high side drivers or both the low side drivers to brake. Never, ever, turn on all four drivers of an H bridge at the same time.
 

3v0

Coop Build Coordinator
Forum Supporter
You need to read Krumlinks post again.
Drive both sides of the H bridge Low ****OR**** high to stop it immedately.
stars mine


DON'T DO THIS!!!! This will short out the power supply and blow out drive transistors! Turn on both the high side drivers or both the low side drivers to brake. Never, ever, turn on all four drivers of an H bridge at the same time.
 

Krumlink

New Member
DON'T DO THIS!!!! This will short out the power supply and blow out drive transistors! Turn on both the high side drivers or both the low side drivers to brake. Never, ever, turn on all four drivers of an H bridge at the same time.
how is that different then what I said?
 
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mokvlcc

New Member
dn't worry guys i got ur point however u wrote it..........thanx alot for ur replies.....i greatly appreciate them
 

duffy

Well-Known Member
I'm sorry, Krumlink, I thought you were suggesting turning on both sides at once.
 

Krumlink

New Member
I'm sorry, Krumlink, I thought you were suggesting turning on both sides at once.


Turning on all one side would kill it. Turning on the same pair (T1, T4) (T2, T3) will electrically brake the motor, hence high braking (T1, T4) turns both sides of the motor High. Low braking (T2, T3) turns both sides low.
 
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