Author Topic: braking system suggestions  (Read 2224 times)

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Offline LeftRiteTopic starter

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braking system suggestions
« on: March 29, 2015, 03:32:01 PM »
I am designing a robot that will carry a large load with the combined weight of around 144lbs. It will have to travel at around 17mph. My plan is to use brushed scooter motors on two wheels because of  price and availability.  I have considered large brushless rc motors, but I understand that they are more sensitive to stall loads.

This brings me to my question: I need this to robot to stop quickly and stay for up to 2 min. I'm not sure how fast motors can stop that much weight. My thought was it needed to have fast acting brakes.

 I wondered if anyone had any suggestions for implementing a fast motor/brakes combination.

Thanks
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Offline mklrobo

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Re: braking system suggestions
« Reply #1 on: March 29, 2015, 06:11:39 PM »
 :) Hello!
I would offer my opinion....
In stopping, there are techniques, such as
motor plugging. This reverses polarity(momentarily), which
causes the motor to stop immediately. This is used in industrial
purposes. This method may not be the best for your purposes.
electric clutches are an option. Or, a combination of electric clutches
and brakes.(The motors are detached from the load when braking
is engauged). You may want to consider the center of gravity for the robot,
because, if the robot is top heavy, the robot may topple over is stopped
immediately. Good luck!!!  ;D ;D ;D 
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Offline Schlayer

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Re: braking system suggestions
« Reply #2 on: April 09, 2015, 07:11:19 AM »
Since scooter motors are sometimes used on Ebikes, you may want to look into something like the compressing brakes on bicycle tires. Its very like how brake disks function on a car and require a simple linear actuation force to trigger, plus those are meant to handle the weight of a person, similar to the weight of your load. You could definitely also look into electronic braking mechanisms such as what mklrobo suggested, or a combination of those. I know that braking systems are often built into RC car transmitters which send power in quick pulses to the motor in the reverse direction (to stop it while it's moving forward) creating the effect of an anti-lock braking system and bringing the vehicle to a halt without simply stalling out the motor entirely. Whether this is safer/better for the motors themselves than the method mklrobo mentioned, I'm unsure.
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