[sudo-discuss] wheelchair motor controller
Robert Benson
sf99er at gmail.com
Thu Jul 16 13:55:08 PDT 2015
i've increased the ohm values as follows:
brake = 150 ohms = 24volts/150ohms=.16ampsX24volts=3.84watts
motor = 515 ohms = 24volts/515ohms=.04ampsX24volts=1.11watts
i'm now using larger cylindrical ceramic resistors w/higher watt ratings
resistors are now staying cool
concerned power to motor (1.11watts) is low & will not raise 150-200lbs
screen
to control the controller with arduino, seems i must bypass the joystick
connector
where d manual?
thanks captain jake for teaching me about resistance - i finally have an
idea on what they do :)
On Thu, Jul 16, 2015 at 9:04 AM, Robert Benson <sf99er at gmail.com> wrote:
> aha. thank you for the invaluable lesson on resistance.
> the relationship between volt/ohm=amp has escaped me until not.
> in ohm's law: v=i*r, the i often confuses me.
>
> maybe only one controller per motor will be suitable but ultimately we
> will want to drive it with dmx(arduino), me thinks
>
> oh, the brake's 100ohm(5w) resistor got hot fast when the wheel started
> spinning. the motor's resistor did not.
>
> On Thu, Jul 16, 2015 at 1:51 AM, Jake <jake at spaz.org> wrote:
>
>> if you put a 1 ohm resistance, you will just blow up the resistor.
>>
>> 24 volts divided by 1 ohm = 24 amps
>> 24 volts times 24 amps = 576 watts
>>
>> you need to find the highest number of ohms that will still cause the
>> motor controller to not give you an error. Lets say you find that a 100
>> ohm resistor (in place of the missing motor) causes the controller to be
>> OK. When you move the joystick, and it tries to turn the fake motor, it
>> will give it up to 24volts. But it's a 100 ohm resistor.
>>
>> 24v / 100 ohm = 0.24 amps
>> 24v * 0.25 amps = 5.76 watts
>>
>> if it works with a 100 ohm, you should use that. 5.76 watts is
>> reasonable. 576 watts is most of a horsepower and is not reasonable.
>> 5
>> in case you're not confused i'll tell you this: the power a motor
>> consumes (from a fixed voltage source for example) depends on the amount of
>> force it's putting out.
>>
>> So if you have a motor just spinning a wheel in the air it doesn't take
>> as much power as if you're making it grind grain, or push a fat person up a
>> steep incline. The ohms you measure when you use a multimeter on the
>> stopped motor correspond to its MAXIMUM power, basically.
>>
>> so if you stopped the motor and applied 24v, 576 watts would flow through
>> it and heat it up pretty fast. But if you let it spin freely in the air,
>> its effective impedance would be much higher than 1 ohm!
>>
>> as for how to isolate the motors for different jobs.. we can read the
>> manual on the control box and adjust the settings, or just hook up the
>> computer control and let it do all the work. I don't know though.
>>
>> -jake
>>
>>
>> On Thu, 16 Jul 2015, Robert Benson wrote:
>>
>> i'm such an idiot. when i checked the motor resistance, i checked the
>>> controller's motor circuit resistance. the actual motor resistance is 1 ohm.
>>>
>>> however, even idiots get lucky...the motor worked with 100ohm. having
>>> realized the above, i will not power it again until i find a 1ohm resistor.
>>>
>>> for the record, moving the joystick in any direction moves the wheel in
>>> some way. so how do we isolate the motors for different jobs?
>>>
>>> On Thu, Jul 16, 2015 at 12:49 AM, Jake <jake at spaz.org> wrote:
>>> what do you mean both motors
>>>
>>> you only have one motor last i checked.
>>>
>>> On Thu, 16 Jul 2015, Robert Benson wrote:
>>>
>>> my ohmmeter had a "k" in front of the ohm symbol when it
>>> read 150 k ; not a M or just the ohm symbol.
>>>
>>> datasheet i posted earlier seemed to suggest the motor is
>>> 120V while the brake solenoid is 24V
>>>
>>> both motors read 150kiloohm :/
>>>
>>> On Wed, Jul 15, 2015 at 11:45 PM, Robert Benson <
>>> sf99er at gmail.com> wrote:
>>> gonna have to have a high wattage rating, huh?
>>>
>>> On Wed, Jul 15, 2015 at 11:41 PM, Robert Benson <
>>> sf99er at gmail.com> wrote:
>>> 150k says the motor
>>>
>>>
>>> on hunt for same
>>>
>>> On Wed, Jul 15, 2015 at 11:30 PM, Jake <jake at spaz.org>
>>> wrote:
>>> a wire jumper is approximately zero ohms, which will
>>> destroy stuff when power flows through it.
>>>
>>> the motor controller is complaining because it sees
>>> infinity ohms across the missing motor's terminals. So just like the
>>> brake, the
>>> solution is to put a resistor across the missing
>>> motor's terminals.
>>>
>>> if we want more than one motor, we can just put the
>>> other motor on the missing connector and use the one controller to control
>>> both
>>> motors.
>>>
>>> if we need more than two motors, we can use relays or
>>> switches with the same controller, or we could get more controllers. But
>>> lets
>>> start
>>> with one or two motors.
>>>
>>> -jake
>>>
>>> On Wed, 15 Jul 2015, Robert Benson wrote:
>>>
>>> agreed
>>>
>>> i was thinking that since controller still said
>>> check right motor connector after i crossed the brake terminals w/resistor
>>> that
>>> i needed to jump it. when i jumped
>>> them the check right motor code went out which
>>> seemed to indicate the error was corrected. luckily i had to hold the jump
>>> wire &
>>> resistors against the contacts so i
>>> noticed the heat immediately after touching the
>>> joystick and cut the power. check right brake code has returned as before.
>>>
>>> maybe building a 120vac/24vdc controller would
>>> be better...we probably want four or more of these puppies for the lighting
>>> trusses
>>>
>>> On Wed, Jul 15, 2015 at 11:00 PM, Jake <
>>> jake at spaz.org> wrote:
>>> you should not short out stuff with even a
>>> thin wire.
>>>
>>> you are going to destroy the motor
>>> controller if you continue on this path
>>>
>>> what are you thinking? do not short out
>>> the motor terminals.
>>>
>>> On Wed, 15 Jul 2015, Robert Benson wrote:
>>>
>>> connected a thin wire across motor
>>> side of connector (while 110ohm across brake side) and got movement but
>>> wire got
>>> real hot...too scared
>>> i'll damage the controller
>>> right now to try a bigger gauge
>>>
>>> On Wed, Jul 15, 2015 at 10:26 PM,
>>> Robert Benson <sf99er at gmail.com> wrote:
>>> connected 110ohm across brake
>>> terminals but no worky
>>>
>>> On Wed, Jul 15, 2015 at 9:44 PM,
>>> Jake <jake at spaz.org> wrote:
>>> should be fine
>>>
>>> On Wed, 15 Jul 2015, Robert
>>> Benson wrote:
>>>
>>> might have to upgrade
>>> the roomba motor & controller to hit mice
>>>
>>> will 150ohms be too
>>> much/work/hurt anything? i found a 100ohm 5w & 50ohm ?w i plan on running
>>> in series
>>> if i dont find a more
>>> suitable value
>>>
>>>
>>> On Wed, Jul 15, 2015 at
>>> 8:21 PM, Patrik D'haeseleer <patrikd at gmail.com> wrote:
>>>
>>> On Jul 15, 2015
>>> 6:05 PM, "Jake" <jake at spaz.org> wrote:
>>>
>>>
>>> if you want
>>> to play with robots i have plenty, like roombas which won't break
>>> your legs
>>> running you over.
>>>
>>>
>>> Roomba + tazer = no more
>>> mouse problems!
>>>
>>> Patrik
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sudoroom.org/pipermail/sudo-discuss/attachments/20150716/a8b7465a/attachment.html>
More information about the sudo-discuss
mailing list