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is there a way of modding it so it can be geared,but according to you which is the best choice(regardless of anything)
by the way can increasing the weight of the tires or bodies increase torque.
BTW: is this true:velocity=2*pi*r*rpmtorque=d*ff=m*aa=change in velocity/time
[...] i have the mass of robot and rpm of motor.Can i be able to calculate the torque?
so if i calculate a using anything even a ticker timer
Hi,It depends on the size of the robot. Do you have a photo? Are you going to use gears with the motor's output shaft to increasing torque?On ebay you will find many inexpensive motors with gears :http://www.ebay.co.uk/sch/i.html?_nkw=gear+motor+kg&_sacat=0&_odkw=gear+motor&_osacat=0&_from=R40and BTW I would guess the top motor is the best. The ones at the bottom, as far as I know have very low torque.
Quote from: sohailsameja on March 06, 2013, 10:30:10 AMis there a way of modding it so it can be geared,but according to you which is the best choice(regardless of anything)Gearing is the only way to reduce angular velocity (RPM) and increase torque of the motor. You can buy required ratio gearbox separately and plug to Your motor.Quote from: sohailsameja on March 06, 2013, 10:33:26 AMby the way can increasing the weight of the tires or bodies increase torque.Increasing weight of the robot will increase torque required to move it.Quote from: sohailsameja on March 06, 2013, 10:33:26 AMBTW: is this true:velocity=2*pi*r*rpmtorque=d*ff=m*aa=change in velocity/timeVelocity formula is correct.Torque formula is not, it should be T = F * r (Torque = Force * radius).Force formula is correct.Quote from: sohailsameja on March 06, 2013, 10:33:26 AM[...] i have the mass of robot and rpm of motor.Can i be able to calculate the torque?To calculate required torque You have to know desired acceleration, mass of the robot and wheel radius.Quote from: sohailsameja on March 06, 2013, 10:33:26 AMso if i calculate a using anything even a ticker timerTo get acceleration simply think this way - decide on the max speed You want your robot to go, and then think of how long You wouldn't mind to wait for robot to reach that speed.Example:I want my robot to go at 5km/h (1.39m/s) max and I'm prepared to wait no more than 2.5s for it to reach that speed;a = 1.39m/s / 2.5s = 0.556m/s2;Now, my robot's mass is 1.6kg, so force required to achieve required acceleration is F = 1.6kg * 0.556m/s2 = 0.8896N (Newton);Say my robot has wheels of 2.5cm radius (0.025m), this tells us that motor should output at least T = 0.025m * 0.8896N = 0.02224N*m (Newton meters) of torque, but we don't want motor to run at 100%, so lets do this NewTorque = 0.02224N*m / 0.75 = 0.03N*m;
The easiest way to increase torque is to use a rubber band across the output shaft of the motor (small diameter) and then across a large wheel/cup/plate/disc on your actual wheel shaft. Maybe even directly around the wheels. Getting the rubber band to stay on and not jump off is tricky; you may need to build some rims with glue or epoxy or plastic or something.
Another cheap method to reduce RPM and increase torque:Mount the motor so that it shaft is parallel to the wheel's axle and the motor's shaft contact the outer edge of the wheel. The reduction ratio is the wheel's diameter divider by the motor's shaft diameter. The torque is increase by the inverse of the speed reduction ratio minus some frictional looses.The trickiest part is adjusting the motor shaft pressure on the wheel. Too little and the shaft slips, too much and the motor won't turn.I've built a couple of robots using this method and they did run well. Best was that the cost was very low.