Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: adil.eshack on March 13, 2008, 01:36:57 PM

Title: HELP NEEDED IN MY ROBOTICS PROJECT (updated) plz read
Post by: adil.eshack on March 13, 2008, 01:36:57 PM
Myself Adil from Kerala,Indial.Final year mechanical engineering student. Myself and 4 others have ventured to do a robotics project

The concept is simple fix a wireless camera to the robot which gives a live feed to a java program and to control the robot movement using the keyboard.

We intend to make a robot around 760mm high and 40cm in dia.Its in the form of a cylinder.It weighs around 4.5 kg. its a three wheeled robot wid seperate drives to the back two wheels and a free to rotate front wheel.Rotation of robot is controlled by rotating the back two wheels at different speeds.the wheel layout is like that of a triangle..

THE PROBLEM : could u please suggest what type of motor to use. We used small DC motors in our small projects. But given its weight wat motor i should use. Also please suggest a way in which i can connect the motor to the wheels so that load is less on motor shaft.

LATEST UPDATE ON MY ROBOT (22.03.2008) : input from a few pundits here helped me narrow down on a stepper motor of a holding torque of around .36 kgm. i will be using two of it.. one for each back wheel. what ur opinion about it?? got two back wheels of 4inch diameter. but the back wheels i got have a larger diameter hole at centre then the motor shaft.. i want to connect the motor shaft directly to wheel.. please suggest a method for that.. all help will be truly appreciated...
Post by: AndrewM on March 13, 2008, 01:49:30 PM
Take a look here:

While you don't have to, you should use a gearbox (or gearhead motor) for your drive wheels which will keep the load off the motor shaft (and also has nice benefits of increased torque, etc)
Post by: bulkhead on March 22, 2008, 01:25:53 AM
40mm = 1.57 inches, is pretty small for fitting a motor.  Your best option for finding a motor would probably be a "right angle drive" type gearmotor.  Still, it seems to me that turning the robot will be an issue.  Having two drive wheels spaced only 4cm apart, attempting to rotate the robot of length 76cm (30 in) seems like it would require too much torque, and the wheels would not have sufficient traction.  Most robots that use this "differential drive" type steering don't have a wheel-wheel distance vs length of robot ratio under roughly 1/2 but 4/76 is...a lot more.

I actually know of any gearmotors that are that small.  Also, will the 2 motors have to be side by side?  That would require each to be less than 0.8 inch in diameter.  6.6 lbs is also a lot for such small motors.  Could you describe what terrain this robot will be in?  Perhaps it would be easier to rethink the robot's method of locomotion rather than searching for motors that would fit these needs.