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 [DPRG] DC motor requirements?? Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] Previous message: [DPRG] DC motor requirements?? Next message: [DPRG] help needed Subject: [DPRG] DC motor requirements?? From: DeltaGraph at aol.com DeltaGraph at aol.com Date: Sat Jul 16 09:43:59 CDT 2005 ```Re: Balancing Robot Motor Requirements I am not going to give you a real answer, but maybe this will give you some ideas for doing research... My mechanical engineering skills are sketchy at best. A few years ago I dug out my physics and dynamics texts and wrote a simulation program (probably full of flaws) then later built a balancing robot almost as good as nbot. For your consideration would be the moment of inertia of the wheels and the inertial properties of the robot body which I recall modeling as two point masses. One mass fixed at the axis of rotation (which I believe I included the mass of the wheels) and another at center of mass of the robot body. I considered inertial properties of the wheels separately To simplify the problem start by fixing the wheels to the ground where they cannot roll. Your problem is now a torque problem except your as your robot center of mass starts rotating it now has inertial kinetic energy which will require motor torque to restore so you now have a nice dynamics problem deciding how fast you will recover from the "fall" from balance. It gets a bit trickier when you let go of the wheels. Now the wheels tend to accelerate when you apply torque which causes a combination of things to happen: 1) Energy is stored in the wheels (rotational moment of inertia -- correct term?) and 2) as the wheels move the base of the robot moves which creates forces acting along a line of action to the body center of mass. I hope this makes some sense. A ball and stick model of the robot might help. Keep in mind. You can make almost anything balance, but how well will be determined by several factors, so I say: Robot Mass Location of Mass from Rotational Axis Wheel Moment of Inertia Wheel Torque Wheel Max Speed Control Algorithm Speed of Control Loop Tilt Sensor Accuracy Rotational Velocity Sensor Accuracy Wheel Encoder Accuracy Your Patients - Ron Grant -------------- next part -------------- An HTML attachment was scrubbed... URL: http://list.dprg.org/pipermail/dprglist/attachments/20050716/a34e4471/attachment.html ``` Previous message: [DPRG] DC motor requirements?? Next message: [DPRG] help needed Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the DPRG mailing list