need help for selection of motor
syaira
Posts: 1
im doing my final year project ,Car For Disabled.The concept is that a new steering system(like motorcycle pedal)will be attached to the old steering system so that both normal and disabled people·can use the car.The·problem is the range of rotation of the normal steering wheel is btwn 0-720 degrees while the new steering system(motorcycle pedal) is btwn·0-90 degrees only.So to synchronize the motion i need to use the motor with a controller.The problem now is i dun really sure wht time of motor and controller is appropriate to control the angle of the motion.can anyone plz help me?
Comments
Think of it this way. For 0-90 deg on the pedal, the wheel needs to turn 0 -720 degrees. So, there is about 8:1 relationship between the two.
To determine when the wheel has gotten to the target position, you'll need feedback in the form of a potentiometer or encoder. The Stamp could be setup to read the pedal position (again with a pot), calculate how far the wheel has to be turned, then watch the steering wheel feedback until it gets there.
As for motors, etc, that will depend on your budget. You might be able to adapt a windshield wiper motor, a power window motor from a junkyard. Or, you may go to an industrial supply company and purchase a gearmotor for the project. For a controller, a packaged H-bridge like the Parallax HB-25 should work well.
Steering a vehicle this way can be very tiring for the driver because the foot must hold the pedal close to the "halfway" position for long periods of time. A pedal with springs to hold it near center can help. Also a "trim" adjustment might be useful. Give yourself lots of time to play with pedal deadband and response time to get acceptable performance. As time permits, you can also explore PID control which will allow the system to differentiate between small, slow changes and fast, large changes of pedal postion.
··· You might even adjust the response according to vehicle speed so the vehicle will be less twitchy at higher speed.
Good luck.
Cheers,
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Tom Sisk
http://www.siskconsult.com
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