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[elnino]

Hi all, I know this seems to be an infrequently visited part of the forum but i'm hoping that someone here can offer some real information. I have searched this forum and all over the internet but i can not seem to find a good solution to my problem.

Basically, I have designed/made a wheel with an optical encoder as the sensor that is also hooked to a large DC motor (from an electric scooter) and i hope to use it for a simulated force feedback (not actual, more like 'dynamic force')

The Optical encoder and joystick interface is working fine. I am using an Arduino Nano to read the encoder and generate a PWM signal for the motor output. It also sends data to a 'Teensy' (Somewhat of another type of arduino) in joystick mode.

The joystick part of it is all working fine, as is a 31khz PWM signal ready for driving a H Bridge. I made a H bridge which works acceptable at lower PWM frequencies but then it is Audible/vibrates. However, if i bump up the frequency, the force is pretty much 0 until it gets to about 80-90% duty cycle.

The H Bridge i made is based on a HIP4081 H Bridge driver and 4 X STP80NF55 FETS (55v, 80A). Design comes from Nuts and volts - www.parallax.com/dl/docs/cols/nv/vol2/col/nv52.pdf and this is the last piece of the puzzle and I don't know if i am better off buying some sort of motor driver or whether some tweaks to the existing H Bridge is all that is needed.

Some on here have talked about 'AMC for $30 on ebay' but i don't know what they are and if i am better off trying to use one of them instead of the DIY H Bridge.

What are those of you with HAPP wheels using to drive the motor???

[Mizoo]

Hi,

I am using an AMC to drive my Happ wheel motor, controlled by a home made force feedback board (http://www.racedepartment.com/forum/thr ... ler.37051/).

The force feedback data returned by the games is a torque value, so when you drive a PM DC motor you have to control the current passing through the windings, via a current sensor.

Are you sure that your driver/transistors work with such frequency/current (oscilloscope traces ?) ?

And to avoid too high current ripple (and torque ripple) the PWM frequency of your H Bridge have to match the time constant of your motor.

Finding a suitable FFB motor is really not easy (cogging torque, stall torque/current, speed, cost, ...).