DC Motor control using PWM


Thread Starter

Andrew Douglas

I have decided to used inclinometers and linear actuators as my input and output devices. I have built one circuit which uses comparators to determine the direction of the drive to the actuators and PWM (using a 555 timer) to vary the speed around the level position. My problem is the PWM circuit requires potentiometers to vary the Mark to space ratio. I was wondering if there is a any way to vary the speed using PWM by the changing voltage input from my Inclinometers. The inclinometers produce a signal ranging from 0V to 12V. Ideally I would like a high mark space ratio at both 0 and 12V getting lesser as it tends to 6V (the equalibrium position as it were.) Any help would be gratefully appreciated. So too would be relevant web sites or literature. Thanks Andrew Douglas

Kipton Moravec

Being a microcontroller fan, I would recommend using a microcontroller to read the data and produce an output. You don't have to worry about linearieties and the algorithm can be anything you want. A number of microcontrollers have PWM as an output, and also have analog inputs so there is very little "extra" hardware required. Also many microcontrollers have free or nearly free software tools. Signal processors as a general rule have more expensive tools. Kip [email protected]
This problem is the "inverse pendulum " I have seen web sites or may be in Mathcad. Let us know if you don't find answer.

Alastair Fordyce

Why bother? Use a gimbled table (see any nautical supplies digest). An excellent use of pure mechanics and gravity that is hard to beat, needs no batteries and has a pretty good IP rating when someone knocks over their coffee/ beer/ beverage of choice.
The art of using the motion controller is yep my choice of weapon a PLC-3AM control chip fired up to say a 8xc196kd procesor using floating magnetic compass ball with inner ball on I/O pic reading motion paths/ I did something like this to keep a chair in an learjet facing east constantly. customer was of a religious sort. A cheap way would be use a 4 way joy stick control like for rc toys hang it like a weighted pendulum upside down run I/O to controller allowing the use of signal return servo motors to position table. But sorry to say I'm with the gent and the marine gimble cup holder. If you be drinking on my boat you would be on the rear deck begging to '"RALPHFFF" the sea god for mercy. AK Halibut luv big chunks. luke