Hi! For a robot I am building for school, we have two stepper motors spit between a 6v power supply. I built it with accuracy in mind, but the steppers are way to slow, going at 20 rpm. Is there any way I can increase the speed on the steppers without sacrificing accuracy or increasing voltage(6v is the max power we can have)? The Robot’s pretty light, so high torque isn't necessary.
To render any opinion, I would need to know more about the stepper motor in question. Can you post a data sheet or other documentation of the specifications?
Also the same sort of data for the stepper motor driver and the stepper power supply.
If you have the ubiquitous 28byj motor then it will be difficult to get more speed. 20RPM on the output shaft is pretty fast considering the gear reduction.
Higher speed requires higher voltage, but with limited current. All that is handled in a dedicated stepper motor driver module.
Yes I am using those motors, hold on Ill post the circuit diagram. Are there any steppers I could replace it with that have a lower gear reduction
To answer that question intelligently we need more information. Please answer the following questions the best you can.
What sort of speed are you looking for? Do you have a number (RPM or steps / second)?
Do you need gear reduction? One reason for gear reduction is to increase torque. How much torque is needed? Again, a number, please.
Is size a criterion? Do the steppers need to be the same physical size? Look at the standard NEMA stepper motor sizes.
Pololu has a great selection of stepper motors. Those motors are bipolar motors and the maximum speed of the motor is determined, mainly, by the supply voltage.
Once a motor is chosen a compatible driver needs to be selected. Pololu is a good source for stepper drivers, too.
Probably the most available motor is the NEMA17 motor. Those are used in 3D printers. They are usually 200 steps /revolution (versus the 28byj at 2048 steps / rev). Now NEMA17 only means the physical size of the motor, you still need to find the motor that will provide adequate torque.
We can help to select a suitable driver once you have selected a motor. The ULN2003 is not useful for a bipolar motor.
Brushed DC motors are better for small robots. They are easier to control, are much more energy efficient than steppers and are available with a wide range of gearboxes.
The easiest way to get started on a small robot is to buy a basic kit with chassis, wheels and motors. This is a randomly chosen example from many that are available: https://www.amazon.com/DFRobot-Pirate-Arduino-Mobile-Platform/dp/B009646R3K
Adafruit has (or had) the same motor with 512step/rev.
Not clear why they could only run it at 20RPM.
I had trouble running common 28BYJ-48 motors faster than about 15RPM.
Maybe you already have the 1/16 version.
Leo..
I suggest you use nema08 or 17 size steppers and for the low voltage you have the drv8834 microstepping drivers.
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