Why does stepper motor stall

Thread: stepper motor stall? Page 1 of 2 1 2 Last Jump to page:. Thread Tools Show Printable Version. Pretty sure you will have the motor tuning set wrong. First off the settings are not in cm but mm and motor tuning is set in steps per mm. To work out your Steps per millimeter take the Micro stepping value set on the drives and divide by the ball screw pitch. If you have any ratio applied you'll need to take this into account.

So lets say you have drives set at Ms and 4mm pitch screw with ratio. The affective pitch will now be 2mm for one revolution of motor. If your just using the parallel port then you could be limited by the Kernal speed depeding on drive settings, pitch etc. Works out like this. Mechanical: Decouple the motor from the screw.

Can you still stall the motor with the hand-wheel? With the system powered i. Then repeat with the axis stalled. From everything you've said you've not indicated lost-steps or loss of direction control - so the BoB sounds okay, as does the integrity of the wiring from the stepper driver to the motor.

Can you describe how you've wired the stepper which colour wires go where. Can you post the specification of the PSU? Can you post the type of stepper drivers that you have? Similar Threads Stepper motor I. Paul- It is not uncommon to use a voltage times higher than the voltage required to produce the current limit.

This is done to beat the "inductance limit". If you have an 8 lead motor and are driving it with a bipolar driver I think you are , then the best configuration is with the coils in parallel. I would also recommend reading the FAQ's on the Geckodrive site. Good information. Your step motor is in mid-band resonance. Mid-band resonance is suppressed with 2nd-order damping rate damping. Electronic damping does the same thing without degrading performance.

Technical stuff: For those who are interested, step motors are mass-spring systems so they have a 90 degree phase relationship between force and velocity. The motor drive is a current source at low speeds that has a 0 degree phase lag.

This makes the loop phase lag 90 degrees and the motor is stable. As speed increases, the drive must revert to a voltage source as inductive reactance and not the drive set current begins to limit current. A voltage source introduces another 90 degrees of phase lag for a total of degrees.

A degree phase lag and a gain above unity defines an oscillator and that is exactly what the motor does. It takes about 1 to 10 seconds to build to this amplitude and the motor makes a growling or warbling sound prior to stalling.

Even if the motor doesn't stall, this oscillation robs the motor of useful torque because it takes energy to resonate the motor. This oscillation is suppressed by adding a phase-lead derivative component term to the loop. Mariss, great to know you're still lurking here -- it's not often we have luminaries like yourself contributing here. I'd say more like a dim-bulb.

I always lurk here because it's a very informative and entertaining website. The word "loop" is used somewhat loosely here, referring to the motor's interaction with power supply voltage. Electronic viscous damping senses the rate of motor load change from the current sense resistors in the drive. The signal is amplified and filtered to separate noise motor step pulse rate from the load rate of change signal.

The clean signal then goes to phase modulator that advances or retards the step pulse timing in the drive. Other effective electronic methods modulates the supply voltage to the drive or using a passive solution, insert a reactance in series with the supply voltage. I prefer the small-signal solution. Last edited by Mariss ; , PM. Microstepping sine-cosine currents can't make mid-band resonance go away. Microstepping does make low-speed resonances go away.

Mid-band resonance begins where the speed-torque curve changes from constant torque to inverse torque with speed. That marks the location where the drive changes from a current source to a voltage source, typically at 4 to 16 revs per second depending on supply voltage and motor inductance.

Step motors also exhibit resonances below 2 revs per second and microstepping eliminates them. Low speed resonance is fundamentally different from mid-band resonance. There are normally 2 to 3 harmonically related resonance speeds like 66, and full-steps per second. They are caused by the overshoot-undershoot "ringing" behavior of a mass-spring system the step motor when it is moving incrementally.

Stepping the motor at it's ringing frequency pumps this resonance; a full-step or half-step drive can pump the motor into violent vibration, shuddering or even running backwards. I get erratic behavior, but no humming just before it stalls. If so, I am going to be satisfied at this point, at least for now, as it seems that I would need extra expense in either a mechanical damper or a different drive circuit.

Thanks Mariss! Connect and share knowledge within a single location that is structured and easy to search. I am trying to run a robot with two wheels using two identical stepper motors and step drives. The problem I am running into is that while one side works perfectly or at least without any noticeable issues , the other side starts stalling after running for a while usually around the step mark. I am using an Arduino Uno to send the step and direction signal using the Stepper library, and the drivers are powered by a 24 V battery.

The resistor on the drive is appropriate for the current required by the motor. I have tried everything I can think of to pinpoint the problem, but I ran out of ideas. I have swapped the drivers and the pin connections. I have also used another motor in place of the stalling one, and it still runs into the same problem. It does not make sense for one of the identical sides to be running fine and the other side having issues. Ok, first of all there is no such thing as identical anything.

Each motor will have it's own set of torque and friction and inductance characteristics. Further, whatever you are driving on each side will also differ in terms of the load applied to the motor. Further still, with open loop systems, two motors can actually interfere with each other mechanically. You could try switching motors from either side and see if the problem follows the motor, i. If it's the latter then I would be investigating what is different about the loads on that side.

However, in general, driving stepper motors without commutational feedback is actually a rather unreliable thing to attempt especially at any considerable speed.

The phase angle at which you step the motors is crucial to dictating whether your motor will accelerate, run, or just stall. This is problematic is a fixed load scenario, and is critical in a variable load application.. The image above shows you how the shaft torque varies depending on it's position relative to the selected phase coil.

As you can see the torque is sinusoidal and zero when the shaft and selected coil are aligned. When driving a stepper motor you want to maintain the torque somewhere in the peak section.

For maximum acceleration you want to switch phases when the shaft reaches half a step away from the selected phase position. At that point, then next phase will be 1. If you switch phases too early you will actually apply negative torque which of course slows the motor and everything gets out of phase, the torque becomes directionally random, and the shaft will stall and just sit there screaming at you.

In order to get steppers to work reliably, you either use a phase stepping time profile which is calculated based on the measured acceleration profile of the system, or you use positional feedback generated by an encoder which has the same, or multiple, pulses per rev as the stepper motor has steps. The acceleration profile method tends to be more problematic since you have to figure out a profile for the best AND worst case loads and those loads need to be relatively constant.

Often best and worst case are so different that a common step profile is impossible to obtain. The encoder method is much more reliable but does of course add extra complexity and cost to the system. Encoders can vary in cost depending on your requirements, especially if they need to be hermetically sealed.