Optimize Stepper Motors With Microstepping

Microstepping increases the accuracy, torque, energy efficiency, and smoothness of applications while at the same time reducing step loss, vibrations, and noise. With up to 256 microsteps per full step, Trinamic transforms digital information into perfect physical motion.

Microstepping

More and more devices require the utmost precision and smooth movement. Thanks to Trinamic's microstepping, stepper motor drives can be controlled with a sinusoidal current waveform by dividing full steps into smaller microsteps. The resulting current control scheme reduces noise and vibrations while increasing the accessible torque and precision. 


Stepper motors are open-loop, cheap, easy to use, and durable motors. They offer several advantages over other electric motors: they have high torque at low speeds and standstill; their speed is easy to control via input pulses; their marginal positioning error is non-cumulative; they have an excellent response to start/stop. This makes stepper motors the obvious choice when precise and reliable positioning is needed. By sending an electrical current through the motor coils, an electromagnetic field is created which forces the magnetic rotor into the desired position. This can be done in full steps, half steps, or smaller microsteps using additional current states.

Microstepping increases the accuracy, torque, energy efficiency, and smoothness of applications while at the same time reducing step loss, vibrations, and noise. This has to do with the mechanical characteristics of a stepper motor: A stepper motor is similar to a mass-spring system. When moving from one position to another, the rotor doesn't immediately find the right position. Instead, it will overshoot and oscillate around the target position until it reached it. And just like with a mass-spring system, the larger the difference from one position to the next, the larger the oscillation.

Microstepping aims to drive motors with a current waveform that's sinusoidal. This means the stator coils are not powered with either full or zero current but with intermediate current levels approximating a complete sine wave shape over 4 full steps. This positions the permanent magnet rotor in intermediate positions in between two subsequent full steps. It even allows for special custom current waveforms adapted to the stepper motor's physics or application. The maximum microstep resolution is defined by the driver electronic's A/D and D/A capabilities. When adapted to a hybrid stepper motor, Trinamic's 256x microstepping provides 51,200 microsteps per full 360º revolutions. That's an accuracy of up to 0.00703125º per full revolution.

Oscilloscope shot of fullstepping
Oscilloscope shot of microstepping

 

 

Microstep Interpolator

Microstepping is a standard feature for Trinamic products and the motion controllers integrated into Trinamic's cDriver products as well as Trinamic's motion control ICs offer the 256 microstep resolution. For many other manufacturers developing components for stepper drives, however, 256x microstepping is beyond their capability. To accommodate easy integration into motion and motor control systems that don't already offer such high step resolution, Trinamic created MicroPlyer™. By interpolating time in-between step pulses, MicroPlyer turns lower step resolutions into microsteps. Reducing the need to change your complete system, the microstep interpolator ensures industry-leading stepper motor control for your application.