The velocity of a standard DC-motor is controlled by applied voltage. In contrast stepper and BLDC motor current needs to be controlled for different motor windings.
Ramping is the stage where velocity is continuously increasing or decreasing. The complexity of ramp generation depends on the application. Simple applications use a linear or trapezoidal ramping. They form polynomial functions of the first degree. Necessary parameters include starting velocity, acceleration rate, and maximum velocity. The velocity starts at a certain value and increases constantly until its target value. Acceleration (first derivative of velocity) is discontinuous at both the start and when reaching the maximum velocity, leading to some jerking in the motion.
Trinamic motion controllers with linear ramping allow for fast and accurate positioning of one or several axes and offload time-consuming real-time tasks from MCUs.
The introduction of additional acceleration segments attenuates the disadvantages of trapezoidal ramping. Trinamic’s advanced sixPoint™ ramping profile allows for faster positioning by adding a freely configurable start/stop frequency to linear motion profiles. In addition, sixPoint™ ramping adds a reduced acceleration value at high velocity to reduce jerking at the end of standard acceleration ramps.
S-shaped ramp profiles are based on polynomial functions of the second degree. The acceleration is always continuous and therefore jerk-limited. Seven ramp segments form the S-shaped ramp, which can be optimally adapted to suit user requirements. High torque with high velocities can be reached by calibrating the bows of the ramp.