Elimination of unintended velocity reversals in s-curve velocity profiles

A system that prevents velocity reversal associated with a motion profile, comprising:

• a load;
• a motion controller that receives at least one of a position, a velocity, an acceleration and a jerk from a user to generate a motion profile to control the motion of the load;
• a drive that receives commands from the motion controller and generates the current required to turn the motor;
• a motor that turns electrical energy received from the drive into mechanical energy and produces torque to move the load to a desired position;
• a critical jerk calculator that calculates a critical jerk value necessary to avoid velocity reversal associated with the motion profile;
• and
• a motion planner that determines which control values to output to the drive based at least in part upon user entered parameters and/or information received from the critical jerk calculator to prevent velocity reversal with the motion profile.

A method for computing a maximum deceleration jerk value for an s-curve motion profile to prevent velocity reversal, comprising:

• setting values for a start speed, a start acceleration, a programmed deceleration jerk limit, a programmed acceleration jerk limit, a programmed deceleration limit, a programmed acceleration limit and a programmed speed limit;
• calculating a product of the start speed value and the start acceleration value;
• determining whether the product of start speed and start acceleration is greater than zero;
• setting the critical jerk value equal to zero if the product is greater than zero;
• setting the critical jerk value equal to the square of the start acceleration divided by the absolute value of the start speed and divided by two if the product is not greater than zero;
• comparing the critical jerk value to the programmed deceleration jerk limit;
• setting the computed maximum deceleration jerk value equal to the critical jerk value if the programmed deceleration jerk limit is less than the critical jerk value;
• and
• setting the computed maximum deceleration jerk value equal to the programmed deceleration jerk if the programmed deceleration jerk limit is greater than the critical jerk value.