ACCEL program instruction Details If profile 0 is used, a square wave acceleration profile is generated at the beginning and end of the motion. If a profile is specified, that profile is invoked for subsequent robot motions. Defined profiles set the maximum rate of change of the acceleration and deceleration. The values set with this instruction define the maximum acceleration and deceleration magnitudes that are achieved. When the eV+ system is initialized, the profile, acceleration, and deceleration values are set to initial values, which can be defined by the ACE controller configuration tools.
As delivered by Omron Adept, the initially selected profile may be either 0 or 1 depending on the type of robot. The settings are not affected when program execution starts or stops, or when a ZERO command is processed. Normally, the robot manufacturer sets the 100% acceleration and deceleration values to rates that can be achieved with typical payloads and robot link inertias. However, because the actual attainable accelerations vary greatly as a function of the end-effector, payload, and the initial and final locations of a motion, accelerations greater than 100% may be permitted for your robot.
The limits for the maximum values are defined by the robot manufacturer and vary from one type of robot to the next. If you specify a higher acceleration than is permitted, the limit established by the robot manufacturer is utilized. You can use the functions ACCEL(3) and ACCEL(4) to determine the maximum allowable acceleration and deceleration settings. For a given motion, the maximum attainable acceleration may actually be less than what you have requested. This occurs when a profile with a nonzero acceleration ramp time is used and there is insufficient time to ramp up to the maximum acceleration.
That is, for a given jerk, a specific time must elapse before the acceleration can be changed from zero to the specified maximum value. If the maximum acceleration cannot be achieved, the trapezoidal profile is reduced to a triangular shape. This occurs under two circumstances: 1. The motion is too short. In this case, the change in position is achieved before the maximum acceleration can be achieved. 2. The maximum motion speed is too low. In this case, the maximum speed is achieved before the maximum acceleration. In both of these situations, raising the maximum acceleration and deceleration values does not affect the time for the motion. Hint:
If you increase the maximum acceleration and deceleration values but the motion time does not change, try the following: increase the program speed, switch to an acceleration profile that allows faster acceleration ramp times, or switch to acceleration profile 0, which specifies a square-wave acceleration profile. eV+Language Reference Guide, v2.x, 18319-000 Rev A Page 50