Cycle Time Independent Profiles
Regular Profiles
The regular profile types in WMX3 are divided into segments, with each segment being a multiple of the cycle time. For example, the Trapezoidal profile type has three segments - the acceleration segment, the constant velocity segment, and deceleration segment.
By rounding each segment to a multiple of the cycle time, the generated profile will have a completely symmetric acceleration curve and a completely symmetric deceleration curve. In addition, if the specified acceleration and deceleration are equal, the velocity curve during acceleration will be symmetric with the velocity curve during deceleration.
However, this can cause extra pulses that might require the velocity to be reduced from the specified value (see Velocity Adjustment from Extra Pulses), and can also reduce the acceleration and deceleration from the specified values. These effects are especially pronounced when the profile completes in a small number of cycles, and/or the cycle time is large. In effect, the profile shape is affected by the cycle time.
Cycle Time Independent Profiles
The cycle time independent profiles do not round each segment to a multiple of the cycle time, and the generated profile shape is the same regardless of the cycle time (although the profile shape is the same for all cycle times, the command that is sent to the servo will be more granular and smoother with a shorter cycle time). The velocity, acceleration, and deceleration will not be reduced from the specified values.
However, the acceleration and deceleration segments may not be completely symmetric in the first and last cycles of acceleration/deceleration. For example, it is possible for the acceleration segment to be 1 cycle shorter or longer than the deceleration segment, even if the specified acceleration and deceleration are the same. Or the jerk might be much smaller in the last cycle of the acceleration or deceleration segment.
In addition, because the segments are not rounded to a multiple of the cycle time, the end velocity will be between 0 and the specified end velocity. Cycle time independent profiles cannot be used for applications that require the end velocity to be exactly the specified value.
Choosing a Profile Type
The benefits and drawbacks of regular profiles and cycle time independent profiles should be considered to select a profile that is suitable for the application. Applications with motion commands that take a very short time to complete, applications with long cycle times, or applications for which the velocity, acceleration, and deceleration should not be modified from the specified values may benefit from using the cycle time independent profiles.
The following table lists each regular profile type and the equivalent cycle time independent profile type.
Regular Profile |
Cycle Time Independent Profile |
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