Sets and gets the duration for ramping up to the peak acceleration, specified in seconds.
profile_object.AccelRamp =<new_value>
-or-
...profile_object.AccelRamp
Prerequisites
Takes effect when the profile_object is passed as a parameter to a Move Class method and the specified motion segment is generated.
Parameters
None
Remarks
When generating a motion segment, the AccelRamp property specifies how long, in seconds, its takes for the Accel to achieve its specified value. Likewise, this time is also used for ramping the Accel down to zero. If the AccelRamp time is set to zero, at the start of a motion, the Accel command instantaneously jumps up to its specified value and then, at the end of acceleration period, instantaneously drops down to zero. A zero AccelRamp time corresponds to a square wave acceleration curve and commands an infinite jerk, i.e. rate of change of the acceleration. A non-zero AccelRamp time produces a trapezoidal acceleration curve, which is often referred to as an s-curve profile.
S-curve acceleration and deceleration profiles limit the impact of starting and stopping motions and help to reduce the excitation of resonances (or ringing) in the robot structure. An s-curve profile can often reduce the settling time at the end of the motion since each axes more smoothly glides into its final position with less oscillations. On the other hand, an s-curve profile will lengthen the planned duration of a motion since the average acceleration and deceleration will be less than a square wave profile. So, while most robots will benefit from s-curve profiles, for low accelerations or for very stiff robots, a square wave acceleration profile may be more beneficial.
The actual acceleration ramp time for a given motion may be different than the AccelRamp value for a number of reasons: if the motion is short, there may not be sufficient time to ramp all of the way up to the Accel value; or the AccelRamp value may be automatically scaled by with the Accel value if the Parameter Database “Couple %accel/%decel to %speed” parameter is set. The Parameter DB value is a convenience feature that automatically scales the specified AccelRamp and Accel values with the Speed so that slow motions have gentler accelerations with shorter ramp times and fast motions accelerate more quickly but have longer ramp times.
When a New Profile is created, its properties are automatically set to the default values specified in the controller’s Configuration Database. Therefore, the AccelRamp parameter only needs to be set if you wish to deviate from the default value.
Examples
Dim prof1 As New Profile ' Create new profile set to default values
prof1.Accel = 50 ' Only accelerate at 50% of nominal rate
prof1.AccelRamp = 0.1 ' Take 0.1 sec to achieve 50% nominal accel
Move.Loc (loc1, prof1) ' Perform motion to previously defined
' location, loc1 with performance “prof1”
See Also
Profile Class | profile_object.Accel | profile_object.Decel | profile_object.DecelRamp