Sets and gets the duration for ramping up to the peak deceleration, specified in seconds.
profile_object.DecelRamp =<new_value>
-or-
...profile_object.DecelRamp
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 DecelRamp property specifies how long, in seconds, its takes for the Decel to achieve its specified value. Likewise, this time is also used for ramping the Decel down to zero. If the DecelRamp time is set to zero, at the start of the motion deceleration period, the Decel command instantaneously jumps up to its specified value and then, at the end of the motion, instantaneously drops down to zero. A zero DecelRamp time corresponds to a square wave deceleration curve and commands an infinite jerk, i.e. rate of change of the deceleration. A non-zero DecelRamp time produces a trapezoidal deceleration 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 decelerations or for very stiff robots, a square wave deceleration profile may be more beneficial.
The actual deceleration ramp time for a given motion may be different than the DecelRamp 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 Decel value; or the DecelRamp value may be automatically scaled by with the Decel 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 DecelRamp and Decel values with the Speed so that slow motions have gentler decelerations with shorter ramp times and fast motions decelerate 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 DecelRamp 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.Decel = 25 ' Only decelerate at 25% of nominal rate
prof1.DecelRamp = 0.1 ' Take 0.1 sec to achieve 50% nominal decel
Move.Loc (loc1, prof1) ' Perform motion to previously defined
' location, loc1 with performance “prof1”
See Also
Profile Class | profile_object.Accel | profile_object.AccelRamp| profile_object.Decel