4/15/2017 10:46 PM  
Joined: 6/29/2012 Last visit: 11/28/2021 Posts: 843 Rating: (7) 
I have a system with Simotion D fw 4.4 where a slave axis is cammed to a master axis. Thanks 
4/18/2017 11:09 AM  
Joined: 10/11/2006 Last visit: 11/24/2021 Posts: 5005 Rating: (651)

Hello, please see page 238. https://support.industry.siemens.com/cs/ww/en/view/109744610 Continuity at boundary points When assigning parameters to a cam object, you can make three different settings in the interpolation tab. These settings specify how the runtime system should handle discontinuity at the boundaries of the cam. The appearance of the cam in SIMOTION SCOUT may be different from when it is used later in the runtime system. ● Noncyclic: Not constant at the boundary points The runtime system uses the cam as specified, including all discontinuities at the boundaries, even if it is applied cyclically. However, the acceleration limits and moment inertia of the mechanical system / drive are the governing factors. ● Cyclic absolute: Positioncontinuous in the boundary points The runtime system converts the cam in such a way that is positioncontinuous and velocitycontinuous at the boundaries during cyclic operation, which can cause changes to occur in the characteristic. ● Cyclic relative: Constant velocity in the boundary points The runtime system calculates the cam in such a way that is has constant velocity at the boundaries during cyclic operation  within mathematical limits, which can cause changes to occur in the characteristic. or page 32: Loading a new camming A new cam is loaded by a recalling an _enableCamming command. Using the synchronizingMode parameter, the synchronization criterion is specified (e.g. at the end of the current camming with AT_THE_END_OF_CAM_CYCLE). If the transition from the old cam to the new cam is already smooth, the synchronization parameters should be selected in such a way that either the synchronization length is very small for master value reference or the dynamics are very high for the forward time reference or, alternatively, use the synchronization profile with backward time reference. 
With best regards, 

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4/18/2017 6:33 PM  
Joined: 6/29/2012 Last visit: 11/28/2021 Posts: 843 Rating: (7) 
Thanks already for the answer, but I have no problems at the boundaries of the cams. 
5/4/2017 12:28 AM  
Joined: 6/29/2012 Last visit: 11/28/2021 Posts: 843 Rating: (7) 
No suggestions so far? 
12/21/2017 9:20 AM  
Joined: 6/29/2012 Last visit: 11/28/2021 Posts: 843 Rating: (7) 
Nobody has experiences, or advices with this way of creating cams in runtime? Thanks. 
1/2/2018 6:11 PM  
Posts: 125 Rating: (11) 
a 5th order polynomial generally will not be achievable with the constraints you want to place (an acceleration limit and a distance limit). The distance delta along with start and end acceleration of 0 is actually defining the max velocity and max acceleration. Literally by definition. as inside that calculation there is an Amax := , and Vmax := What happens then for any arbitrary solution would be a piecewise combination of segments, very likely with some pretty wild oscillations in velocity and acceleration and direction reversals, and/or nonzero start and end accelerations. So with that also undesirable, it's actually a very nontrivial problem to solve. As I interpret, the constraint is actually: use the distance with start and end A=0, but increase the distance such that peak acceleration and velocity are limited, but at the same time don't go over a maximum distance and no direction reversals. A 5th order polynomial, by itself, will very often have "no solution" to this desire. Some math (beyond my ability at the moment) would at least help with getting better guesses to the limit function. Plugging in startA=0, endA=0, acceleration limits and velocity limits, and then coming up with the best guess or minimum distance delta. 
1/3/2018 10:40 AM  
Joined: 6/29/2012 Last visit: 11/28/2021 Posts: 843 Rating: (7) 
Let us say that there is no restriction for master distance. Of course you give in a master start point (or end point) but the total master distance is not free to be calculated by the function. 
1/3/2018 11:20 PM  
Posts: 125 Rating: (11) 
DavidBrown: Interpreting what you typed as 'what about if distance no longer matters', then at that point program it to do a _setCammingOffset or _setGearingOffset with the dynamic response parameters in which you define the peak velocity and acceleration constraints and let Simotion handle it. Yes Simotion may whine in its usual way with an alarm about velocity or acceleration being limited, but regardless it will do it. This is opposed to coming up with a supposedly perfect cam to do the offset motion, but suddenly the masteraxis speeds up a little and your slaveaxis goes out of bounds in accel or velocity anyway. Is it possible to determine a travel distance (the unknown value) knowing what all the acceleration and velocity limits are, master staying at constant velocity, and knowing what your initial speed is? Yes. Some search terms are: scurve motion profile equation scurve trajectory calculation But it becomes very difficult very quickly to get any usable answer. 
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