OpenSML
Open Sources SoftMotion Light For CiA402 Servo Drivers
Tips:
Library file should worked on CODESYS and TwinCAT3, Quadratic velocity ramp calc we used S7RTT Library.
There is suggest to read keba servoone usermanual to get more information about cia402.
Also i suggest that use Absolute Encoder, You don’t need do reference travel at every start.
And if you have any questions please feel free to push your issues.
Why
Codesys is the best PLC programming platform. With the Raspberry Pi, you can get an advanced plc programming environment at a very low price. However, the softmotion license was canceled in the latest version of codesys for raspberry pi. (> 3.5.14.40, which means Raspberry Pi 4 must pay to get a softmotion license)
The motion control used by most customers is very simple and does not involve interpolation motion.
This project aims to provide the open source cia402 motion library for codesys or twincat users.
Target
In theory, an interpolation procedure can be made, similar to CNC. I am still working hard for this, but time is not guaranteed.
How
I only use ST (Struct text language) programming and add as many comments as possible.
Example for MC_Power:
Power_X(Axis:=Axis_X,xEnable:=Enable);
Example for Home And Absolute Position Move:
CASE iState OF
0:
Power_X(Axis:=Axis_X,xEnable:=xStart);
IF Power_X.xDone THEN
iState:=10;
END_IF;
10:
Home_X(Axis:=Axis_X , xEnable:=xHomeEnable);
IF Home_X.xDone THEN
iState:=20;
END_IF
20:
ProfilePosition_X(
Axis:=Axis_X ,
xEnable:=xMoveEnable ,
xExecute:=xMoveExecute ,
xContinueMove:=FALSE ,
xRelativeMode:=FALSE ,
diTargetPosition:=diTarget ,
udiProfileVelocity:=udiVel);
END_CASE
Example for Cyclic Synchronous Position Mode:
Power_X(Axis:=Axis_X,xEnable:=Enable);
SyncPosition_X(
Axis:=Axis_X ,
MaxVelocity:=2000 ,
MaxAcceleration:=20000 ,
MaxJerk:=200000 ,
CycleTime:=0.001 ,
TargetPosition:=rTarget ,
xEnable:=TRUE ,
lrScale:=1.0 ,
xSimulation:=TRUE,
xError=> );
TODO
| FuncBlock |
Status |
Name |
| Struct |
:white_check_mark: |
OpenSML_Axis |
| Power |
:white_check_mark: |
OpenSML_Power |
| Reset |
:white_check_mark: |
(use OpenSML_Power) |
| Home |
:white_check_mark: |
OpenSML_Home |
| Halt |
:white_check_mark: |
OpenSML_Stop |
| MoveAbsolute |
:white_check_mark: |
OpenSML_ProfilePosition |
| MoveVelocity |
:white_check_mark: |
OpenSML_ProfileVelocity |
| MoveRelative |
:white_check_mark: |
OpenSML_ProfilePosition |
| Stop |
:white_check_mark: |
OpenSML_Stop |
| Jog |
:construction: |
- |
| TouchProbe |
:construction: |
- |
| Cyclic Synchronous Velocity Mode |
:white_check_mark: |
OpenSML_SyncVelocity |
| Cyclic Synchronous Position Mode |
:white_check_mark: |
OpenSML_SyncPosition |
Velocity Ramp
Quadratic velocity ramp calculate is very difficulty. Its simple when calc a curve, but its complexable when break a move without speed jitter.
I had create a 6th velocity ramp base g2 at https://github.com/feecat/OpenSML/issues/4#issuecomment-1146995447 , But it cannot break a move. This is unacceptable for most applications.
Struckig and Ruckig is a good choose, We had use it in v2.x. However, It have some problem when calc. So in V3.x we changed to S7RTT planner.
At this trace,
POU.otg.CurrentPosition from struckig.POU.Axis1.fSetPosition from SM3_Basic.POU.csp.otg.CurrentPosition from OpenSML_SyncPosition.
They overlap perfectly, diff < 1e-5.
Overflow
PDO use DINT as TargetPosition, Range is -2147483648 ~ 2147483647. It could overflow. For Example:
A Servo Driver use 24bit encoder, its 16777216 pulse/rev(16#1000000). Normally Driver parameter will to be divided by 16(16#10), So its 1048576 pulse/rev(16#100000) for EtherCAT PDO(TargetPosition). If we use pitch=5mm ball screw, its 209715.2 pulse/mm.
So, if we dont want overflow, The position range is -10240 ~ 10239mm.
Overflow will automatic sum at some servo driver. so driver can accept overflow. But, if overflow happend, and OpenSML_SyncPosition FunctionBlock xEnable drop down, we cannot know how many overflow happend. When xEnable up, Actual position not equal OpenSML_SyncPosition feedback. It could make some exception move.
If you need a large move range, make sure not overflow. Also, Some servo driver cannot accept overflow.
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