Usecase

MCD has built-in cylinder  functionality. However, the configuration requires indepth knowledge and is prone to interrupting the simulation when not configured  properly.

Often only the basic behavior of a pneumatic cylinder is needed but not the specific details regarding presure or flowrate. Therefore a simplified method for simulation cylinders is used.

Features

• Simulate pneumatic/hydraulic cylinder
• move cylinder to given endpoints by toggling one variable (valve)
• specify endpoint
• limit force

Implementation

The cylinder simulation is based on a PositionControl and an Expression Block Template. Expression Blocks are simmilar to SignalAdapters. It comprises Inputs, Outputs, Parameters, States and Expressions. Simple logic can be used to control its signals. The use of an Expression Block Template enables creating reusable functionality.

Logic:

valve is on ? set PositionControl to max : set PositionControl to min

SlidingJoint at min ? set sensorMin true

SlidingJoint at max ? set sensorMax true

Usage

1. Define a PositionControl to be used as cylinder.
2. OpenExpressionBlockTemplate.xmlviaExpression Block->Load from Template File
3. Connect the Signal Inputs:currentPosition to the PositionControls SlidingJoint and select Parameter Name position
4. Connect the Signal Outputs:positionSetpoint to the PositionControl and select Parameter Name position
   
5. Set the desired cylinder travel in Inputs:min/max
6. Use a SignalAdapter to connect to the Expression Block. 
   1. on: valve on/off
   2. atMin: sensor for min limit
   3. atMax: sensor for max limit

Example