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Application of OpenModelica 1.12.0 for the Simulation of Mobile Machinery
Linköping, 05/02/2018
OpenModelicaWorkshop 2018
Volker Waurich
Endowed Chair of Construction Machines
Outline
1. automation of a wheel loader
2. pile model
3. virtual sensors
4. operator control
5. wrap-up
Linköping 05/02/2018 Simulation of Mobile Machinery slide 2
outline
AUTOMATION OF A WHEEL LOADER
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wheel loader operation
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automation of a wheel loader
• effective earth-moving dependsstrongly on operator skill level
• potencial for energy saving, increase in productivity, costreduction
• cutting and filling the bucket iscrucial
automation of a bucket filling
process
considerations
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automation of a wheel loader
F
α
bucket trajectory tire slip and wear performance
hardware setup
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automation of a wheel loader
CAN BCAN C
CAN D
CAN A
DAQ
ECU VKM
ECU HM
ECU FA
ECU MS
ECU AH
lidar process controladditional equipment
simulation setup
Linköping 05/02/2018 Simulation of Mobile Machinery slide 7
automation of a wheel loader
wheel loadermechanics and hydraulics
analyticalpile model
virtual 3D environment
process control
PILE MODEL
Linköping 05/02/2018 Simulation of Mobile Machinery slide 8
analytical pile model
• 2D-model in the centre plane of bucket
• analytical computation of component forces
• F_cut = f(cutting depth);
Linköping 05/02/2018 Simulation of Mobile Machinery slide 9
pile model
F_load
F_cut
F_downhill
F_friction
F_bottom
bucket
pose
cutting
depth,
intersection
area
forces,
loaded
mass,
contour
persistent contour
• pile surface must be persistent between loading cycles
• segmentation of surface
• enter segment: compute cutting depth
• leave segment: move contour, add load
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pile model
pileHeight[i] := min(pileHeight[i],bucket.z);
not in continuous models (online minimum problem)
persistent contour
• discrete behaviour with sampled time or state events is not efficient
• realtime criteria
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pile model
intersec = getExtIntersection(pile, bucket.x, bucket.z, time);
external C-model
VIRTUAL SENSORS
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3D-perception by distance measurement
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virtual sensors
Lidar: TOF-measurements oflaser beam
detection of angle of reposeand distance to pile Velodyne VLP-16
3D-lidar in unity
Linköping 05/02/2018 Simulation of Mobile Machinery slide 14
virtual sensors
• comprehensive 3D world in unity
• virtual lidar using raycast() - bunch
• Velodyne VLP16 style UDP package
3D-environments in Modelica?
• coupling of unity with Modelica model
• model sends pose of sensor mounting
• sensor pose moves lidar gameObject
• lidar gameObject sends distance data
Linköping 05/02/2018 Simulation of Mobile Machinery slide 15
virtual sensors
OPERATOR CONTROL
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operator model
• to accomplish driving tasks, working cycles
• emulate real operator
• algorithm for automated functions
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operator control
task,
perceptionoperator
model
actuator
signals
operator model
• modelling approach: discrete state machine
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operator control
operator control
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operator control
• target speed of cylinders , target wheel drive
WRAP-UP
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summary
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wrap-up
• OpenModelica is feasible to model mobile machinery (i.e. 3D mechanics, hydraulics, control)
• Modelica lacks comprehensive 3D-modelling and interaction
• tool-coupling to 3D-simulation software is a straightforwardpossibility to interact with 3D-worlds
OpenModelica achievements
• improvements with external C (Windows) enhance system simulations with hardware, networks and virtual
sensors
• important library improvements with OM 1.12.: OpenHydraulics and M_DD
hydraulic drive simulation and external tool coupling
• synchronous and state-machines operator control and process logic modelling
• 3D visualization
Linköping 05/02/2018 Simulation of Mobile Machinery slide 22
wrap-up
outlook
• better 3D modelling in OM (live 3D models?)
• closer interaction with 3D-tools
• wheel-ground models
• multiple, persistent soil interaction
• collision detection
• hardware-in-the-loop (realtime!)
• ECU-coupling
• HMI-App design
• IoT interfaces (MQTT)
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wrap-up
IMU via CAN in OMEdit
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Thank you for your attention.
Thank you OM-developers for your support.
Volker [email protected]
