Creation of Digital Twin for a Feller Buncher

Denis Kartachov, Professor Inna SharfMcGill Aerospace Mechatronics Lab, Department of Mechanical Engineering, McGill University – Montreal, QC, Canada

I N T R O D U C T I O N

• Timber harvesting is an important business in many

countries worldwide including Canada

• Variety of machinery used such as feller bunchers,

forwarders, and skidders which all rely on operator

judgement and control to function

• Difficulties in finding operators due to roughness of

work conditions and high training costs

• Lack of automation in industry is a potential for human

error, safety hazards and suboptimal efficiency

PHONE

(SLIDESHOW)

O B J E C T I V E S

• Develop model of a feller buncher in the Vortex Studio

physics engine

• Integrate into the model a virtual forest with realistic

terrain properties

R E S U LT S

Motivation

• Creation of digital twin allows for analysis of the

operation of the machine without needing to operate a

real one

• Control strategies can be integrated directly into the

model

• Model can be used as a test bed for dynamic stability

and motion planning algorithms

3D MODEL

Created a 3D model of the machine based on a real

Tigercat L855E feller buncher

• Used Solidworks to accurately trace out the shapes of

each part (cabin, end effector, etc.)

• Added materials and textures for aesthetic purposes in

Blender

F U T U R E W O R K

• Incorporate a real forest into model from data set

containing information on a natural forest in

Petawawa, Ontario

• Implement realistic tree models using the method of

solids of revolution and theory on moments of inertia

• Integrate dynamic stability and motion planning

algorithms into virtual machine

VIRTUAL MACHINE

Developed virtual machine in the Vortex physics engine

• Configured inertial properties of machine parts (mass,

center of mass, inertia matrix)

• Implemented realistic track system, hydrostatic

transmission and hydraulics system

• Derived and implemented arm inverse kinematics for

velocity based control of end effector using joystick

ሶ𝑝1 =𝑑1ℎ1 sin 𝜃1 + 𝛼

𝑝1ሶ𝜃1 ሶ𝑝2 = −

𝑑2ℎ2 sin 𝜃2𝑝2

ሶ𝜃2 ሶ𝑝3 =𝑑3ℎ3 sin 180° − 𝛽 − 𝜃3

𝑝3ሶ𝜃3

Fig. 1: L855E Tigercat feller buncher in operation

Fig. 2: Slideshow of L855E Tigercat feller buncher model

Fig. 3: Arm inverse kinematics diagram

I would like to express my sincere gratitude to Professor Inna Sharf for her guidance throughout the project, for inviting to the NCRN AGM & Trials 2019 and for giving me the opportunity to interact with many students and experts in the engineering disciplines.

REFERENCESZhu, M. (1994). Master-slave force-reflecting resolved motion control of hydraulic mobile machines (Doctoral dissertation, University of British Columbia).Lynch, T. B. (2012). On Moments of Inertia for Logs and Tree Segments. Forest Science, 58(4), 399-404.

Fig. 4: Real-time tracking of end effector (a) position and (b) velocity in world inertial frame

Simulation Time (s)

(a)

(b)

End E

ffecto

r W

orl

d P

ositio

n (

m)

End E

ffecto

r Absolu

te V

elo

city (

m/s

)

PartMass (kg)

Joint-to-Joint Length(mm)

Cabin 5000 -

Boom 2000 3268

Stick 1000 3279

End Effector

2600 -

Table 1: Machine parameters

Many thanks to Francis Charette and UdayalakshmiVepakomma at FPInnovations for their invaluable partnership and help in the forestry projects. I would also like to thank Marek Teichmann and Andreas Enzenhofer at CMLabs for their readily available support with the Vortex Studio software.

ACKNOWLEDGEMENTS

Eq. 1: Boom piston velocity as a function of boom angle

Eq. 2: Stick piston velocity as a function of stick angle

Eq. 3: End effector piston velocity as a function of end effector angle

X-AxisY-AxisZ-Axis

}Ground