Creation of Digital Twin for a Feller Buncher Denis Kartachov, Professor Inna Sharf McGill Aerospace Mechatronics Lab, Department of Mechanical Engineering, McGill University – Montreal, QC, Canada INTRODUCTION • 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) OBJECTIVES • Develop model of a feller buncher in the Vortex Studio physics engine • Integrate into the model a virtual forest with realistic terrain properties RESULTS 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 FUTURE WORK • 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 ሶ 1 = 1 ℎ 1 sin 1 + 1 ሶ 1 ሶ 2 =− 2 ℎ 2 sin 2 2 ሶ 2 ሶ 3 = 3 ℎ 3 sin 180° − − 3 3 ሶ 3 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. REFERENCES Zhu, 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 Effector World Position (m) End Effector Absolute Velocity (m/s) Part Mass (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 Udayalakshmi Vepakomma 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-Axis Y-Axis Z-Axis } Ground