Automotive Engineering Laboratory

<<Professor>>  Junya Yamakawa

Junya Yamakawa

Name: 
Junya Yamakawa
Title: 
Professor 
Laboratory: 
Automotive Engineering Laboratory 
E-mail: 
Junya Yamakawa
Website: 
Current Teaching: 

Vehicle Dynamics, Physics I, Machine Design and Drawing I, Introduction to Mechanical Engineering, Mechanical Engineering Experiments, Off-Road Vehicle Engineering II

Research Interests: 

Interaction problem between soil and vehicles, Traveling performance of off-road vehicles

Current Research: 

The effect of cyclic steering on dry sand
Tire model for traveling on dry sand
Development of numerical analysis method on interaction problem between soil and vehicles
The method of driving force allocation for vehicles with independent wheel drive

Future Research: 

Analysis method for moving wheel and soil deformation
Measurement of stress distribution on wheel surface contacting on soil

Keywords: 

Off-Road Vehicle, Terrain, Finite Element Method

Topics: 

・The effect of cyclic steering on dry sand
Vehicles traveling on sandy ground are exposed to risk of standstill. Drivers living in desert area experimentally know that a driving technique with continuous right-and-left cyclic steering is effective to reduce the risk. However, the mechanism of this effect has not been studied. In order to investigate the effect of cyclic steering on sand, wheel sinkage and travel distance of small size single wheel were measured under constant wheel velocity with sinusoidally-varied steering. The experiment showed that the cyclic steering reduces the wheel sinkage and extends the travel distance.
・Development of tire model for traveling on dry sand
In order to develop a tire model for vehicles traveling on dry sand, longitudinal and lateral forces acting on a small model tire with sideslip angle due to the interaction with dry sand were measured under controlled sinkage and constant slip ratio. Based on the experimental data, a tire model was expressed as simple functions of slip ratio, sideslip angle and sinkage to compute the longitudinal and lateral forces of the tire traveling on dry sand with sideslip angle.
・Mobility of wheels in low gravity environment
What characteristics should vehicles possess if they are sent to the Moon, whose gravitation is only 1/6 of that on the Earth? It is known that the Moon surface is covered with loose regolith and displays low stiffness. This condition is disadvantageous for the propulsion of a vehicle. However, the weight of the rover becomes 1/6 of that on the Earth. Does this mean that if the vehicle which can run on reproduced Moon surface on the Earth is sent to the Moon, it can be expected to run without problems? In order to find out the mobility performance of wheeled vehicle, model wheel tests on dry sand were conducted under low gravity conditions in an aircraft with parabolic flight. The experiment showed that traveling performance becomes low for less gravity conditions.

Publications: 

1. Steering and Driving Systems and Turning Characteristics of Multiaxle Vehicles (Transactions of the Japan Society of Mechanical Engineers, C, 70, 694, 2004)
2. Traveling Characteristics of Electric Multi-axle Vehicles
(Effect of Wheel Speed and Torque Commands on a Model Vehicle)
(Transactions of the Japan Society of Mechanical Engineers, C, 72, 723, 2006)
3. A Method of Driving Force Allocation to Reduce Slip Loss
for Multi-Wheel Vehicles with Independent Wheel Drive
(Formulation and Numerical Simulation)
(Transactions of the Japan Society of Mechanical Engineers, C, 73, 729, 2007)
4. A Method of Torque Control for Independent Wheel Drive Vehicles on Rough Terrain (Journal of Terramechanics, 44-5, 2007)
5. Investigation of Optimal Steering for Multi-Wheel Vehicles on Steady Turn (Transactions of Society of Automotive Engineers of Japan, 39, 1, 2008)
6. Optimal Driving Force Distribution and Steering Angles of
Multi-Wheeled Vehicles on Steady Turn
(Validation by Model Vehicle Experiments)
(Transactions of the Japan Society of Mechanical Engineers, C, 74, 740, 2008)

Education: 

The National Defense Academy (Mechanical Engineering)
University of California at San Diego, Master's Degree Program (Mechanical Engineering)
University of California at San Diego, Doctoral Degree Program (Mechanical Engineering)

Doctorate: 
Ph.D. 
Experience:

Associate Professor, 2003-2010
Professor, 2010-

Membership: 

The Japan Society of Mechanical Engineers, The International Society for Terrain-Vehicle Systems, The Japan Society for Terramechanics, Society of Automotive Engineers of Japan, The American Society of Mechanical Engineers

Awards: 

Best Session Paper Award (The International Society for Terrain-Vehicle Systems, ISTVS, 1999)
Best Conference Paper Award (ISTVS, 2002)
Best Session Paper Award (ISTVS, 2004)
Soehne-Hata-Jurecka Award (ISTVS, 2005)
Best Session Paper Award (ISTVS, 2005)
Poster Session 2nd Place (ISTVS, 2007)
Best Session Paper Award (ISTVS, 2010)
The Yamazaki Prize (Scholarship and Education Foundation of Defense Academy, 2011)