In order to fully understand the dynamic behavior of the vehicle, accurate experimental data of the tire-road contact forces and moments are needed. INSIA Dynamometric wheels measure these forces and moments by mounting in a very special way a set of strain gauges on the vehicle’s wheels. The strain gauges are grouped in at least three concentric circumferences and in equidistant radial lines. The strain signals of the same circumference are linearly combined to obtain at least two new signals that only depend on the contact forces and moments. The influence of the angle rotated by the wheel, the temperature or the centrifugal forces is eliminated in these new signals by using a technique based on the elimination of Fourier harmonics.  

The contact forces and moments are obtained from these new signals by solving two systems of linear equations with three unknowns each. An onboard electronic system including telemetry is being developed in the University of La Coruña.

“Now, it is possible to use dynamometric wheels in Research Centres and Universities, and for other applications that used to be economically unfeasible” 

• Universities/Research Centers: Universities and research centers can use dynamometric wheels to model vehicles and tires. The objective of tire modeling is to find mathematical expressions related to the forces and torques appearing in the tire-road contact with different variables. In order to verify the quality of these formulated mathematical models and verify whether they adjust to reality or not, obtaining experimentally the contact forces and moments becomes necessary.
• Tire and automotive component manufacturers: Tire manufacturers need to compare the forces generated and transmitted by different tire models to determine the best alternative for a certain application. In addition, the design and validation of automobile components requires a detailed knowledge of the forces and the moments acting on the tire-road contact, which allows vehicle designers to produce safer and more reliable, efficient, and durable components.  
• Automobile companies: The performance of the active safety systems of the vehicle, such as ABS and ESP, can be significantly improved if more detailed information in real time of the forces applied to the tire-road contact could be obtained. This information, which can be used to determine possible dangerous situations, can be obtained by using dynamometric wheels. Therefore, safer vehicles that include dynamometric wheels can be produced. 

• If the automotive industry were a country, it would be the world’s sixth largest economy [OICA, 2005]:
• No. of manufactured vehicles in a year: 66 million.
• Turnover: 2,000 billion euros.
• R&D investment: 85 billion euros.
• More than the 80% of the vehicles include sensors. 60-70 individual sensors can be found in a single vehicle [Bosch, 2009].
• The potential of using dynamometric wheels as an information source for ABS and ESP is very high:
• Only Bosch produces 65,000 units of ABS daily [Fedit, 2010].
• All vehicles  produced in the UE since 2011 must have ESP.

• Commercial dynamometric wheels have different inertial properties than the original wheels of the vehicle, and can therefore alter their dynamic behavior.  INSIA dynamometric wheels are produced by directly instrumenting the vehicle’s wheels, so its dynamic behavior remains unaltered.
• Commercial dynamometric wheels have a very high cost, much higher than the price of the whole vehicle (approximately 100,000 Euros for cars and 200,000 Euros for trucks) and are prohibitive for most potential customers such as universities and small research centers. The estimated cost to produce these INSIA dynamometric wheels is approximately of 2,000 Euros, which makes affordable to  run a car with four dynamometric wheels.
• Errors below 2% have been obtained in the static experimental tests.

“INSIA dynamometric wheels can be used to produce safer and more reliable, efficient and durable vehicles”