The tire–terrain interaction is an essential criterion for assessing tire performance. Understanding the complex characteristics of the dynamic interactions of tires and terrain required a detailed and deep study on the characteristics of the contact patch area of the tire. Most of the studies conducted to determine the properties of the contact patch considered the tire-road interaction in a static condition and there are a limited number of research studies that focused on the dynamic behavior of the tire at the contact area especially when the real-time measurement of the dynamic contact area of the rolling tire with high slip ratio is the matter of interest. In order to completely understand the tire dynamics at the contact patch, a novel optical method based on light refraction and reflection is proposed for the measurement of contact area between the tread of the tire and a rigid transparent surface. To this end, constructing an indoor test rig is required. In this research, a three-dimensional drawing software Autodesk Inventor has been used to analyze a customized testing facility. An indoor test rig has been designed and manufactured to visualize the contact area of a rolling tire. A supporting mechanical system incorporated into this test rig allows providing the tire with variable camber angles and slip ratios. For the rolling tire, a digital camera GoPro has been used under a glass panel to record the tread pattern in detail when the tire passes over it during the test, to represent the footprint for a high slip ratio. From the image obtained with this system, the length, width, ratio, and shape of the patch can be determined, which are related to the effect on tire traction performance. This study specifically proposes a digital image correlation technology that can be used to capture the contact patch of a passenger car tire 205/55R16 and to obtain the geometry features of the contact area. Based on the appropriate image processing techniques in the MATLAB, a precise reconstruction of tire footprint was realized. The results for the footprint properties of the tire with an applied normal load of 4 kN and tire inflation pressures of 21 Psi for free rolling, static state, and the slip ratio of 0%, 2%, 4%, 6%, 8%, 10%, 12%, 15%, 20%, 25%, 30%, and 35% are presented. Presented results in the paper will show that the system is robust enough to obtain a real-time dynamic measurement. The novel method based on digital image processing revealed by the author can be validated as a precision measurement system of footprint characteristics. / Master of Science / The tire–road interaction is an essential criterion for assessing tire performance. Most of the studies conducted to determine the properties of the contact area considered the tire-road interaction in a static condition and there are a limited number of research studies that focused on the dynamic behavior of the tire at the contact area. Thus, a novel optical method based on light refraction and reflection is proposed for the measurement of contact area between the tread of the tire and a rigid transparent surface. To this end, constructing an indoor test rig is required. In this research, a three-dimensional drawing software has been used to analyze a customized testing facility. An indoor test rig has been designed and manufactured to visualize the contact area of a rolling tire. A digital camera has been used under a glass panel to record the tire footprint in detail during the test. The length, width, ratio, and shape of the tire footprint can be determined, which are related to the effect on tire traction performance. Based on the appropriate image processing techniques in the MATLAB, a precise reconstruction of tire footprint was realized. The results for the footprint properties of the tire with an applied normal load of 4 kN and tire inflation pressures of 21 Psi for free rolling, static state, and the different slip ratios are presented. Presented results in the paper will show that the system is robust enough to obtain a real-time dynamic measurement.

Applications like military, agriculture, and extra-planetary explorations require the successful navigation of vehicles across different types of terrain like soil, mud, and snow. As the properties of the terrain heavily influence the interaction with the tire, it is necessary to characterize the terrain from a tire performance and vehicle mobility perspective. Failure to properly understand the tire-terrain interaction can lead to undesirable conditions like loss of vehicle mobility due to excessive sinkage. As a result, it is essential to understand the tire terrain interaction between an off-road tire and a sandy terrain. This study was done to assess the performance of tires in both pure slip (only traction and braking) and combined slip conditions (steering and acceleration). A single-wheel indoor test rig was used to conduct tests under different conditions and a force transducer was used to capture the forces and moments generated in the tire hub. In addition to this, the tire footprint was captured with the help of a light-based 3-D scanner. Key parameters were defined in the 3D scan, and these parameters were correlated to the input test conditions. Additionally, a grid of force sensors was made, and measurements of the normal force acting at a depth below the undisturbed terrain were taken. Inferences were made about the linear speed of the wheel and the length of the pressure bulb under the tire. / Master of Science / Several applications like military, extra-terrestrial exploration, and motor racing require vehicles to navigate off-road terrains like soil, snow, and ice. The tire interacts with these off-road terrains very differently from the way it interacts with the road. It is important to understand this interaction correctly as this interaction generates all the forces needed by a vehicle to perform various maneuvers like acceleration, braking, and turning. If not accounted for properly, there can be undesirable conditions like loss of vehicle mobility due to excessive sinkage in sand. Tests were performed where an off-road tire ran on a non-cohesive, loose soil under different slip ratios, slip angles, and camber angles in an indoor test rig. The forces and moments acting on the tire during the tests were measured and its variation with input conditions was studied. A light-based 3D scanner was used to capture the tire rut profile on the soil after each test. The important parameters of the tire rut were defined and the variation of these parameters with input parameters were studied. Additionally, the stresses developed below the soil surface were measured with the help of a sensor grid, which was also used to verify the linear speed of the tire and infer the length of the zone inside the soil that is affected by the tire.