## 2 Materials and Methods  
### Design Requirement  
The aim of the present research project is to develop a rollover test bench for vehicles of the type ATV-Quad. In order to achieve this objective, the stages of the design, manufacturing and validation of a test project were carried out. It presented the following main characteristics:  
The development of the rollover tests reported in this manuscript was carried out using this newly conceived test bench, which was designed and developed specifically for the mentioned research rising of the wheels in the rollover test. * The tilting speed of the structure is at least 1\({}^{\circ}\)/s. * The data acquisition is performed at a minimal sampling rate of 100 Hz. * The video recording system is placed at 45\({}^{\circ}\), referred to the front view. * The inclinable structure presents a single plane and adjustable tilt angle, in a range from 0\({}^{\circ}\) to 80\({}^{\circ}\), measured with respect to a horizontal ground reference. * It presents a flat and rigid surface and large enough to contain the four wheels of the tested ATV. * The electronic system for the measurement of the tilt angle presents a measurement range from 0\({}^{\circ}\) to 180\({}^{\circ}\) and a resolution of at least 0.1\({}^{\circ}\). * The surface holds a load cell under every one of the wheels of the vehicle. Each cell presents a measurement range up to 700 kg and a resolution of at least 0.5 kg. * High friction surface in the upper part of the load cells, to prevent slippage of the wheel. * The vehicle is fastened to the bench by using belts, loose enough to allow a total decompression of the suspension and a minimal bench in the Public University of Navarre, were completed. This project was carried out, starting from the project reported by [16] and following their main results. The design of the test bench is composed by three differentiated stages: (i) structural design, (ii) electronic system design, and (iii) control algorithm design. The requirements of the structural design stage are the following:  
1. The test bench is composed by two squared platforms: a fixed one and a mobile one. Their dimensions are 3000 \(\times\) 3000 mm\({}^{2}\). The mobile platform is able to rotate with respect to the fixed one by means of a pair of hydraulic cylinders. They can simulate a vehicle rollover and a tilt angle of 75\({}^{\circ}\), referred to the ground, can be reached. 2. It presents four mobile connections where the load cells have been installed, to allow the development of rollover tests at different directions. A function of the load cells is to determine the time, when the overturn of the vehicle is produced. 3. According to the rollover tests protocol, it is necessary to take into account that some of the tests are non-destructive ones; hence, some anchor points are installed in the sides of the bench in order to fix the vehicle, preventing its collision to the ground. Moreover, a bed of tires has been prepared, directly on the ground, in the impact area of the vehicle after the rollover test, for the non-destructive tests. 4. The angular velocity control of the test bench can be set up by means of a console panel. The preset values are 4\({}^{\circ}\)/s for a fast rotation, and 0.2\({}^{\circ}\)/s for a reduced angular velocity. On the other hand, the requirements for the design stage of the electronic system are as follows: 1. The test bench counts in a subsystem to measure the tilt angle of the mobile platform. Thanks to this subsystem, it is possible to measure the rollover angle of the tested ATV-Quad. The measurement range of the system is 0\({}^{\circ}\)-90\({}^{\circ}\), that is to say, from a horizontal position of the mobile platform to a perpendicular direction, referred to the ground. A display shows the tilt angle measurement, at every instant, which is also recorded. 2. Another subsystem determines the precise instant of time, where the rollover is produced, as well as the rollover angle.