Keywords

1 Introduction

The ANGUILA F13 is a formula-type vehicle designed and built for the FORMULA SENA ECO competition by university students and SENA apprentices with SENA instructor guidance [1], The design of the vehicle was carried out taking into account the regulations foreseen by the organizers of the event and the requirements demanded by the optimal performance conditions of the vehicle.

This type of events aimed at students related to the development of prototyping in a competitive way, allows the development of professional skills and abilities for the generation of value of future professionals through practical mechanisms that test the capabilities and creativity of the work team [2, 3]. In this sense, the FORMULA SENA ECO competition is aimed directly at students with the potential to generate innovative proposals to the academic and training environment of robotics.

In the arc of this competition, it is mentioned that the steering system is vital in the race strategy, control and safety of the vehicle, For this reason its proper implementation and configuration is important for the correct functioning of the car on the track, in the design many factors that could affect the direction of the vehicle were taken into account, for example the turning force of the wheels, the inclination of the car, the steering column among others. It should also be considered that the vehicle is piloted by a person therefore it must provide a minimum of safety to safeguard the integrity of the driver, taking into account this, The frame and survival cell play an important role in the safety of the pilot, as does the direction that in the event of a frontal collision must broken, thus preventing the rudder from moving in the direction of the pilot.

The objective sought by the article is the design and analysis of the geometry of the steering system considering the factors of safety, vehicle stability, vehicle control, optimize the maneuverability of the single-seater, in addition to characteristics such as weight and aerodynamics for this, the location of the elements, the material to be used and the geometry of the components that comprise the complete system must be taken into account.

2 Material and Method

This article shows an applied and experimental research process, which shows the process of development of the single-seater vehicle. The method used for the design of the steering system had reference frame geometry, the rules of competition, the battle and track of the vehicle and the angle camber, caster and ackerman.

On the track the proper implementation and configuration of the system is important for the correct functioning of the vehicle. In the design process, many factors were taken into account which could affect the direction of the vehicle, from the turning force of the wheels, the inclination among others.

3 Results

3.1 Positioning of the Steering Rack

The steering rack was placed behind the chassis, 110 mm from the front tube of the chassis and, in turn, this will be held by anchors, which are attached to the front tube of the chassis; The positioning of the rack influences the length of the steering arms and the steering of the vehicle. Staples were used to ensure the fixation of the bottle.

3.2 Wheelbase

Figure 1 shows the dimensions of the vehicle as it is the wheelbase of the vehicle, which is the distance between the axle of the front tire and the axle of the rear tire [4], this measurement plays an important role in the stability of the vehicle; Taking this into account a vehicle with a long wheelbase has greater stability than a short wheelbase. For the design of the Anguilla F13 a wheelbase of 2310 mm was used, considering that the regulations of the contest specified the maximum total length that the vehicle could have.

Fig. 1.
figure 1

Track and Wheelbase of a formula vehicle upper view.

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3.3 Front Track of the Vehicle

The path of the vehicle is the distance from the center of the tire on one side to the center of the tire on the other side Both the front and rear track width is the distance, The front track does not need to match the rear track, commonly the front track is shorter than the rear track for stability, traction and rotation of the vehicle. In Fig. 2, the perspective view of the vehicle model is shown, allowing us to know from where the measurement of the Track and the Wheelbase are taken [4, 5].

Fig. 2.
figure 2

Track and Wheelbase of the vehicle seen in perspective

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Table 1 shows the dimensions of the car with which the calculation of the angle Ackerman will be carried out.

Table 1. Dimensions of the Single-Seater Vehicle.
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3.4 Steering Column

The steering column is sectioned into 3 parts, because it gives the pilot greater security in the event of a crash. This column was designed based on the positioning of the steering rack. The steering column goes through two bearings for its mobility and has an anchorage at an angle that in the event of an accident, breaks forward of the pilot, preventing said column from causing injuries to the pilot. For the design of the steering column material, the torque in which the column would work was taken into account by applying the following formula:

$$\frac{{F}_{p}}{{F}_{v}}=\frac{{R}_{v}}{{R}_{p}}$$
(1)

Fp: Force obtained in the drive pinion of the steering box. (N).

Fv: Force applied to the steering wheel. (N).

Rp: Steering box drive pinion radius. (m).

Rv: Steering wheel radius. (m).

$$ F_{v} = \frac{{F_{p} R_{p} }}{{R_{v} }} = \frac{{\left( {\frac{\mu .\,m.\,g}{2}} \right) \cdot R_{p} }}{{R_{v} }} = \frac{{(0,8)(500\;kg)(0,4)\left( {9,8\frac{m}{{s^{2} }}} \right)(0,0365\;m)}}{2(0,25\;m)} = 114,5N $$
(2)

Taking into account that the force exerted was 114.5N on the material. Table 2 shows the characteristics of ASTM A36 Steel, which was selected for being able to withstand said stress.

Table 2. Characteristics of the Material Used
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3.5 Steering Column Simulation

From the defined load of 114.5N, the simulation of the steering column is carried out in the Solidworks program in its Solidworks Simulation complement, which is shown in Fig. 3, where it shows the fastening point and the effort made, symbolized by colors.

Fig. 3.
figure 3

Steering Column Torque Analysis SOLIDWORK Software.

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As can be seen in the simulation, the maximum effort is 127 MPa, this means that the steering column will fully fulfill its function without suffering damage.

3.6 Effect of Universal Joints on the Steering Column

The use of cardan joints have a direct effect on the rotation of the axes, since they add a better mechanical operation to the steering column, the advantage that this type of element has compared to other employees in similar jobs, is to improve performance. When performing a certain turn according to the abrupt conditions of the environment, that is, that the movements that are generated are smooth, a cardan joint adds a response form based on sinusoidal functions [5], where the speed of turns of the axes is found between the maximum and minimum angular velocity limits, as can be seen in Fig. 4.

Fig. 4.
figure 4

Cardan jointed steering column.

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Despite this, because the steering column turning speeds are very small, this effect is almost nil, and always tends to remain or handle the actual steering turning speed.

3.7 Steering Arms

The steering arm makes the coupling between the steering bottle and the fastening point on the rim as shown in Fig. 5, the dimension of the steering arm of the F13 eel vehicle was 487.55 mm. For the steering arms, ASTM A36 STEEL was used, which, when faced with stress simulations, had satisfactory results.

Fig. 5.
figure 5

Steering arm, fork, bottle and tire.

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3.8 Ackerman Plates

The Ackerman angle is a method created to solve the problem of the inner and outer wheel when turning a vehicle, creating a circle of different radii. [6, 7]. Because the steering rack only allows a linear movement of the bar is 139 mm, it is necessary to use an Ackerman, with the aim of providing sustainability in closed and open curves, in the case of the ANGUILLA FS-13, the Ackerman It will allow you to spin more than normal. Table 3 describes all rack positions and the resulting external and internal angle of the tires.

Table 3. Ackerman Angle Calculation.
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4 Conclusions

The vehicle performed well in cornering, also stability and smooth steering handling. The steering arm did not present problems of rotation, mechanical lock, twisting or breaking due to overexertion. The materials used for the construction of the suspension and steering met the minimum stress requirements. It is recommended to make an ackerman table with different measurements, to adjust the vehicle to a position that gives an optimal behavior of the vehicle in the race.

The process carried out in the present study allows to demonstrate the effectiveness of the formative results of a competence related to the area of robotics; where students can generate effective and functional value propositions within a controlled environment and accompanied by a group of tutors and expert evaluators [8, 9].