# Design Optimization of Underground Mining Vehicles Based on Regenerative Braking Energy Recovery
## 3 Analysis of Energy Consumption after Installing the Regenerative Braking Energy Recovery System
### Analysis of Forces on the Underground Mining Vehicle  
To enhance our comprehension of the operational characteristics of underground mining vehicles equipped with regenerative braking systems on specific tracks, this study employed physical modeling and analyzed the forces exerted on the vehicle. The mining vehicle was dissected into intricate components, namely the chassis, track, body, electric motor, transmission system, and braking system. Detailed descriptions of the design features of the electric motor, transmission system, and braking system were provided. This encompassed explanations regarding the traction force produced by the electric motor, the transmission efficiency of the transmission system, and the structure of the braking system. Continuing the discussion of operational characteristics, the analysis focused on the forces acting on the vehicle during different operational scenarios, such as acceleration, deceleration, and braking. The effects of these forces on the vehicle's performance were carefully examined, enabling a comprehensive understanding of the vehicle's dynamics. Overall, by considering the various components and their interplay, this study aimed to shed light on the operational behavior of underground mining vehicles equipped with regenerative braking systems, ultimately contributing to the advancement of this technology in the mining industry. As shown in Figure 8, the force analysis diagram of the mining vehicle indicates that during normal operation, the vehicle experiences traction force provided by the traction motor \(F_{t}\), frictional resistance between the wheels and the track \(F_{t}\), air resistance \(F_{t}\), gravitational force mg, and bearing friction \(F_{z}\). According to [PERSON]'s second law,  
\[\text{Ma}=\Sigma\text{F}_{t}-\Sigma\text{F}_{r} \tag{1}\]  
where \(\Sigma\text{F}_{t}\) represents the sum of the traction forces exerted on the vehicle, \(\Sigma\text{F}_{r}\) represents the sum of the resistances, a represents the acceleration of the vehicle, unit: \(\text{m}/\text{s}^{2}\). Let us analyze the resistances experienced by the mining vehicle during its operation:  
The main resistances acting on the mining vehicle while in motion consist of rolling resistance, air resistance, and uphill resistance. 1. Rolling resistance:  
Since underground mining vehicles usually travel on specific tracks, the rolling resistance is generated from the friction between the vehicle's wheels and the track. The rolling resistance experienced by the mining vehicle can be approximated as:  
\[\text{F}_{r}=\text{G}_{r}\text{mgcos}\alpha \tag{2}\]  
Figure 7: Site map of the mining vehicle operating track. where \(\alpha\) is the road slope and \(\rm G_{r}\) is the rolling resistance coefficient. The rolling resistance coefficient represents the rolling friction performance between the wheel and the rail. One common estimation method is to use an empirical formula for the rolling resistance coefficient:  
\[\rm G_{r}=\frac{1}{R} \tag{3}\]  
where \(\rm R\) is the rolling radius, which can be estimated using the radius of the mining vehicle's wheels. Air resistance:  
The resistance experienced by the mining vehicle is mainly composed of shape resistance and shell friction. It can be represented as:  
\[\rm F_{w}=\frac{1}{2}\rho A_{f}C_{D}(V-V_{w})^{2} \tag{4}\]  
where \(\rho\) is the air density, \(A_{f}\) is the frontal area of the vehicle, \(C_{D}\) is the air resistance coefficient, and \(V_{w}\) is the wind speed. Uphill resistance:  
Uphill resistance is a component of the parallel force to the gravitational force that occurs when the vehicle climbs a slope. Let us assume \(\lambda\) as a sign coefficient factor; \(\lambda=1\) when the vehicle is going uphill and \(\lambda=-1\) when the vehicle is going downhill.