# Research on a Comprehensive Evaluation Method of Train Anti-Slip System Performance
## 4 Construction of a Comprehensive Test Platform for Anti-Slip Evaluation
### Software Design  
The comprehensive test platform for anti-slip evaluation mainly included testing and analysis software and real-time simulation software. The testing and analysis software included a braking system communication module, a data acquisition and transmission module, a human-machine interaction module, a network communication module, and a data storage module. Real-time simulation software mainly included a vehicle longitudinal dynamics model that could reflect the motion state of the vehicle, and a wheel-rail adhesion model that reflected the wheel-rail contact characteristics. Figure 4: The actual platform. During the braking process, without paying attention to the vertical and horizontal comfort indexes of the carriage and temporarily disregarding the curve passing conditions, the performance indexes of the train braking conditions are mainly related to the longitudinal freedom of the vehicle. Therefore, the vehicle dynamics model was simplified and established, only considering its longitudinal freedom [11]. The following is a description of the dynamic equations for each submodule established based on reference [11]. (1) Wheelset  
Under the rotating state of the wheelset, the main forces on the wheelset are the friction force of the brake shoe and the adhesion of the track to a single wheel. In the translational state, the force acting on the wheelset is the primary suspension force and the track adhesion force. Equations (18) and (19) respectively represent the dynamic equations for the two states. \[I_{w}\ddot{\theta}=K\cdot\varphi_{K}\cdot R_{w}-F_{bw}\cdot R_{w} \tag{18}\]  
\[M_{w}\cdot\ddot{x_{w}}=F_{fw}-F_{bw} \tag{19}\]  
where \(M_{w}\) is the single wheel mass, \(I_{w}\) is the wheel moment of inertia, \(R_{w}\) is the vehicle radius, \(\theta\) is the wheel angle, \(K\) is the equivalent clamping force, \(F_{bw}\) is the longitudinal force of the track on the single wheel, \(F_{fw}\) is the force of the primary suspension on the single wheel, and \(\varphi_{K}\) is the friction coefficient of the brake shoe. (2) Frame  
The longitudinal degrees of freedom of the frame are mainly affected by the primary and secondary suspension forces. The number of primary suspension forces is four, and the number of secondary suspension forces is two. The dynamic equation is Equation (20). \[M_{f}\cdot\ddot{x_{f}}=4*F_{wf}+2*F_{cf} \tag{20}\]  
where \(M_{f}\) is the mass of the frame, \(x_{f}\) is the longitudinal displacement of the frame, \(F_{wf}\) is the force exerted by a single primary suspension on the frame, and \(F_{cf}\) is the force exerted by a single secondary suspension on the frame. Figure 5: Design of 1M1T air braking system. (3) Vehicle body  
The longitudinal degree of freedom of the vehicle body is mainly affected by the secondary suspension force and the coupler force. The number of secondary suspension forces is 4, and the dynamic equation is Equation (21). \[M_{c}\cdot\ddot{x_{c}}=4*F_{fc}+F_{coupler1}-F_{coupler2}-F_{resistance} \tag{21}\]  
where \(M_{c}\) is the mass of the vehicle body, \(x_{c}\) is the longitudinal displacement of the vehicle body, \(F_{coupler1},\ F_{coupler2}\) are the coupler forces at both ends, and \(F_{resistance}\) is the basic resistance. (4) Primary suspension force, secondary suspension force, coupler force  
In the modeling of this system, the primary and secondary suspension forces, as well as the coupler forces, were simplified as spring damping mechanical models. The dynamic formulas are shown in Equations (22)-(24).