Tuning Sliding Mode Controllers for String Stability

Due to their outstanding robustness properties, feedback loops based on the ideas of sliding mode control are well suited for the application in platooning scenarios. In this chapter, homogenous platoons without any communication between the vehicles in the platoon are investigated. It is demonstrated that neglecting actuator dynamics during the design phase of sliding mode controllers leads to chattering which becomes evident as stable self-sustained oscillations (limit cycles) within the control loop. In this contribution, the characteristics of these limit cycles are exploited to adjust the velocity-dependent inter-vehicle distances such that a string stable platoon can be achieved although the actuator dynamics are neglected in the design phase of the controllers. Two well-known sliding mode algorithms, a classical first-order concept and the super twisting algorithm, are investigated and simulation results are presented.