Stochastic predictive freeway ramp metering from Signal Temporal Logic specifications

We propose a ramp metering strategy capable of treating exogenous arrivals as random variables since freeway network arrivals are stochastic by nature. In order to express desired temporal properties of the network, we adopt Signal Temporal Logic (STL) as our specification language and present a general framework for synthesizing controllers for piecewise affine systems subject to stochastic uncertainties. We synthesize controllers that satisfy these stochastic STL specifications through sample average approximation techniques. We further showcase our approach for a freeway ramp metering example, we use sampling techniques to obtain ramp flows that minimize the expectation of the total travel time.