Command modification using input shaping for automated highway systems with heavy trucks

A good solution to traffic congestion problems in many parts of the world is putting more vehicles on existing roads and operating them closer to each other and safely. This notion of more efficient use of existing roads and highways has led to the idea of the Automated Highway Systems, especially in the form of platooning. A number of vehicles (automated with sensors and actuators) form a "platoon" with small inter-vehicle spacing (1--2 m) and platoons are coordinated by the highway infrastructure.; Automation of commercial heavy vehicles is particularly challenging since they may have a large variation in parameters such as vehicle mass, are strongly influenced by road grade changes and have generally lower actuation (engine and brake) authorities. When actuators saturate, the followers (vehicles behind the first vehicle in a platoon) may not be able to keep up with the leader (the first vehicle in the platoon), which could lead to collisions. This thesis addresses the issue of parameter variation and actuator saturation with a robust and economical estimation scheme and a proper maneuver design methodology.; First, this work demonstrates that road grade can be reliably estimated using the ratio of the vertical to horizontal velocities from the GPS velocity measurements. Accurate estimation of road grade enabled the estimation of other important vehicle parameters (mass estimates of +/-2% and +/-5% for a passenger car and a heavy truck, respectively).; This work also presents a new method for maintaining and improving string stability through a proper maneuver generation, and thus, preventing actuator saturation in the automated vehicles on highways. The input shaping idea is used for maneuver generation where the reference commands are first fed through an input shaper so that harmful components in the reference commands are reduced or removed. The convex optimization approach to input shaper design developed in this work can efficiently and systematically addresses actuator saturation with time domain constraints as well as ride quality and robustness with frequency domain constraints. Such input shapers can prevent actuator saturation by dynamically bounding the reference commands, and therefore, generating smooth, non-saturating trajectories that ultimately guarantee the string stability.