As autonomous vehicles are starting to become a reality, accurate path following is needed. Pure Pursuit and Vector Pursuit algorithms are commonly used to control the steering actuators. Unfortunately, these algorithms do not take under consideration that real world actuators have steering rates that have maximum acceleration and speed of the changes to the steering and therefore the curvature rates of the vehicle as it is following a trajectory. This is even more evident in large vehicles that require significant torque to move the steering column like trucks and heavy industrial equipment. Therefore, if these vehicles attempt to closely follow trajectories at higher speed, the vehicles will undoubtedly understeer as the steering actuators do not have enough time/power to catch up with the curvatures dictated by the path even if kinematically and dynamically, the vehicles can safely perform the turns. The invention presented relates to the creation of a control system that takes under consideration these maximum curvature rates as part of the control of the autonomous vehicle. The invention involves the development of a control system that controls to follow an arbitrary trajectory comprising a vehicle with an actuated steering column, where the actuator has a maximum steering rate and/or maximum steering acceleration and/or a maximum steering jerk; a system for controlling the vehicle speed (actuated accelerator and/or brake), a trajectory (possibly composed of waypoints) that dictates the path to be followed by the vehicle, a maximum allowed deviation from that trajectory, and a controller that modifies the velocity of the autonomous vehicle to allow the vehicle to follow the trajectory within the maximum allowed deviation.
Path Follower with Limited Steering Rate Controller
2021-02-11
Patent
Electronic Resource
English
IPC: | G05D SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES , Systeme zum Steuern oder Regeln nichtelektrischer veränderlicher Größen / B60W CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION , Gemeinsame Steuerung oder Regelung von Fahrzeug-Unteraggregaten verschiedenen Typs oder verschiedener Funktion / B62D MOTOR VEHICLES , Motorfahrzeuge |
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