Motion planning and control of an automated crack filling robot for unknown environments
Creators: name: Hunte, Kyle
Publisher: name: No Publisher Supplied
Year: 2023

description: Maintaining civil infrastructure systems is an important task because the economy requires a reliable mechanism that facilitates the transportation of goods and services. Roads and bridges are a major component of the infrastructure, and around the globe, significant resources are spent yearly on maintenance. The economic and social cost of maintaining a safe and reliable infrastructure is tremendous. To improve and automate the current technologies used in maintaining roads and bridges, this thesis describes the steps to design an automated crack-filling robot. The thesis focuses on the motion planning and control design of a robot to solve the Sensor-Based Inspection and Footprint Coverage (SIFC) problem with the application to the crack detection and repair of civil infrastructure systems. Instead of directly solving the SIFC problem, we first consider the motion planning of the mobile robot to fill the cracks as fast as possible for a given known crack map. That is, no complete sensor coverage is considered first. Then, to solve the SIFC problem, it is assumed that the crack information is known and the problem is decoupled into the two coverage planning problems using classic cell decomposition methods to achieve complete coverage of the workspace by the sensor and complete coverage of the cracks by the robot's footprint. A near-optimal complete coverage plan is proposed to guide the robot for the SIFC but with an offline-constructed crack graph. Similar to the Chinese Postman Problem, the least-cost route is selected to traverse the constructed crack graph. Finally, the thesis proposes a complete online motion planning solution for the SIFC problem, called the online sensor-based complete coverage (oSCC) planning algorithm. The oSCC detects unknown cracks using onboard sensors when the robot traverses the cracks to conduct the filling actuation in the shortest distance. The main approach of the oSCC algorithm is based on the constructed crack graph and the Reeb graph online to represent the environment while simultaneously filling the detected cracks with the least cost. The system design is evaluated by considering several metrics, such as the time to fill the cracks, explore the workspace area, and the effectiveness of the filling algorithm. Experiments are conducted using different crack densities. From the experiments conducted, the design has been shown to achieve coverage of the cracks, and the cracks were filled when the robot passed an area with cracks. The main contribution of the work lies in the development of a complete, near-optimal motion planning and control scheme for the SIFC problem with application to robotic crack filling. The main attractive features of the new planning algorithms are twofold. First, the new oSCC algorithm guarantees the complete sensor coverage of the free space in the entire workspace and simultaneously complete robotic footprint coverage of the detected targets (e.g., cracks). The total distance traveled by the robot is minimized and the resulting near-optimal path is obtained in polynomial time. Second, the motion control of the robotic filling mechanism is coordinated with the planned mobile robot trajectory to efficiently fill all cracks underneath the robot footprint.