Electrical and Electronic Engineering - Theses
Permanent URI for this collection
Search Results
1 - 1 of 1
-
ItemA Model-based Approach for High Performance Motion Control in Industrial Machines( 2020)Industrial robotics typically consider laser/water cutting, grinding, etc. Within these machines, the motion controller is responsible for the positioning of the end effector. The performance of the motion controller directly influences the quality of the resulting product as tolerance/accuracy are surrogates for machining quality. This is particularly relevant in tracking and contouring applications when the system has structural flexibility, and no direct feedback measurement of the end-effector position is available. Traditional control architectures in machining are unable to explicitly bound tracking and/or contouring errors, and conservative operation is used to ensure satisfactory performance of the overall system. Bounding errors without unduly compromising machine throughput requires advanced control algorithms. The development of such algorithms is the focus of this thesis. Although numerous control methods are proposed, the proportional integral derivative (PID) based cascaded control is still the most prevalent in the industry. Based on this fact, the research starts by objectively assessing the tracking control performance on a single-axis industrial platform. The results provide practitioners with an in-depth understanding of the benefits and limitations of existing control algorithms as well as the motivation to consider advanced controllers as alternatives to the PID-based approach. For the single-axis tracking problem, this research proposes a model predictive based approach that guarantees a desired level of tracking error is met for the cases where the structure is flexible and the end-effector position is estimated. To achieve this, a robust control invariant set is estimated using a computationally tractable algorithm and incorporated into the problem formulation. The applicability of the proposed approach is successfully demonstrated via simulation and experiments conducted on a commercial single-axis system. In terms of biaxial applications, the dual-drive gantry machines are widely used in industry for manufacturing. However, the non-synchronised movement of the dual drive may lead to deterioration in contouring accuracy. In this research, we propose two model predictive based control architectures based on the switched linear time invariant control-oriented models, that is able to guarantee a two-dimensional contouring tolerance in the presence of uncertainty arising from imperfect drive synchronisation. The performance and computational tractability of the proposed approach are demonstrated using high fidelity simulation and experiment.