Optimal Placement of Actuators Via Sparse Learning for Composite Fuselage Shape Control

Abstract

Shape control is a critical task in the composite fuselage assembly process due to the dimensional variabilities of incoming fuselages. To realize fuselage shape adjustment, actuators are used to pull or push several points on a fuselage. Given a fixed number of actuators, the locations of actuators on a fuselage will impact on the effectiveness of shape control. Thus, it is important to determine the optimal placement of actuators in the fuselage shape control problem. In current practice, the actuators are placed with equal distance along the edge of a fuselage without considering its incoming dimensional shape. Such practice has two limitations: (1) it is non-optimal and (2) larger actuator forces may be applied for some locations than needed. This paper proposes an optimal actuator placement methodology for efficient composite fuselage shape control by developing a sparse learning model and corresponding parameter estimation algorithm. The case study shows that our proposed method achieves the optimal actuator placement for shape adjustments of the composite fuselage.

Link Adjustment for Assembly Deviation Control of Extendible Support Structures via Sparse Optimization

“…Obviously, the larger the value of λ is, the smaller the number of adjusted links will be. Thus, it can be inferred that there is at least a value of λ that satisfies the requirement of ||x||0 = n [34].…”

“…x x p Kx η (34) where K is the Jacobian matrix of the mapping function f with respect to x, and ||• ||∞ denotes the infinite norm. The proof of the maximum value is provided in appendix.…”

Optimal Shape Control via $L_\infty$ Loss for Composite Fuselage Assembly

“…Similar to [10], U i , i = 1, 2, can be obtained from the surrogate model. Notably, the registration between two fuselages is needed if the number of measurement points for the pair of fuselages is not the same, which can be easily solved through a method that is proposed in [8].…”

“…By minimizing the 2 loss of dimensional errors in relative to the design shape, they calculate the optimal forces applied from actuators for single fuselage shape control. Based on the surrogate model, Du et al [10] propose an optimal actuator placement strategy for the shape adjustment of composite fuselages; their strategy reduces the forces applied from actuators and also dimensional deviations after shape control. However, all these works only consider shape adjustments of a single fuselage, and aim to adjust the incoming fuselages to the design shapes in terms of the 2 loss, which meets the requirement of a single shape adjustment.…”

“…As shown in [10], one other direct result is that the optimal placement of actuators can also lead to the improvement of the performance in shape control. In the current paper, as a part of the optimal shape control strategy for the composite fuselage assembly, we also consider the optimal placement of actuators for two fuselage assembly.…”