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Abstract:In welding automation, growing interest can be recognized in applying teams of industrial robots to perform manufacturing processes through collaboration. Although robot teamwork can increase profitability and cost-effectiveness in production, the programming of the robots is still a problem. It is extremely time consuming and requires special expertise in synchronizing the activities of the robots to avoid any collision. Therefore, a research project has been initiated to solve those problems. This paper will present strategies, concepts, and research results in applying robot operating system (ROS) and ROS-based solutions to overcome existing technical deficits through the integration of self-organization capabilities, autonomous path planning, and self-coordination of the robots' work. The new approach should contribute to improving the application of robot teamwork and collaboration in the manufacturing sector at a higher level of flexibility and reduced need for human intervention.

The optimal startup policy of a jacketed tubular reactor, in which a first-order, reversible, exothermic reaction takes place, is presented. A distributed maximum principle is presented for determining weak necessary conditions for optimality of a diffusional distributed parameter system. A numerical technique is developed for practical implementation of the distributed maximum principle. This involves the sequential solution of the state and adjoint equations, in conjunction with a functional gradient technique for iteratively improving the control function.This paper presents an optimal policy for startup of a jacketed tubular reactor in which a first-order, reversible, exothermic reaction is taking place. The optimal control policy is determined by using a distributed maximum principle. The control or decision variable is the wall temperature of the reactor, which is manipulated to minimize a given performance index. Computational results are obtained for a case with and without a constraint on the maximum reaction temperature.The mathematical model for the jacketed tubular reactor is a continuous distributed parameter flow system, which gives rise to a set of coupled nonlinear, one-dimensional, second-order, parabolic partial differential equations. A distributed maximum principle used by previous workers, for example Denn et a1 ( I ) , is extended to a general system of nonlinear diffusion equations, with twopoint boundary conditions consisting of linear relationships between the dependent variables and their axial gradients. A set of necessary conditions for optimality is obtained for a fairly general performance index.In general, equations of the type treated cannot be solved by analytic methods and even numerical techniques for coupled, highly nonlinear, axial diffusion equations are not generally available. Therefore an iterative computational technique involving a gradient in functional space is presented, which enables the numerical implementation of the distributed maximum principle. It is shown that the technique is capable of accommodating inequality constraints on state variables by the addition of an appropriate penalty function to the performance index. A D I S T R I B U T E D MAXIMUM P R I N C I P L EA distributed maximum principle is presented for determining weak necessary conditions for optimality for a class of distributed systems. Due to the complexity of partial differential equations, a completely general maximum principle, as exists for lumped-parameter systems (2, 3 ) , has not been found. However, sufficient generality has been retained that the results apply to a wide variety of systems of interest in process control. System Description Attention will be focused on systems which may be described by a general nonlinear vector partial differential equation of the form U t ( X , t ) = f{u(x,t), U z w ) , u z z (~, t ) ,(1) where u is an s-dimensional state vector defined on a normalized one-dimensional spatial domain x from x = 0 to x = 1 and over a fixed time interval t = 0 to t = tj. T...

A new investigated concept for passive load alleviation is to exploit the nonlinear behavior of wing design components to trigger a deformation which reduce loads once a critical load level is reached. The necessary deformation is a torsional rotation which is supposed to reduce the angle of attack. For this target, wingbox sections are investigated regarding their nonlinear behavior with finite element analysis. Parameter studies feature anisotropic carbon fiber reinforced polymer (CFRP) layups for the skins, layups and thicknesses for spars and the presence of stringers. Results show a desired nonlinear progressive bending-torsion coupling for an unstiffened wingbox section, when the upper skin and the rear spar are modified. After modification they are allowed to buckle within the load envelope. The skin has an anisotropic layup. The rear spar needs to be thinner than the front spar. Both modifications result in progressively increasing torsional rotation of the wingbox with increasing load. Stringers are not applied because they limit the nonlinearity which is not desired for the envisioned load alleviation technique.

Aircraft wings with passive load alleviation morph their shape to a configuration where the aerodynamic forces are reduced without the use of an actuator. In our research, we exploit geometric nonlinearities of the inner wing structure to maximize load alleviation. In order to find designs with the desired properties, we propose a topology optimization approach. Passive load alleviation is achieved through bending–torsion coupling. The wing twist will reduce the angle of attack, thus lowering the aerodynamic forces. Consequently, the objective function is to maximize the torsion angle. Since shape morphing should only affect loads that exceed normal maneuvering loads, a displacement constraint is enforced, preventing torsion at lower force levels. Maximizing the displacement will lead to topologies for which the finite element solver cannot find a solution. To circumvent this, we propose adding a compliance value to the objective function. This term has a weighting function, which controls how much influence the compliance value has: after a set number of iterations, the initially high level of influence will drop. We used a geometric nonlinear finite element formulation with a linear elastic material model. The addition of an energy interpolation scheme reduces mesh distortion. We successfully applied the proposed methodology to two different test cases resembling an aircraft wing box section. These test cases illustrate the methodology’s potential for designing new geometries with the desired nonlinear behavior. We discuss what design features can be deduced and how they achieve the nonlinear structural response.

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