Design optimisation of industrial robots using the Modelica multi-physics modeling language
Superior performance of industrial robots can only be achieved if the interaction of mechanics, electronics and software is taken into account already in the design phase. Conventional approaches to modelling, however, cannot cope with such multi-physics systems. The new Modelica modelling language has been specifically developed for this purpose. It also significantly increases re-usability of model components, since components adapt to the connection structure in which they are used. In the European resarch project “Real-time Simulation for Design of Multi-physics Systems“ (RealSim), efficient tools for modelling, simulating and optimising industrial robots are developed. A general Modelica MultiBody library (freely available from [1] or [2]) formed the basis for the development of a specific robot component library. A development environment for creating robot models out of the available components was provided, in which initial calculations to verify the first rough design can also be performed. Tools for automated optimisation were developed that take the initial design as the starting point. Afterwards, the performance of a design can than be verified in a real-time simulation before investing in building a real prototype. These powerful development tools provide the basis for an even more efficient development process and superior robot performance in the future.
From research to products: the KUKA perspective on European research projects
Building on the recent experience of the KUKA Robot Group, this article shows the broad spectrum of topics addressed in European robotics research projects. It describes recently completed research projects that resulted in products that would not have been developed otherwise. These include the AMIRA Project, the HANDFLEX Project, and the REALISM Project. The diversity of topics covered illustrates the great potential for innovation in this area.
Flight control system design considering rate saturation
Abstract In this paper the design process of modern flight control systems is discussed with respect to pilot-in-the-loop oscillations (PIO) due to rate saturation. At first the PIO phenomenon is characterised briefly. Well-known design criteria with respect to flight control system stability and handling qualities based on linear aircraft models are presented. A new design criterion considering the nonlinear effects of rate limiting is described. The criterion is based on the ‘open loop onset point’ (OLOP) of the rate limiter in a Nichols chart. The background for the development, and the verification of the OLOP-criterion are presented briefly. In order to demonstrate the applicability of the OLOP-criterion in the design process a simple example is examined. The flight control system parameters of a basically unstable aircraft are optimised with respect to the linear design criteria and the OLOP-criterion. Two alternative designs were discussed, a ‘nominal design’ and a ‘low gain design’ with reduced feedback loop gain. The low gain design is favourable with respect to rate limiting in the feedback loop of the flight control system, which is proved by nonlinear simulations in the time domain. Finally, the utilisation and the design of a rate limitation in the forward path of the flight control system are discussed.