Integrated Design of Mechatronic Servo Systems
Creators: name: Roos, Fredrik
Publisher: name: Zenodo
Year: 2007
Subjects: Mechatronics
Servo Systems
Design and Optimization
Integrated Design

description: Abstract<br> Traditional methods for mechatronics design are often based on a sequential approach, where the<br> mechanical structure is designed first, and then fitted with off-the-shelf electric motors, drive<br> electronics, gearheads and sensors. Finally a control system is designed and optimized for the already<br> existing physical system. Such a design method, that doesn’t consider aspects from a control point of<br> view during the design of the physical system, is unlikely to result in a system with optimal control<br> performance. Furthermore, to separately design and optimize each of the physical components will,<br> from a global perspective, generally not result in a system that is optimal from a weight, size or cost<br> perspective.<br> In order to reach the optimal design of an integrated mechatronic system (mechatronic module) it is<br> necessary to treat the system as a whole, considering aspects from all involved engineering domains<br> concurrently. In this thesis such an approach to integrated design of mechatronic servo systems is<br> presented. A design methodology that considers the simultaneous design of the electric machine,<br> gearhead, machine driver and control system, and therefore enables global optimization, has been<br> developed. The target of the design methodology is conceptual design and evaluation. It is assumed<br> that the load to be driven by the servo system is known and well defined, a load profile describing the<br> wanted load motion and the corresponding torque, is required as input. The methodology can then be<br> used to derive the lightest or smallest possible system that can drive the specified load. Furthermore,<br> the control performance is evaluated and optimized, such that the physical system design and the<br> controller design are integrated.<br> The methodology is based on modelling and simulation. Two types of component models have been<br> developed, static and dynamic models. The static models describe relations between the parameters<br> of the physical components, for example a component’s torque rating as function of its size. The<br> static models are based on traditional design rules and are used to optimize the physical parts of the<br> system. The dynamic models describe the behaviour of the components and are used for control<br> system design and performance optimization.<br> The gear ratio is identified to be the most central design variable when designing and optimizing<br> electromechanical servo systems. The gear ratio directly affects the required size of the gearhead,<br> electric machine and the machine driver. But it has also large influences on the system’s control<br> performance. It is concluded that high gear ratios generally are better from a control point of view<br> than low ratios. A consequence of this is that it is possible, without compromising the control<br> performance, to use less expensive (less accurate) sensors and microprocessors in high gear ratio<br> servo systems, while low gear ratio systems require more expensive hardware. It is also concluded<br> that it is essential to include all performance limiting phenomena, linear as well as non-linear, in this<br> type of integrated analysis. Using for example a linearized system description for controller design,<br> means that many of the most important couplings between control system and physical system design<br> are overlooked.