Roland Kasper

An Adaptive FPGA-Based Mechatronic Control System Supporting Partial Reconfiguration of Controller Functionalities

Adaptive systems based on reconfigurable hardware provide an attractive platform for the implementation of mechatronic controller functionality. Such control algorithms comprise various operating states, parameter sets or algorithms that depend on changing external conditions. This paper presents an implemented and tested adaptive mechatronic control system, supporting the partial reconfiguration of real-time controller functionality. It provides a distributed reconfiguration and activation management as well as on/off-chip communication solutions including a delta-sigma ADC and an USB 2.0 interface. All functionality and the reconfiguration management are implemented directly in hardware using bit serial methods. This approach avoids real-time problems and takes advantage of high level parallel signal processing

A power drive control for piezoelectric actuators

Today piezoelectric actuators are used in a growing number of applications. This article presents a new switching amplifier circuit for multilayer actuators, which allows a fast and precise driving as well as the recovery of energy from the actuator. Having modeled the power electronic analog circuit, its behavior could be well reproduced by a simulation. The design of a digital controller, which was considerably facilitated by this simulation, is presented. This controller and the analog switching amplifier as well as a model of the piezoelectric actuator are part of mixed analog digital simulation.

Design of a wheel-hub motor with air gap winding and simultaneous utilization of all magnetic poles

This paper presents a new structure of BLDC motor applied for a wheel-hub motor for an electric vehicle. Today the physical structure of BLDC motors is dominated by a massive stator with salient poles as a framework for the windings. This construction results in high weight and in significant energy losses caused by eddy currents and hysteresis losses in the stator material. Furthermore, a huge amount of conductor material is needed, mostly with limited cross-section areas, so that resistive losses occur. In this paper a new approach to a permanent excited electrical motor is presented that allows for stator constructions with reduced weight, size, resistive and magnetic losses in combination with a very compact and high efficient air gap winding that allows for simultaneous utilization of all permanent magnets to generate very high torque. The design of a wheel-hub motor useful to drive a 4WD electric vehicle is presented.

Power Drive Circuits for Piezo-Electric Actuators in Automotive Applications

This article presents two designs of power amplifiers to be used with piezo-electric actuators in diesel injectors. The topologies as well as the controller approach and implementation are discussed.

Dynamic reconfiguration of mechatronic real-time systems based on configuration state machines

Data flow and FSMs are used to specify real-time systems in the field of mechatronics. Their implementation in FPGAs is discussed against the background of dynamic reconfiguration which can be used to reduce the amount of logic resources. Bit serial algorithms come into operation for data flow implementation. Particular attention has been paid for synchronization in dynamic reconfigurable systems. Typically a control system uses different functions depending on its operating state; dynamic reconfiguration is used to switch between them. Reconfiguration is triggered in a distributed way by the active states of all FSMs and executed in a central way by a general control module. Synchronization and message passing is guaranteed by a distributed communication system.

Object-oriented behavioural modelling of mechatronic systems

Mechatronic systems overcome the traditional borders of classical engineering disciplines. Behavioural modelling allows the developer to describe the behaviour of components and systems from arbitrary disciplines. This paper introduces a way to transform the functional models of those systems into an object-oriented description. The objects implementing this integration of behaviour and animation are called virtual objects. Ideally these objects can be recognised and handled by a user like their real world counterparts. Complex tasks like design, manufacturing etc. no longer have to be done with expensive and difficult to handle real components.

Implementation of a reconfigurable hard real-time control system for mechatronic and automotive applications

Control algorithms implemented directly in hardware take advantage of parallel signal processing. Furthermore, implementing controller functionality in reconfigurable hardware facilitates modification of controller structure and parameters during run-time. In this paper, we introduce an implemented and tested reconfigurable hard real-time control system based on an FPGA device. It supports dynamic partial reconfiguration of controller functionality by self-reconfiguration mechanisms. Self-reconfiguration is performed using an internal configuration interface. We also present sophisticated on-chip and off-chip communication solutions. Specification of controller functionality involves finite state machines (FSMs) and comprises parts of the distributed communication and reconfiguration solution

A New Software Approach for the Simulation of Multibody Dynamics

This paper introduces a new modular software approach combining symbolical and numerical methods for the simulation of the dynamics of mechanical systems. It is based on an exact, noniterative object-oriented algorithm, which is applicable to mechanisms with any joint type and any topology, including branches and kinematic loops. The simulation of big well-partitioned systems has complexity O(N), where N is the total number of simulated bodies. A new design software Virtual System Designer (VSD) integrates this method with the three-dimensional computer aided design tool Autodesk Inventor, which minimizes the cost of the development of models and the training of design engineers. The most time-expensive routine of the simulation process in VSD is the calculation of the accelerations of each body, which needs to find the roots of matrix equations. Accounting for the sparsity of matrices can significantly improve the numerical efficiency of the routine. The preprocessing module, developed using Maple software, performs the symbolic simplification of the matrix multiplications and QR decompositions procedures. The new coordinate projection method is demonstrated. The results of the simulation of the dynamics of a double insulator chain example show the methods stability and effectiveness.

A Reconfigurable Delta-Sigma ADC

FPGAs are an increasing alternative for implementing signal processing in mechatronics. But unfortunately they lack an on-chip ADC. This paper presents the approach and results of a bit serial implementation of a reconfigurable delta-sigma ADC using Texas Instruments four channel delta-sigma-modulator ADS1204. Filtering and decimation is accomplished in three stages by different filter types. The implementation has been done on a Xilinx Virtex4 using VHDL for specification. Bit serial arithmetic has been used to reduce implementation cost

Mechatronic model of a novel slotless permanent magnet DC-motor with air gap winding design

This paper presents a mechatronic model of a novel slotless permanent magnet DC-motor with air gap winding. Besides technical advantages of this type of motor like high power density, high torque, very low weight and high efficiency, the motor design allows a very precise and efficient modelling with limited effort. A nonlinear model of magnetic field density can be extracted from a detailed nonlinear FE-model build in ANSYS/Maxwell, approximated by Fourier series and then used to model driving torque and back EMF, representing the coupling between electrical and mechanical subsystems. Analytically founded numerical models for driving torque and back EMF will be given. Real geometry of the phase winding is taken into account to improve model accuracy. The electrical subsystem will be described as coupled three phase system, whose parameters can also be extracted from the nonlinear FE-model with high accuracy. Together with a mechanical model of the rotor a MATLAB/Simulink model is build and extended by models of the hall sensors to detect rotor position and commutation logic to control the HEX-Bridge during operation. Finally, results of a complex simulation model, based on the parameters of the prototype of a wheel-hub motor, implementing the new motor design, are getting shown. Simulation results compare very well to measured data. Simulation time is very short due to the efficient approximation of magnetic flux density.