Искусственные мышцы в бионике и робототехнике

Drilling bars with great overhang are used for the purpose of deep drilling. Vibrations of the drilling bar and changing cutting forces based on form and position errors of a pilot hole are interrupting influences within the manufacturing process. Therefore the Fraunhofer IPT is developing an intelligent adaptronic drilling tool which enables the use of different redundant adaptronic systems each consisting of piezoactuators, solid-state joints and sensors in order to improve the accuracy of the drilling process. This paper presents the physical state-space model of the static und dynamic behaviour of one adaptronic system as the basis for further control synthesis and describes a useful tool for the multidiscipline design of the system. The starting model parameters are calculated by FEM-simulation and are fitted to measured data by an optimisation-algorithm based on Newton's method. By describing the piezoelectric hysteresis the linear model of the mechatronic transfer behaviour is extended to a nonlinear model, which is the starting point for complex control designs for adaptronic machine tools. Entnommen aus TEMA</a

Design of piezo-based AVC system for machine tool applications

The goal of machine tools for Ultra High Precision Machining is to guarantee high specified performances and to maintain them over life cycle time. In this paper the design of an innovative mechatronic subsystem (platform) for Active Vibration Control (AVC) of Ultra High Precision micromilling Machines is presented. The platform integrates piezoelectric stack actuators and a novel sensor concept. During the machining process (e.g. milling), the contact between the cutting tool and the workpiece surface at the tool tip point generates chattering vibrations. Any vibration is recorded on the workpiece surface, directly affecting its roughness. Consequently, uncontrolled vibrations lead to poor surface finishing, unacceptable in high precision milling. The proposed Smart Platform aims to improve the surface finishing of the workpiece exploiting a broadband AVC strategy. The paper describes the steps throughout the design phase of the platform, beginning from the actuator/sensor criteria selection taking into account both performance and durability. The novel actuation principle and mechanism and the related FE analysis are also presented. Finally, an integrated mechatronic model able to predict in closed-loop the active damping and vibration-suppression capability of the integrated system is presented and simulation results are discussed

Adaptive cutting force control on a milling machine with hybrid axis configuration

In the re-contouring process of aircraft engine components, the unknown geometry and inhomogeneous material properties of the workpiece are major challenges. For this reason a new repair process chain is supposed which consists of noncontact geometry identification, process simulation and NC-path planning, followed by a force controlled milling process. A new milling machine prototype is employed to ensure an effective force control loop. By use of a magnetic guided spindle slide, higher dynamics and precise tracking are enabled. Since variation of the process forces result in variable control plant characteristics, an indirect adaptive controller has been designed. Consequently, models of actuator and process are presented and the estimation of the present parameters by a recursive least square algorithm is outlined. Once the parameters are known, the control polynomials are calculated on the basis of a pole placement control approach. First experimental results of a force controlled milling process are put forward.DFG/SFB/87

Regular adaptronic products enhanced with the fractional order control

Adaptronics is already present in many mechatronic products (e.g. agriculture, white goods), enhancing vibro-acoustic features in terms of comfort and product features without any substantial design modification. Comprehensive utilization of advanced adaptronics features (e.g. MR dampers) is possible fully to utilize only with proper process control. Here is suggested enhanced adaptronics features utilization with the fractional order control

Real-time performance of mechatronic PZT module using active vibration feedback control

This paper proposes an innovative mechatronic piezo-actuated module to control vibrations in modern machine tools. Vibrations represent one of the main issues that seriously compromise the quality of the workpiece. The active vibration control (AVC) device is composed of a host part integrated with sensors and actuators synchronized by a regulator; it is able to make a self-assessment and adjust to alterations in the environment. In particular, an innovative smart actuator has been designed and developed to satisfy machining requirements during active vibration control. This study presents the mechatronic model based on the kinematic and dynamic analysis of the AVC device. To ensure a real time performance, a H2-LQG controller has been developed and validated by simulations involving a machine tool, PZT actuator and controller models. The Hardware in the Loop (HIL) architecture is adopted to control and attenuate the vibrations. A set of experimental tests has been performed to validate the AVC module on a commercial machine tool. The feasibility of the real time vibration damping is demonstrated and the simulation accuracy is evaluate