Sensors in production systems such as machine tools or robots may be classified into four categories (Figure 2-1). They are activated either during operation or in the set-up phase. Three types of sensors may be applied during the operation: those which measure kinematic values such as position, velocity, orientation or angular velocity, sensors which are applied to control the process in adaptive control systems, and sensors which are used to monitor the production systems and to provide diagnostic functions to assure a high availability of the systems | Sensors in Manufacturing. Edited by . Tonshoff I. Inasaki 47 Copyright 2001 Wiley-VCH Verlag GmbH ISBNs 3-527-29558-5 Hardcover 3-527-60002-7 Electronic 2 Sensors for Machine Tools and Robots . Tönshoff Universität Hannover Hannover Germany Sensors in production systems such as machine tools or robots may be classified into four categories Figure 2-1 . They are activated either during operation or in the set-up phase. Three types of sensors may be applied during the operation those which measure kinematic values such as position velocity orientation or angular velocity sensors which are applied to control the process in adaptive control systems and sensors which are used to monitor the production systems and to provide diagnostic functions to assure a high availability of the systems. Sensors for process control functions are shown in Chapters 3 and 4 and will not be mentioned here. Sensors which are applied in the set-up phase are used after assembly to adjust or test the accuracy of the systems or to calibrate the interacting members of the kinematic chain. Position Measurement In this section sensors are described which measure linear or rotational movements mainly during operations of machine tools and robots. These sensors became of es- Fig. 2-1 Sensors in production systems 48 2 Sensors for Machine Tools and Robots sential importance with the introduction of position control loops for numerical controlled machines Figure 2-2 1 . The applied electric and in a few cases hydraulic or pneumatic drives are not able to be positioned by themselves in a control chain but need a feedback of a position signal. An exception to these control loop-based drives are the digital controllable stepping motors. Their application is limited because of accuracy dynamics and power. Thus every numerical controlled axis of a machine tool or robot that means every feed movement needs at least one position sensor. Since the feed movement in a machine tool eg the tool .
