14 research outputs found
Multi-sensor Doppler radar for machine tool collision detection
Machine damage due to tool collisions is a widespread issue in milling
production. These collisions are typically caused by human errors. A solution
for this problem is proposed based on a low-complexity 24 GHz
continuous wave (CW) radar system. The developed monitoring system is able to
detect moving objects by evaluating the Doppler shift. It combines incoherent
information from several spatially distributed Doppler sensors and estimates
the distance between an object and the sensors. The specially designed
compact prototype contains up to five radar sensor modules and amplifiers yet
fits into the limited available space. In this first approach we concentrate
on the Doppler-based positioning of a single moving target. The recorded
signals are preprocessed in order to remove noise and interference from the
machinery hall. We conducted and processed system measurements with this
prototype. The Doppler frequency estimation and the object position obtained
after signal conditioning and processing with the developed algorithm were in
good agreement with the reference coordinates provided by the machine's
control unit
Extended Kalman Doppler tracking and model determination for multi-sensor short-range radar
A tracking solution for collision avoidance in industrial machine tools based
on short-range millimeter-wave radar Doppler observations is presented. At
the core of the tracking algorithm there is an Extended Kalman Filter (EKF) that provides dynamic estimation and localization in real-time. The
underlying sensor platform consists of several homodyne continuous wave (CW) radar modules. Based on In-phase-Quadrature (IQ) processing and
down-conversion, they provide only Doppler shift information about the
observed target. Localization with Doppler shift estimates is a nonlinear
problem that needs to be linearized before the linear KF can be applied.
The accuracy of state estimation depends highly on the introduced
linearization errors, the initialization and the models that represent the
true physics as well as the stochastic properties.<br><br>
The important issue of filter consistency is addressed and an initialization
procedure based on data fitting and maximum likelihood estimation is
suggested. Models for both, measurement and process noise are developed.
Tracking results from typical three-dimensional courses of movement at short
distances in front of a multi-sensor radar platform are presented