Partial automation of a concrete spraying device for mining and tunnel construction
In the age of industry 4.0 and the progressive automation of machines and vehicles, concrete spraying processes in mining and tunnelling are still carried out manually today. The concrete spraying vehicle is usually controlled manually by an operator using a remote control. The shotcrete application and the quality control are subject to the subjective impression of the operator. The operator decides by eye how much concrete has to be applied at which point of the tunnel ceiling and also whether enough concrete has been applied. Under the usual working conditions in tunnel construction (operator is behind the vehicle, concrete mist, etc.) and a layer thickness of approx. 10 cm with a permissible deviation of a few centimetres, the quality of the working process cannot be guaranteed continuously in this way.
In order to support the operator and increase the success of the process and quality control, GTA Maschinensysteme GmbH, together with the Institute for Advanced Mining Technologies at RWTH Aachen University, developed a new type of concrete spraying vehicle. The special feature of this vehicle is that it is equipped with various sensors that support and improve the various work steps. The work steps are detailed:
- Initial recording of the tunnel profile
Application of the shotcrete slab
Final quality control
Using laser scanning technology, the profile of the ridge or tunnel surface is first recorded before work begins. The concrete spraying process is then monitored. By correlating the nozzle position with the concrete flow rate, virtual layer thickness monitoring can be realized. The position of the boom arm, on which the laser scanner and the concrete spray nozzle are located, is determined with the aid of Ultra-Wideband (UWB) radio technology and inertial navigation (INS). By means of clever sensor data fusion, the end of the boom arm can be precisely located.
Finally, a second laser scan can be used to check the success of the work on the finished concrete slab. The documentation of the laser scan of the current driving or tunnel section can also be used to prove the quality of the work.
The development of the localization technology consisting of UWB and INS including the skilful sensor data fusion was carried out at the Institute Advanced Mining Technologies. In addition, the laser scanner technology and the associated software were developed at AMT. Special attention was paid to the algorithms and time synchronization of the UWB modules.
The partner, GTA Maschinensysteme GmbH from Hamminkeln, developed the low-vibration support arm to enable the use of the laser scanner technology. Furthermore, the virtual monitoring of the concrete spraying process was developed by the expertise of GTA Maschinensysteme GmbH.