Collision Avoidance System for the RP Survey and Visual Inspection Train in the CERN Large Hadron Collider

We present a working prototype of a low-cost collision avoidance system for the retractable Radio-Protection (RP) arm, to be mounted on the Train Inspection Monorail (TIM) which is located in the European Organization for Nuclear Research (CERN)'s Large Hadron Collider (LHC) tunnel. Such a system is needed to permit the safe movement of the TIM with personnel present in the tunnel while the RP arm is extended to allow on-board sensors to take radiation measurements. The prototype used a series of eight TeraRanger One (TR1) Infrared (IR) Time-of-Flight (ToF) sensors to take distance measurements of the tunnel floor and overlying obstacles. A real-time system was then designed and deployed on the microcontroller mounted on the TeraRanger Hub (TRH). Sensor characterisation tests were also performed on the TR1 sensors to determine their performance and also allowed for calibration to be performed to improve the measurement accuracy for different materials.