Collision Avoidance for a SCARA Robot on Construction Sites

Autonomous robots on construction sites are designed with the objective to take over time-consuming tasks while also relieving human construction workers. However, to operate safely, they must reliably detect obstacles and avoid collisions. The proposed approach targets this problem for a SCARA-like granular-fill insulation distributing robot, using ultrasonic distance sensors. Mounting the sensors on the robot's links allows to observe the workspace at a sufficient rate and accuracy. A microcontroller reads out the sensor data and transfers it to the PLC in charge. Furthermore, an efficient sensor error detection principle for the developed sensor suite is demonstrated. Experiments conducted in a laboratory environment prove the functionality of the system. Collision avoidance with various obstacles commonly found on construction sites is realized reliably over a multitude of test runs. The system dependably detects and reacts to obstacles of varying sizes and materials in a safety margin of 300mm within at least 160ms, sufficient for applications in building construction sites.