160-GHz Radar Proximity Sensor With Distributed and Flexible Antennas for Collaborative Robots

There is a growing demand for collaborative robots in order to improve the efficiency of industrial processes and to push Industry 4.0 forward. The challenge for these robots is the compliance of the safety regulations to protect human workers from injuries. Therefore, a large number of sensors for the close range (several centimeters up to some meters) around the robot are needed. For a protective cover around the robotic arms all sensors must cooperate and process their information together. This paper presents a close range proximity sensor based on a 160-GHz radar MMIC with a transition to two flexible dielectric waveguides. On the low-loss waveguides, leaky-wave antennas with a large field of view are distributed. This reduces the number of sensors and achieves a coverage area for one sensor of more than $\mathrm {2200~ \text {c} \text {m} ^{2}}$ for a distance of 30 cm. For distances below 30 cm the sensor has blind areas. However, the expected extended targets like body parts can still be detected and the proximity sensor will stop the robot in the danger area. Additionally, the flexible waveguide offers the possibility to place the antennas almost arbitrarily around the robotic arm. For a single target scenario it is even possible to determine the target position by multilateration with only one receive channel.