3D measurement sensor system for rough terrain mobile robots

Purpose ‐ The purpose of this paper is to propose a sensor system and its measuring strategy. The proposed system is regarded as a total system of a robot and a sensor. It can make full use of a robot's degrees of freedom (DOF) for not only locomotion but also sensing. Design/methodology/approach ‐ The sensor system is composed of a connected crawler robot and a simple sensor unit. The connected crawler robot consists of five connected flat crawler stages; each stage has motor-driven crawlers on its left and right side. The left and right crawlers are driven by motors independently. The five stages are connected by motor-driven joints, which can be arbitrarily controlled. The sensor unit is made up of a position sensitive detector and two active joints. Generally, all sensors have a measurable range limit. If the object is bigger than the measurable range, it is impossible to recognize the object's shape. However, this sensor system compensates for this problem due to a combination of sensor unit's motion and robot's motion. The robot's DOF are ordinarily used for going forward. In this moving, if the sensor detects a bigger object than its measurable range, the robot's DOF are used for lifting up sensor unit. Therefore, the robot's DOF are exploited for both locomotion and scanning. Findings ‐ The experiment was done by using proposed measurement strategies. Through this experiment, the maximum distance error was 0.037?m, that fulfils the required sensor's accuracy. This experiment confirmed that the measurable range was expanded by making full use of the robot's DOF and sensor's DOF. The robot's DOF which is ordinarily used for moving is applicable to expand measurable range. Therefore, it was possible to expand measurable range by making full use of the robot's DOF without mounting extra equipments or mechanism on the robot. Hence, it was enable to exert enough sensing function even if the sensor's structures and robot's structure are also simple, by using both the robot and the sensor's functions effectively and simultaneously. Originality/value ‐ General existing mobile robot systems have both mobile function and sensing function, they are completely separate. However, this sensor system is regarded as a total system of robot and sensor. It can make full use of a robot's DOF for not only locomotion but also sensing. This sensor system makes full use of a robot's DOF. Hence, it is enable to exert enough sensing function even if the sensor's structure and robot's structure are also simple. There is originality on this point.