Monitored and controlled underwater scissor arm manipulator using Pixy camera

Underwater vehicle manipulator system (UVMS) generally consists of a camera unit and robotic manipulator. Its main function is to replace human work in underwater manipulation tasks. Most commercially available manipulators are not designed for autonomous underwater vehicle (AUV) because the vehicle does not have sufficient power supply to drive these manipulators which are electro-hydraulically driven. A proposed solution is to invest in development of low power underwater manipulator to deepen studies in AUV. Thus, this research has an objective of developing an underwater manipulator for small scale AUV. In this research, the manipulator is used in an object recovery task. An acrylic scissor arm which is electro-mechanically driven is used as manipulator in this research. Permanent magnets are used as its end effector. A Pixy CMUcam5 vision sensor is paired with this manipulator to navigate the AUV and control the manipulator. The usage of planar pressure housing helps in reducing light refraction effect of underwater environment that may affect the sensor’s accuracy. From the simulation done using Solid Works, it is found out that type 316L stainless steel is the best choice for the manipulator developed. To evaluate the performance of the UVMS developed, a series of tests are carried out. Based on the results obtained, it is known that the system has high speed and consistency with minimum time delay between input and output. As long as an object has distinct colour signature from its background and its surrounding is clear and well illuminated, the Pixy vision sensor can detect that object regardless of the distance between the sensor and the object.