A Method for Supervisory Control of Manipulator of Underwater Vehicle

Abstract

A novel method for supervisory control of multilink manipulators mounted on underwater vehicles is considered. This method is designed to significantly increase the level of automation of manipulative operations, by the building of motion trajectories for a manipulator working tool along the surfaces of work objects on the basis of target indications given by the operator. This is achieved as follows: The operator targets the camera (with changeable spatial orientation of optical axis) mounted on the vehicle at the work object, and uses it to set one or more working point on the selected object. The geometric shape of the object in the work area is determined using clouds of points obtained from the technical vision system. Depending on the manipulative task set, the spatial motion trajectories and the orientation of the manipulator working tool are automatically set using the spatial coordinates of these points lying on the work object surfaces. The designed method was implemented in the C++ programming language. A graphical interface has also been created that provides rapid testing of the accuracy of overlaying the planned trajectories on the mathematically described surface of a work object. Supervisory control of an underwater manipulator was successfully simulated in the V-REP environment.

Development of a Control System for Multilink Manipulators on Unmanned Underwater Vehicles Dynamically Positioned over Seafloor Objects

“…As compared to the method [25], which uses point clouds to identify objects in a similar way, the synthesized system makes it possible to perform operations that do not require an operator's intervention. A significant advantage of the system is also the opportunity to use the underwater acoustic channel of communication with the UUV to transmit to the operator the information necessary for assessing the accuracy of object identification and building the MM trajectories to the operator.…”

“…As a result of the intersections, sets of points С 𝑖 and С 𝑖 ′ are formed, which are the projections of the test trajectory onto the surfaces of the actual and simulated objects, respectively. The coordinates of the points С 𝑖 and С 𝑖 ′ can be calculated using the modified Möller-Trumbore algorithm [25] in the following form:…”

“…The coordinates of the points C i and C i can be calculated using the modified Möller-Trumbore algorithm [25] in the following form:…”

“…To build trajectories of movements of the MM working tool, special methods are required for various manipulative operations over the bottom surface and certain objects with already known shapes [8,18,[23][24][25]. These methods take into account the positions of the object's surface, the MM's working zone and the angle of approach to the object relative to each other.…”

“…These methods take into account the positions of the object's surface, the MM's working zone and the angle of approach to the object relative to each other. In particular, the method [25] allows building complex spatial trajectories of the MM working tool on the object surface using point clouds obtained from MVS. However, it is unsuitable for automated manipulations, since the type of trajectory and its location on the object are determined by the operator and set by pointing the UUV camera optical axis.…”