Autonomous and manual driving of a multiple turret system in extreme environment

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2021-6
Yerlikaya, Ümit
In this thesis, firstly two methods are developed to obtain multi-dimensional configuration space for path planning problems. In typical cases, the path planning problems are solved directly in the 3-D workspace. However, this method is inefficient in handling the robots with various geometrical and mechanical restrictions. To overcome these difficulties, path planning may be formalized and solved in a new space which is called configuration space. In the first method, the point clouds of all the bodies of the system and interaction of them are used. The second method is performed via using the clearance function of simulation software where the minimum distances between surfaces of bodies are simultaneously measured. A sample 4-D configuration space of a double-turret system is obtained in these two methods. As a result of this, the difference between these two ways is about 1% which depends on the point cloud density. Then, Instead of using the tedious process of manual positioning, an off-line path planning algorithm has been developed for military turrets to improve their accuracy and efficiency. In the scope of this research, an algorithm is proposed to search a path in three different types of configuration spaces which are rectangular, circular and torus shaped by providing three converging options named as fast, medium and optimum depending on the application. With the help of the proposed algorithm, 4-dimensional (D) path planning problem was realized as 2-D + 2-D by using 6 sequences and their options. The results obtained were simulated and no collision was observed between any bodies in these three options. Finally, with the help of new collision avoidance algorithm, all types of turrets can be driven more efficiently and safely according to the specified speed, acceleration and jerk limits. Since all possible worst scenarios are examined one by one, it is guaranteed that the algorithm provides collision free motion in both simulations and real-time tests. A configuration space where worst scenarios can occur is created for the performance measurement of the algorithm, and the same space is used in all tests. As a result of these tests, it is shown that there is no collision. Finally, by adding cascade position control loop, the departure from the starting point to the desired target point is achieved without any collision. The most important feature that distinguishes this algorithm from others is both speed and position can be controlled and during transition phase, the target point can be changed instantly. In addition, no target position is required for the system to move collision-free, only axis speed commands are sufficient. Since the algorithm does not intervene in the speed and torque loops in contrast to potential field-based methods, it can be added to ready-to-use systems by manipulating only the speed references.
Citation Formats
Ü. Yerlikaya, “Autonomous and manual driving of a multiple turret system in extreme environment,” Ph.D. - Doctoral Program, Middle East Technical University, 2021.