Optimal turning trajectory planning of an LHD based on a bidimensional search

To solve the problem of smooth turning of an autonomous underground load-haul-dump loader (LHD), in this paper, a method for turning trajectory planning of an LHD was proposed. This method is a type of hybrid trajectory planning method based on a bidimensional search. According to the characteristic of the problem, the longitudinal and lateral decomposition method was applied, and the basic algorithms are a sampling method and an optimization algorithm. The algorithm consists of three main steps that are parameter generation of the optimal model based on a bidimensional search strategy, trajectory calculation based on quadratic programming models, and determination of the optimal trajectory based on an articulated angle and collision avoidance constraints check. The novelty of this method lies in the proposed two-dimensional search strategy and trajectory optimization models. The two dimensions are the driving time and mileage of the trajectory in the turning area; the trajectory optimization model is based on the quadratic programming that can quickly generate the optimal trajectory in both dimensions according to the turning area entering speed and position of the LHD. This trajectory planning method is simple in structure and easy to implement. Moreover, it can satisfy the real-time requirement of the controller on the trajectory generation time by adjusting the key parameters. Based on the characteristics of the trajectory planning method, it is not only suitable for real-time trajectory planning but can also provide basic constraints for intelligent control and optimal scheduling of intelligent mines. A series of case studies was conducted to show the effectiveness and superiority of the proposed method. The case studies show that the optimal trajectories according to different entering speeds and positions can be obtained through the proposed method. A prototype experiment was performed to show the feasibility of the proposed trajectory planning method. This method generates trajectories that are easy to track and control because the velocity, articulated angle, and angular velocity change gently.