Patterns of Seed Penetration by the Date Stone Beetle Coccotrypes dactyliperda (Coleoptera, Curculionidae, Scolytinae)

The cryptic spermatophagus date stone beetle (Coccotrypes dactyliperda Fabricius, 1801) tunnels into palm seeds for oviposition and subsequent establishment of brood galleries. Based on behavioral observations this paper describes the biomechanical and gustatory parameters that govern the initial excavation of the tunnels and the subsequent establishment of the galleries. When tunneling into Canary Islands Date Palm (Phoenix canariensis Chabaud, 1882) seeds, penetration principally occurs at the dorsal side of the seed, in particular the groove, which allows the beetle to gain the required traction. Tunneling is executed in a circular fashion with clockwise or counter-clockwise repositioning in approximately one-eighth to one-quarter turns. Biomechanically, the three pairs of legs provide thrust (hind legs), pivoting (mid legs), and lateral control (fore legs). Gustatory cues, the nature of which remains unclear at this point, prevent the beetle from tunneling through to the other side.

The taxi function

<p>This paper investigates the lane keeping control and the lateral control of autonomous ground vehicles, robots or the like considering the road agency formation unit (RAFU) functions. A strategy based knowing the real position of several points of the trajectory is proposed to achieve the lateral control purpose and maintain the lane keeping errors within the prescribed performance boundaries. The RAFU functions are applied to achieve these goals. The stability of these functions, their applicability to approach any arbitrary trajectory and the easy control of the possible error made on the approximation are useful advantages in practice.</p>

Robust Prescribed Performance Control of Uncertain Vehicle Lateral System under State Constraints

In the study of the zero-error tracking control problem for vehicle lateral control systems under full-state constraints and nonparametric uncertainties, the zero-error tracking control problem is presented in this paper. A neural adaptive tracking control scheme is proposed by combining the error transformation of the vehicle lateral control system with the barrier Lyapunov function, which realizes that the tracking error of the vehicle lateral control converges to a prescribed compact set at a controllable or specified convergence rate in a specified finite time. The scheme has the following significant characteristics: 1) Based on the Nussbaum gain, the preset new energy finite-time control algorithm, the tracking error of the vehicle lateral control system with non-parametric uncertainty and external disturbance decreases to zero with t → ∞. In addition, it also has the control ability to cope with the presence or even unknown moment of inertia of the system. 2) Barrier Lyapunov function (BLF) ensures the bounded input of the neural network during the whole system envelope, and ensures the stable learning and approximation of the neural network. Furthermore, the bounded stability of the closed-loop system is proved by Lyapunov analysis. Finally, the effectiveness and superiority of the proposed control method are verified by simulation.