Surface vibration tactile feedback is capable of conveying various semantic information to humans via handheld electronic devices, such as smartphones, touch panels, and game controllers. However, covering the entire contacting surface of the device with a dense arrangement of actuators can affect its normal use. Determining how to produce desired vibration patterns at any contact point with only a few sparse actuators deployed on the surface of the handheld device remains a significant challenge. In this work, we develop a tactile feedback board in the size of a smartphone with only five actuators, and achieve the precise production of vibration patterns that can focus at any desired position on the board. Specifically, we investigate the vibration characteristics of a single passive coil actuator and construct its vibration pattern model for any position on the feedback board surface. Optimal phase and amplitude modulation, determined using the simulated annealing algorithm, is employed with five actuators in a sparse array. The vibration patterns from all actuators are superimposed linearly to synthetically generate different onboard vibration energy distributions for tactile sensing. Experiments demonstrated that point-wise vibration pattern production on our tactile board achieved an average level of about 0.9 in the Structural Similarity Index Measure (SSIM) evaluation, when compared to the ideal single-point-focused target vibration pattern. Four point-wise patterns focused on the top, bottom, left, and right parts of the tactile board were applied, to guide continuous directional movements without visual assistance, which shows significant implications for machine-assisted cognition based on vibration tactile feedback.

As one technique for autonomous driving, vehicular networks can achieve high efficiency with vehicle-and-infrastructure cooperation, bringing high safety and many value-added services. To achieve higher communication efficiency, much effort has been done to cope with the resource allocation issues for vehicular networks. Nevertheless, due to the strong nonconvexity and nonlinearity, the classical joint resource allocation problem in vehicular networks is typically NP-hard. The multiagent reinforcement learning (MARL) has emerged as a promising solution to tackle this challenge but its stability and scalability are not satisfactory when the amount of vehicles gets increased. In this article, we mainly investigate the issue of joint spectrum and power allocation in vehicular communication networks, and carefully consider the interactions between the vehicles and environment by incorporating the cooperative stochastic game theory with MARL, named complete-game MARL (CG-MARL), to achieve a better convergence and stability with the theoretical computational complexity$\mathcal {O}(n^{N})$with$n$denoting the dimension of action space and$N$denoting the number of V2X Vehicular. Furthermore, the mean-field game (MFG) theory is employed to further enhance the MARL for decreasing the horrible computing resource consumption caused by the CG-MARL to$\mathcal {O}(n^{2})$while maintaining an approximate performance. The simulation results demonstrate that the proposed mean-field-aided MARL (MF-MARL) for vehicular network resource allocation can achieve 95% near-optimal performance with much lower complexity, which indicates its significant potentials in the scenarios with massive and dense vehicles.