In the spraying industry, the trajectory planning is the core part of industrial robots because model variety and shape of work-piece surfaces become the core problem of trajectory generation. In order to quickly plan the spraying trajectory and process of industrial robots, this paper proposes a trajectory generation model based on k-means mean clustering and a fitting optimization method based on NURBS curve. The model obtains point cloud data, classifies and iterates the curvature according to the curvature threshold, and then plans the trajectory of each region according to the height and Angle of the spray gun in the spraying experience base to obtain the regional spraying trajectory points. The NURBS curve is used to optimize the trajectory. In addition, on the basis of the above, a method based on infrared imaging target detection technology is proposed to quickly identify the acquired trajectory information and convert it to the coordinate system suitable for spraying robot operation.

With the rapid explosion of data volume from mobile networks, edge caching has received significant attentions as an efficient approach to boost content delivery efficiency by bringing contents near users. In this article, cache-enabled heterogeneous networks (HetNets) considering the limited backhaul are analyzed with the aid of the stochastic geometry approach. A hybrid caching policy, in which the most popular contents are cached in the macro BSs tier with the deterministic caching strategy and the less popular contents are cached in the helpers tier with the probabilistic caching strategy, is proposed. Correspondingly, the content-centric association strategy is designed based on the comprehensive state of the access link, the cache and the backhaul link. Under the hybrid caching policy, new analytical results for successful content delivery probability, average successful delivery rate and energy efficiency are derived in the general scenario, the interference-limited scenario and the mean load scenario. The simulation results show that the proposed caching policy outperforms the most popular caching policy in HetNets with the limited backhaul. The performance gain is dramatically improved when the content popularity is less skewed, the cache capacity is sufficient and the helper density is relatively large. Furthermore, it is confirmed that there exists an optimal helper density to maximize the energy efficiency of the cache-enabled HetNets.

The communication channel is becoming more and more complicated, which increases difficulty of signal detection of the spectrum band. The performance of signal detection is degraded due to the frequency shift and fading of the doppler multipath channel. In this paper the weak signal detection based on cyclostationary property is considered and energy detection of cyclic-autocorrelation function (EDCAF) is proposed to detect the primary signal in doppler multipath channel. Simulation shows that the proposed method has better performance than that of other detection algorithms. Furthermore, the EDCAF is simple and direct, which is feasible for cognitive radio networks.

Disseminating spatial data and delivering GIS functionality via Internet has become common-place. However, building a popular online mapping services system that serving staggering amount of Internet users remains as a challenge. This paper describes the Internet mapping architecture based on cluster technology enhanced by mapping-oriented load balancing algorithm.