Inspired by the mechanisms of idiotypic network hypothesis and ant finding food, a hybrid ant colony and immune network algorithm (AC-INA) for motion planning is presented. Taking the environment surrounding the robot and robot action as antigen and antibody respectively, an artificial immune network is constructed through the stimulation and suppression between the antigen and antibody, and the antibody network is searched using improved ant colony algorithm (ACA) with pseudo-random-proportional rule and super excellent ant colony optimization strategy. To further accelerate the convergence speed of AC-INA and realize the optimal dynamic obstacle avoidance, an improved adaptive artificial potential field (AAPF) method is provided by constructing new repulsive potential field on the basis of the relative position and velocity between the robot and obstacle. Taking the planning results of AAPF method as the prior knowledge, the initial instruction definition of new antibody is initialized through vaccine extraction and inoculation. During the motion planning, once the robot meets with moving obstacles, the AAPF method is used for the optimal dynamic obstacle avoidance. The simulation results indicate that the proposed algorithm is characterized by good convergence property, strong planning ability, selforganizing, self-learning, and optimal obstacle avoidance in dynamic environments. The experiment in known indoor environment verifies the validity of AAPF-based AC-INA, too.
To solve the trajectory tracking of service robots in autonomous navigation, a novel self-tuning proportional–integral–derivative controller identified by a radial basis function neural network (radial basis function proportional–integral–derivative controller) is presented. The error regarding the lateral distance and directional deviation angle of the service robot is taken as the control deviation in the radial basis function proportional–integral–derivative controller. During the trajectory tracking, the proportional–integral–derivative parameters of the proposed controller can be adaptively adjusted online by using a radial basis function identification network. To keep the tracking effect of the service robot from being influenced by the initial values (i.e. the initial proportional–integral–derivative parameters and their learning rates) of the radial basis function proportional–integral–derivative controller, a chaos small-world algorithm is introduced to optimize them. The simulation results of the trajectory tracking show that the proposed controller can realize online adjustment of proportional–integral–derivative parameters according to actual conditions of service robots and is characterized by strong noise and disturbance suppression capability. The optimization of the radial basis function network controller based on chaos small-world algorithm can further improve the trajectory tracking precision. Additionally, experiments in the indoor environment further support the validity of the proposed radial basis function proportional–integral–derivative controller for trajectory tracking of service robots.
Objective: This meta-analysis is the fi rst to evaluate the associations of circulating and dietary intake of vitamin D with risk of risk of renal cell carcinoma (RCC). Our fi ndings showed that higher circulating vitamin D level and dietary vitamin D intake were associated with a reduced risk of RCC. The possible explanation might be attributed to the anti-infl ammatory effect, inhibiting cell proliferation, inducing cell differentiation and apoptosis. Materials and Methods: We searched the MEDLINE, EMBASE, and Scopus databases from their inception points through December 2018 for observational studies. The pooled relative risks (RRs) with corresponding 95% CIs were calculated using randomeffects or fi xed-effects models. The Newcastle-Ottawa scale was employed to assess the quality of the included studies. Results: A total of 9 publications were included in this meta-analysis. An overall analysis of the highest versus lowest intake levels revealed that circulating vitamin D level was protectively associated with risk of RCC 0.76 (95% CI: 0.64-0.89, P=0.001), with no evidence of heterogeneity (I2=38.8%, P=0.162). In addition, dietary vitamin D intake was associated with a reduced risk of RCC (RR: 0.86; 95% CI: 75-0.99, P=0.030). Statistical heterogeneity was not identifi ed (I2=28.8%, P=0.199). Subgroup analyses results showed the gender differences, and the associations were signifi cant in results with women participants (RR: 0.70; 95% CI: 0.55-0.88) and case-control studies (RR: 0.80, 95% CI: 0.67-0.95).
Conclusion:Higher circulating vitamin D level and higher dietary vitamin D intake both might be associated with a reduced risk of RCC. Further high-quality randomized controlled trials are required in the future to confi rm our results.
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