Hierarchical fuzzy control based on spatial posture for a support-tracked type in-pipe robot

Autonomous movement is important for the in-pipe robot. Because of the complex environment of the pipe, traditional control methods such as proportional–integral–derivative (PID) can not be used to implement autonomous movement for the support-tracked type in-pipe robot. A hierarchical fuzzy controller is proposed in this paper, which consists of fuzzy steering control and fuzzy posture control. The fuzzy steering control is utilized to control the robot’s turning movement in the elbow pipe, while the fuzzy posture control is used to adjust the posture of the robot in the straight pipe. The robot’s posture will periodically coincide after every 120°, when the robot rotates around its central axis. The symmetry is helpful to reduce the 12 × 7 × 7 three-dimensional fuzzy posture control rule table to five 7 × 7 two-dimensional fuzzy rule tables. A support-tracked in-pipe robot prototype is developed to verify the performance of the hierarchical fuzzy controller. Simulation and experimental results show that the robot with the controller could successfully pass the 45° and 90° elbows with a smaller change of posture compared to the case without the controller. As the robot with the controller could pass the elbow without obvious posture change, the proposed controller can be utilized to implement autonomous movement of an in-pipe robot. Video

Modeling of Natural Ventilation Using a Hierarchical Fuzzy Control System for a New Energy-Saving Solar Greenhouse

Natural ventilation as part of a greenhouse environment control system can save energy, reduce pollution, and cut the costs of production. Many studies have used the energy balance method to model greenhouse environments and calculate the rates of ventilation needed to control them. However, the efficacy of this method is influenced by many factors. There are often many parameters in the energy balance model, related to the greenhouse structure, crop growth, and climate. Thus, the effectiveness and applicability of greenhouse ventilation systems based on energy balance can be compromised. Here, we study a hierarchical fuzzy control method and use simple fuzzy logic controllers to control the coordination and opening angles of a new energy-saving solar greenhouse roof and sidewall ventilation. This design reduces the complexity of the fuzzy rule base and the fuzzy subsystem related to the physical model, therefore making it easy to design and build. The system uses the fuzzy tool in the Matlab environment, enabling a quick design, and the fuzzy inference engine fis.c file (Fuzzy Inference System) to load the design results into the fuzzy control system, thus making the modification and maintenance of the system easier. The experimental data showed that the new hierarchical fuzzy control reduced temperature fluctuations and maintained temperature closer to desired temperature than a non-fuzzy control method. Moreover, this method can also be easily used to control other equipment in the greenhouse. Keywords: Hierarchical fuzzy model, Natural ventilation, Matlab, Solar greenhouse.