Purpose: With the dramatically increasing number of substations, robots are expected to inspect equipment in the power industry. However, a traditional robotic system cannot work stably because of the strong electromagnetic field in substation. The purpose of this paper is to present a robust and stable robotic system for inspecting the substation equipment without the involvement of workers. Design/methodology/approach: The paper presents in detail a robotic system that consists of a monitor center and a robot. With the monitor center, the workers could send inspection tasks and monitor status of the robot timely. Once a fault is detected, the alarm message will flash immediately to remind the workers. The patrol mode of the robot comprises teleoperation, regular inspection, special inspection and a key return mode. The robot only relies on a low-cost magnetic sensor for lateral positioning and radio frequency identification technology for longitudinal positioning when working under patrol mode. At each stop point, the substation equipment can be recognized quickly through accurate matching with the template image stored in the database. Findings: It is shown that the robot could work efficiently and reliably in power substations. The positioning error is proved to be within 5 mm, compared to that of 20 cm by implementing integrated global positioning system-dead reckoning navigation. Because of the high positioning accuracy, it is much easier to recognize the substation equipment. It is observed that nearly 99 per cent of equipments can be recognized. Research limitations/implications: The proposed robotic system is tested in a simple substation environment. While the proposed system shows satisfactory positioning results, further studies considering changeable weather condition will focus on improving the equipment recognition rate in such environment, such as rainy, snowy and strong sunlight. Practical implications: The key contribution of this paper is that it provides a robotic system to inspect substation equipment instead of workers, to improve working efficiency and to reduce manpower cost. Originality/value: This paper presents a robotic system to inspect substation equipment instead of workers. Four patrol modes are designed to meet the inspection demand. Comparing with the previous robotic systems, this system contributes to higher position accuracy and higher equipment recognition rate.

Navigation is necessary for autonomous mobile robots that need to track the roads in outdoor environments. These functions could be achieved by fusing data from costly sensors, such as GPS/IMU, lasers and cameras. In this paper, we propose a novel method for road detection and road following without prior knowledge, which is more suitable with small single lane roads. The proposed system consists of a road detection system and road tracking system. A color-based road detector and a texture line detector are designed separately and fused to track the target in the road detection system. The top middle area of the road detection result is regarded as the road-following target and is delivered to the road tracking system for the robot. The road tracking system maps the tracking position in camera coordinates to position in world coordinates, which is used to calculate the control commands by the traditional tracking controllers. The robustness of the system is enhanced with the development of an Unscented Kalman Filter (UKF). The UKF estimates the best road borders from the measurement and presents a smooth road transition between frame to frame, especially in situations such as occlusion or discontinuous roads. The system is tested to achieve a recognition rate of about 98.7% under regular illumination conditions and with minimal road-following error within a variety of environments under various lighting conditions.

Objective: The objective of this study was to investigate the effects of inverted photoperiods on the blood pressure and carotid arteries in spontaneously hypertensive rats (SHRs) and Wistar–Kyoto (WKY) rats (homologous control group). Methods and results: This study used two inverted photoperiods [inverted light:dark (ILD)16 : 8 and ILD12 : 12] to create the model. A total of 27 male SHR and 27 male WKY rats were randomly divided into six groups (nine rats per group): SHR (LD12 : 12), SHR (ILD16 : 8), SHR (ILD12 : 12), WKY (LD12 : 12), WKY (ILD16 : 8) and WKY (ILD12 : 12). We recorded the trajectory of the activity rhythm of the rats and performed carotid vascular ultrasound examination, MRI (arterial spin labelling) analysis and carotid biopsy. The results showed that inverted photoperiods increased the blood pressure, carotid intima-media thickness, resistance index and blood flow velocity. In addition, inverted photoperiods led to the development of carotid arterial thrombosis, significantly reduced cerebral blood flow and increased the number of collagen fibres. Moreover, it increased the expression of angiotensin receptor and low-density lipoprotein receptor in the carotid arteries, leading to decreased expression of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase and nitric oxide synthase. Inverted photoperiods induced the formation of atherosclerotic plaque. Multiple results of SHR were worse than those of WKY rats. Conclusion: Taken together, inverted photoperiods can produce a series of adverse consequences on blood pressure and carotid arteries. Hypertension can aggravate the adverse effects of inverted photoperiods.