In this paper, a novel stochastic optimal control method based on a stochastic model predictive control framework is proposed. The proposed method is formulated as mixed integer linear programming using statistical information and binary variables, which allows us to obtain the deterministic optimization problem from the stochastic optimization problem. Moreover, it does not need to assume a class of stochastic process such as white noise. This paper also shows that the present method can be applied to real stochastic systems that have only low computation specifications, through an example problem on online optimal mode management for a Plug-in Hybrid Vehicle. The usefulness of the method is demonstrated via a detailed numerical simulator named ADVISOR, and the results show that the amount of the fuel consumption is reduced and computation time is small enough for the problem.
Visual object tracking techniques are widely required by many vision applications. The color-based particle filter is known as one of useful methods for robust object tracking. However, the conventional color-based particle filter has a problem that it is not robust against self-occlusion. Self-occlusion occurs when a part of a target object is hidden by itself from a camera. When the target object moves or rotates, a part of the target disappears because the self-occlusion occurs and other part appears because the self-occlusion is resolved. The conventional color-based particle filter often fails to follow such a change of the target's appearance due to self-occlusion during the tracking process. In this paper, we propose a novel method for robust object tracking against the self-occlusion. The proposed method is based on the color-based particle filter, and it also uses depth information obtained by an RGB-D camera. When the self-occlusion occurs and the target's appearance changes, the proposed method extracts a region for the target object in the input image by the graph cuts based on depth information. However, this process often includes unnecessary regions, especially when some objects are close to the target. Then, the proposed method distinguishes the region for the target from unnecessary ones by investigating expanse of colors around the target. Therefore, the target model is correctly updated and the robust tracking is achieved. In order to verify the effectiveness of the proposed method, we carried out an experiment to compare the proposed method with the conventional one. Experimental results show that the proposed method works well.
For a control system operated by a human, human assist control to avoid accidents attracts much attention in recent years. In this paper, we propose a novel definition of a control barrier function and a human assist control law with the proposed control barrier function. This paper proves that the proposed human assist control guarantees the safety of the control system under the human operation. Moreover, the paper shows that the control is the minimum of all safe inputs and a continuous function of both state and human inputs. The effectiveness of the proposed method is confirmed by computer simulation and experiments of a four-wheeled mobile robot.
The thermal flow sensors are widely accepted in semiconductor industry because they can measure the flow rate of various types of gases based on each reference flow data. However, it is difficult to obtain such data for some reactive gases because due to corrosion of the gas measurement system. To overcome such difficulties, this paper proposes a multi-domain physical model of the thermal based flow sensor taking account of both electrical and thermal characteristics. The proposed model is analyzable based on the physical properties of the target gas, and its validity is demonstrated through comparison with experimental data.
In the steel industry, the role of the slab yard which is the intermediate process between the steelmaking and the rolling is becoming significant. By promoting the logistics from steelmaking to rolling, we can reduce the cost of fuel to reheating and improve the productivity. In the slab yard, slabs are expected to be sorted into stacks as little transport as possible and as high as possible. It is the slab stacking problem. In this paper, we find a slab stacking problem has the similar structure with the vertex coloring problem. There are some kinds of formulations for the vertex coloring problem. We show the fractional programming formulation and the asymmetric representatives formulation for the vertex coloring problem are useful for this problem. Finally we prove the efficiency of those methods compared with the conventional method by the computational experiment with the real operational data.
The number of residents in care facilities has increased with the increase in the number of elderly people in Japan. In the previous study, we developed a device equipped an apron with an accelerometer, and the iAcc value of the device during swallowing was significantly larger than that during rest in both young and elderly people. However, there is still left a problem of the motion artifact of the subjects. In this study, we proposed a signal processing method which is robust to the motion artifact of the subjects. The iAcc value of X axis during chewing was larger than that of Z axis in the all young and four fifths in the elderly people. The iAcc value of Z axis during swallowing was larger than that of X axis in the all young and four fifths in the elderly people. The iAcc values obtained from the proposed method were robust to the motion artifact of the subjects.
The authors have researched into path-planning of Unmanned Aerial Vehicles (UAVs) for automatic visual inspection system. It is a important function for inspections to ensure accuracy and consider efficiency of operations in data-gathering to detect anomalies. In this research, it is assumed that the 3D model of a target facility, required accuracy of gathering data and specs of instruments are given. Under this assumption, in our previous method, the measuring positions were calculated systematically, which means the positions of UAVs to gather the accurate data of the target facility were calculated. Then, by setting the measuring positions as waypoints of UAVs, a general path-planning method was used to plan the flight path which is appropriate for visual inspection. Although accuracy of operations was ensured, efficiency could not be considered sufficiently. This paper presents a new path-planning method ensuring accuracy and considering efficiency. In our new method, the triangular polygons for shape description of the 3D model are reconstructed using k-means++ clustering in order to ensure accuracy and consider efficiency in calculation of measuring positions. The proposed method is compared with the previous method through computer simulations using the 3D models of two typical bridges: a girder bridge and an arch bridge.