The attitude of a satellite is usually controlled by more than 3 reaction wheels. However, to prepare an accident of these wheels, it is important to consider the attitude control by 2 wheels. Especially, when the initial angular momentum of the system is not zero, the system has a drift term and it is impossible to control to arbitrary attitude. Therefore, the purpose of this research is to control the direction of a satellite's communication antenna to the target direction. To achieve this purpose, we introduce an idea of equal ratio divergence with Rodrigues parameters. This idea is based on the feature of Rodrigues parameters: By diverging Rodrigues parameters with keeping some ratio, the attitude converges to specified value corresponding to the ratio. To use this feature,we transform the system into a time-state control form. By stabilizing a time-state control form, the antenna achieves the target conditions. Moreover, controllable attitudes become clear by analyzing this method. In addition, proposed method can also works to control the attitude arbitrarily when the angular momentum is zero. Note that this method can be used only when one of the wheel is set along the antenna.
To promote more effective use of the thermal storage systems, optimal operation scheduling of heat source facilities with thermal load prediction is indispensable. Although conventional scheduling method considered the predicted load as a true value, load prediction error is inescapable and could lead to deterioration of actual operational cost. In this paper we propose a robust optimal operation method to reduce negative effect of the prediction uncertainty. The effectiveness of the proposed method is evaluated with the simulation model describing the actual building HVAC (Heating, Ventilating and Air-Conditioning) systems.
In an indoor area with clear route for movement, an electric wheelchair should run automatically while avoiding obstacles and stopping at hallway intersections to wait for user input. We previously proposed a path control method for vehicles using a time-state control form with rototranslational coordinate transformations. Here, we propose a path control method with a disturbance observer for electric wheelchairs using an intersection recognition technique. Using labeling processing, the least squares method, and other processes, the intersection recognition technique estimates the center of intersections from laser rangefinder data, and the disturbance observer reduces the influence of the driver’s weight. These methods are combined and applied to a remodeled electric wheelchair, and its effectiveness is confirmed by experiments.
A new algorithm is proposed to estimate parameters of SISO system. The proposed method is applied to the errors-in-variables (EIV) models. The algorithm uses an iterative calculation and it consists of two parts. One part is the estimation of the system parameters using the variances of errors. The other part is the estimation of the variances of errors using the system parameters. The estimation of the system parameters is one of the least squares identification algorithms using eigenvector. The variances of errors is estimated by solving linear simultaneous equations derived from the difference equation of the system. An experimental result and some simulations show the effectiveness of the proposed method. The proposed method is simple and easy to be understood. Therefore, it is easy to adopt the proposed method in practical system.
An improved adaptive trajectory control of a rigid link robot manipulator in which Middleton’s control input and the adaptation law with a certain smooth projection algorithm to ensure the positive definiteness of estimated inertia matrix are used was proposed by Sawada. However, it cannot be applied when the manipulator is composed of the links whose length are extremely different with each and the tip load varies significantly. Using prior knowledge about upper bound of tip load and range of robot arm,manipulator’s parameters without tip load, we propose a method to extend the class of robot arm that can be applied by designing the special convex set of adjustable parameters in which the positive definiteness of the estimated inertia matrix is ensured and true parameters are contained.