This assistance apparatus for upper limbs was developed for patients who can control their fingers but they cannot lift up their arms themselves, for example myopathy and hemiplegic patients. The purposes of the research in this paper are as follows: 1) to design the simple shaped arm and make the easy control system taking into account the practical use of patients, 2) to confirm the decrease of muscle activity while using the apparatus as an ADL assistance device for myopathy patients, 3) to grasp the tendency of the cerebral activity while using the apparatus as a Neuro-Rehabilitation assistance device for hemiplegic patients. The mechanism of assistance is utilizes the differential gears to lose the weight and volume of the mechanical arm. That enabled us to configure three motors to drive two DOFs (Degrees of freedom) for the shoulder and one DOF for the elbow around the root of the mechanical arm. The arm can lift up to 4 kgf (39.2 N) at the tip of the extended arm, and each maximum angle velocity is 1.57 rad/sec. This arm has two support trays, for wrist and upper arm. Each tray is equipped with a pressure sensor at the contact point to the user's arm, and by using the measured result of these four sensors, the control computer can learn the status of the user's arms. Furthermore, to realize other ADL (activities of daily living) motions (for instance, eating, writing, putting on making up, wiping his/her face, and so on) themselves, we proposed to control the device using the targeted posture map for the mechanical arm. At first, various desired or necessary postures of the assisted arms for the equipped person are determined, and each posture is defined as a control target. Next, each target (which is relatively close) is mutually connected, and the map can be accomplished. However, most of user can use the device without watching the map, because each target in the map is connected with the input signal of the same direction, which the user wants to move his/her hand. To be able to choose the appropriate input for each patient, various input interfaces, for example, joy-stick, push buttons, sensor glove using bending sensors, and so on, are equipped. The muscle activity while using the device was measured, and compared the %MVC data between using the device or not. As a result, the activity decreased up to 60%, and the effectiveness of this device could be confirmed. Finally, to expand the usage of this apparatus to encompass Neuro-Rehabilitation as well, the cerebral activity while using the device for rehabilitation with a near-infrared spectroscopy (NIRS) was measured. Then the data from using the device or not, and input motion from a third person were compared. By using this device, the cerebral activity decreased especially when the target motion was complex. However, when the subject input the motion themselves, the cerebral activity increased more than the data is input by a third person, especially, according to the complexity of the target motion. Therefore, for use in Neuro-Rehabilitation, we found it was important for the subject to input the target motion him/herself.
This paper deals with the design and experimental evaluation of an explicit tracking control system for a hydraulic actuator. The tracking control of hydraulic system has been widely applied to many application fields. However, since the hydraulic system has inherently hard nonlinear properties in dynamics, it is difficult to precisely control the position of the hydraulic system. Therefore a robust tracking control scheme was proposed to guarantee the tracking performance in this paper. To design the robust tracking control system, backstepping with sliding mode controller was applied. In order to evaluate the performance of the proposed controller, the experimental results were conducted.
In some engineering applications, it is desirable to calculate the local velocity of geometric objects or boundaries of physical phenomena to understand the deformation speed of the objects or the mechanisms of the physical phenomena. Furthermore, knowledge of the velocity distribution will help designers create better mechanical systems. To determine the velocity of the boundary of a 2D object or 2D phenomenon, we first construct an implicit surface taking the time component into consideration by the radial basis function, then we calculate the local velocities of the boundary using the generated implicit surface. We apply our method to calculate flame velocity in a combustion chamber.
Gear is one of the most commonly used and important components in machine system. Mainly gear failure may cause serious damage of the whole equipment, even huge economic losses. Therefore, it is important to detect the gear damage as early as possible. This paper provides a method of diagnosis and location for gear damage based on statistical approach and discrete wavelet transform (DWT). The vibration signals of gear box and bearing box are measured as analytical data. To emphasize the failure features of the measured signal, gear motion residual signal is obtained from the raw signal and provides a better indication of the existence of failures. Additionally, the method of discrete wavelet transform is employed to reduce the noise from the residual signal and decompose the signal into several decomposition levels. Because of the good sensitivity to the altering of vibration signal, statistical parameters such as standard deviation, kurtosis and so on are extracted from the raw signal and the reconstructed signal by DWT as failure features for detecting the gear damage. For a comparison of the raw signal and the reconstructed signal, the variation of statistical parameters among different kinds of test gears is also discussed by the significance test. The validity of the presented method is testified by some experiments under different conditions. Three kinds of gears namely normal gear, spot damaged gear and pitted gear are tested on the power circulating type gear testing machine, and the vibration acceleration on both gear box and bearing box is obtained. The experimental results show the effectiveness of this method on the diagnosis of gear damage.
Industries need to concurrently evaluate productivity and energy consumption when designing and improving manufacturing systems. Manufacturing system simulations to evaluate productivity have often been used. However, manufacturing system simulations to concurrently evaluate productivity and energy consumption have not been proposed. The purpose of our research is to establish a system for concurrent evaluation of productivity and energy consumption in a manufacturing system simulation. First, in this study, necessary items and requirements to evaluate productivity and energy consumption are analysed. Secondly, a prior evaluation system considering the necessary items and the requirements is proposed. A state transition model for facilities, a simulation system and a visualization system are proposed to realize the prior evaluation system. Finally, case studies for a small-scale machining line and a middle-scale semiconductor manufacturing line are carried out to confirm the efficiency of our proposed prior evaluation system.
In this paper, we propose to apply robust optimization approaches to the problem of identical parallel machine scheduling with processing time uncertainty. Box uncertainty and cardinality-constrained uncertainty are considered, and robust counterpart is reformulated as deterministic MILP problems. We explore the impact of the protection level, and show the trade-off between robustness and conservativeness. The results of numerical experiments demonstrate that the robust counterpart with cardinality-constrained uncertainty outperforms that with box uncertainty with respect to the mean and standard deviation of realized objective values. However, the robust counterpart with box uncertainty has an advantage in that it requires less computational efforts to solve the problem.