Precise repetitive works have been widely conducted by automatic machines in industry. Then, periodic disturbances induced by the repetitive works must be compensated to achieve precise motions. In this paper, a periodic disturbance observer (PDOB) based on a disturbance observer (DOB) structure is proposed. The PDOB compensates a periodic disturbance including a fundamental wave and harmonics rather than a sinusoidal wave by using a time-delay element. Furthermore, an adaptive PDOB is also proposed to enable to compensate also frequency-varying periodic disturbances. An adaptive notch filter (ANF) is used in the adaptive PDOB, which estimates a fundamental frequency of the periodic disturbance. In experiments using a multi-axis manipulator, practical performances were verified. The proposals provide a new framework based on the DOB structure to design controllers using a time-delay element.

This paper proposes a novel motion reproduction method based on environmental disturbance (EnvDs) compensation. The preservation of skillful techniques is an important issue. Although the motion-copying system (MCS) was proposed to deal with this problem, a clear strategy still does not exist for adapting to the environmental variances between the motion saving and reproduction phases. Conventional methods cannot adapt to the difference properly because their control systems are just one-degree-of-freedom (DOF) control systems. In this paper, variances were defined as EnvDs, and the effect on the MCS was demonstrated. A 2-DOF control system structure was developed to compensate for EnvDs. The effectiveness of the proposed system was demonstrated through analysis and experimental results.

Multimedia technology has been widely spread as the basis for human communications. For example, telephone, television and radio broadcasting are good tools for remote communication. Recently, communication tools such as the portable telephone and Internet spread all over the world. These devices substitute humans eyes and ears. Haptic information has paid attention as the third multimedia information. Especially a transmission technique of real-world haptic information is demanded. This paper proposes a novel haptic transmission in different motion area, named ldquomobile-haptordquo. The ldquomobilehaptordquo consists of a mobile robot and a joystick. A mobile robot has infinite area for its motion. On the contrary, a joystick is fixed for operation by a human. To transmit haptic information in the ldquomobile-haptordquo, bilateral control with dimension scaling is proposed. As a result, intuitive manipulation becomes possible by using the ldquomobile-haptordquo. Effectiveness of the proposed method is verified by experimental results.

Recently, real-world haptics has been attracting attention for human support system. In this paper, the motion-copying system based on real-world haptics is focused. The motion-copying system is the system which stores and reproduces human motion based on force and position information acquired by the bilateral control. As the applications, the motion-copying system is expected to be used in various fields such as industrial applications, medical and welfare human assist. However, in the conventional motion-copying system, it is difficult to reproduce the saved motion precisely when the environmental location in the motion-loading system is different from that in the motion-saving system. In this paper, a novel motion-loading system for the change of the environmental location is proposed. By using the proposal, it is possible to reproduce the motion even though the environmental location is varied. Validation of the proposal is verified by experimental results.

Periodic disturbances occur during repetitive operations, and compensation for the periodic disturbances is an important issue to realize precise machine works because the periodic disturbances deteriorate the control precision. In addition, the periodic disturbance becomes a frequency-varying periodic disturbance when the periodicity of the operations changes, which makes the compensation difficult. To eliminate the frequency-varying periodic disturbance, an adaptive periodic-disturbance observer (APDOB) was proposed. However, the APDOB has a problem that the design of the APDOB is complicated with six design parameters. This article proposes a differential evolutionary algorithm with local search that optimizes the six design parameters of the APDOB for the optimal frequency-varying periodic disturbance compensation. The proposed method based on a memetic algorithm framework can explore globally using the differential evolutionary algorithm and explore locally using the local search including the Lévy flight. Moreover, the proposed method can reduce the number of the design parameters.

This paper proposes an identification method of unknown environment for motion control. The proposed method can estimate a physical model and its parameter simultaneously by using element description method. In this paper, the proposed method is applied to identification of environmental characteristics. General identification methods need to decide a physical model of target in advance. In another approaches such as neural network and black-box modeling methods by database, notwithstanding achieving input-output characteristics, these methods are difficult to understand the physical meaning of target environment. On the contrary, the proposed method can identify not only parameter but also a physical model of environment, which is the merit of the proposed method. Also the physical meaning of target environment is understandable according to element description. By using the proposed method, ideal controller for contact task can be designed based on environmental model and its parameter. It may be possible to discover a new physical property of environment.