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There are currently many quadruped robots suited to a wide range of applications, but traversing some terrains, such as vertical ladders, remains an open challenge. There is still a need to develop adaptive robots that can walk and climb efficiently. This paper presents an adaptive quadruped robot that, by mimicking feline structure, supports several novel capabilities. We design a novel paw structure and several point-cloud-based sensory structures incorporating a quad-composite time-of-flight sensor and a dual-laser range finder. The proposed robot is equipped with physical and cognitive capabilities which include: 1) a dynamic-density topological map building with attention model, 2) affordance perception using the topological map, and 3) a neural-based locomotion model. The novel capabilities show strong integration between locomotion and internal–external sensory information, enabling short-term adaptations in response to environmental changes. The robot performed well in several situations: walking on natural terrain, walking with a leg malfunction, avoiding a sudden obstacle, climbing a vertical ladder. Further, we consider current problems and future development.

Many working processes in manufacturing factories involve the manipulation of deformable objects, and the automation of such working processes is necessary. However, because the manipulation of deformable objects by robots is generally difficult to achieve, such automation has progressed little. The insertion task involved in the formation of rubber hoses is an example of such a task. In the two stages of this study, to automate the rubber hose insertion task, two end effectors for a dual-arm robot and an integrated end effector for a single-arm robot were developed, along with their corresponding manipulation plans. The hose insertion task was successfully performed by both robots.

Most industrial robots are driven through reduction gears such as Harmonic Drives and RV gears. Due to the flexibility of the drive system, vibratory behavior occurs during operation. When flexibility is considered, the drive system of the robot joint can be modeled as a resonant mechanical system called a two-inertia system. Conventionally, studies of two-inertia system have discussed semiclosed-loop control using only motor information and a state observer. On the other hand, joint torque sensing of robots has been studied in the harmonic drives that are widely used in robot joints. The joint torque sensor is becoming available with higher performance. In this paper, we consider the control of a robot arm having two-inertia resonance by using the joint torque sensor. The performance of the torque sensor and that of the observer are compared. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 75–84, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20226

Since timing belt drives have the advantages such as lower costs and accurate transfer characteristics, the timing belt drives are widely used in industrial machines and office automation equipments. However, there are problems of periodic transfer variations caused by eccentricity of the pulleys, interlock of the teeth of belt and pulley etc. Though it can be said that high gain feedback is effective to suppress the periodic variations, high gain feedback makes the system unstable easily due to elasticity of drive system, modeling error and so on. In this paper, we propose the control technique to suppress these periodic variations by using disturbance observer. First, we analyze the mechanism of the variations caused by eccentricity of the pulleys that is the most influential above all. We suggest sinusoidal model for the transfer variations as disturbances, and show the effectiveness of the disturbance compensation by implementing I-P speed control with the disturbance observer.

The development and simulation of robots that have athletic skill close to human beings is very much useful for testing and developing sport goods. This paper discusses the development and simulation of a tennis robot. The developed tennis robot has two joints controlled by a servolike human muscle, and its characteristics are satisfying and similar to a human. The simulation for the whole system including racket, ball and tennis robot is set up. The simulation results agree well with experimental results.

Semi-closed-loop control of a robot achieves only the control of the angular position of the motor, so it is not clear whether the end-effector is precisely positioned or not. Closed-loop control would improve positioning accuracy, but industrial robots which have elasticity in their driving systems might become unstable easily because of the noncollocated positional relationship between sensors and actuators. This study, which is aimed at realizing high-speed and high-precision closed-loop control, uses an intelligent electrorheological fluid (ER fluid). In the next section, a brief introduction is given with respect to two types of ER fluids and the development of ER dampers. Following this is a description of the experimental apparatus, which consists of an ER damper and a one-link robot arm. A discussion of its mathematical model follows. In addition, the effects of an ER damper to the resonance/antiresonance characteristics of 2-inertia systems are discussed. Next, the design of the hierarchical control system is discussed. Firstly, the design of the inner loop controller for motor velocity control is presented. As an outer loop controller, an H/sup /spl infin// controller is obtained by using a mixed sensitivity design method of robust control theory. Then it is shown that the ER damper makes the design of a high gain controller possible while maintaining robust stability. Finally, the effectiveness of the proposed control method is demonstrated by experiments.

Flexibility in joint drive systems causes robot arm vibration. The conventional semi closed-loop control cannot provide a high servo stiffness and large bandwidth for industrial robots. To achieve a high speed and high precision control, it is important to reduce vibration of robot arm and effect of disturbance. For this purpose, state feedback control becomes more and more important in practice. In this paper, we present an analysis and design of state feedback control for two-inertia system. From the viewpoints of non-negative positional stiffness and internal feedback construction, the domain of pole assignment is analyzed. The effect of disturbance is compared and evaluated for three optimum pole assignments, and the worst case of disturbance is also introduced. It is shown that choice and design of optimum pole assignment are very important when considering the effect of disturbance.

Human-machine cooperative systems have been proposed. Most of them consider carrying, positioning and assembling tasks. Precise tracking tasks are also required in factories. However, an assist system for tracking task has not been studied well. In this paper, we aim to realize the human-machine system that assists a tracking task. In order to achieve the goal, the virtual friction field is proposed. Isotropic and anisotropic friction fields are presented and they are applied to the rotating object which should be tracked. The tracking task experiments are carried out and it is shown that the virtual guide of the friction improves the tracking performance effectively.

Because a direct-drive (DD) motor system does not use a reduction gear unit, the drive system can be made constructively simple and stiff. However, the disturbance torque directly influences the motor shaft. High gain feedback control is effective for reducing the influence of the disturbance torque. The high servo gain makes the control system vibratory or unstable. Therefore, the servo gain must be low for stability, and the influence of the disturbance become large. In this study, the DD motor system using an electrorheological (ER) fluid damper is discussed. By applying the ER damper to the DD motor system, the gain margin of the system becomes large and the servo gain can become high. Finally, it is shown that the proposed DD motor system is effective in improving the servo gain.