Takanori Emaru

Research on estimating smoothed value and differential value by using sliding mode system

To be able to recognize an environment, a robot should have as many sensors as possible. When we use sensors, we must consider the characteristics of the sensors, such as range, processing time, error, and so on. In this paper, we focus on the ultrasonic wave sensor that is today the most common sensor employed on indoor mobile robotic systems, and we propose a new technique for estimating the smoothed value and the differential value of the distances measured by the ultrasonic wave sensor. In proposing this system, we take the characteristics of the sensors mentioned above into consideration. In spite of the many methods proposed, it is still very difficult to eliminate the noise of sonar completely. Therefore, we smooth the distance value by assuming the continuity of the signal obtained by the sonar, and taking advantage of this continuity, we compose a robust estimator. The estimator is based on the sliding mode system.

Development of a Cyclogyro-based Flying Robot with Variable Attack Angle Mechanisms

This paper presents an experimental study on the development of a cyclogyro-based flying robot with a new variable angle of attack mechanism. A cyclogyro is a flying machine supported in the air by power-driven rotors that rotate about a horizontal axis, like the paddle-wheels of a steamboat. Machines of this type have been designed by some companies but there has been no record of any successful flights. Our design starts with a new variable angle of attack mechanism with an eccentric (rotational) point in addition to a rotational point connecting to a motor. The main feature of the mechanism with the eccentric rotational point is the ability to change attack of angles in accordance with the wing positions (as determined by the rotational angles of the cyclogyro) without actuators. The design parameters (wing span, the number of wings, and eccentric distance) of the flying robot are determined through a series of experiments. Experimental results show that the cyclogyro-based flying robot with the new variable angle of attack mechanism is capable of generating sufficient lift force for flying.

Development of a Cyclogyro-Based Flying Robot With Variable Attack Angle Mechanisms

This paper presents an experimental study on the development of a cyclogyro-based flying robot with a new variable angle of attack mechanism. A cyclogyro is a flying machine supported in the air by power-driven rotors that rotate about a horizontal axis, like the paddle-wheels of a steamboat. Machines of this type have been designed by some companies but there has been no record of any successful flights. Our design starts with a new variable angle of attack mechanism with an eccentric (rotational) point in addition to a rotational point connecting to a motor. The main feature of the mechanism with the eccentric rotational point is the ability to change attack of angles in accordance with the wing positions (as determined by the rotational angles of the cyclogyro) without actuators. The design parameters (wing span, the number of wings, and eccentric distance) of the flying robot are determined through a series of experiments. Experimental results show that the cyclogyro-based flying robot with the new variable angle of attack mechanism is capable of generating sufficient lift force for flying.

Implementation of unconsciousness movements for mobile robot by using sonar sensor

Generally, animals have multiple sensoria, but they cannot process all environmental insults because their ability of processing the environmental information from sensoria is limited. However, all animals seem to be acting appropriately in complex environments. This is not because animals process all environmental information, but because they can decide flexibly the order of what to do first and can utilize efficiently a limited resource. In other words, animals can ignore efficiently extraneous matter. In this paper, we attempt to implement the schema of IGNORE in order to utilize a limited resource of autonomous mobile robot by using the concept of consciousness. Especially, we focus on the unconsciousness movements such as obstacle avoidance or speed control of autonomous mobile robot. If these functions were implemented without heavy load to the system, the whole performance of the robot system will be increase. In this paper, we implement the unconsciousness movements by using poor sensor and processor. Furthermore, we consider the possibility to construct a fruitful combination of conscious and unconscious movements.

Propose the controlling strategy of wheeled mobile robot based on the consciousness

We have proposed a new approach to utilize the infinitesimal reflected waves by integrating the reflected waves. This method enables robot to move in unknown environments as it controls its speed smoothly. It is implemented using a transducer with a scanning system, and has a great ability of obtaining the traversable area for a robot in unknown environments in which the distance cannot be precisely measured. The proposed system, termed the integration-type ultrasonic wave sensor system, has following arbitrary parameters that the system designer can determine: sampling time of sonar, sampling time of scanning, range of scanning, speed of scanning, and so on. It is very difficult to determine them appropriately in response to changing environments or tasks. In this paper, we try to determine the arbitrary parameters of the integration-type ultrasonic wave sensor system on the basis of the consciousness. We have proposed the speed control or obstacle avoidance by using the integration-type ultrasonic wave sensor system, and we define it as the unconsciousness movements. On the other hand, higher-level tasks such as navigation or map building are defined as the consciousness movements. The purpose of our research is to propose a simple construction and controlling method of the robot system by introducing the concept of consciousness. In preparation for this purpose, some experiments and discussion will be performed in this paper.

System configuration of smoothed and differential values estimator by using linear and sliding mode system

We have proposed the new nonlinear filter to estimate the smoothed and differential values by using sliding mode system (ESDS). It works very effectively to eliminate the impulse noise by keeping the sudden shift of the signals. In order to construct ESDS, it requires the system that is globally uniform and asymptotically stable at the origin. As the stable system, the minimum time system that is one of the sliding mode systems has been used. In this paper, we apply the linear system and sliding mode system that has a linear switching line as the stable system, and we clarify the validity of our theorem and configuration of ESDS.

Avoid crosstalk of sonar by using sliding mode system

For autonomous mobile robots, sensors are very important to recognize an environment. In this paper, we discuss an ultrasonic wave sensor, which today is the most common technique employed on indoor mobile robotic systems, and we propose a new technique to avoid crosstalk of sonar sensors. Even though many methods have been proposed to avoid crosstalk, it is very difficult to eliminate the influence of crosstalk perfectly. In this paper, supposing the continuity of the distance signal given by the sonar, we smooth the distance value. The estimator is based on the sliding mode system.

Development of Control System by Nonlinear Compensation Using Digital Acceleration Control

Proportional-Integral-Derivative (PID) control has been most commonly used to operate mechanical systems. In PID control, however, there are limits to the accuracy of the resulting movement because of the influence of gravity, friction, and interaction of joints. We have proposed a digital acceleration control (DAC) that is robust over these modeling errors. One of the most practicable advantages of DAC is robustness against modeling errors. However, it does not always work effectively. If there are modeling errors in the inertia term of the model, the DAC controller cannot control a mechanical system properly. Generally an inertia term is easily modeled in advance, but it has a possibility to change. Therefore, we propose an online estimation method of an inertia term by using a system identification method. By using the proposed method, the robustness of DAC is considerably improved. This paper shows the simulation results of the proposed method using 2-link manipulator.Copyright

Apply nonlinear filter ESDS to quantized sensor data

Proportional-Integral-Derivative (PID) control is widely used to control mechanical systems. In PID control technique, however, there are limits to the accuracy of the resulting movement because of the influence of gravity, friction, and interaction of joints caused by modeling errors. Digital acceleration control has robustness for the modeling errors. But it requires position, velocity, and acceleration of a controlled object to construct a controller. In this paper, we use the novel digital differentiator, ESDS. It enables digital acceleration control without increasing the number of sensors. Furthermore, the proposed method works effectively for quantized sensor data. The validity of the proposed method is confirmed by simulations and experiments using 2-link manipulator.

Speed control of a sonar-based mobile robot determining sensing and action strategy simultaneously

Today, the ultrasonic TOF (time-of-flight) ranging system is the most common sensing system employed in indoor mobile robotic systems, primarily due to the easy availability of low-cost systems, their compact size, simple circuits, and their ease in interfacing with computers. TOF ranging systems measure the round-trip time required for a pulse of emitted energy to travel to a reflecting object and then echo back to a receiver. However, ultrasonic TOF ranging systems tend to neglect infinitesimal reflected waves below the threshold level. We have proposed a new approach to utilize the infinitesimal reflected waves by integrating the reflected waves. This is implemented using a transducer with a scanning system, and has a great ability of obtaining the travelable area for a robot in environments in which the distance cannot be precisely measured. The proposed system is constructed in a simple manner so as to improve the utility value of the sonar. This paper introduces the speed control strategy under uncertainty of sensor information. By considering the uncertainty of sensor information, we change the action strategy. By changing the action strategy, sensor information which is obtained by the robot changes at the same time. By using this relationship, we construct the robust robot system. The validity of the proposed method is investigated by applying this method to an autonomous mobile robot in various environments such as one with multiple obstacles, at the end of the hall, and so on.