Kiyoshi Ioi

A mobile micro-robot using centrifugal forces

This paper deals with a new mobile micro-robot using centrifugal force. Though Many kinds of mobile micro-robots using PZT elements have been developed, their elements generally require some kinds of high voltage amplifiers accompanied with electric cable lines, which make the micro robot difficult to move around freely in a long and thin pipe. The micro-robot proposed here consists of many brush fibers, two coreless motors and a button electric cell. These coreless motors with eccentric weights generate centrifugal forces which transmit to the elastic brush fibers, and consequently produce driving forces of the micro-robot. First, I derive a translational moving model of the mobile micro-robot using centrifugal forces. Next, some simple prototypes of this robot are developed, and the characteristics of their high velocity are examined by experiment. And then, the rotational property of the micro-robot that produced by the angular velocities of the two coreless motors is discussed by a yawing model. Finally, I verify the validity of the proposed mathematical model by comparing simulation results with experimental results.

Evaluation of quad ducted‐fan helicopter

Purpose – With the purpose of clearing up the risk to rotor blades, this paper develops a quad ducted‐fan helicopter using four ducted‐fans instead of four rotor blades in a quad rotor helicopter.Design/methodology/approach – Auto hovering test, auto cruise test, and altitude control simulations were conducted to estimate the flight performance of the quad ducted‐fan helicopter.Findings – Flight performance of the test quad ducted‐fan helicopter is almost same as a commercial quad rotor helicopter, and it succeeds to decrease the risk to the rotor blade. However, endurance is shorter than that of the quad rotor helicopter, because of the ducted‐fan characteristics.Research limitations/implications – The test quad ducted‐fan helicopter can fly for about four minutes with two packs of fourcell (16.8 V)‐2200 mAh Lipo batteries, and it needs about 3.3 times as much energy as quad rotor helicopter. The authors will improve the performance of quad ducted‐fan helicopter by aerodynamics analysis and design of duc...

Study on turning motion of micro robot driven by cyclic force

Deals with the turning motion mechanism of a brush-type micro robot using cyclic centrifugal forces. Many wheeled robots usually turn along the tangential velocity generated by their rolling wheels. The micro robot studied here has a turning property different from usual wheeled mobile robots. To realize the micro mobile robot the mechanism accompanied with many brush legs has been often applied so far. However, the turning motion mechanics has not been clarified. The paper clarifies the mechanics. First, we derive a two-dimensional rolling model of the brush-type robot driven by cyclic centrifugal forces, and indicate the existence of the lateral force acting toward the robot by the computer simulation and the simple mathematical analysis. Next, to confirm the turning motion mechanics caused by the lateral force, we obtain many experimental results of the circular trajectory using three kinds of prototype. Finally, we conclude the validity of the turning motion mechanics caused by the lateral force that the cyclic centrifugal force generates.

Mechanical and control design of caster for low vibrations and crashes of carts

This paper presents the mechanical and control design of a caster to reduce the impulsive accelerations and residual vibrations of carts. The main theme is to remove the cart disturbances from roads by mechanical and control design. The mechanical design based on the center of percussion of the caster is proposed to reduce the impulsive accelerations caused by road bumps, and the reduction effect for the cart is confirmed by experiments. Then what is called a skyhook control is applied to reduce the residual vibrations after running over road bumps. The simple skyhook control is proposed by using only the absolute velocity and acceleration, and is verified to be effective in the reduction of both the vibration and the impulsive acceleration toward the cart by experiments.

Estimation of Surface Properties Using A New Robotic Finger

We present simultaneous estimating the position and the mechanical impedance of unknown surfaces using a new robotic finger. Successfully treating such a simultaneous sensing device will contribute to reducing the inspection time required for industrial products, and could also be useful for detecting unknown surfaces such as in disaster zones. We propose a new robotic finger that is equipped with a force sensor and a resonant mechanical element on its fingertip. The force sensor is used as a surface detector to sense the reaction force from unknown surfaces, and the resonant mechanical part acts as a scaling amplifier to estimate the mechanical impedance of unknown surfaces. We verify the usefulness of our robotic finger by experiments.

Path-planning and navigation of a mobile robot as discrete optimization problems

There is huge diversity among navigation and path-planning problems in the real world because of the enormous number and great variety of assumptions about the environments, constraints, and tasks imposed on a robot. To deal with this diversity, we propose a new solution to the path-planning and navigation of a mobile robot. In our approach, we formulated the following two problems at each time-step as discrete optimization problems: (1) estimation of a robots location, and (2) action decision. For the first problem, we minimize an objective function that includes a data term, a constraint term, and a prediction term. This approach is an approximation of Markov localization. For the second problem, we define and minimize another objective function that includes a goal term, a smoothness term, and a collision term. Simulation results show the effectiveness of our approach.

Development of a compact and rapid wall-climber

This paper presents a new compact and rapid wall-climber. First the compact structure of the robot is introduced, which has a pair of driving wheels and a tilt-variable thruster with a set of coaxial propellers. Next the whole dual-control system is constructed, which is composed of both the remote and autonomous control. Then basic experiments are shown concerned with the tilt angle control and the wheels velocity control. Finally the dynamical model of the robot is derived to estimate and design the motion profiles and performance. Some important points of the motion control are discussed by simulation results using the dynamical model.

Experiments and simulations of wall running and transferring of a climbing robot

This paper reports experimental and simulation results of a compact wall-climbing robot. The robot has been developed with the aim to detect or repair inspections and flaws on walls. First, the mechanical structure of the robot is summarized, and the remote and autonomous control system is also described. Next, we focus on running on walls and transferring between two different walls. The experimental results are compared to the simulation results based on the dynamical model of the robot. Two proposed methods for wall transferring are experimentally verified, and these experiments have good agreements with the simulations.

Navigation of a Mobile Robot Formulated in Terms of Discrete Optimization Problems

The problem of navigation of an autonomous mobile robot has a great variety of solutions, depending on the premise conditions regarding the properties of the robot, the surrounding environment, and the user specifications. In support of a navigation scheme that can cope flexibly with this variety, this paper proposes a method that formulates the problem in terms of discrete optimization problems. In the proposed method, the problem of robot position/posture estimation from map and sensor data and the problem of deciding the action at each instant are formulated as separate discrete optimization problems. In the former, our approach is an approximation of the Markov localization algorithm. The proposed method is then applied to a navigation problem in a known environment with fixed obstacles, and the effectiveness and feasibility of the method are verified by simulation results.

Modeling of a Balancing Robot on a Rolling Pipe

In this paper, we describe the modeling of a balancing robot. The balancing robot is a biped stepping robot, and aims to balance on a rolling pipe. The motion equations of the balancing robot and rolling pipe are formulated in order to grasp the robot motion and to design a stable robot controller for balancing on the pipe. Particularly, the calculation procedure of the contact forces is proposed, which generates between the robot foot and the pipe surface. Finally, simulation results are shown based on the formulation.