Masami Iwase

Internal model and saturating actuation in human operation from view of human-adaptive mechatronics

Human-adaptive mechatronics (HAM) is the area of mechatronics which adapts to the operator skill and assists its improvement. The analysis of human control action is one of the fundamental problems in the study of HAM. A special feature of human control action is the action being saturated with respect to the amplitude and velocity. At the same time, the human does not pay attention continuously to the response but intermittently scans and gets the information. In this paper, the continuous control action based on the scanned information is studied, and the desired trajectory of the human control action is considered to be generated by the closed-loop system including the internal model in the feedback path. Since the visual information is scanned intermittently, the closed-loop reference generator is considered as a sampled-hold system. The feedforward function of the cerebellum can be interpreted as the reference generator with a long scanning interval for the skilled operation. The saturating control action causing the pilot-induced oscillation is studied by taking the swing-up control of a single pendulum from the pendant to the upright position as an example. The two swing-up control laws are studied for reachability of the unstable nonlinear pendulum. One is the linear combination of sine function of the position and angular velocity, and the other is the variable-structure control for the sliding-mode function similar to the linear combination control law. The reachability is analyzed successfully by the color map.

Control strategy for a snake-like robot based on constraint force and verification by experiment

This paper aims to develop a method for the locomotion of a snake-like robot, and proposes a control strategy based on the friction force between robotpsilas body and the ground. Our concept of a control system design is that a control law should be based on the friction force as a real snake is. Both the motion equation of the robot and the friction force are derived by the projection method proposed by W. Blajer. The friction model is evaluated in the cost function of the control system design based on state dependent Riccati equation. As a result a derived control law takes the friction effect into account. We also build an experimental system. The effectiveness of the proposed method is verified by simulations and experiments.

A Consideration of nonlinear system modeling using the projection method

This paper considers modeling of nonlinear systems, especially nonholonomic systems, by the projection method proposed by W. Blajer. The projection method focuses on constraints of a system, and it can make a model of a non-holonomic system in the similar way of a holonomic system. The projection method also permits us the modeling as follows: first of all, the sub-model of each component is derived, and combining them gives the entire model. In this way, the complex and large system modeling can be decomposed into each easy-small sub-modeling.

Analysis of intermittent control systems by human operations

Human adaptive mechatronics is the coined name for a research project at Tokyo Denki University sponsored by Ministry of Education, Sports, Culture, Science and Technology (MEXT). Human adaptive mechatronics consists of human and mechatronics, and aims to develop Mechatronic systems adapting and assisting human operations. In this paper, the human control action of human-in-the-loop system is studied paying attention to the sampling effect via visual feedback. To analyze the performance of human operations with such factors, the swing-up of a pendulum by human was studied.

Analysis of safe manual control by using Furuta pendulum

This paper focuses on the interaction of manual and automatic control in a demanding task where the process is unstable and has actuator limitation. The problem is inspired by control of high performance aircrafts but which is similar to controlling the arm of a Furuta pendulum while maintaining the stability of the pendulum. The task is to control the position of the pendulum arm manually while maintaining the pendulum in the upright position. The analysis of regions for safe maneuvers is important to realize the desired control system.

A design of servo controller for nonlinear systems using state dependent Riccati equation

In this paper, we present a new servo controller for nonlinear manipulator system designed by using the idea of the model-following servo controller. The control method proposed does not require the linearization but can consider the internal forces at joints. In order to derive the nonlinear model including the internal forces at each joints during the control, the projection method proposed by W. Blajer et al.(1992) is employed. The nonlinear control input is given by repeated computation of the Riccati equation depending on the state, called State Dependent Riccati Equation. To verify the effectiveness of the approach, we have designed and realized the proposed tracking controller for two link SCARA type robot.

Non-Uniform Velocity Profile Compensation for an Electric Bicycle Based on Repetitive Control With Sinusoidal and Non-Sinusoidal Internal Models

This paper considers the application of repetitive control in improving the comfort of electric bicycle riders under uphill riding condition. A particular problem addressed is the nonuniform torque input from the rider. The human torque input can be decomposed into two parts: the DC or near-DC local average torque and the fluctuating torque. The latter is due to nonuniform pedal torque production by the rider and is near periodic. It makes the acceleration and the velocity of the bicycle non-uniform, which is pronounced at low speeds. This makes uphill climbing a difficult task for the rider. Repetitive control will be used in this paper to compensate for this component during low speed uphill riding. We will consider both sinusoidal and non-sinusoidal periodic models for the non-uniform torque generated by the rider. The time-varying characteristic of the rider input will be dealt with by both time domain and pedal-angle domain methods. Simulation results for both cases will be shown and compared.Copyright

On a Jansen leg with multiple gait patterns for reconfigurable walking platforms

Legged robots are able to move across irregular terrains and those based on 1-degree-of-freedom planar linkages can be energy efficient, but are often constrained by a limited range of gaits which can limit their locomotion capabilities considerably. This article reports the design of a novel reconfigurable Theo Jansen linkage that produces a wide variety of gait cycles, opening new possibilities for innovative applications. The suggested mechanism switches from a pin-jointed Grübler kinematic chain to a 5-degree-of-freedom mechanism with slider joints during the reconfiguration process. It is shown that such reconfigurable linkage significantly extend the capabilities of the original design, while maintaining its mechanical simplicity during normal operation, to not only produce different useful gait patterns but also to realize behaviors beyond locomotion. Experiments with an implemented prototype are presented, and their results validate the proposed approach.

Control design of electrically-assisted steering systems for bicycles with child restraint seats

Recently, bicycles biking with children are attracting much attention in Japan, but a variety of dangerousness comes up biking with children. Then, a law for safety of bicycles with children has been established 2009. Consequently, bicycle manufacturers have provided bicycles adapting to new safety standards by improving structure, strength, stiffness, braking and steering performance. However, unfortunately, consideration from the dynamics aspect comes short in such bicycles. Our previous research has shown that the bicycle stability is best if a child restraint system is installed above the front wheel. On the other hand, increasing the moment of inertia when a child sits on the front seat might cause steering instability. Hence, in our research, to overcome the problem, an electrically-assisted steering system for those bicycles has been proposed. In this paper, a control method based on disturbance observer-based control for the assisted steering system is presented. The effectiveness of the proposed system with each control method is verified by frequency analysis, numerical simulations and experiments.

Motion analysis by experiment and simulation for riding bicycles with children

The purpose of this paper is motion analysis by experiment and simulation for riding bicycles with children. It is very important to think about stability when the bicycle is driving with children. However, such a research is not so performed. Therefore, analysing human motions in the such case by some experiments and simulations, dynamic characteristics of the such case are shown. The modeling of bicycle is performed, and the model is used for the simulations.