Tetsuya Kinugasa

Passive walking of biped emu with attitude control of body

The purpose of this paper is to show realization of passive walking of a biped robot emu that is composed of one body and two legs. The semi-passive walking means that a biped robot walks passively on gentle descent accompanying with attitude control of the body. In the beginning of this paper, we outline the formulation for the passive and semi-passive walking. We analyze, next, stability of the semi-passive walking to regard the system as a discrete dynamical system. Finally, we show some simulated and experimental results to verify the validity of the controlled system and the analysis.

Effect of circular arc feet on a control law for a biped

The purpose of our research is to study the effects of circular arc feet on the biped walk with a geometric tracking control. The biped studied is planar and is composed of five links and four actuators located at each hip and each knee thus the biped is underactuated in single support phase. A geometric evolution of the biped configuration is controlled, instead of a temporal evolution. The input-output linearization with a PD control law and a feed forward compensation is used for geometric tracking. The controller virtually constrains 4 degrees of freedom (DoF) of the biped, and 1 DoF (the absolute orientation of the biped) remained. The temporal evolution of the remained system with impact events is analyzed using Poincare map. The map is given by an analytic expression based on the angular momentum about the contact point. The effect of the radii of the circular arc feet on the stability is studied. As a result, the speed of convergence decreases when the radii increases, if the radius is larger than the leg length the cyclic motion is not more stable. Among the stable cyclic motion, larger radius broadens the basin of attraction. Our results agree with those obtained for passive dynamic walking on stability, even if the biped is controlled through the geometric tracking.

Study on a practical robotic follower to support Home Oxygen Therapy patients — Prototype cart development applying the inverted pendulum control

We have proposed a practical power assist robotic cart, which we call ‘Robotic Follower’, to support daily lives of the patients undergoing Home Oxygen Therapy (HOT). And to achieve the purpose, we have developed several types of Robotic Follower. In this paper, we describe our newly developed Robotic Follower with which the inverted pendulum control technology is applied to control Robotic Follower, and then we investigate its effectiveness and prove its availability.

Prototype “RT04” that uses flexible mono-tread mobile track

It is expected that robotics is introduced into search and rescue activity, planetary explorer and investigation in extreme environment etc. The robots in such environment need high mobility against extremely rough terrain. Pressure exerted on the terrain is distributing wider, thus tracked vehicles are advantageous, accordingly. Since it is difficult for usual tracked vehicle composed of a pair of tracks to change length/width ratio a lot from 1/1 because of its turning property, serially connected tracked vehicles and paddled tracked vehicles have been introduced in order to improve the mobility. We have proposed a tracked vehicle called flexible mono-tread mobile track (FMT). The body of FMT except both side wall is completely wrapped around only by a track belt, which is possible to prevents sharp or thin edges of obstacle and cloth from penetrating. However the prototypes have rail colliding and derailing problems of the track belt caused by flexion and surface profile of the ground. The objective of the paper is, therefore, to develop a new prototype of FMT called RT04. RT04 adopts one degree of freedom rotational joint in stead of the flexible components and accurately designed guide rail system in order to prevent the belt from colliding or derailing. Rubber sponge grouser is also introduced against obstacle penetration and impact from the ground. Finally, some experimental tests validate the prototype.

Mobility and Operability of Flexible Mono-Tread Mobile Track (FMT)

In the paper, we show mobility and operability of flexible mono-tread mobile track (FMT) through experiments. For mobility, FMT can climb over a thin plate, recover from lying position on its side, and side wind. As a result, it is partly proven that FMT has enough ability for the complex environment. For operability, FMT is better than a differential type track vehicle in the case that vehicle traces to gentle curves. Since the both mechanism have advantages and disadvantages such that the differential type track can turn in smaller radius, it is useful that we choose better one to adapt various situations.

A proposal of flexible mono-tread mobile track — a new mobile mechanism using one track and spine-like structure —

In the past decade, search robots in rescue operations have been focused on and developed for the purpose of finding survivors trapped in the rubble of collapsed buildings. Most of them adopt serpentine mechanisms: they comprise of track-equipped segments that are connected by joints to obtain greater mobility in extremely complex environments. However, they might gather to catch debris between tracks or become stuck due to the mechanisms, in addition, increasing the number of segments would result in gaining weight and complicated mechanism and control system. In this paper, a new mobile mechanism: flexible mono-tread mobile track is proposed and a prototype ldquoRescue mobile track No.2 (RT-02) WORMYrdquo is developed. The vehicle is composed of a ldquoflexible chainrdquo and a spine-like structure. It is examined on mobility performance in irregular environments.

3D quasi-passive walking of bipedal robot with flat feet: quasi-passive walker driven by antagonistic pneumatic artificial muscle

In this paper, We develop three-dimensional quasi-passive walker with flat feet driven by an antagonistic pneumatic artificial muscle. An antagonistic mechanism is constituted by a pair of McKibben muscles. And an antagonistic pneumatic system is used as joint actuators of linkage mechanisms which control the torque, joint stiffness and position simultaneously. However, it is more difficult to control the pneumatic actuator than a usual electric motor. Therefore, we also examined the structure of an ankle and the control method of an antagonistic pneumatic system. As a result, a three-dimensional quasi-passive walking is realizable by means of adjusting the stiffness of an ankle joint. From experimental results of quasi-passive walking, the average gait were obtained with the travel distance 1350 mm, the stride of a step 90 mm, and the number of steps 15 steps. It was demonstrated that the quasi-passive walking is stabilized when both the robotic motions in a lateral plane and in a sagittal plane are synchronized.

Experiment of maneuverability of flexible mono‐tread mobile track and differential‐type tracked vehicle

Purpose – The purpose of this paper is to compare the maneuverability of flexible mono‐tread mobile track (FMT) and usual differential‐type tracked vehicle (DTV) through some experiments. A new mobile mechanism: FMT has been proposed which is employing “flexible chain” and vertebral structure, thereby the body flexes in 3D. As a result of the specific turning mechanism, steering performance of FMT is different from that of DTV. Hence, maneuverability of FMT and DTV would be different.Design/methodology/approach – The vehicles are maneuvered to trace two types of lines: a semi‐circle and right‐angled line segments by four operators. The distance and the displacement of direction of the vehicles from the target line are measured. The maneuverability was discussed based on the experimental results for FMT and DTV.Findings – Some of the characteristic features on maneuverability of FMT and DTV have been made clear.Originality/value – FMT is a new mobile mechanism for tracked‐vehicle and the maneuverability of...

Development of a mobile robotic cart to support HOT patient's going out via Force and Inverted pendulum control

Home Oxygen Therapy (HOT) patients must take the conveyance cart to carry oxygen equipment when they go out. However the equipment is heavy enough to discourage the patients from going out. Therefore, in this study, we attempt to develop a mobile robotic conveyance cart to support HOT patients going out by applying Force control and Inverted pendulum control which can also prevent the falling over of the cart. In this paper, we describe the control principle of Force control with Inverted pendulum control by several dynamical simulations, and we also show the effectiveness of our proposed control system by several experiments.

Measurement System for Flexed Shape of Flexibly Articulated Mobile Track

This paper proposes and validates a system for measuring the flexed posture of the flexible mono-tread mobile track (FMT) using a flexible displacement sensor (FDS). The FMT proposed previously has a single track and vertebral structure. The flexed posture of the FMT determines its turning radius and direction; thus, knowing its posture is important. However, it is impossible to measure the shape of flexible mobile systems using sensors located internally, such as a rotary potentiometer, or located externally, such as a laser scanner. To solve the problem, we introduce the FDS to measure the flexed FMT shape. The sensor consists of two fixed electrodes, a sliding electrode, and a nylon string coated with carbon (NSCC). It works as a flexible potentiometer by moving the sliding electrode along the NSCC while maintaining electrical contact. The measurement system is implemented in a prototype of the FMT called RT02-WORMY and is validated in a series of experiments.