Kiyoshi Komoriya

A high stability, smooth walking pattern for a biped robot

Biped robots have better mobility than conventional wheeled robots, but they tip over easily. In order to walk stably in various environments such as rough terrain, up and down slopes, or regions containing obstacles, it is desirable to adapt to such ground conditions with a suitable foot motion, and maintain the stability of the robot by a smooth hip motion. We propose a method to plan a walking pattern consisting of a foot trajectory and a hip trajectory. First, we formulate the constraints of a foot trajectory, and generate the foot trajectory by 3rd order spline interpolation. By setting the values of constraint parameters, it is easy to produce different types of foot motion. Then, we formulate a hip trajectory using a 3rd order periodic spline function, and derive the hip trajectory with high stability. Finally, the effectiveness of the proposed method is illustrated by simulation examples.

Position estimation of a mobile robot using optical fiber gyroscope (OFG)

Recognition of the actual position is very important for a mobile robot to move around in its environment. The most common method of position estimation is dead reckoning usually achieved by integrating wheel rotation along the path. This method, however, has a serious problem that the estimation errors are accumulated. In this paper we propose using an optical fiber gyroscope (OFG) combined with the information provided by the wheel encoders to improve the accuracy of position estimation. The formulation using a Kalman filter to combine the information of the encoders with that of the OFG is described. The simulation results and the experimental results show the effectiveness of the proposed method.<<ETX>>

Development of a finger-shaped tactile sensor and its evaluation by active touch

A finger-shaped tactile sensor previously reported in a scaled-up version was miniaturized and its signal processing speed improved. The miniaturized tactile sensor consists of a hemispherical optical waveguide with an elastic cover, a fiber-optics plate (FOP), a position-sensitive detector (PSD), and infrared light-emitting diodes (LEDs) for the light source. When an object comes in contact with the sensor, the elastic cover is depressed and light from the LEDs, which normally maintains total internal reflection within the waveguide, is scattered at the contact location of the waveguide and the cover. The scattered light is transmitted to the PSD through the FOP. The contact location and the normal to the surface of the object are determined from the output of the PSD. The sensors fundamental characteristics were evaluated through experiments using the miniaturized version. The sensor was installed at the tip of a robotic finger to create an active touch system. By combining tactile sensing and motion control of the finger, the profile of an unseen object was successfully delineated.<<ETX>>

Balance control of a piped robot combining off-line pattern with real-time modification

Since a biped robot tends to tip over easily, stable and reliable biped walking is a very important achievement. In this paper, we propose a balance control method based on an off-line planned walking pattern with real-time modification. First, a method of generating a highly stable, smooth walking pattern is presented. Then, a method of real-time modification consisting of body posture control, actual zero moment point control and landing time control based sensor information is proposed. By combining the proposed off-line walking pattern with real-time modification, the biped robot can walk smoothly and adapt to unknown environments. The effectiveness of the proposed method is confirmed by dynamic simulator such as walking on unexpected irregular rough terrain, soft ground and in environments in the presence of disturbances.

Trajectory Design and Control of a Wheel-type Mobile Robot Using B-spline Curve

In flexible trajectory control of a mobile robot it is preferable to design a smooth trajectory which passes specified points with specified tangents in a two dimensional plane. A trajectory design method which satisfies the above condition is presented using a Bspline curve. In order to use the designed B-spline curve for a two-wheel-driven-type mobile mechanism the possibility of using curvature data is examined. Possible speed patterns for the minimum travel time along a curve specified by curvature data is demonstrated given hardware constraints. Trajectory control of experimental hardware demonstrates the feasibility of using the the designed B-spline curve to control the trajectory of a wheel-type mobile robot.

Remote coordinated controls in multiple telerobot cooperation

Various coordinated control schemes are explored in the multi-operator-multi-robot (MOMR) tele-collaborative system through a network with time delay. Multi-robot cooperation has rapidly emerged in many possible applications such as the plant maintenance, construction, and surgery, because it would have a significant advantage over a single robot in such cases. Thus, time-delayed control of a multi-robot system is expected to play an important role in remote operations, too. However, the effect of time-delay would pose a more difficult problem to the MOMR teleoperation systems and seriously affect their performance. In this work, first, we have built an experimental system to investigate the remote cooperation in MOMR teleoperation. Then, different coordinated control methods are proposed to cope with the collision, arising from the time delay over the network. To verify the validity of the proposed schemes, we have carried out various experiments on a planar block arrangement by two slave arms employing graphic simulators and a LAN subject to a significant communication delay.

Impedance shaping based on force feedback bilateral control in macro-micro teleoperation system

In the teleoperation between different-scale worlds, it is important to consider the scaling effect problem. An impedance shaping bilateral teleoperation that considers this problem is needed to provide the human operator with natural sensation while tele-manipulating objects in the micro world whose main physical characteristics are different from those in the macro world. In this paper, we propose a bilateral control scheme which provides the operator with an impedance shaped out of the real one. This control scheme is based on force feedback bilateral control with scaling transfer function gains. By choosing not only the geometrical scaling gains but also the dynamic scaling ones as the scaling transfer function gains, the impedance that is presented to the operator can be shaped out of the real one. Finally, we present experimental results that verify the validity of the proposed control scheme.

Telexistence cockpit for humanoid robot control

In the fiscal year of 1998, The Ministry of Economy Trade and Industry (METI) of Japan launched a national 5-year project called the Humanoid Robotics Project. As a part of this project, we are developing a novel humanoid robot telexistence (tel-existence) system to assist and cooperate with people. This paper describes a newly developed telexistence cockpit for humanoid robot control, and shows a technical demonstration to evaluate the developed cockpit and the robot. A human operator controls the robot within the remote cockpit as if he or she were inside the robot itself. The telexistence cockpit consists of three subsystems: a three-dimensional (3D) audio/visual display subsystem, a telexistence master subsystem, and a communication subsystem between the cockpit and the robot. A series of real images are captured by cameras mounted on the robot and presented on the visual display, and the human operator in the cockpit observes them with a sensation of real-time presence. He or she can intuitively control the arms and hands of the slave robot through the telexistence master subsystem with force feedback.

Tactile sensor based manipulation of an unknown object by a multifingered hand with rolling contact

A new motion control system using tactile feedback is investigated for the manipulation of an object by a multifingered hand where the fingertips and the object make rolling contact. The proposed control system is capable of determining the motion of fingers so that the hand manipulates the object along the desired trajectory according to the tactile feedback at the fingertip. The advantage of the algorithm developed here is that geometrical information about the object to be manipulated is not necessary and therefore the algorithm can be applied to the manipulation of an unknown object. First, a mathematical model of the kinematics of the manipulation with rolling contact at the fingertip is formulated. Next, a trajectory planning algorithm for the fingers is derived. Finally, the previously developed finger-shaped tactile sensor using an optical waveguide is installed on the two-fingered hand, and the superiority of the proposed algorithm is demonstrated through computer simulations and experiments.

Dynamic grasping force control using tactile feedback for grasp of multifingered hand

Dynamic grasping force control for a multifingered hand is proposed and investigated. The grasping force of the finger is dynamically adjusted according to the tactile feedback so that each fingertip force always stays inside the friction cone detected by the tactile sensor and the fingertips maintain firm contact without any undesired slip no detaching from the surface of the object while grasping it. The proposed method can be applied for real-time control of the hand since it requires few numerical calculations. The validity of the proposed method is experimentally confirmed using a two-fingered hand with finger-shaped tactile sensors.