We present a real-time algorithm which can recover the 3D trajectory of a monocular camera, moving rapidly through a previously unknown scene. Our system, which we dub MonoSLAM, is the first successful application of the SLAM methodology from mobile robotics to the "pure vision" domain of a single uncontrolled camera, achieving real time but drift-free performance inaccessible to structure from motion approaches. The core of the approach is the online creation of a sparse but persistent map of natural landmarks within a probabilistic framework. Our key novel contributions include an active approach to mapping and measurement, the use of a general motion model for smooth camera movement, and solutions for monocular feature initialization and feature orientation estimation. Together, these add up to an extremely efficient and robust algorithm which runs at 30 Hz with standard PC and camera hardware. This work extends the range of robotic systems in which SLAM can be usefully applied, but also opens up new areas. We present applications of MonoSLAM to real-time 3D localization and mapping for a high-performance full-size humanoid robot and live augmented reality with a hand-held camera

/pdf/monoslam-real-time-single-camera-slam-ydmj8dc1vj.pdf

MonoSLAM: Real-Time Single Camera SLAM

We introduce a new method of a biped walking pattern generation by using a preview control of the zero-moment point (ZMP). First, the dynamics of a biped robot is modeled as a running cart on a table which gives a convenient representation to treat ZMP. After reviewing conventional methods of ZMP based pattern generation, we formalize the problem as the design of a ZMP tracking servo controller. It is shown that we can realize such controller by adopting the preview control theory that uses the future reference. It is also shown that a preview controller can be used to compensate the ZMP error caused by the difference between a simple model and the precise multibody model. The effectiveness of the proposed method is demonstrated by a simulation of walking on spiral stairs.

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Biped walking pattern generation by using preview control of zero-moment point

From exploring planets to cleaning homes, the reach and versatility of robotics is vast. The integration of actuation, sensing and control makes robotics systems powerful, but complicates their simulation. This paper introduces a versatile, scalable, yet powerful general-purpose robot simulation framework called V-REP. The paper discusses the utility of a portable and flexible simulation framework that allows for direct incorporation of various control techniques. This renders simulations and simulation models more accessible to a general-public, by reducing the simulation model deployment complexity. It also increases productivity by offering built-in and ready-to-use functionalities, as well as a multitude of programming approaches. This allows for a multitude of applications including rapid algorithm development, system verification, rapid prototyping, and deployment for cases such as safety/remote monitoring, training and education, hardware control, and factory automation simulation.

V-REP: A versatile and scalable robot simulation framework

It is known that for a large magnitude push a human or a humanoid robot must take a step to avoid a fall. Despite some scattered results, a principled approach towards "when and where to take a step" has not yet emerged. Towards this goal, we present methods for computing capture points and the capture region, the region on the ground where a humanoid must step to in order to come to a complete stop. The intersection between the capture region and the base of support determines which strategy the robot should adopt to successfully stop in a given situation. Computing the capture region for a humanoid, in general, is very difficult. However, with simple models of walking, computation of the capture region is simplified. We extend the well-known linear inverted pendulum model to include a flywheel body and show how to compute exact solutions of the capture region for this model. Adding rotational inertia enables the humanoid to control its centroidal angular momentum, much like the way human beings do, significantly enlarging the capture region. We present simulations of a simple planar biped that can recover balance after a push by stepping to the capture region and using internal angular momentum. Ongoing work involves applying the solution from the simple model as an approximate solution to more complex simulations of bipedal walking, including a 3D biped with distributed mass.

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Capture Point: A Step toward Humanoid Push Recovery

For 3D walking control of a biped robot we analyze the dynamics of a 3D inverted pendulum in which motion is constrained to move along an arbitrarily defined plane. This analysis yields a simple linear dynamics, the 3D linear inverted pendulum mode (3D-LIPM). Geometric nature of trajectories under the 3D-LIPM and a method for walking pattern generation are discussed. A simulation result of a walking control using a 12-DOF biped robot model is also shown.

The 3D linear inverted pendulum mode: a simple modeling for a biped walking pattern generation

This paper studies a falling motion control of a human-size humanoid robot when it falls forward. Safe knee landing of the robot is realized as a first step to minimize the damage of the falling over. The landing follows the detection of the falling, the decrease of the knee height after the detection, and the brake of landing speed. It is confirmed that the proposed method can soften the landing impact significantly by the proposed method.

Safe knee landing of a human-size humanoid robot while falling forward

This paper describes a biped walking control method for a collision of a swinging foot on uneven terrain. Because a swing leg moves to a desired landing position, an unexpected collision on a terrain may be happened by a distance error between a foot and a terrain. A swing foot has to not only absorb a impact force, but also changes a trajectory as long as a swing foot contacts on a terrain. Furthermore it is required to keep a balance against a contact force. To prevent a trip over and a losing balance by contact on a terrain, two reactive key components are installed: 1) Set appropriate impedance gains of the feet according to a walking phase, 2) Update the desired landing position to the COG (Center of Gravity) pattern generation immediately as a detecting/releasing contact. In this paper, focused on a swing motion, a robust biped walking with a collision of a swinging foot on a uneven terrain is realized. The proposed method is validated through simulation results with the HRP-2 humanoid robot.

Reactive biped walking control for a collision of a swinging foot on uneven terrain

Cooperative transportation of an object by two or more mobile robots requires each robot to exert an appropriate force to support and move the object, to move along the object, and to maintain its attitude. A mechanically unstable robot, such as a wheeled inverted pendulum, needs to control the force and follow the object as standing stably against the force in an integrated manner. We call this a cooperative behavior. To realize this behavior of a wheeled inverted pendulum, we built control systems to estimate the external force and maintain standing and to exert a specified force. We applied them to a wheeled inverted pendulum. Experiments were conducted of cooperative transportation between a human and the robot. In the future, we aim to realize cooperative transportation by two wheeled inverted pendulums using the control systems.

Cooperative behavior of a wheeled inverted pendulum for object transportation

This paper presents preliminary results on generating turning motion of a humanoid robot by slipping the feet on the ground. We start by presenting the fact that such slip motion is used by humans based on actual human motion capture data, and show how this is necessary for sophisticated human-like motion. To generate the slip motion, we predict the amount of slip using the hypothesis that the turning motion is caused by the effect of minimizing the power generated by floor friction. Verification is conducted through both simulation and experiment with the humanoid robot HRP-2. A ldquotwirlrdquo utilizing both feet slip is successfully demonstrated.

A friction based “twirl” for biped robots

This paper describes a possibility of a running humanoid robot based on the physical properties of an existing humanoid robot HRP-2L. To generate running motion, we develop a general method to control the total linear/angular momentum of a multi-link system. By this method, we can generate a reliable running pattern. Conducting simulations which take into account physical restrictions, we show that our humanoid robot can run at least at 0.5 m/s.

Shuuji Kajita

Papers

Safe knee landing of a human-size humanoid robot while falling forward

Reactive biped walking control for a collision of a swinging foot on uneven terrain

Cooperative behavior of a wheeled inverted pendulum for object transportation

A friction based “twirl” for biped robots

Running pattern generation and its evaluation using a realistic humanoid model