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

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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 presents a user interface for teleoperating a biped humanoid robot and discusses the interface design. Teleoperation interfaces can be classified as either direct- or indirect-type, and the latter is employed by our interface because our goal is to use humanoid robots for disaster response, and the indirect-type interfaces have advantages for such applications. The basic design of our interface and concrete functions for operating the robot are described. The interface visualizes the last state of the robot and its environment, and the operation is performed by executing commands, including robot state acquisition, measurement, walking, reaching, and manipulation. Communication between the interface and the robot is requested only when a command is executed. The developed interface was tested with the HRP-2 robot and two example tasks, i.e., walking on uneven terrain and rotating a valve. We verified that the robot was able to complete the tasks by teleoperation using our interface.

Development of an indirect-type teleoperation interface for biped humanoid robots

We are studying a leg-wheeled robot with the ability of going up and down stairs. We already developed a 'biped type leg-wheeled robot' which has ability to pass over stairs with short treads, but it could not negotiate the stairs fast. In this paper, in order to realize the fast negotiation of stairs, we propose a new dynamic trajectory planning method to make the staggering distance smaller and the landing stabler. We also propose a method to connect the dynamic trajectory control motion in statically unstable state and the structure changing motion in statically stable state. As the result, we realize the fast going up and down stairs by this robot successfully and confirm the effectiveness of our proposed method.

Dynamic Control of Fast Passing Over Stairs by a Biped Type Leg-wheeled Robot Considering the Continuity of Dynamic Trajectories

We discuss a feedback controller to stabilize biped walking which has toe support phase mimicking human gait. Using a reference walking pattern proposed in our previous work [11], our stabilizer can realize reliable walking. To evaluate the quality of stabilization, we propose two indicators, the maximum floor reaction force and the root mean square of the CoM tracking error. From our walking experiments, these indicators suggest us two policies of control parameter tuning, (1) not to control ZMP at toe support, and (2) not to use the ZMP phase-lead compensation for sagittal motion. These findings were validated by simulations of linear inverted pendulum model. It is shown that the observed behavior of the controller is caused by large velocity dissipation at support exchange.

Evaluation of a stabilizer for biped walk with toe support phase

The establishment of an intuitive and effective whole body operation method is essential for the utilization of humanoid robots in real world tasks. Here we introduce a method for humanoid robot foot teleoperation, as a part of our whole body teleoperation system using only a simple joystick device. This paper explains a framework for real-time foot operation which incorporates the operator's foot command and robot's autonomy in maintaining balance. We describe the algorithm of an autonomous function which shifts the position of the robot's center of mass interactively based on the operator's command and the current feet condition of the robot. We report on successful experimental results of teleoperating a real humanoid robot HRP-2 using the proposed method.

A stable foot teleoperation method for humanoid robots

A significant feature of humanoid robots is their potential to make various expressions as humans do, and this feature will allow the use of humanoid robots as assemblies of content technologies. Technical issues required for the practical use of humanoid robots are discussed in terms of robot hardware, motion expression generation, vocal expression generation and integrated GUI (Graphical User Interface), and the development of technologies to solve the issues and their integration have been carried out. As a result, we have produced HRP- 4C, a life-size biped humanoid robot with realistic human-like appearance, and Choreonoid, an integrated software interface that allows us to choreograph motions with robots as done with CG characters. Experiments on creating contents with these technologies verified the potential of humanoid robots as assemblies of content technologies.

https://www.jstage.jst.go.jp/article/synth/4/2/4_2_80/_pdf

Shuuji Kajita

Papers

Development of an indirect-type teleoperation interface for biped humanoid robots

Dynamic Control of Fast Passing Over Stairs by a Biped Type Leg-wheeled Robot Considering the Continuity of Dynamic Trajectories

Evaluation of a stabilizer for biped walk with toe support phase

A stable foot teleoperation method for humanoid robots

Toward the use of humanoid robots as assemblies of content technologies