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.

/pdf/biped-walking-pattern-generation-by-using-preview-control-of-84qdve2k8v.pdf

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.

/pdf/capture-point-a-step-toward-humanoid-push-recovery-12jssfk8t5.pdf

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

We have developed a robot called a ' structure type four-wheeled robot' which, with a simple structure, has ability to pass over a step. This robot has only one degree of freedom to change the body's structure and can run on four wheels (4-wheeled mode) or on two wheels like a wheeled inverted pendulum (2-wheeled mode). For the realization of stepping up and down, there are three difficult problems to be solved: stable control in 2-wheeled state, transfer from 4- to 2-wheeled mode (swing-up), and transfer from 2- to 4-wheeled mode (landing). The control method we have developed for a wheeled inverted pendulum is used to control the 2-wheeled state using the signal of a rate gyroscope. In this paper, we mainly discuss control methods for transfers from 4- to 2-wheeled mode and from 2- to 4-wheeled mode. Especially in the transfer from 4- to 2-wheeled state, we make effective use of the driving torque of the motor which change the body's structure. In the transfer from 2- to 4-wheeled state, we have investigated a control method for soft landing to minimize the touch-down impact of the robot which is nonholonomic system. By combining our control methods, we have realized an experiment of passing over a step successfully.

A four-wheeled robot to pass over steps by changing running control modes

This paper studies the real-time gait planning for a humanoid robot. By simultaneously planning the trajectories of the COG (Center of Gravity) and the ZMP (Zero Moment Point), the fast and smooth change of gait can be realized. The change of gait is also realized by connecting the newly calculated trajectories to the current ones. While we propose two methods for connecting two trajectories, i.e. the real-time method and the quasi-real-time one, we show that the stable change of gait can be realized by using the quasi-real-time method even if the change of the step position is significant. The effectiveness of the proposed methods are confirmed by simulation and experiment.

Analytical Approach on Real-time Gait Planning for a Humanoid Robot

In this paper, a realtime control of dynamic biped locomotion using sensor information is investigated. We adopted an ultrasonic range sensor mounted on the robot to measure the distance from the robot to the ground surface. During the walking control, the sensor data is converted into simple representation of the ground profile in realtime. We also developed a control architecture based on the Linear Inverted Pendulum Mode which we had proposed for dynamic walking control. Combining the sensory system and the control system enabled our biped robot, Meltran II, to walk over the ground of unknown profile successfully.

Control of Dynamic Biped Locomotion Based on Realtime Sensing of the Ground Profile

For the purpose of realizing the humanoid robot walking on uneven terrain, this paper proposes the kinodynamic gait planning method where both kinematics and dynamics of the system are considered. We can simultaneously plan both the foot-place and the wholebody motion taking the dynamical balance of the robot into consideration. As a dynamic constraint, we consider the differential equation of the robot’s CoG. To solve this constraint, we use a walking pattern generator. We randomly sample the configuration space to search for the path connecting the start and the goal configurations. To show the effectiveness of the proposed methods, we show simulation and experimental results where the humanoid robot HRP-2 walks on rocky cliff with hands contacting the environment.

Kinodynamic Planning for Humanoid Robots Walking on Uneven Terrain

In this paper, we describe VocaWatcher, a novel robot motion generator that enables a humanoid robot to sing with realistic facial expressions and naturally synthesized singing voices. This robot singer is an important and attractive humanoid robot application for the entertainment scene; moreover, it promotes state-of-the-art integration of robot engineering, music processing, and image processing. To overcome the difficulties of generating natural facial expressions that are precisely synchronized with singing voices, VocaWatcher imitates a human singer by analyzing a video clip of a human singing, recorded by a single video camera. VocaWatcher can control mouth, eye, and neck motions by imitating the corresponding human movements, which are estimated without using any markers in the video. It can also synthesize singing voices by imitating the pitch and dynamics of the human singing in the same video.

/pdf/vocawatcher-natural-singing-motion-generator-for-a-humanoid-35yqhyvkus.pdf

Shuuji Kajita

Papers

A four-wheeled robot to pass over steps by changing running control modes

Analytical Approach on Real-time Gait Planning for a Humanoid Robot

Control of Dynamic Biped Locomotion Based on Realtime Sensing of the Ground Profile

Kinodynamic Planning for Humanoid Robots Walking on Uneven Terrain

VocaWatcher: Natural singing motion generator for a humanoid robot