How to carry a telescope
Obviously, it depends on its size. But here I’m speaking about the ALMA (Atacama Large Millimeter/submillimeter Array) which will be fully operational in 2012 and will be composed initially of 66 high-precision telescopes. These 12-meter submillimeter quality antennas will weigh about 115 tons and be installed at an altitude of about 5,000 meters. Now, the first ALMA antenna transporter has been successfully tested. Even if it’s not the world’s biggest truck, this is still a ‘colossus on wheels.’ This 28-wheel truck is 10 meters wide, 20 meters long and 6 meters high, weighs 130 tons and has as much power as two Formula 1 engines. It should be operational by the end of 2007. read story
Homography-based 2D Visual Tracking and Servoing
The objective of this paper is to propose a new homography-based approach to image-based visual tracking and servoing. The visual tracking algorithm proposed in the paper is based on a new efficient second-order minimization method. Theoretical analysis and comparative experiments with other tracking approaches show that the proposed method has a higher convergence rate than standard first-order minimization techniques. Therefore, it is well adapted to real-time robotic applications. The output of the visual tracking is a homography linking the current and the reference image of a planar target. Using the homography, a task function isomorphic to the camera pose has been designed. A new image-based control law is proposed which does not need any measure of the 3D structure of the observed target (e.g. the normal to the plane). The theoretical proof of the existence of the isomorphism between the task function and the camera pose and the theoretical proof of the stability of the control law are provided. The experimental results, obtained with a 6 d.o.f. robot, show the advantages of the proposed method with respect to the existing approaches.
New York Times on the Real Transformers
A lengthy New York Times article by Robin Marantz Henig offers an overview of the state of real world robots to be found in research labs. She visits the robot labs of MIT to see Mertz, Kismet, Leo, and other social robots. She talks to Rodney Brooks about his “scientific midlife crisis”. She mentions historical robots like Elktro and talks with Sherry Turkle about the danger of robot boyfriends. There is also a discussion of robot self-awareness, consiousness, and emotion in robots. About the only thing not covered in this article is transformers or other shape-shifting robots. -more-
Instrumentation and Algorithms for Posture Estimation in Compliant Framed Modular Mobile Robots
Posture sensing techniques for Compliant Framed Modular Mobile Robots (CFMMR) are presented in this paper using a new Relative Posture Sensor (RPS) combined with standard sensors in a tiered fusion algorithm. The RPS consists of a compliant frame member instrumented with strain gauges and associated algorithms such that the RPS can predict relative posture. The first tier of the fusion algorithm uses traditional Kalman filters and rigid axle kinematic models to predict the global posture of each axle. In the second tier, a Relative Measurement Stochastic Posture Error Correction (RMSPEC) algorithm is introduced to fuse disparate axle data using the RPS. Experimental results are derived from over 60 trials operating the robot on high traction carpet, low traction sand, and sand with rugged rocky terrain. Results comparing the proposed sensory system with standard sensory systems demonstrate that the proposed techniques yield accurate relative posture estimates and posture regulation even on rugged terrain, which is a vast improvement over previous results.
Simultaneous Motion and Structure Estimation by Fusion of Inertial and Vision Data
For mobile robotics, head gear in augmented reality (AR) applications or computer vision, it is essential to continuously estimate the egomotion and the structure of the environment. This paper presents the system developed in the SmartTracking project, which simultaneously integrates visual and inertial sensors in a combined estimation scheme. The sparse structure estimation is based on the detection of corner features in the environment. From a single known starting position, the system can move into an unknown environment. The vision and inertial data are fused, and the performance of both Unscented Kalman filter and Extended Kalman filter are compared for this task. The filters are designed to handle asynchronous input from visual and inertial sensors, which typically operate at different and possibly varying rates. Additionally, a bank of Extended Kalman filters, one per corner feature, is used to estimate the position and the quality of structure points and to include them into the structure estimation process. The system is demonstrated on a mobile robot executing known motions, such that the estimation of the egomotion in an unknown environment can be compared to ground truth.
Integration of Vision and Inertial Sensors for 3D Arm Motion Tracking in Home-based Rehabilitation
The integration of visual and inertial sensors for human motion tracking has attracted significant attention recently, due to its robust performance and wide potential application. This paper introduces a real-time hybrid solution to articulated 3D arm motion tracking for home-based rehabilitation by combining visual and inertial sensors. Data fusion is a key issue in this hybrid system and two different data fusion methods are proposed. The first is a deterministic method based on arm structure and geometry information, which is suitable for simple rehabilitation motions. The second is a probabilistic method based on an Extended Kalman Filter (EKF) in which data from two sensors is fused in a predict-correct manner in order to deal with sensor noise and model inaccuracy. Experimental results are presented and compared with commercial marker-based systems, CODA and Qualysis. They show good performance for the proposed solution.
A very robust 50-atom-thick nanosheet
A team of U.S. scientists has discovered that by tightly packing molecules, they could obtain nanothin sheets of materials showing surprising strength. As one enthusiast researcher says, “It’s an amazing little marvel.” The team adds that “even when suspended over a tiny hole and poked with an ultrafine tip, the membrane boasts the equivalent strength of an ultrathin sheet of plexiglass that maintains its structural integrity at relatively high temperatures.” This could lead to highly sensitive pressure sensors in precision technological applications. read story
Instrumentation and Algorithms for Posture Estimation in Compliant Framed Modular Mobile Robots
Posture sensing techniques for Compliant Framed Modular Mobile Robots (CFMMR) are presented in this paper using a new Relative Posture Sensor (RPS) combined with standard sensors in a tiered fusion algorithm. The RPS consists of a compliant frame member instrumented with strain gauges and associated algorithms such that the RPS can predict relative posture. The first tier of the fusion algorithm uses traditional Kalman filters and rigid axle kinematic models to predict the global posture of each axle. In the second tier, a Relative Measurement Stochastic Posture Error Correction (RMSPEC) algorithm is introduced to fuse disparate axle data using the RPS. Experimental results are derived from over 60 trials operating the robot on high traction carpet, low traction sand, and sand with rugged rocky terrain. Results comparing the proposed sensory system with standard sensory systems demonstrate that the proposed techniques yield accurate relative posture estimates and posture regulation even on rugged terrain, which is a vast improvement over previous results.
Creating High-quality Paths for Motion Planning
Many algorithms have been proposed that create a path for a robot in an environment with obstacles. Most methods are aimed at finding a solution. However, for many applications, the path must be of a good quality as well. That is, a path should be short and should keep some amount of minimum clearance to the obstacles. Traveling along such a path reduces the chances of collisions due to the difficulty of measuring and controlling the precise position of the robot. This paper reports a new technique, called Partial shortcut, which decreases the path length. While current methods have difficulties in removing all redundant motions, the technique efficiently removes these motions by interpolating one degree of freedom at a time. Two algorithms are also studied that increase the clearance along paths. The first one is fast but can only deal with rigid, translating bodies. The second algorithm is slower but can handle a broader range of robots, including three-dimensional free-flying and articulated robots, which may reside in arbitrary high-dimensional configuration spaces. A big advantage of these algorithms is that clearance along paths can now be increased efficiently without using complex data structures and algorithms. Finally, we combine the two criteria and show that high-quality paths can be obtained for a broad range of robots.
Motion Planning for a Class of Planar Closed-chain Manipulators
The paper reports studies on the motion planning problem for planar star-shaped manipulators. These manipulators are formed by joining k “legs” to a common point (like the thorax of an insect) and then fixing the “feet” to the ground. The result is a planar parallel manipulator with k - 1 independent closed loops. A topological analysis is used to understand the global structure of the configuration space so that the planning problem can be solved exactly. The worst-case complexity of the algorithm is O(k3 N 3), where N is the maximum number of links in a leg. Examples illustrating the method are given.