This study discusses kinematic and dynamic precession models for a rolling ball with a finite contact area and a point contact respectively.In literature, both conventions have been applied.In this paper, we discuss in detail the kinematic and dynamic models to describe the ball precession and the radius of a circular rolling path.The kinematic model can be used if the contact area and friction coefficient are sufficient to prevent slippage.The dynamic precession model has significance in multi-body simulation environments handling rolling balls with ideal point contacts.We have applied both the kinematic and dynamic precession model to evaluate the no-slip condition of the existing GimBall-robot.According to the result, the necessity of an external precession torque may cause slipping at lower velocities than expected if ignoring this torque., ̇ Precession rate, spin rate (rad/s) ̈ Precession acceleration of the ball (rad/s 2 ) ω Forward rolling rate of the ball (rad/s) ̇ Forward rolling acceleration (rad/s 2 ) μ Friction coefficient at contact μ a Friction coefficient share for acceleration force μ T Friction coefficient share for vertical torque

Dynamic models describing the ball-robot motion form the basis for developments in ball-robot mechanics and motion control systems. For this paper, we have conducted a literature review of decoupled forward-motion models for pendulum-driven ball-shaped robots. The existing models in the literature apply several different conventions in system definition and parameter notation. Even if describing the same mechanical system, the diversity in conventions leads into dynamic models with different forms. As a result, it is difficult to compare, reproduce and apply the models available in the literature. Based on the literature review, we reformulate all common variations of decoupled dynamic forward-motion models using a unified notation and formulation. We have verified all reformulated models through simulations, and present the simulation results for a selected model. In addition, we demonstrate the different system behavior resulting from different ways to apply the pendulum reaction torque, a variation that can be found in the literature. For anyone working with the ball-robots, the unified compilation of the reformulated dynamic models provides an easy access to the models, as well as to the related work.

This work presents an assessment of different control techniques based on Limit Cycle Walking. The study is performed on a two-dimensional kneed bipedal simulator developed with Open Dynamics Engine, which includes realistic configuration of weight allocation, link length, inertia distribution and impacts. The controllers are model-based driven from an analytic 2D kneed biped. Several controllers from the Computed Torque (CT) family together with a Passivity Based controller (PBC) are compared based on their energy efficiency and robustness. The previous controllers are used in their original form, with minor adjustment to handle hybrid systems such as the kneed biped case. PBC proved not suitable for real implementation however a combined strategy between PBC and a soft PD control has shown promising results. PD Computed Torque control also offered high tolerance to disturbances with reasonable energy consumption. Furthermore, the performance of all the controllers showed high dependency on the parameters of the robot.

The aim of this study is to increase the versatility of Limit Cycle Walking (LCW) robots by proposing several ideas to control their velocity. The velocity control methods presented are to be used with Computed-Torque Control (CTC). This controller utilizes a passive reference model walking down a gentle slope which provides the reference trajectory to follow. The controllers were tested on a rigid body simulator. The results show that the methods based on scaling the amplitude (step length) of the reference trajectory and changing the reference slope angle, provide an energy efficient and stable way to control the walking speed. Both of these methods also provide continuous trajectories to standing pose and running gait.

One problem in current human-robot task communication is the laborious need to define action and target object parameters for each task request. This paper's solution to the problem is to enable indirect task communication by mimicking the human cognitive ability to understand affordances, i.e. action possibilities in the environment with respect to different actors. This enables humans to communicate tasks using only the task-related action or target object names, and thus avoid the need to remember explicit task request utterances. The proposed task communication is integrated as a subsystem into an existing service robot, and its functionality is evaluated through a set of user experiments in an astronaut-robot task communication context. Affordance-based indirect task communication is shown to successfully reduce the workload experienced by the human and to decrease task communication times, while also being the preferred way to communicate tasks.

Mars is currently the centre of interest for space exploration. Tremendous efforts are still in progress to find clues of existence of life on Mars. Rovers are major sources of information of Mars. This paper focuses on a robotic roving vehicle robot for scientific applications (ROSA) having its initiative of European Space Agency (ESA). ROSA being a tethered rover makes possible to reduce the weight/size of rover because power is delivered through tether. Additionally, tether provides communication lines between the lander and the rover. Tethered robots require complex control system. This paper presents a specialized tracking system for rover's 40 m tether. The proposed system is capable of tether tracking within resolution of plusmn6 cm. The same strategy can also be used in other tethered robots for rescue, security, underwater, mines hunting and cleaning petroleum tanks after minor modifications.

This paper describes methods for determining the quality of terrain, while driving, with a mobile robot that can measure the vertical, horizontal and rotational strain forces affecting its wheels or feet. These methods are all sense-by-touch, and can be used to calculate various parameters relating to the interaction between the robot and terrain, and the geometry of the terrain. The parameters can then be used for mapping, path planning or determining suitable modes of locomotion.

Numerous studies in the field of service robotics for elderly and disabled have been done. However, the overall user needs are rarely deeply considered. This work surveys the needs and challenges for assisted living at home for the elderly and disabled. Automation technology solutions for today and for the future to help the people to live better, safer and longer are researched. This work is part of future senior living-assistive automation-project. This project is shortly described. Research consists of three phases. In questionnaire-study phase opinions and needs for home automation and home robotics are analyzed. Interview-study phase includes interviews with different specialists, the elderly and disabled themselves, and excursions to care houses and other related institutions. Literature-study reveals user needs as well, but it concentrates more on solutions than the other phases. Multiple needs and solutions were found. They have been discussed and the results are presented in an organized table.

In this paper, a method of generating a three-dimensional (3-D) geometric model for large-scale natural environments with trees is presented. The environment mapping method, which uses range images as measurement data, consists of three main phases. First, geometric feature objects are extracted from each of the range images. Second, the relative coordinate transformations (i.e., registrations) between the sensor viewpoint locations, where the range data are measured, are computed. Third, an integrated map is formed by transforming the submap data into a common frame of reference. Tree trunks visible in the range images are modeled with cylinder segments and utilized as reference features for registration computation. The final integrated 3-D model consists of the cylinder segments representing the visible sections of the tree trunks, as well as of the ground elevation data. The constructed environment map can be utilized as, for example, a virtual task environment for outdoor robotic machines such as new-generation forest working machines or service robots.

This paper presents a human dead-reckoning system for beaconless indoor positioning. The system is based on traditional dead-reckoning sensors like compass, gyro, and accelerometers. Due to the difficult kinematics of a human, there are no ready solutions for the odometry. This problem is solved by using a self-made stride length measurement unit and laser odometry. All the sensors are integrated to a complete system including sensor fusion. The functionality of the integrated system is verified with tests in an office environment. Finally the test results are analyzed.

The goal of this research is to develop the human robot interface for a multi-task outdoor robot called WorkPartner (Wopa). Due to the nature of the robot, the interface is designed to support learning and continuous cooperation with the human operator in various outdoors work tasks. The natural human communication methods like speech and gestures are promoted in order to ease the operator's load. The additional interface hardware is also designed to be as natural to the human cognition as possible. All methods and hardware presented have been tested with Wopa.

WorkPartner is the prototype of a lightweight mobile service robot designed to work interactively with humans in outdoor environment. The mobility is based on a hybrid system, which combine benefits of both legged and wheeled locomotion to provide at the same time good terrain negotiating capability and large velocity range. The working tool is a two-hand human like manipulator which can be used for manipulation or handling of tools. The robot is called WorkPartner, because the goal is to make an adaptive and learning robot, which can carry different tools and work interactively with a human. The user or operator can be physically present on the same site as the robot and communicate with it by using speech and gestures, or he can use telepresence from a distance place and communicate via Internet. In each case communication takes place via a new type of user interface based on multimedia and cognition.

A generic control architecture for cooperative robot systems is introduced. Functioning of this architecture is evaluated with underwater robots performing exploring and exploiting task in process environment. This has been performed in simulator and partly by real robots. The results allow optimization of resources in the given task.

Societies are formed as collaborative structures to execute tasks that are not possible or are difficult for individuals alone. There are many types of biological societies formed by animals, but societies formed by machines or robots are still rare. This paper introduces the concept of an application oriented robot society formed by autonomous underwater robots. The Bacterium Robot Society is a generic concept with many potential applications. As an example of such application a scenario, where robot society serves as a mobile distributed sensor instrument inside a process plant, is presented.

The authors deal with Esprit II programme PANORAMA project which develops a generic perception and navigation system for mobile robotic machines operating in partially unstructured environments like outdoor work sites. The system is described in a general level and the functions of the subsystems are explained. One of the subsystems, the piloting system, is considered in more detailed. The final demonstration which is done by using a full scaled mining machine, is explained and results and experiences on the project summarized.

The authors discuss the overall structural design of a self-contained hydraulic six-legged machine, called MECANT I, which has been constructed for studying possible applications of legged vehicles in natural environments, like forests. First, the main mechanical solutions and control hardware of the machine are presented. The systematic approach to the motion planning of a legged vehicle and some algorithmical features are discussed. The special features of the leg control are presented. The use of a simulator in the design work is discussed, and the main principles of the control software structure, which supports fast software design and testing, are presented. Some continuing research topics and the present situation are discussed.>