Multi-contact vertical ladder climbing with an HRP-2 humanoid

We describe the research and the integration methods we developed to make the HRP-2 humanoid robot climb vertical industrial-norm ladders. We use our multi-contact planner and multi-objective closed-loop control formulated as a QP (quadratic program). First, a set of contacts to climb the ladder is planned off-line (automatically or by the user). These contacts are provided as an input for a finite state machine. The latter builds supplementary tasks that account for geometric uncertainties and specific grasps procedures to be added to the QP controller. The latter provides instant desired states in terms of joint accelerations and contact forces to be tracked by the embedded low-level motor controllers. Our trials revealed that hardware changes are necessary, and parts of software must be made more robust. Yet, we confirmed that HRP-2 has the kinematic and power capabilities to climb real industrial ladders, such as those found in nuclear power plants and large scale manufacturing factories (e.g. aircraft, shipyard) and construction sites.     

Object Touch by a Humanoid Robot Avatar Induces Haptic Sensation in the Real Hand

Humanoid robot embodiment is a recently developed form of mediated embodiment. In 2 studies, we report and quantify a new haptic (touch) illusion during embodiment of a humanoid robot. Around 60% of the users in our studies reported haptic sensations in their real hand when they observed their robot avatar touching a curtain with its hand. Critically, our study shows for the first time that users can experience haptic sensations from a nonanthropomorphic embodied limb/agent with visual feedback alone (i.e. no haptic feedback provided). The results have important implications for the understanding of the cognitive processes governing mediated embodiment and the design of avatar scenarios.     

Non-decoupled Locomotion and Manipulation Planning for Low-Dimensional Systems

We demonstrate the possibility of solving planning problems by interleaving locomotion and manipulation in a non-decoupled way. We choose three low-dimensional minimalistic robotic systems and use them to illustrate our paradigm: a basic one-legged locomotor, a two-link manipulator with a manipulated object, and a simultaneous locomotion-and-manipulation system. Using existing motion planning and control methods initially designed for either locomotion or manipulation tasks, we see how they apply to both our locomotion-only and manipulation-only systems through parallel derivations, and extend them to the simultaneous locomotion-and-manipulation system. Motion planning is solved for these three systems using two different methods: (i) a geometric path-planning-based one, and (ii) a kinematic control-theoretic-based one. Motion control is then derived by dynamically realizing the geometric paths or kinematic trajectories under the Couloumb friction model using torques as control inputs. All three methods apply successfully to all three systems, showing that the non-decoupled planning is possible.     

Realistic haptic rendering of interacting deformable objects in virtual environments

A new computer haptics algorithm to be used in general interactive manipulations of deformable virtual objects is presented. In multimodal interactive simulations, haptic feedback computation often comes from contact forces. Subsequently, the fidelity of haptic rendering depends significantly on contact space modeling. Contact and friction laws between deformable models are often simplified in up to date methods. They do not allow a "realistic" rendering of the subtleties of contact space physical phenomena (such as slip and stick effects due to friction or mechanical coupling between contacts). In this paper, we use Signorini's contact law and Coulomb's friction law as a computer haptics basis. Real-time performance is made possible thanks to a linearization of the behavior in the contact space, formulated as the so-called Delassus operator, and iteratively solved by a Gauss-Seidel type algorithm. Dynamic deformation uses corotational global formulation to obtain the Delassus operator in which the mass and stiffness ratio are dissociated from the simulation time step. This last point is crucial to keep stable haptic feedback. This global approach has been packaged, implemented, and tested. Stable and realistic 6D haptic feedback is demonstrated through a clipping task experiment.     

Design and Control of a Small-Clearance Driving Simulator

This paper presents a driving simulation whose aim is twofold: (1) to investigate the possibility of reducing motion clearance to achieve compact and low-cost driving simulators and (2) to evaluate multimodal and immersive virtual reality motion restitution in platooning driving. The choice has been made for a driving simulator having at least two degrees of freedom (DOF). These consist of the longitudinal displacement and seat rotations. The simulator is also equipped with a force feedback steering wheel for virtual drive assistance. These components are gathered on a serial kinematics-type platform to facilitate a control scheme and avoid the architecture complexity. A comparative study was made to devise a motion cueing strategy, taking into account both the psychophysical and technological constraints. Experimentations were carried out for several case combinations of the longitudinal displacement and seat rotations.     

Adaptive Haptic Feedback Steering Wheel for Driving Simulators

Controlling a virtual vehicle is a sensory-motor activity with a specific rendering methodology that depends on the hardware technology and the software in use. We propose a method that computes haptic feedback for the steering wheel. It is best suited for low-cost, fixed-base driving simulators but can be ported to any driving simulator platform. The goal of our method is twofold. 1) It provides an efficient yet simple algorithm to model the steering mechanism using a quadri-polar representation. 2) This model is used to compute the haptic feedback on top of which a tunable haptic augmentation is adjusted to overcome the lack of presence and the unavoidable simulation loop latencies. This algorithm helps the driver to laterally control the virtual vehicle. We also discuss the experimental results that demonstrate the usefulness of our haptic feedback method.     

Teleoperation based on the hidden robot concept

Overlaying classical teleoperation control schemes based on a bilateral master-slave coupling, a teleoperation architecture designed in a general teleworking context is proposed. In this scheme, the executing machine is perceptually and functionally hidden to the operator by means of an intermediate functional representation between a real remote world and man. As any executing machine, and more particularly a robot, will be replaced by man, the image of the robot will not appear in the intermediate representation. This principle is thus named: “the hidden robot concept.” In this approach, the teleoperation problem is divided into two main parts: 1) choosing the appropriate intermediate representation and determining its interaction and relation with man and 2) building the relations and transformations between the intermediate representation and the real remote environment. The constituents of this teleoperator are outlined in this paper and an experiment validating this concept is presented     

Integration of humanoid robots in collaborative working environment: a case study on motion generation

This paper illustrates through a practical example an integration of a humanoid robotic architecture, with an open-platform collaborative working environment called BSCW (Be Smart-Cooperate Worldwide). BSCW is primarily designed to advocate a futuristic shared workspace system for humans. We exemplify how a complex robotic system (such as a humanoid robot) can be integrated as a proactive collaborative agent which provides services and interacts with other agents sharing the same collaborative environment workspace. Indeed, the robot is seen as a ‘user’ of the BSCW which is able to handle simple tasks and reports on their achievement status. We emphasis on the importance of using standard software such as CORBA (Common Object Request Broker Architecture) in order to easily build interfaces between several interacting complex software layers, namely from real-time constraints up to basic Internet data exchange.     

A Model-Based Controller for Interactive Delayed Haptic Feedback Virtual Environments

This paper addresses the stability of time-delayed force-reflecting displays used in virtual reality interactive systems. A novel predictive-like approach is proposed. The developed solution is stable and robust. Neither time delay estimation nor time delay behavior's knowledge are required. The controller applies to constant or time-varying delays without any adaptation. In this research, efforts are devoted towards making results easy to implement in commercial haptic libraries and interface build-in controllers. Moreover, although this study focuses on virtual environments haptics, it can easily spread to force feedback teleoperators.