Michel Lauria

SWARM-BOT: from concept to implementation

This paper presents a new robotic concept, called SWARM-BOT, based on a swarm of autonomous mobile robots with self-assembling capabilities. SWARM-BOT takes advantage from collective and distributed approaches to ensure robustness to failures and to hard environment conditions in tasks such as navigation, search and transportation in rough terrain. One SWARM-BOT is composed of a number of simpler robots, called s-bots, physically interconnected. The SWARM-BOT is provided with self-assembling and self-reconfiguring capabilities whereby s-bots can connect and disconnect forming large flexible structures. This paper introduces the SWARM-BOT concept and describes its implementation from a mechatronic perspective.

Design and Control of a Four Steered Wheeled Mobile Robot

This paper presents the kinematical analysis of AZIMUT-2, a four steered wheeled mobile robot. The utilization of a new wheel concept called the AZIMUT wheel allowed us to create an innovative omnidirectional non-holonomic robot. Novelty of this wheel concept resides in the non-conventional positioning of the steering axis and the wheel axis. We propose a kinematical model based on the geometrical constraints of these wheels. The degree of mobility, steerability and maneuverability are studied. Additionally, we describe a special design implementation of the wheel mechanism to overcome a hyper-motorization issue inherent to the wheels geometrical properties. Finally, we describe AZIMUT-2s two operational and seven locomotion modes, along with a control algorithm based on the kinematical model of the robot

Differential elastic actuator for robotic interaction tasks

For complex robotic tasks (e.g., manipulation, locomotion), the lack of knowledge of precise interaction models, the difficulties to precisely measure the task associated physical quantities (e.g., position of contact points, interaction forces) in real-time, the finite sampling time of digital control loops and the non-collocation of sensors and transducers have negative effects on performance and stability of robots when using simple force or simple movement controllers. To cope with these issues, a new compact design for high performance actuators specifically adapted for integration in robotic mechanisms is presented. This design makes use of a mechanical differential as its central element. Results shown that differential coupling between an intrinsically high impedance transducer and an intrinsically low impedance mechanical spring provides the same benefits as serial coupling, but in a more compact and simple design. This new actuator, named Differential Elastic Actuator (DEA), provides interesting design implementations, especially for rotational actuators used for mobile robot locomotion.

Natural interaction design of a humanoid robot

Designing robots that interact naturally with people requires the integration of technologies and algorithms for communication modalities such as gestures, movement, facial expressions and user interfaces. To understand interdependence among these modalities, evaluating the integrated design in feasibility studies provides insights about key considerations regarding the robot and potential interaction scenarios, allowing the design to be iteratively refined before larger-scale experiments are planned and conducted. This paper presents three feasibility studies with IRL-1, a new humanoid robot integrating compliant actuators for motion and manipulation along with artificial audition, vision, and facial expressions. These studies explore distinctive capabilities of IRL-1, including the ability to be physically guided by perceiving forces through elastic actuators used for active steering of the omnidirectional platform; the integration of vision, motion and audition for an augmented telepresence interface; and the influence of delays in responding to sounds. In addition to demonstrating how these capabilities can be exploited in human-robot interaction, this paper illustrates intrinsic interrelations between design and evaluation of IRL-1, such as the influence of the contact point in physically guiding the platform, the synchronization between sensory and robot representations in the graphical display, and facial gestures for responsiveness when computationally expensive processes are used. It also outlines ideas regarding more advanced experiments that could be conducted with the platform.

Dual-Differential Rheological Actuator for High-Performance Physical Robotic Interaction

Todays robotic systems are mostly rigid and position-controlled machines designed to operate in structured environments. To extend their application domains to partially unknown, dynamic, or anthropic environments, improved physical-interaction capabilities are required. In this new context, to blend the requirements for safety, robustness, and versatility is often a challenge, in part, because commonly available actuator technologies are inadequate. This paper presents our solution with the introduction of the dual-differential rheological actuator (DDRA) concept, which is based on the synergistic combination of an electromagnetic (EM) motor and two differentially coupled magnetorheological (MR) brakes. This paper describes the approach and the prototype design. It then discusses performances in force, motion, and interaction control.

Toward autonomous, compliant, omnidirectional humanoid robots for natural interaction in real-life settings

The field of robotics has made steady progress in the pursuit of bringing autonomous machines into real-life settings. Over the last 3 years, we have seen omnidirectional humanoid platforms that now bring compliance, robustness and adaptiveness to handle the unconstrained situations of the real world. However, today’s contributions mostly address only a portion of the physical, cognitive or evaluative dimensions, which are all interdependent. This paper presents an overview of our attempt to integrate as a whole all three dimensions into a robot named Johnny-0. We present Johnny-0’s distinct contributions in simultaneously exploiting compliance at the locomotion level, in grounding reasoning and actions through behaviors, and in considering all possible factors experimenting in the wildness of the real world.

Pushing a robot along - A natural interface for human-robot interaction

Humans use direct physical interactions to move objects and guide people, and the same should be done with robots. However, most of todays mobile robots use non-backdrivable motors for locomotion, making them potentially dangerous in case of collision. This paper presents a robot, named AZIMUT-3, equipped with differential elastic actuators that are backdrivable and torque controlled, capable of being force-guided. Real world results demonstrate that AZIMUT-3 can move efficiently in response to physical commands given by a human pushing the robot in the intended direction.

Dual differential rheological actuator for robotic interaction tasks

Robots fail to perform complex manipulation or locomotion tasks when using simple force or motion controllers applied to classic actuators. Stability and safety issues arise for reasons such as high output inertia and the non-collocation of sensing and actuating transducers. This paper presents a new actuation concept, integrating a DC motor and two differentially coupled magnetorheological brakes, promising safe and versatile interaction capabilities. This paper focuses on the underlying mechanism and a case study with a proof-of-concept prototype.

Force-guidance of a compliant omnidirectional non-holonomic platform

Physical guidance is a natural interaction capability that would be beneficial for mobile robots. However, placing force sensors at specific locations on the robot limits where physical interaction can occur. This paper presents an approach that uses torque data from four compliant steerable wheels of an omnidirectional non-holonomic mobile platform, to respond to physical commands given by a human. The use of backdrivable and torque-controlled elastic actuators for active steering of this platform intrinsically provides the capability of perceiving applied forces directly from its locomotion mechanism. In this paper, we integrate this capability into a control architecture that allows users to force-guide the platform with shared-control ability, i.e., having the platform being guided by the user while avoiding obstacles and collisions. Results using a real platform demonstrate that users intent can be estimated from the compliant steerable wheels, and used to guide the platform while taking nearby obstacles into consideration.

Teleoperation of AZIMUT-3, an omnidirectional non-holonomic platform with steerable wheels

AZIMUT-3 is an omnidirectional non-holonomic (or pseudo-omnidirectional [1]) robotic platform intended for safe human-robot interaction. In its wheeled configuration, shown in Fig. 1, AZIMUT-3 uses eight actuators for locomotion: four for propulsion and four for steering the wheels, which can rotate 180 degrees around their steering axis. Propulsion is done using standard DC brushless motors (Bayside K064050-3Y) with optical encoders (US Digital E4-300-157-HUB, 0.3 deg of resolution), capable of reaching 1.47 m/s. The platform uses steerable wheels motorized using differential elastic actuators (DEA) [2], [3], which provide compliance, safety and torque control capabilities. AZIMUT-3s hardware architecture consists of distributed modules for sensing and low-level control, communicating with each other through a 1 Mbps CAN bus. A Mini-ITX computer equipped with a 2.0 GHz Core 2 duo processor running Linux with real-time patches (RT-PREEMPT) is used on-board for high-level control modules. Nickel-metal hydride batteries provide power to the platform for up to 3 hours of autonomy. A passive vertical suspension mechanism (Rosta springs) is used to connect the wheels to AZIMUT-3s chassis, allowing them to keep contact with the ground on uneven surfaces. The platform has a 34 kg payload capacity and weights 35 kg.