Alter-Ego: A Mobile Robot With a Functionally Anthropomorphic Upper Body Designed for Physical Interaction

Historically, robots first found application in factories and plants. Until recently, the most noticeable examples of robot systems directly sold to the consumer were limited to edutainment systems (e.g., NAO [1]), automated chore robots [26], and social telepresence platforms [27]. Initially, telepresence robots consisted of a mobile base with an interactive screen. Today, following a trend of anthropomorphization of technology, human-like upper bodies have begun to replace those simple screens (e.g., Pepper [2] and R1 [3]) and share the same social communication modalities of humans, e.g., body posture, gestures, gaze direction, and facial expressions. Unfortunately, social robots are mostly designed to speak and make gestures and have limited capabilities when it comes to physically interacting with people and their surrounding environments.


I. INTRODUCTION
Historically, robots found application mostly in factories and plants.Until recently, the most noticeable examples of robot systems directly sold to the consumer were limited to edutainment systems, automated chore robots, and social telepresence platforms.Initially, all robots belonging to this latter category, consisted in a mobile base toppled by an interactive screen.Nowadays, following a trend of anthropomorphization of technology, humanoid torsos are starting to replace those simple screens sharing the same social communication modalities of humans, e.g.body posture, gestures and facial expressions.On the other hand there are promising examples (e.g.Walkman [1]) of humanoid robots developed to operate in unstructured environments and perform challenging interaction tasks, e.g.: walk on rough terrains, move heavy objects, solve complex bi-manual manipulation tasks.One of the key aspects which led to the effectiveness of these robots was the use of enabling technologies capable to let the robots interact with the surrounding world, as e.g.active impedance control and series elastic actuation.Indeed, these same technologies are one of the main enablers that let robot arms cross the borders of industrial work cells, to become collaborative robots that can work in close contact with people and share the same operating space.It is in the opinion of the authors that the application of the same Soft Robotics technologies, * Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genova, Italia † Centro di Ricerca E. Piaggio e Dipartimento di Ingegneria dell'Informazione, Universit di Pisa, Pisa, Italia which includes series elastic and variable impedance actuation, in a consumer-oriented scenario, together with the capillary diffusion of reliable and affordable computational, networking and sensing technologies, will enable the massive diffusion of a novel generation of robots capable to deal with challenges imposed by real world scenarios.
Inspired by DARPA Robotics Challenge (DRC) 1 and the more recent announcement of the ANA -Avatar XPRIZE (XP) 2 , in this talk we present ALTER-EGO (Fig. 1), a robust and versatile mobile platform, capable to perform safe physical human-robot interactions and to operate in different working scenarios.
This talk is extracted from [2].Most of the hardware and software technologies adopted, developed and explicitly designed for ALTER-EGO, are distributed under an opensource framework, and are available on the Natural Machine Motion Initiative website3 (NMMI).

II. ALTER-EGO ALTER-EGO is powered by Variable Stiffness Actuators (VSA). Moreover, each of its arms mounts an anthropo-(a)
(b) Fig. 2. ALTER-EGO used in immersive tele-operation mode operating in a domestic environment.The pilot station is composed by wearable devices like Oculus Rift and MYO armbands.In (a), the robot is used to prepare food for pets.In (b) a box is retrieved from a mail man using the robot.morphic synergistic artificial hand inspired by the human motor synergies.The upper body is mounted on a two-wheels self-balancing mobile base to minimize the robot footprint and increase agility.ALTER-EGO can be used also in teleoperation.In particular, when used in combination with a pilot station mainly composed of lightweight and wearable Input/Output devices, the system features an immersive control mode.This modality, when combined with the use of Tele-Impedance control [3], is able to match the pilot and robot mechanical behavior, not only in terms of movements, but also in terms of mechanical impedance, as derived from the user muscle activation.

III. ROBOT AVATAR IN A DOMESTIC ENVIRONMENT
Fig. 2 shows ALTER-EGO operating in a domestic usecase scenario.Action showed are mostly executed with the immersive tele-operation operating mode, envisioning that an hypothetic user can jump inside the robot from its work location and teleport himself at home to assolve some domestic tasks.In Fig. 2(a), the pilot use the robot to prepare food for a pet.In Fig. 2(b), a mail man is delivering an object to the pilot house.In this circumstance the operator use ALTER-EGO to pick up a credit card, retrieve the box from the mail man, pay, and come back to the house.The experimental activity was performed from two different locations posed at a distance of five kilometers (pilot station placed at the Engineering building of the University of Pisa).Although not exhaustive such experience demonstrate the potential and effectiveness of the approach.

IV. CONCLUSIONS
In this talk we presented ALTER-EGO, a dual-arms mobile platform developed whit soft robotic technologies both for the actuation and manipulation layer.Features resulting from this kind of technologies, like flexibility, adaptivity and robustness allow ALTER-EGO to interact with environment and objects, as well as allow to improve safety when the robot is in action around humans.

Fig. 1 .
Fig. 1.ALTER-EGO, a soft dual-arm mobile platform equipped with variable stiffness actuation units and soft under-actuated hands.