One of the cutests robots showcased at Innorobo 2014 is Elisa-3 a two-wheeled mini-robot by GCtronic a spin-off of the Autonomous System Lab at the EPFL (Swiss Federal Institute of Technology Lausanne). This little brother of the e-puck robot also targets the education and research community. The cylindrical small case (5 cm of diameter and 3 cm heigh) of this mobile robot encloses several components that were selected or designed carefully.
First and foremost, the wheels are magnetic. This allows Elisa to stick and move on a vertical metal board (See videos below) which can be very convenient when giving a lecture or making a demo. The rational behind using magnetic wheels instead of simple static magnets attached to the body of the robot is threefold. First, the magnets do not introduce extra weight since we need wheels anyway. Besides, having magnets at the edges makes the robot more stable. With an even distribution of mass, it is less prone to slip sideways. Last, according to Elisa’s designers, using magnets as wheels minimizes magnetic disturbance that may occur when multiple robots come close to each other.
Regarding onboard computations, Elisa embeds an Atmel ATmega2560 8 bit microcontroller that runs at 8MHz. This makes Elisa Arduino compatible. You can use the Arduino IDE for developing for the Elisa, since the robot is treated like an Arduino board by the IDE. For scientists that prefer to use Matlab, there is a support for that too. The ePic2 Matlab interface was adapted to work with the Elisa-3 robot.
Multi-robot systems has been part of concernes taken into account by Elisa’s designers. We already discussed magnetic interferences that are minimized by turning magnets into wheels. The other aspect of robotics fleets is communication. Elisa-3 comes with a wireless interface similar to that of wireless mice. It seems that this interface is lighter than bluetooth and allows higher throughput (10Hz with a fleet of 100 robots).
Energy is the last characteristic we’ll be discussing. With its LiPo rechargeable battery, this little robot can last 3 hours with motors continuously running at 0.12 m/s which is 20% of top speed (0.6 m/s). This results were obtained on a flat surface with all IRs and LEDs on. However, on a vertical board, the robot consumes approximatively twice as much energy as it requires when it runs on a horizontal terrain. But, when it runs out of battery, Elisa-3 can recharge by autonomously docking into a base station (see Video 1)
Video 1: Elisa-3 magnetic wheels enable vertical motion
Video 2: Elisa-3 Obstacle Avoidance Demo