Rhoban Project, in collaboration with Flowers team shows its robots in the French pavilion of the international expo 2012 of Yeosu, Korea. Every day from 2012.05.12 to 2012.08.12. Over this period, around 500 000 visitors are expected in the pavilion, 8 millions in the whole expo. Rhoban Project is a group mixing academic researchers, artists and others people interested in designing original robotic creatures. Have a look here.
The show presents the work of the project about humanoid robots. The main question that we explore is compliance / soft motor control. Indeed, usually a robot is controlled “in position”: this means that the angle of each joint of the robot is defined for any time; and at any time, each joint takes this angle whatever force/energy it needs and whatever obstacle it meets. The robot is stiff. By several aspects, this method has been proved to be very efficient in the industry world (precision, repeatability, power). However, it becomes less adapted when one wants to make robots go out of the context of factories. This is the case if we think to personal robotic, where the robot works at home among people, or interventions on a disaster site: the environment of the robot is not known in advance in these applications.
Taking that into account, we design soft robots, like animals, and like human in particular. This allows the robot to handle partially or completely unknown environments. Soft joints adapt by themselves their own positions in order to fit the environment and perturbations. In this way they look and construct by themselves unplanified stable states or trajectories for the robot – motor intelligence -. Thanks to compliance, animals enforce locomotion in an unequalled efficient and robust way!
Compliance/softness allows also the robot to learn from human. Indeed, the softness of joints allows physical interaction between the human and the robot. The user can manipulate directly the robot in order to show him new motions; and the robot, while performing some other things (like balance keeping for instance), can learn from people new motor behaviours. Thanks to compliance, its motor system remains “open” to its environment. Such interaction is also a privileged way to enforce collaborative tasks between humans and robots like typically transporting heavy charges.
Also, we designed an anthropomorphic arm of real size. It has 7 principal joints plus a hand with several degrees of freedom (4 to 12). Our design relies on low cost elements in order to fit cost constraints in view of large public deployment. This implies a low precision and a low power. For that, we use elastics and springs to reduce backlash and as energy accumulators.
We explore softness at different levels of robotic design:
– mechatronic control: how the motors must be controlled by electronic and software in order to give a soft behaviour to a joint.
– morphology. Morphology is crucial for many tasks, and especially locomotion. The motor behavior, and in particular the stability of the robot depends directly on its morphology. The morphology of our humanoid robots are highly inspired by the one of the human: it is particularly original for the vertebral column of Acroban which is designed according to physiology studies emphasizing the essential joints of the human vertebral column. Together with the pelvis, this allows very subtle motions close to human.
– mechanics. We explore the use of compliant materials (plastics, elastics, silicone, springs) in order to add natural flexibility to the robot, like does the cartilage for animals. We also design a linear free joint in the hip, controlled by a damper, which is new in humanoid robotics. This makes the robot semi-passive as this joint only reacts mechanically to environment without any specific control. Compliant and flexible mechanical elements absorb shocks, and also behave as energy accumulators.
In the expo, you will find:
- The small humanoid robot SigmaBan (which usually plays soccer 🙂 ) doing tree swing while Acroban pushes him. This installation shows how our robots can interact physically thanks to soft control. Indeed, the arms and the spine of Acroban are compliant, which allows him to feel the swing and pushing it on time while keeping balance.
- Then another Acroban performs some dances and sometime interacts with people, who can takes his hands and play with him.
- Finally, the dance of Acroban is accompanied by a funny show performed by 5 pairs of real size anthropomorphic arms who seems to play rock music !… Each arm has 11 degres of freedom, including 4 articulated fingers. The arms reproduce the human morphology.
Among others media, the expo attracted attention from Korean media, see: