New breakthroughs in flexible robots: Italian Coman robots
most humanoid robots developed in the past decade are rigid joints, which will cause problems if they want to interact with people. If they accidentally hit people or lose their balance and fall down, their inflexible arms and legs may cause harm to people. Recently, researchers have shown increasing interest in developing robot joints with various rigid standards, which will improve the safety of robots, but so far, few teams have created a complete finished robot. Now, a team of the Italian Institute of Technology (IIT) is gradually approaching this goal with their Coman robot (flexible humanoid robot)
Coman, modeled after a four-year-old child, is 94.5 cm tall (from neck to foot) and weighs 31.2 kg. The 25 degree of freedom (DOF) robot combines rigid and flexible joints (as shown in the figure below). The flexible joint (14 DOF) relies on a series flexible brake. These brakes, customized by the IIT team, are known to be used for bending or extending robotic arms and legs. These brakes are small and modular, which makes them ideal materials for building multi degree of freedom robots such as humanoid robots. Researchers have also developed customized torque sensors for each elastic joint, including a six dimensional force/torque sensor for the ankle
so how does this flexibility help? The elastic brake adds spring to Coman walking: in the walking experiment, the body of the robot naturally absorbs the reaction force of the ground at each step without applying additional control. Without specific foot devices or active control, it is difficult for rigid braking humanoid robots to achieve this. When a stable control mode is applied, the robot can stabilize itself even on a moving platform or when it overturns
coman's internal structure is made of titanium alloy, stainless steel and aluminum alloy, wrapped with ABS plastic exoskeleton. The following pictures show the position and structure of the series elastic brake (SEA), which is distributed at the hips, knees, ankles, shoulders and elbows of the robot
in the process of developing flexible humanoid robots, the team also invented a method to determine the optimal joint elasticity, but this method is an extremely time-consuming trial and error process, which still lacks sufficient data support. Their method is based on resonance analysis and energy storage maximization criteria, which provides a framework for other researchers exploring flexible robots
some of the earlier robots exploring flexible joints include Wendy (1998) and twendy one (2007) of Waseda University. These service robots are designed to assist the elderly. For safety reasons, they use specially developed joint devices to build flexible arms, but this joint device is slightly cumbersome. Recently, MEKA robotics manufactured a humanoid robot with flexible arms, while roboray of Samsung and DLR biped of German Aerospace Center have moment controlled robot legs. Think again that Baxter of rethink robotics also has flexible arms
not under the demands of law and environmental protection, IIT team is the leader in building a humanoid robot with flexible arms and legs, which has the thermal conductivity coefficient of China's building exterior walls and windows 3-4 times that of developed countries. Members of the team include Nikos g. tsagarakis, Stephen morfey, Gustavo Medrano Cerda, Li Zhibin, and Darwin g. Caldwell. If you want to know why this robot has no head and has the function of maintaining the peak force during the experiment, don't worry: its head is under development. We heard that the researchers also completed a pair of robot hands. We expect that more new parts will be integrated into this robot soon
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