StarlETH

This fully actuated robot features four identical, completely symmetric articulated legs connected to a single rigid main body. Each leg has three degrees of freedom (DOF) that are arranged in mammalian-style with successive hip abduction/adduction, hip flexion/extension, and knee flex- ion/extension. To achieve fast swing leg motion, we put emphasis on a lightweight construction with all ac- tuators tightly integrated at the main body. Using ro- tational actuators in all joints makes a large range of motion possible, so that the leg can be fully retracted and extended. Having a body length of about 0.5 m, segment lengths of 0.2 m, and a total weight of 23 kg,this robot is comparable to a medium-sized dog. StarlETH is driven by highly compliant series elastic actuators which have very similar properties of our muscles and tendons. They act as compliant elements to temporarily store a large amount of energy. Me- chanical springs decouple the motor and gearbox from the joint to protect the gearbox from impact loads at landing, to intermittently store energy, and most im- portantly, to allow for high fidelity joint torque control. This opens a very broad spectrum of opportunities to implement novel locomotion control algorithms. The system is equipped with an inertial measurement unit (IMU) that allows, in combination with the accurate kinematic information from the joint encoders, to precisely estimate the state of the robot. Hence, all maneuvers can be executed without additional per- ception or using a motion capture system.  

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References

• M. Hutter, C. Gehring, M. Bloesch, M. Hoepflinger, C. D. Remy, R. Siegwart, “StarlETH: A Compliant Quadrupedal Robot for fast, efficient, and versatile Locomotion”, external page Proc. of the International Conference on Climbing and Walking Robots (CLAWAR), 2012.  [full paper]