Using Elastically Actuated Legged Robots in Rough Terrain: Experiments with DLR Quadruped bert

Abstract

This paper addresses walking and balancing in rough terrain for legged locomotion in planetary exploration as an alternative to the commonly used wheeled locomotion. In contrast to the latter, where active balancing is not necessary, legged locomotion requires constant effort to keep the main body stabilized during motion. While common quadrupedal robots require to carefully plan motions through torque control and force distribution, this paper presents an approach where elastic elements in the drive train function as an intrinsic balancing component that allows to ignore inaccuracies in the locomotion pattern and passively accommodate for terrain unevenness. The approach proposes a static walking gait algorithm, which is formulated for a general quadrupedal robot, and a hardware foot design to support the locomotion pattern. The method is experimentally tested on an elastically actuated quadrupedal robot.

Using Nonlinear Normal Modes for Execution of Efficient Cyclic Motions in Articulated Soft Robots

“…We consider here the application of proposed algorithm to the quadruped Bert [13]. This system is built using four of the above discussed soft segmented legs.…”

“…We will introduce a simplified control strategy, and we will test its effectiveness on this system to implement swing-like oscillations. Preliminary application to the articulated soft robotic quadruped Bert [13] is also provided, showing that these techniques can be employed to implement locomotion.…”

Practical Approach to Characterize Realistic Motor Dynamics for Robotic Simulation Independent of the Use Case

“…Especially in rough and uneven terrain, adaptable foot placement allows for more flexibility of legged robots in comparison to their wheeled counterparts [1]. Therefore, various legged robots are being developed with one of the most intensely researched type being quadrupeds, such as MIT's Mini Cheetah [2], EPFL's Cheetah Cub [3], ANYmal [4], Boston Dynamics' Spot robot [5] as well as Bert [6], [7] (see Fig. 1) developed by the German Aerospace Center (DLR).…”