This article shows accurate and autonomous creation of free-form trenches using a walking excavator. We present hardware extensions and modifications for full automation, a mapping approach specifically tailored to excavation, environment collision-free trajectory planning on these maps, an arm controller aware of various limits and an improved state machine that enables the execution on real hardware. Furthermore, previous work about excavation planning and the design of a single soil-independent dig cycle is extended and transferred from simulation to hardware. The entire system is tested on a foursegment, piecewise-planar trench and a free-form curved trench. Both shapes were successfully excavated with unprecedented accuracy.

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A taxonomy for gesture-based interaction between a human and a group (swarm) of robots is described. Methods are classified into two categories. First, free-form interaction, where the robots are unconstrained in position and motion and the user can use deictic gestures to select subsets of robots and assign target goals and trajectories. Second, shape-constrained interaction, where the robots are in a configuration shape that can be modified by the user. In the later, the user controls a subset of meaningful degrees of freedom defining the overall shape instead of each robot directly.A multi-robot interactive display is described where a depth sensor is used to recognize human gesture, determining the commands sent to a group comprising tens of robots. Experimental results with a preliminary user study show the usability of the system.

Abstract-This paper presents the realization of the worldwide first automated walking excavator chassis. To this end, the authors build a new generation of high-performance hydraulic valves with integrated pressure feedback to achieve fast and accurate cylinder force tracking. This allows to automatically adapt the legs to uneven terrain and to optimally shape the ground reaction forces in order to change orientation and height of the cabin. Due to the contact redundancy, automated balancing is implemented as a contact force optimization problem including constraints on contact forces and joint torques. The corresponding prioritized optimization problem can be simplified by using a quasi-static approximation of the system dynamics and a complexity reduction due to the kinematic structure of the legs. Our approach considers the unknown configuration and load of the cabin, arm, and bucket as system disturbances, whereby gravitational effects are approximated as well as possible. It is tested in a Gazebo simulation and validated in different experiments using a prototype walking excavator machine. The proposed method revolutionizes operator control of these versatile but complex multi-purpose vehicles: instead of manual and coordinatively very demanding cylinder position adjustment, the operator can command simple high-level commands like cabin pose. Furthermore, it significantly reduces peak forces in the cylinders and at the contact points, which causes less damage to the mechanics and the ground.

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