Rendezvous and Docking of Mobile Ground Robots for Efficient Transportation Systems

Abstract

In-Motion physical coupling of multiple mobile ground robots has the potential to enable new applications like in-motion transfer that improves efficiency in handling and transferring goods, which tackles current challenges in logistics. A key challenge lies in achieving reliable autonomous in-motion physical coupling of two mobile ground robots starting at any initial position. Existing approaches neglect the modeling of the docking interface and the strategy for approaching it, resulting in uncontrolled collisions that make in-motion physical coupling either impossible or inefficient. To address this challenge, we propose a central mpc approach that explicitly models the dynamics and states of two omnidirectional wheeled robots, incorporates constraints related to their docking interface, and implements an approaching strategy for rendezvous and docking. This novel approach enables omnidirectional wheeled robots with a docking interface to physically couple in motion regardless of their initial position. In addition, it makes in-motion transfer possible, which is 19.75% more time- and 21.04% energy-efficient compared to a non-coupling approach in a logistic scenario.

Figures (6)

• Figure 1: The proposed approach allows robots to physically couple in-motion and enables in-motion transfer. In a logistic scenario, this facilitates transporting packets with the same destination together in bundles, thereby reducing overall travel distance, energy consumption, and time.
• Figure 2: Illustration of the robot modeling. Robot $i$ is a grey disk with radius $r$ (). The heading $\theta^i$ is depicted as a blue arrow ($\rightarrow$). The docking interface is located on the margin of the disk and depicted as a green rectangle ($\blacksquare$). The heading of the docking axis is depicted as a green arrow ($\rightarrow$).
• Figure 3: Illustration of the approaching corridor and the docking axis displacement. The robots are depicted as grey disk (). The docking interface is located on the margin of the disk and depicted as a green rectangle ($\blacksquare$). The heading of the docking axis is depicted as a green arrow ($\rightarrow$). The approaching corridor is depicted as a green zone around around the docking axis(). The collision avoidance zone is depicted as a red zone ()
• Figure 4: Experiment 1 - The robots' docking axes are perfectly aligned at the beginning. The goal is that the robots satisfy the coupling constraints before arriving at the goal point and thus physically couple in motion.
• Figure 5: Experiment 2 - The robots' docking axes are not aligned at the beginning. The goal is that the robots satisfy the coupling constraints before arriving at the goal point and thus physically couple in motion.