Autonomous navigation and charging. We develop docking system for mobile robots

December 21, 2021  |  Development

Docking is an important part of autonomous navigation. Without it, robots would not be completely self-sufficient. RoboTech Vision is also aware of this and is therefore finishing other applications alongside the finalization of autonomous navigation on the road or in the vineyard. For example, these include a user interface and a custom docking system. The first autonomous charging tests have been excellent.

Docking not only requires hardware but also software. While small position deviations are accepted when navigating on the road or in the vineyard, high precision is required when recharging. The robot must not only reach the docking station before it discharges, but it must also start from the required direction and successfully connect to the connector. The solution was developed by robotic engineer Ing. Jakub Lenner during his studies at university. He returned to docking during the development of autonomous navigation at RoboTech Vision.

Charging a car or tractor

RoboTech Vision does not plan to use the system only on its robots. As they develop algorithms that can be deployed on different types of chassis and devices, there is a need to be able to autonomously recharge, for example, a tractor or a car in the future. Docking using a marker is already widespread in the market for drones or walking robots. The difference is that the solution for a mobile robot with a differential or Double Ackerman chassis requires a more accurate determination of the orientation of the marker relative to the robot, due to the large distance.

“With a mobile robot, it’s important that it aligns to the exactly to the centre of the docking station. As unlike a drone or walking robot, neither the differential nor the Double Ackerman chassis can move in any direction, just as a car cannot move sideways, the three markers serve to ensure that the robot knows the orientation of the station from a distance and is able to turn correctly towards the connector while moving along a relatively short path,” says Lenner.

Although, during testing, there has not yet been a situation where the robot has not stopped exactly in the middle, this scenario is also envisaged. For cases like this, the algorithm will be modified so that the device itself knows that it is in the wrong position in the station and tries to reverse again to reposition more accurately. Some existing solutions even include a movable connector that adapts to the robot’s incorrect position. The company is still working on the hardware. The solution will be part of all autonomous navigation and robots.

Battery and spray status

If the robot is so far away that the camera cannot see the marker, it will navigate to the station using a map with a waypoint. “The robot constantly monitors the battery status while moving along the road or in the vineyard and when it reaches critical values, it stops the task and takes the shortest route to reach the charging station using GPS coordinates. When returning, the RTV Sensor Box detects any obstacles in the way and avoid them. Both types of navigation – global and reactive – are used here,” adds Ing. Matej Vargovčík, who develops AVN algorithm.

The company has thought of different situations and during the winter period, when it is not possible to test the device outdoors, the company has prepared a simulation of a robot in a vineyard, which not only runs out of battery power, but also runs out spray. The RoboTech Vision team will be testing the new features on the Crawler robot in the vineyard this spring.