Locomotion: moving with 6 legs

Moving with six legs is quite a challenge. The reason that Zebro has six legs, however, justifies the difficulties. Insects, who often have 6 rotating legs, are very good in moving across rough terrain. So are Zebro's! By walking forward, Zebro walks normally and can easily climb obstacles up to half its height. For climbing, it turns around. Using its C-shaped legs to hook unto objects its way, it can climb up to 1,5x its own height. DeciZebro can climb small stairs

Locomotion: in depth

Zebro is equipped with a dedicated locomotion controller. This controller is responsible for translating the commands received from the top level controller, who interprets sensor data, to actual movement. The locomotion controller individually tells a position the legs need to go to. The legs in turn, having an internal feedback loop that continually checks leg position follow these commands and confirm the succesful execution of a command to the locomotion controller The locomotion controller runs a MaxPlus based algorithm to continually update the leg position, and plan ahead.

The entire locomotion system has been built up in a modular fashion, allowing us to quickly remove, replace or swap entire leg modules. Each Zebro is equipped with 6 of these modules; 1 for each leg

Credit: Laurens Kinkelaar

Robot Cooperation

Zebro's are built to copy the cooperative behavior we see in groups of animals in nature. This means Zebro's can only communicate with local neighbours, and have to make their own decisions. There cannot be a central computer that drives the swarm, so that the swarm is not dependent on a single source of instructions. This is quite complex, since all robots now have to communicate with their neighbours and make choices based
on this communication. Below, a simulation is shown where robots move autonomously, but still as a group. To achieve this, three types of algorithms are used: Attraction/Repulsion, Obstacle Avoidance and Alignment. More algorithms are being developed to facilitate fully autonomous charging, efficient exploration and data sharing intelligence.

Simulation by: Jurrian de Groot

Zebro Species

Zebro's come in all kinds of sizes! Just like ants, who divide tasks between workers, gatherers and soldiers, Zebro's are
meant to cooperate. The DeciZebro is the main swarming robot, and will be the first to actually demonstrate
swarming behavior. Deci is about 30cm long and can climb up to 15 centimeter high obstacles. PicoZebro is the
smallest Zebro, the size of a matchbox. It can reach tight spots and will be equipped with an array of sensors
KiloZebro is the 'mothership' of the swarm, and could be used as a mobile charging station or drone platform.

KiloZebro

KiloZebro is our behemoth Zebro. Weighing in at over 20 kilograms, being about
1 meter long and being equipped with 200W motors, it is very powerful.
KiloZebro is envisioned to travel with large swarms of DeciZebro's, functioning as a
'mothership'. It could be equipped with large solar panels or batteries and function as
a mobile charging station. Also, it could be equipped with several drones for rapid
aerial scouting.

PicoZebro

PicoZebro is the smallest Zebro currently under development. It is the size of a matchbox
The body consists of six printed circuit boards that click together. The Pico is small enough
to crawl under obstacles that Deci or Kilo can't get under. It is capable of autonomous
behavior using a simple proximity sensor and an optional camera.

DeciZebro

DeciZebro is the flagship Zebro designed to form the backbone of any swarm
Being the size of an A4 paper (290x180mm) it will be capable of travelling
up to 10 kilometers an hour in the future. The robot is designed for series
production and assembly. A prototype series of 10 robots has been created, with
which succesful autonomous behavior has succesfully been demonstrated
Currently, a localization and communication module is being developed that
will allow DeciZebro's to localize each other and communicate with each other
even in large swarms. This step is critical in the development of succesful
decentralized swarming behavior, and DeciZebro will be one of the first,
if not the first, robot to demonstrate this worldwide.