The Hexbug Spider XL is an interesting toy – originally it comes as cheap remote-controlled robot, but at the same time it can be viewed as a cost efficient chassis to build an autonomous robot. There are two motors inside of this spider: one of them controls six-legged crawling motion and the second motor allows to rotate its head on 360 degrees. 3 AA-bateries set internal mechanisms in motion. A two-channel RC remote is used to control this fascinating creature. Our intern – Nadja Hölzl – hacked this robot by adding an Arduino Uno for local control of the actuators. As sensors for detecting obstacles we added small-range proximity sensors. Some parts of modified robot were created using 3D printer. The application of this approach helped us to fix all necessary components on the top of the robot during prototyping phase and refine its visual representation.
An autonomous robot requires both: actuators and sensors. Actuators are responsible for moving and sensors help to measure a physical quantities. Without actuators a robot cannot perform any practical task. If your robot doesn’t have sensors, then it’s blind. In our case, actuators are two motors for moving of the spider. Proximity sensors help to perceive distance to obstacles.
Our hack starts from disassembling – the head of the spider should be removed in order to get access to the motors. To fix all necessary components on the spider, we selected leveling architecture. It allows to add, change or remove parts of the robot without much effort. In general this approach is good for prototyping, but is not optimal in terms of space requirements and used plastic.
First, we designed new head for the robot, which is the base for all next layers. There are two oval holes for wires on the top of this model. From two sides of the head you can see the sockets for the bars, which are used to fix other layers.
A 9V battery is used to power all electronic components of the spider. The holder for battery contains sockets where you can attach up to 10 proximity sensors. TCRT5000 is the reflective optical sensor which we use in our experiments to measure a distance to obstacles. Due to distinguishing shape of the spider, we designed a special bar to hold these proximity sensors.
Unfortunately, current from Arduino board is not sufficient to run the motors. Therefore we used an Arduino motor shield to control two motors of the robot. Using this shield you can easily connect and operate the two motors.
We used Blender, which is free and open source 3D animation suite, to model all parts of the modification for Hexbug Spider. 3D printer Makerbot Replicator 5G turned the virtual designs into real physical objects.
And finally you can relax and watch how this graceful creature explores its environment.
All 3D models are freely available on Thingiverse, so you can download them, possibly modify and print on a 3D printer.