The mascot of GitHub, the well-known file hosting platform aimed at developers and owned by Microsoft, is a cross between an octopus and a cat. It’s not called for nothing Octocat. Using a Raspberry Pithe technicians of Infineona giant in the semiconductor market, whose solutions are aimed at automotive, industrial systems, power sensors and connected systems, explain that they have created Octocat using pneumatic tentacles.
The project, published on Hackster, can be replicated by any maker and extended to their own projects. Infineon in fact, he shared the list of hardware components, the programming code and the 3D models used.
How to use a Raspberry Pi board to move an octopus’s tentacles
No animals were harmed to carry out the Infineon experiment successfully. The company’s experts had fun 3D printing the head of Octocat with a FDM printer, then refining the result by hand. Next, they made a couple of molds for the tentacles using some silicone for the actual implementation.
The use of pneumaticwith actuators connected to the individual tentacles, therefore made it possible to pilot the movements of the cute octopus-cat via a single-board computer Raspberry Pi.
Specifically, the creators of the project explain that they used a set Of pneumatic valves connected to DC Motor Control HAT of Infineon itself. The valves are able to manage movements by filling small channels created inside each individual tentacle with air.
According to Infineon, its DC Motor Control HAT it houses a TLE94112ES chip that provides 12 half-bridge drivers and is capable of overseeing the operation of a variety of actuators, including the pneumatic valves implemented in the tentacle system.
The set of pneumatic valves used to manage the movements of the tentacles via Raspberry Pi.
What is a HAT in the case of Raspberry Pi
HAT stands for “Hardware Attached on Top“: This is a hardware expansion compatible with Raspberry Pi boards. It connects directly above the board invented by Eben Upton via i GPIO connectors (General Purpose Input/Output) and provides additional functionality, such as motor controllers, sensors, audio interface, and so on. On Amazon Europe it is possible to find an infinite number of HAT modules for Raspberry Pi boards.
Infineon has exploited the DC Motor Control HAT to control motors and actuators via Raspberry Pi and a series of libraries both in Python e C++. On this page you can find the list of “ingredients” for the realization of the entire project in total autonomy.
This is the result of the work, with the octopus mascot of GitHub that moves its tentacles, controlled by the Raspberry board.
The software configuration to animate the octopus tentacles via Raspberry Pi
Infineon explains that it used its multi-half-bridge library, also shared on GitHub, to control the movements of the TLE94112ES motor. These instructions offer concrete ideas for the practical use of the library, also excellent for other projects.
The developers start by defining all the necessary libraries to get the HAT working for Raspberry Pi. The variable MOVEMENT_INTERVAL represents the delay between the sequences of movements. The two log functions make it easier to debug the code and improve the readability of the output.
The most important aspects of the code that moves the tentacles
The next part of the code available at Hacksterdefines a class Octocat which in turn exploits the class Tle94112Rpi of the library multi-half-bridge. A time of “cooldown” in milliseconds, activated between individual movements. This is an experimentally determined time window to allow the suction cups of the tentacles to deflate after each movement, in order to avoid damage.
Followed by mapping of individual valves used on the suction cups: this process allows them to be represented one by one or in groups, so as to easily direct them.
The code shared by Infineon therefore defines two types of movement: lifting and lowering of the suction cups. Finally, delays are established for individual suction cups and groups of them.
The main function is moveTentaclewhich is displayed as part of the class Octocat and used to actually control the suckers from the program flow. This function uses two parameters as input: the suction cup or group of suction cups you want to control and which movement they must perform (lifting or lowering). The main-loopfinally, it constitutes the sequence of movements that the suction cups must perform.