FAC system 4 gripper Rubik's Cube Solver

Overall design

After finishing our first FAC system Rubik cube solver back in 2015 we decided to make a 4 gripper solver in FAC as well, but not before we made a 3 gripper Rubik cube solver in Meccano first. So after finishing the Meccano solver the basic design of a 4 gripper protoype was more or less ready by the mid of 2016. Making a nice oak woodcase and incorporating all the mechanical components, electronics and hiding all the wires was done by the end of 2018. The programming part started more or less the same time. During the programming the gripper mechanics had to be modified a couple of times in order to achieve a durable gripping performance.

img Cube solver as per april 2021

Gripper design and gripping performance

The grippercomponent has been entirely redesigned compared to our 3 gripper solver. Initially I followed the old school method to define the designparameters of the linkage diagram. A learnfull process, but quite time consuming. img Old school prototyping of a linkage based gripper (july 2015)

After having set the designspecifications I designed a complete gripper system in AutoCad to be sure there are no desigflaws left and to assure the freedom of movements -gripping and rotating- of each seperate gripper. img A digital study to check for designflaws

During testing in the real machine it became clear, that the gripangle was a bit unfortunate resulting in a less effective gripping performance. The gripper had to be modified, but I didn’t want to change it conform the method of the old school prototyping. Searching on Internet for a good linkage mechanism design software I came across the linkage program of David Rector. With this package I was able to finetune the parameters of the gripper mechanism resulting in an optimal performance of the gripper as a whole. img Prototyping a linkage based gripper With linkage design software (february 2020)

Initially grippertips were made in black coloured PETP (also known as Arnite), but the final grippertips, based on the latest insights regarding gripping performance were made with a 3D printer. Between the grippertip and the cube low density rubber of approx 2mm thickness has been used to achieve a firm gripping.

Autotron july 10 and 11, 2021: exhibiting the 4 gripper FAC solver for the first time


img No complaints about the level of attention!

Controller board, programming and overall schematics

The Raspberry Compute Module Board represents the heart of the machine.

Raspberry and Arduino are awesome tools for physical computing. These are open source microcontroller boards including a free software development environment. You can make interactive objects that can sense inputs from switches, sensors, and computers, and then control motors, lights, and other physical outputs like in the real world! More info about these tools can be found at the Raspberry and Arduino website.