Tell me more: a deeper dive into the CABLEBOT

The following video describes the components and functions of the ROMI cablebot and design for distributed manufacturing. Funded by EU Grant 773875.

Videos are available in:

• Hi-res (1080p Apple ProRes)
• Mid-res (1080p H265)

Video script:

(BARBERAN) We designed the cable as a tool to observe the farms. To do the work that we cannot do every day, to observe and recollect images and information about the plants, so we can use those images later to understand what's happening with our plants with their farms with their crops. The simplest path we arrived to, to get a camera and an image capturing device to move in our farm and the cheapest one, is just hang a cable and put a robot on top of that cable in a way that it can move automatically by itself. Whenever you schedule (it) to get pictures (it) will just wake up, go ahead, take photographs of the farm and come back and upload those photographs to a server so you can process them and go to (its) home and be safe of the environment.

That offers a lot of challenges that we face like types of cables, the length of the cables, how fast you need to move, I’m vibrating and my images are not good etc. So we face this with the limitations of trying to build a robot that's replicable by anyone, that can be done with all the free tools that we just thought of, and we tried to solve it with 3d printed pieces we choose a construction material that's aluminium with plastic that we can mill and ‘CNC’ in any cheap CNC. We chose almost (only) commercial components like screws like springs like stuff like that, so all this device can be built easily by anyone.

A robot that hangs on cables faces different challenges. One of the biggest challenges is the tension of the cable, that is depending on the length of the cable, the type of cable, and the type of installation. So we designed a spring system that allows the robot to come up and down. Adjusting and adapting to the tension, okay you can see it here also that's designed digitally here, and all the pieces are inside here okay. The more heavy part of the cable bot is as close as we can to the centre of gravity, close to the cable so we have a brushless motor here that's controlled by some electronics that need to be in the back of the of the cable bot. We have these kind of wings that hold the cable bot against the cable with a couple of pulleys. And inside all these parts we have all the electronics designed specifically to fit those wings you can see here this that seems to be un-cabled but it is cabled all the cables are inside, everything is cabled here with exception of the motor that we're doing some tests right now and with exception of this that we are using it to prototype right now.

We have a power module on the bottom that with two screws you can remove completely and interchange it by another one. Why did we do this? Because the idea is that accessibility to batteries is different depending on the place, and depending on the time, so this is a module that you can replace with a different technology, maybe in your area you cannot use lithium batteries because they are not accessible so you can use another type of battery and change the design of of the cable from here to the bottom.

After the battery in the bottom we have the camera module. With this camera module the idea is that's not only for this guy (cable bot), this can be used in any of the other robots of the ROMI project, or in any type of free development. So this is just basically a device that has enough electronic brains to control this device to order (for it) to move and go there and once (it) is where (it) wants (it) can take pictures and align (Itself) to the proper orientation. (It) can also correct vibrations on real time so if the cable bot is vibrating because there's too much wind or the cable is too long and you are vibrating, then you can correct that with the with the camera module.

We also have here another brushless motor that controls this movement and is controlled by (it)self so as you can see it's a complex system, We have different controllers and different drivers for mechanical parts, motor parts etc, and also optics here. All of those have a software interface that allow them to communicate in a transparent way, in a way that they can also communicate with the servers and with the same servers that the other robots communicate, so you can share all the information between the different parts of the system. And also we are trying to keep all the developments in terms of libraries aligned in a way that we can use exactly the same protocols and standards here, that we do in the rover, that we do in the plant scanner etc.

The modelling and the robot are built with open source and free tools, and we build free designs but also electronics. The electronics are designed in-house and we also use open source and free tools to build them. In this case ‘KiCAD’ and we produce them right now, it's just prototypes but we publish all the designs so anyone can produce them by themselves. We try to keep it as simple as we can and we use commercial products that are built by companies that are committed to free hardware also in a way that you can even if this company stops producing that specific board you can find replacements or build your own or change your own.

So in the case of the cable bot we have three main boards one is the board that holds the brain of the camera module, that controls the orientation of the camera, takes pictures and also sends communication in terms of position to the board that controls motors, end stops and is aware of the geo-position of the robot. At the end we have a power, a very simple power distribution board to take care of fuses of trying to to save all the parts of the cable bot from problems with power and distribution of power from the battery module.