Remote contrtolled manipulator to eradicate common wild oat

[eskoilola]

As every Project this one starts with planning. It has to, since I am on an assignment in Germany and my home is back in Finland.

So what is this common wild oat and why should it be eradicated from a field ?

Common wild oat is a plant that competes with oat, wheat and other cultivated plants. It is considered as noxious weed. If a field is infested by this plant, some countries demand a guard period of several years during which the field has to be treated in such a way that nothing grows on it. You do the math.

The common wild oat (Avena fatua) is really hard to eradicate. There are chemicals to do that but those are really expensive and cannot be used with all cultivated plants.

Usually this weed is eradicated mechanically by picking it up and then burning the weed. This is a tedious process since it is not easy to pinpoint the weed among the cultivated plants especially if it is oat that should be grown.

Therer are vechiles that are designed to be used on the field and then inspect the field just by driving and eyeballing. This Needs 2 persons to do the Job efficiently and even then the result might not be perfect. Further more, this weed has to be picked when it is possible to pinpoint it. Not sooner, not later. So there is no bad weather.

What if this Job could be done sitting on Your Coach ?
What if the System could help in pinpointing the weed ?
What if there were more than just one eradicator on the field - say 10 of them

So I have been thinking over this. Some might call it a Robot - IMHO it is NOT a Robot - it is a rermote controlled Manipulator with some autonomy to make it more manageable.

The very first thing is to decide the General structure of this Manipulator. There are some requirements that originate from the very Environment it is goint to be used.
- There are ditches and other formations that the Manipulator should be able to cope with
- The Manipulator should be able to turn the right side up  no matter how it is oriented
- The Manipulator should be water resistant. It is not a submarine but it should be able to move over shallow Ponds
- It should not crush the cultivated plants when moving.

My personal winner at the Moment is a 6 legged walker.

[JHovel]

I will read your project log with great interest if you continue to report here. This is a very complex design issue and fascinating to me - although I have no need for such a device, of course. But the fundamental design process is of great interest.
Thanks for the introduction!
Cheers,
Joe

[hermetic]

Can't imagine how you would build a robot or remote controlled vehicle to pick wild oats, AND make it cheaper, faster and more reliable than people. I used to do this for a local farmer friend of mine, really easy because we did it shortly before harvest, and at that time the wild oats are about a foot taller than the crop, just walk along the field in the sunshine pulling them up and putting them in a bag. Very pleasant way to spend a day! You would have the cost of a machine that would only get a couple of weeks work in a year, and spend the rest stored up getting damp and breaking down. Most problems with combine harvesters are due to them being left idle most of the year.

[eskoilola]

So 6 legs. Symmetric or asymmetric....

I think it might be a good idea to make this walker symmetric because:
- all legs would be identical and could be fabricated more easily. For example the number of molds will be less
- symmetric design is able to walk to any direction without complex turning. There is no direction
- replacement of a broken leg is simple. Just make another one
- each leg can have it's own dedicated controller with some degree of autonomy. Makes software design somewhat easier
- each leg would also have it's own power controls, valves and other stuff like that which is another benefit of symmetric design

Asymmetric design might give less complexity as all legs do not need all the freedoms. Asymmetric design might also contribute to speed. Fortunately the speed is not an issue here. This device does not need to run like a cheetah.

So I think it will be a 6 legged symmetric walker. Unfortunately it most likely will have top and under sides. Getting rid of that would certainly give some advantages. Some of the on-board devices will have their own orientation requirements. Power supply for one. This cannot run on batteries - there must be some sort of a generator onboard the alternative being very short working time or very costly batteries.

[eskoilola]

Can't imagine how you would build a robot or remote controlled vehicle to pick wild oats, AND make it cheaper, faster and more reliable than people.

You are VERY right on making it faster. Also, the ideology behind means that there is at least one real person steering the device. So that might save the cost of one person.

Being MORE reliable - maybe not. Being easier to work with ... depends on how well the thing was designed.
The cost of a device like this depends also on design. With mass production the cost can be pushed down to unbelievable figures. I am also sure that the camera system can use filters to make the weed stand out better.

Many nordic countries have fluctuating weather conditions around August and September (the harvesting time). If it is raining cats and dogs the crop will be somewhat spoiled - too wet to be harvested or has to be dried with high cost. However, no matter what kind of weather it is or whether the harvesting succeeds - the wild oat MUST be eradicated. The alternative is a multi-year long quarantine which is really costly.

There is yet another point of view into this. The great internet.
How about playing weed-hunt and get paid to do that ?
If You are a person with disabilities and want to do something meaninful then this might be one way to go.

Also, it does not need to be limited on picking weed into a plastic bag for burning - one could also harvest some actual crop like apples or herbs.

Finally - I like challenges - and finally after finally this might never become a commercial product but it will be fun to fabricate it.

[RotarySMP]

Great project concept.

Why the human? Given the cost of labour northern europe, completly eliminating the need for labour in this process must be an attractive goal.  What about splitting the spotting and pulling into two separate datalinked machines. The spotting sounds like the perfect application for a flying drone, which could quickly survey the field and pinpoint the wild oats, meaning the walker can save time manoeuvring directly to the suspect, rather than surveying a whole field.

How are you thinking about doing the machine identification? Is there some obvious difference such a reflectivity a certain spectrum, or are you going to need a neural networks based recognition software and do some training for it to recognise leaf features?

How hard is it to pull these weeds? When I think of the weeds in my rose garden, there are some with strong stalks and weak roots which are easy to pull, and then there are the barstards with weak stalks and strong roots which just break off and grow straight back.

Will this walker be tethered to the drivers vehicle for electrical power, or autonomous. You would need a lot of power to do a whole field on autonomous battery power.
Mark

[eskoilola]

Why the human?
As much as I like the idea of having an autonomous machine left alone in the field outrooting the weeds I really hate the idea of machines completely replacing humans. Maybe I am a communist?
The best neural network by far is sitting right between our ears. I have been working with neural networks, genetic algorithms and whatnot with my daily job. These have limitations and require a slow and painful learning which in this case might become quite overwhelming because of the diversity on the tasks.

How are you thinking about doing the machine identification?
I assume You mean the regognition of the bad guys here. Obviously it has to do with some sort of optical regognition. I am pretty sure that the weeds have some optical properties that the actual crops do not have. For example how do they react on UV light or other parts of the light spectrum? The result could be superimposed on top of video feed to make the weeds stand out.

What about splitting the spotting and pulling into two separate datalinked machines.
The walker itself must be linked to a server with a data link. Analyzing the entire field in advance with a drone or similar is tempting as this would help in finding the weeds as the viewing angle is different. This also means that it should be possible to clearly identify the weeds. What it also means is accurate navigation. Is it possible to do this without accurate navigation?

How hard is it to pull these weeds?
It depends on the weed and the soil. The wild oat has to be pulled all the way out - roots and all. If my memory serves me correctly these are not that hard to pull out but the top of the plant is quite weak so it has to be gripped near ground. It could be a pair of rolls for example. Sort of a mangle.

You would need a lot of power to do a whole field
Correct. Therefore some sort of a generator must be on board. Battery is definitely not an option. The construction should be such that almost any generator with suitable AC output can be used.

[CrazyModder]

Crazy project, I like it. 

On the power aspect. Don't forget that it is easy to multiplicate machines. I would not rule out batteries just yet. You could have a non-moving generator at the edge of the field (hence, no limits on size/fuel), and then use more bots than you normally would. Some of them will be charging while others will be working, and there will be a constant exchange. Obviously you have to get your calculator out to check if it is really feasible and take into account how well the batteries will hold up (basically, the e-car problem). But this may make the moving parts so much smaller, lighter and hence cheaper that it may just be worth it.

[eskoilola]

I have been looking around internet for hydraulic joint. Did not find anything that would be suitable.
Those that I found were capable to lift a car or broke a leg with ease. This "animal" does not need that sort of strength.

I also thought that the hydraulic actuators might be a little bit leaky. If the fluid volume is big enough and if there are bending sensors on each joint then leakiness is no more a problem. If these can be made without soft sliding parts - the better.

Hrere is an illustration of my thoughts about this thing. Has anyone made or seen that kind of hydraulic actuators ?

[eskoilola]

After some search I finally found the english name of this type of actuator. It is called Rotary Vane Actuator. And they are really expensive  .

I will try to fabricate at least one when I get back home from this darn assignment. It does not seem to be too challenging to do as it is symmetric and round. Precision required - yes.

I had earlier a Russsian made mini lathe called M2. With that one I learned to do things with this type of equipment. The result: at least 50 kilograms of scrap iron and maybe 3 kilograms of good stuff.

I actually found a picture of this lathe. It has a round bed and is supposed to be quite accurate. I can tell: It is nothing but accurate.


The lathe I have now has not been used at all - it is brand new. I have to clean, oil, level and calibrate it. I also purchased my very first micrometer  .

What I really learned with that russsian lathe was grinding HSS. I seldomly use carbide as it is initially so dull. Carbide also seems to make a better finish if the cut is deeper so with carbide one has to plan ahead. Sharpening a HSS tool is just 20 wipes with the Norton oilstone (grey side) and there You are. Razor sharp. Do that with carbide.

Edit: There is an entire page dedicated to this exotic lathe.
http://www.lathes.co.uk/russian/

[fcheslop]

The actuator always reminds me of the Kimble steam engine
Iv used those actuators on small scale automation although they were pneumatic. Iv also come across hydraulic machines that used water instead of oil for the fluid. From memory Im sure they had adjustable stops to set the amount of movement and a damping regulator to slow them down as they neared the end of there stroke
http://www.john-tom.com/ElmersEngines/20_Kimble.pdf
cheers

[eskoilola]

Now. a bit of hydraulic mathematics done by a person who has never-ever done that before.
I tried to figure out what kind of pressures and fluid flows is this about.
I also found out that there are a lot of www sites that have calculators for this but they are almost all talking about inches....

Here is an illustration I draw for myself to figure that out


First I tried to calculate the displacement for one degree rotation angle with the following dimensions:
Shaft diameter: 20mm
Cylinder diameter: 100mm
Cylinder height: 100mm
After some calculation the displacement came into a VERY comfortable figure 2.09 cubic centimeters.

After that I decided that one degree would cause 10 mm movement on the end of the leg. So for every centimeter there is a displacement of 2 cubic centimeters. Just for pure luck the leg is about 50 centimeter long in this case - which is near the length I like.

Now, if there is a pressure of 1 kilogram per square centimeter then the force at the end of the leg will be 2 kilograms.

With those dimensions of the actuator I need a pressure of 25 kilograms per square centimeter to be able to lift 50 kilograms.

Now I need Your opinion on a few things here:
1. are my calculations and estimation even near what that could be in reality ?
2. is a pressure of 25 kilograms per square centimeter manageable ?

Thanks for reading !

Edit: About using water as hydraulic fluid. In Finland we must add some antifreeze to it. A bio version of that would be Vodka !