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Universal 5 axes manipulator that serves many purposes. In electric and hydraulic variants. Rope operated worm robot may be added in the future.

industrial robot diy worlddevelopment gvcs pivot automation 5axis hydraulic electric

manipulator's Introduction

Robotic Manipulator

The pivot of many machines of the world development global village construction set.

Core

scalable (scale up to use for forest work, as crane or defense herc)
hydraulic (electrical delivered too little payload for DIY heavy duty transmission)

High Level Overview

Developers:

worlddevelopment e.V. & other world citizens

manipulator's People

Contributors

Stargazers

Watchers

Forkers

johndpope

manipulator's Issues

Joint rigidity: Replace the thick plastic sheet with 1 thin metal + 1 plastic sheet.

Currently such metal sheets are impossible to manufacture because the possibilities of worlddevelopment are limited (no press, no lathe, no mill, no sheet cutter).

Once the 5 axis manipulator is constructed, a mill immediately is within reach as all mill requirements but the trajectory support are easier to achieve than those of the fruit nut vegetable carer.

Joint transmission: Planet gear interfacing ring gear is made of metal instead of plastic leading to erosion.

This has the benefit of longer life because this planet gear is in the pinion role leading to more wear because the gear teeth have to more often do more work.

The major disadvantage of it though is that metal to metal contact will lead to immense wear in the shell, i.e. the robotic manipulator links which needs evaluation to check if this makes it the weakest part.

Joint transmission: Torque is too low, has to lift 20 Kg, lifts only 9 Kg.

To ensure speedy design iterations finding a somewhat working hardware configuration, a spreadsheet is used instead of the detailed CFD simulation.

From the first estimations for the joint transmission in the worlddevelopment engineering.ods spreadsheet it became apparent that the current transmission ratio of 15 is too low:

Increase arm segment length to > 1 m to increase radial reach to something more useful.

This is a last minute change. Luckily some extra metal has been bought. Let's hope it will suffice for the new segment length of 1.5 m.

Reasoning

Increasing the maximum radius (pick up) range to 1.5m + 1.5m + .5m = 3.5m will result in an effective delta reach of at least 2.5m (see below).
Major mount point next to fruit nut vegetable bot is walker whose standardized mobile frame is a square of 3m if its legs are included. => 1.5m are lost with and 1m without legs, resulting in a delta reach of 2.5m which is plenty compared to the previous 1.5m.
An increased effective radius reach has more benefits than drawbacks:
- + More things can be lifted as approaching them closer than 2m will seldomly be possible in the wilderness.
- + The manipulator purpose is no longer restricted to just milling or a very small farm field.
- + Area of operation (e.g. caring for food) is PI * radius^2 which with assumption of min effective reach radius of 3m is PI * (3m)^2 = approximately 28.5m^2. Add to this the fruits that are hanging high and there will be quite a nice harvest. (operating space of the manipulator is kind of spherical, i.e. 3D).
- - Increasing the segment length will reduce accuracy as long as code, electronics, transmission ratio et alia remain fix.
- + Fewer designs.
- + Less prototypes to build, test.
- + Scale up by factor 2 now results in a reach of 5 m which is enough for using walker as backhoe or forest "harvester" or harvest crane or animal feeder or manure remover or have it help with construction work (vertical overall radius is 7m then, see first point of this list).

See why walker + manipulator are the pivot projects of world developers? ;-)

Source all parts required for the hydraulics

Joint 0,1 collide

Solution: Swap joint 0 motor position with gear, replace ring with gear, increase bearing sheet size.

Use hydraulics as despite the new - for DIY, heavy duty quite high - transmission ratio of 28, the payload of 12Kg is still to low.

Furthermore the hydraulic approach is easily scalable while routing bigger and still matching gears is very problematic, also in terms of link, transmission weight.