Obligatory First Featherweight Build Log (FeatherDozer)

[Eidg]

Wow nice looking robot, love it.

[Sam_Gad]

Thanks

If only my driving was as good haha....

[Sam_Gad]

Entry 6 - 2nd Event Robodojo 26/09/20

Event 2 - Robodojo 26/09/20

Confident in at least one of my modifications, I headed back up to Leeds for another dose of addictive, intense fun!
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As before I will go over some of the highlights from the event which can be found on Joe Brown's YouTube channel (link to full event below)

https://www.youtube.com/watch?v=UKYZ...annel=JoeBrown

As the day panned out, it was clear that the additional front forks worked as intended to be able to lift effectively resulting in 3 wins, 2 losses and an unofficial 4th place for the day. It is always good to see incremental improvements that are a direct result of a relatively simple modification.

The Hells Angel 2 Fight

This fight was by far the highlight of my day. Dave's formidable axebot can cause significant damage and is driven extremely well. Midway through the fight I was having drive problems due to the only non-loctited grubscrew in the entire robot (my bad) coming lose on the left side drive gear. What is clear when watching the fight back, is that I was relatively lucky winning this fight, as up to the very end when Hells Angel ended up out of the arena, I was taking damage and not driving well. The out of the arena came in the final few seconds of the fight and was my only real contribution, but a wins a win.
However I did not get away without a number of axe marks in the robot and it was nice to see that some of the hits were lessened by the use of the scoop as a shield.....

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Dave came VERY close to the link....
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Luckily all of the damage was superficial, so I swapped the lower scoop sections for the repaired ones from event 1 and kept going.
Despite the positives from this event, it was clear that still I need more practice with this robot as the main contributing factor to both my losses was my driving which resulted in getting stuck under the HDPE floor panels. This hopefully has been rectified in my improvements listed below.

Next Steps & further improvements

As a result of facing many powerful axes, it is clear that I needed to better protect the lifter relay wires as well as the area around the link before it gets sniped as was done to a certain toaster .
Therefore, I will be adding a guard to either side that needs to be substantial enough to take hits but not get in that way of either the lifter mechanism or accessibility to the link.
Also as I get more experience driving FeatherDozer, I have come to the conclusion that in addition to practice, I need more low speed control. The F80 speed controllers are a good starting point for brushless ESC's but are lacking in low speed control and with an unfriending way of making adjustments on the fly. So I have decided to have them on standby as spares and use an alternative speed controller setup.

I will go through these modifications in the next entry.

[Sam_Gad]

Thanks Andrew (from a reply earlier in this thread),

When we are able to get back to fighting safely, I look forward to hopefully getting a chance to fight the glorious toaster

PS sorry I missed replying to your post earlier

[Ocracoke]

I love the look of this, soooooo much better than what I am coming out with at the moment, gonna have to up my building game with Azriel 2.0.

You mentioned F80 speed controllers with SimonK firmware. I am in the middle of writing a SimonK based program to flash speed controllers with and be intrigued as to validate what my program is coming out with against what you are using here. Would you be able to show what configuration you have in your .asm file at all?

[Sam_Gad]

Hi Lucy,

Thanks once again for the complements! I basically followed the configuration that Robert Cowan used in his SimonK flashing tutorial video as I was relatively new to esc modification (I have more of a mechanical engineering background). As there is very little is the way of safety protection when you start changing the config file, it was a set and forget job as a good starting point.

I am currently at work at the moment (for some reason I am a key worker for my company) but I can send the file this evening.

[Ocracoke]

Thanks for the heads up, looking forwards to seeing the file

[Sam_Gad]

Thanks Brandan ,

The inspiration came from wanting to build an overhead sawbot (which I still want to do but there are already 2 feather sawbots in the UK). So the front end kind of comes from Skorpios as when it is not wheeling, it is very good at getting under other bots.
After realising that a sawbot was a bit too ambitious for a first build, it evolved into the design I have today.

[Sam_Gad]

Okay.

After digging out my old windows 7 laptop, I managed to find the program used to flash the F80 escs (KKmulticopter). Unfortunately the file used is not there (sorry ) plus the program does not seem to be working properly anymore. Has anyone had issues when trying to compile the firmware from the master from github (When I click download on the firmware complier tab, nothing happens)?

Anyway, I will have to try to get this program working on windows 10 as it doesnt seem to be working anymore (lucky I moved onto different firmware). Here is the tutorial used to flash the esc's. As the F80's are basically the same as the F60s that Robert uses, it was a simple case of following the instructions for the correct starting point.

https://www.youtube.com/watch?v=MQQX...el=RobertCowan

Sorry I can't be more of a help.

[Ocracoke]

No worries I have a USBAsp with a stamper pad on it for flashing so I don't need to solder the connections as Robert has to.

Has anyone had issues when trying to compile the firmware from the master from github (When I click download on the firmware complier tab, nothing happens)?

I have been able to download it before, it isn't being blocked by a firewall or anything like that?

[Sam_Gad]

Hi Lucy,

I use a similar method as I knew I did not need to flash as often and I did not want a lot of random wires poking out. I will give a check this evening on my firewall settings and see what happens.

Thanks for the tip

[Sam_Gad]

Entry 7 - Fixes & Changes

Fixes & Changes

First item on the agenda post event 2 was to fix all areas of damage. The notable areas for repair included:

• Axe damage to arm & self-righter brackets (superficial)
• Axe damage to main bulkheads (superficial)
• Axe damage to electronics covers (superficial)
• General wear & tear of lower front scoops (superficial)
• General damage to fixed front forks - Spare set of forks to be made

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Robot teardown revealed no internal damage. I have included the image below is I think it is a good representation of the up to date condition & layout of main chassis as seen in previous posts.

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Relay & link outer protection
As with many other components on FeatherDozer, I wanted to add additional protection to the relays (and link on the right side) without compromising the look of the robot. These panels are easily removeable with just 2 bolts per side and do not interfere with either the lifting mechanism or the ability to install/ remove the link. Below is the CAD and installation of the protective panels.
Mk1.5 CAD 4 - Side Guard.PNGMk1.5 CAD 5 - Side Guard 2.PNG



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New drive speed controllers
After using a basic recalibration of the Hobbyking F80 speed controllers for 2 events, I decided I wanted more adjustability of settings with a high emphasis to low speed control. In an ideal world, I would be moving into motors and escs with direct feedback from the motor via a position sensor to have better low speed control (e.g. VESCs), however, I do not (as usual) have the space in this design but I wanted to try an alternative.
The speed controllers I have been testing are 80 amp BLHeli_s ESCs designed for high performance drones. From what I have seen, this type of controller is common within bettleweights but not with featherweights. As the setup can be changed without modification via an Arduino, I can now make setup changes quickly as well as play with numerous settings with lower risks. These speed controllers are not prefect as current limiting functionality is not available . However I thought I would give them a go and early testing of gyro assisted drive setup was relatively unsuccessful. To try to help these speed controllers survive, I have added a larger heatsink and more shock damping (fire resistant foam).
Early load testing (pushing me along with my office chair) have been positive and I now have better control at low speed with may help some of the lack of control I was having. The F80 speed controllers will become spares in case of issues in real combat with the new ESCs.
Below is a comparison of the old ESC on the right and the new one with is much smaller and lighter.
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New Lifter motor
As the final event of 2020 was cancelled due to lockdown, I have had some additional time to change the motor in the lifting mechanism as the arm operation is a bit slower than I wanted. The original motor is a standard 18V 775 brushed motor that came with the gearbox from Gimson robotics. As the robot is currently running on 4s lipos, the full capability of this motor is not being utilised. Therefore the new motor is a Vex 775 pro as it is a 12V version of the same motor size. I am hoping that the full speed and torque range can be used with the lower voltage motor. Alternatively I am also considering a brushless setup alternative for the future but it will require a motor of a high KV rating to increase the speed of the mechanism.

For now, this bring us up to date (early 2021) as we are all experiencing the joys of national lockdown. When the next event happens I will be ready and the meantime, I will continue drive testing and practice.

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[dotDominic]

I'm really impressed by the creativity of this design. Usually the "way" to make a pushing robot is 4 wheel drive or a low angled wedge. I've seen Featherdozer fight in several videos and been curious about the machine for a while. Having read these posts just now it's definitely become one of my favourite featherweights around at the moment - a really interesting read. Thanks for describing your design so thoroughly

[Sam_Gad]

Wow! Thank you for the very high praise

Yes, FeatherDozer (I still hate the name) would probably be better as a low, 4WD lifter, but I wanted a design as compact as possible and look a bit different, hence the 2WD. The next design (many ideas and designs in progress) will be an evolution of FeatherDozer to hopefully take on the big featherweight spinners.

As I decided to do the write up here, I could go slightly more technical as I have seen in other build diaries. Plus I've had plenty of practice writing technical reports due to my job.

I hope we can get back to fighting in the near future.

Thanks again to all for your kind words

[Sam_Gad]

Quick Updates

.....And we are back!

After 4 months of not posting on this thread I am finally heading out to another event (Robodojo May event).

Only a quick update today.

In this time the only aspect I have changed is my team name. The previous team name (just Send it Robotics) was a good start but is a little bit too generic for my liking. The new team name is Learn the hard way Robotics.

Once this event is complete, I will have a better idea of the direction I want to take with FeatherDozer for the rest of the year. This could include weapon upgrades, drive motor changes and additional protection where needed (I'm looking at you drive gears....).

For now, here is the recently repainted FeatherDozer ready to head up north.


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