So, our team did a stress test on the Rhino drivetrain last night:
Slow motion Youtube video of the drop.
We loaded it to the max weight of 120 lbs. and dropped it intentionally on a corner of the drivetrain. We elevated it approximately 9 inches off of the ground, which we believe is a reasonable test and could easily happen when traversing the defensive elements.
Overall, it performed well. There was no bending or damage of any kind. So far, we are happy with the performance.
Excellent work! Thanks for sharing.
I think the Rhino will receive additional stress tests as the Stronghold season progresses.
Awesome video!
Has anyone tried T-Boning the rhino chassis to see how it handles that defensive scenario?
Always good to test and plan for extremes! Something to keep in mind is that your robot can be a max of 120lbs but you have an additional 14lb battery and bumpers that can be up to 20lbs.
I agree with Mike I’d be very interested to see how the Rhino tracks hold up to sideways pushing under defense.
Total weight was actually about 130 lbs. We ran out of steel tubes after that… We were pleasantly surprised by how solid the rhinos were. (Surprised is a little strong, I generally trust AndyMark to make quality products, but it was still nice to see.)
For anyone wondering, they’re tied together with 4 bars of 1010 80/20 extruded aluminum, which is heavier than the REV Extrusion recommended by AndyMark. We already had the 1010 in the shop, REV Extrusion was sold out, and we didn’t mind a little extra weight to have fewer worries about how solid base of the chassis was.
The sides of the Rhinos are 3/16" aluminum plate with supports every few inches and are incredibly solid, so we are not too worried about T-boning. (That said, we are planning on having full length bumpers and external frame rails to help protect them as well.)
Watched the video and one thought came into my head… what if it did damage it? Did you have a backup plan in mind? 
Better to know now, before competition.
I think Mike is searching for its ability to spin off of a robot playing defense on it not the structural integrity. If a track drive is hit close to its center of rotation it may have issues spinning off a robot playing defense on it creating a death spin type scenario where you cannot drive forwards or backwards out of the Tbone. This results in both robots making circles locking your robot up instead of enabling it to score. A lot of wheeled Tank style robots have had this issue as well. One way to mitigate this is to use low coefficient of friction bumper materials. This decreases the amount of friction between the two surfaces that your robot is trying to slide off of. You could also think of a way to change your center of rotation by dropping an omni wheel. Remember its not a pin unless your robot is up against a field surface so in theory they could do it the whole match.
This is a good test. Thank you for providing this video. We did some tests akin to a Dukes of Hazard ramp jump, which was less quantifiable than this drop test. We also did a “run it into a wall” test which proved to be successful (no broken parts).
Sincerely,
Andy B.
Cool test. 9 inches of drop can be a pretty significant amount of impact. What was the surface it was dropped on? Carpet actually does help a bit with distributing the force over a longer time.
Count me in on the T-Bone question/interest. I think those of us interested in this is less about the frame getting bent, and more about the dynamics observed on carpet as well as possibly throwing a track when really high side loads are applied.
What speed?
Agreed. This is my primary concern.
If anyone has test video and would like to share, much appreciated!
-Mike
^ +3 for the T-Bone Test.
We will be doing that sometime next week (build suspended by mid-terms now) so if anyone gets results sooner, sharing them would be appreciated.
One of the reasons we haven’t chosen the rhino chassis is because we were afraid of it being T-boned and the belts getting of it.
Our team has ordered the treads, and I’ve been a little worried about just the four crossmembers. Although it looked fine in the video, I think a bellypan and/or diagonals would really help.
I’m not convinced a belly pan would help. In fact, it may hurt.
Look at the 11 second mark, that frame looks to flex, which may help in keeping the frame from being damaged.
This is the thinking behind the energy absorbing structures in modern cars that allow them to protect occupants better than older cars with “a massive frame” where the forces from the impact are transmitted through the frame to the passenger compartment.
I can’t speak to the Rhino units in particular, but the belts on them look awfully similar to some belts made by Brecoflex that my old team used for several years. They were expensive (read: $150+/belt) and had a tendency to break under heavy side-loading. With all the up and down shock loading of the drivetrain in 2016 traversing DEFENSES, I would be extremely skeptical of any belted drives.
Thank you all for the information!
I am now also very interested in the T-bone test, hopefully we can do it soon if nobody else is able to post results earlier.
Regarding the belts breaking - I am also very concerned about that. We have 2 spares (from our practice chassis), hopefully that will get us through our first regional if they start breaking.
Reminds me of one of the coolest pair of videos on youtube (to me, anyways)
Dropping a F-18 Hornet at maximum landing weight from 20 feet up.