Hexbug VEX Strandbeast - impressions, thoughts, ideas

So I found the Hexbug VEX Strandbeast on sale at our local science museum, and I picked it up.

Here some first impressions, and some thoughts. Let me know what you think.

In general, this is a big and ambitious build. The printed instructions in the box had a few errors and omissions, but it was easy enough to figure out how things should work. In particular there were some issues on setting up the legs so that the walk cycle is correct. I note that in the downloadable instructions these issues have been fixed, the online version is much clearer!

I had some issues getting the robot to work in autonomous mode. The way the brain is programmed is by setting DIP switches on the brain that define the relation between sensor input and the motors. It would be useful if these switches were set to a sensible default, or if there were a few examples of settings that do something useful (eg. avoid obstacles, stop before crashing, etc).

I think there should be a note in the instructions about avoiding friction. If you snug the rubber stoppers on the shafts right against the plates, they add a LOT of friction, enough to prevent the robot from moving. I also found that it was critical to align all the small gears and all the big gears correctly, otherwise it was possible to slightly twist a shaft and have the big gear “off by one”, which also created a lot of resistance.

A final issue is that the robot is big & heavy, and this is all powered off 3x AA batteries. So the robot is a little slower, and also burns through batteries quite quickly. This is made worse by the fact that the battery covered is buried deep within the robot when assembled, and not easily accessible. In the short term, I used VEX IQ parts to rebuild the robot in a way that the batteries were much more accessible.

I am intrigued by the possibility of swapping in VEX IQ parts for the motors/sensors/brain, this would dramatically improve performance I think. I note that the smaller motors that come with the kit are mounted on standoffs, so the VEX IQ motors actually fit perfectly (without standoffs). There seems to be plenty of room for the VEX IQ brain too.

I am also interested in using some of the kit specific parts in conjunction with other VEX builds. For example, the “shoulder blades” in the Strandbeast kit don’t serve any functional purpose, so they could be replaced with beams, and then used as a scoop/blade in another build.

Hi Chuck, thanks for your quick response!

In general I found the Strandbeast to be a fun and interesting project, once I’d overcome the issues I mentioned.

I think what would be welcome in the instructions for the DIP settings is a higher level description of what the robot would do, with the examples, eg:

  • If the robot comes up against a wall, it will back away from it
  • If the robot comes up against a wall, it will stop
  • If the robot comes up against an obstacle, it will turn and then keep moving in the same direction
You can also experiment with moving the sensors around, for example have both of them on the front, pointing out at an angle. Could be a good maze navigator.

I had the StrandBeast at the VEX 2015 World Championships in the VEX IQ Super Users group and it got a lot of use. It definitely chewed up a ton of batteries and it was a bit awkward to open up the battery box and replace them. With fresh batteries it worked extremely well over the course of 3 days. It is a very cool model but definitely not an easy build. Highly recommended in spite of the batteries not lasting very long.

Wanted to add that I went ahead and did the “brain transplant”, put in a VEX IQ brain and motors instead of the standard ones. The whole process took 15 minutes, and it works GREAT. The robot moves much faster, and the VEX IQ controller is easier to use.

The VEX IQ motors exactly replace the smaller motors, and the brain fits nicely between the central plates using standoffs. You can use the standoffs from the Strandbeast motors! The top and bottom beams fit exactly as before. I used slightly different braces to attach the faceplate, so that it can be removed easily for battery replacement.

It works with the driver control program as-is, though clearly there are opportunities for a more customized software approach.

I would highly recommend this kit to a school that already has VEX IQ, since it gives access to some interesting parts and mechanisms. (Probably not qualified for competition?)

The motors, sensors, brain and controller that came with the Strandbeast can be used to make an RC car or lightweight robot with VEX IQ parts, they work really well with a lighter build.



I’ve done the swap for all the Hexbug. Spider and the Ant are the hardest to do since the IQ brain is much bigger than the Hexbug version. But the extra in the motors makes it worth while to do. I’ve been starting to “kitbash” on what I can make when I mix and match parts.

And here’s what I did with the Strandbeast original brain and motors.

Here’s the strange thing: the thing in the picture works perfectly. The motors work fine as a skid steer setup. The lights work fine, basically both green when moving forward, red when moving back, and green and red when turning, with green in the direction of the turn. However, this setup has NOTHING to do with the instructions! Note how the motor connector is upside down, and one of the LEDs is flipped! It doesn’t work any other way!

I am still trying to figure out a way to get the sensors to work, currently most configurations I try lead to one motor turning constantly.

It would be great to have some detailed “behind the scenes” instructions on how that little brain works.