Let's Make Robots!

Building the perfect Beast (robot chassis)

2012 may be the year of the Dragon for China but it is the year of the robot chassis for me. I am trying to create a new range of robot chassis's and I'd like to know what features my robot building friends would like to see in a chassis. Obviously low cost and high quality are preferable but what else?

For example size? As far as I can see there is already a range of sizes on the market. Is there a size that's missing? I was looking at some cool wheels that were about 250mm (10 inch). Would you want a huge chassis and for what purpose?

Features? Is there a feature that you want but can never find on a chassis? More mounting holes, built in battery charger or motor driver?

Clutches? many gearboxes, even with metal gears can be damaged through accidental collisions or child abuse (the child abuses the robot).

Encoders? single pulse, quadrature, what is the minimum resolution?

Wheels? big, small, thick thin, mecanum, omni, wheels with retractable claws, what is missing from the online range?

 

To give you some idea of projects I am working on so far:

  • Low cost, miniature 6WD Wild Thumper.
  • New improved QuadBot chassis with clutches on all servos to protect the gear trains.
  • Robot hand/wrist with full range of movement (13 DOF).
  • An advanced balancing chassis with sensors.

Tell me what you want in a robot chassis.

 

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I missed this post earlier this year, I'm glad someone added to it. 

My $0.02:  Being only a couple 'bots into my hobby I've been very selective on what I've bought because I want to buy parts that are versatile and reconfigurable. I will say one one thing though, the simple, small 2 wheel 'bot has been done to death. I've been looking for a chassis that is durable - preferable using metal for the platforms, with brackets that support the SR04/5 ultrasonic sensors, larger wheels and fairly strong gear motors included and can be used indoors or outdoors. The 6 wheel Wild Thumper that is out there is great, but too expensive. It's got to be under $100 for me. I'm thinking four wheels, but with steerable front wheels and maybe even having all 4 wheels steerable. Decent ground clearance is a plus too - like 3 inches or so so it can clear obstacles.

My second preference would be a generic 4 legged walking chassis with a platform sizable enough to accomodate sensors and breadboards.  The price would also need to be <$100 and come with servos, mounting equipment, the platform (or two) and battery box. A central SPST ON/OFF switch mounted on the platform with connection to the battery box for either of these robots would also be helpful.

Good Luck!

Personally I would love to see some mini/micro/nano chassis. Perhaps using tiny gearmotors or servos. Something simple and cost effective.

On the other range, a less expensive mechanics kit for a humanoid bot (I'm thinking $200 and under), if that price range is even feasable. Maybe make it barebones and the user can add their own servos, electronics etc. More complete than piecing together your own from scratch.

How I want the perfect chassis to be... I Dont know.  I'd like a big one with motors and motorcontroller mounted. So I don't have to guess what kind of motors to choose. But at the same time I want there to be motor options, so I can change to a slower/stronger motor or a faster one if that suits my needs that day.

One feature that I like isn't really a feature, but I still like it: Hackability! I like to open it up and use it in another fashion than stated in the manual. I've done 5 or 6 different projects based on the Mr. Basic kit, and none of them involved assembling them correctly. This might just be me, but you asked for our opinion, and that is one feature that makes a kit more valuable to me.

So: try to standardise as much as possible, if two mounting holes on the front are set 10 mm appart and two other mounting holes for a completely different purpose on one side are 9 mm appart, Why not change one of them to make them the same? It might not seem logical from a construction point of view, but for a chronical hacker it's bliss.

Thick, slightly oversized walls. So I can drill my own holes without compromising structural entegrity.

(and if you ever plan to make an upgrade to Mr. basic, give me a hint, and I'll drop you a few ideas)

It seems to me that Mr. Basic had 2 big drawbacks. 

  1. The multi-segment drive shafts are never completely straight causing unwanted friction before vibrating loose.
  2. The crown gears alway break.

I have already suggested to the boss that Mr. Basic needs to be revamped. I now have some much stronger crown gears but at this point I have no time to redesign the chassis to use single drive shafts.

As for your other suggestions, they are noted and I will try to implement as many as possible in future designs.

I was just looking on the Robosavvy website and saw that Dagu even makes a 6DOF arm. I think I'll need to order that 2DOF arm and mount in on my Rover 5 :) Maybe you can consider adding a digital compass on your next controller. I think they are more usefull then an accelerometer for a wheeled/tracked robot.

The problem with compass modules is they need to be isolated from things like traces on your boards with high current running through them. Compass modules are best as a separate board that can be mounted away from motor controllers and servos.

I'm guilty of hacking my kid RC toys after they break.  Waiting on Spy Gear Spy Video Car VX-6 to die.  The wheel design works on carpets and tile floor well while resisting dog hair.  The motors are quiet which is nice for testing when everyone's asleep.  

Cyclaws RC is on my wish list too.  Transforming crawl wheels would work great outdoors.

I think that a cool new product that can be released in to the market is the robot arm that is included in "Mr. Tidy" that can be selled alone, if it have a good price sure that i buy one

The arm from Mr. Tidy is sold seperately by some online stores.

These are Coolio grippers as seen with Mr.Tidy visits Switzerland

I have used both the prototype and the improved retail version,  motors have plenty of grip and the encoders help to position both  the grip and elevation , the version i had also have limit switches.On the Mr.Tidy chassis it was also possible to monitor the motor currents so you could sense when you gripped something ... or if you tryed to lift something to heavy.... very very neat feature.