OK - this is going to be a detailed development blow by blow account of my latest build. the name comes from one of my favorite fossils of the Cambrian (see video), and I hope there will be some passing resemblance as this thing develops.
I've been away from my robots for a bit, but came back to find my old hexapod with 3 Servos and wanted to go that extra mile, I still have my first attempt, and I don't think it's too bad considering - see the video
My objectives on starting are to have something that will evolve over time and that I can use as a platform for a variety of useless activities, and so I can experiment with a number of techniques which I'm new to.
20/1/16 Phase 1 Objectives :
a) Develop visio templates of a number of key components that I can use again and again - by making these reasonably accurate I hope to be able to do a lot of design on my laptop and have a fairly finished idea before I start cutting plastic and metal - If anyone is interested I can make the shapes available for other developers
b) The bot when finished, should be robust and capable of using as a carrier for later tinkering - my first incarnation will be either RC or digital TV remote driven just like my first hexapod, but will have ultrasonics and will develop in later phases into a more antonymous beast.
c) Maneuverable, cheap to build out of the bucket load of bits and pieces I have left over, and hopefully aesthetically pleasing - I will be using some generic bits that I've already got, so the processor will be a PS2 Stamp augmented with a propeller servo driver, but this could easily be substituted for an Arduino, and in the current climate this would be a better choice except for the fact that I have a lot of leftover stamp bits.
d) Provide a land platform for the FPV video set I picked up at Christmas ( Brand new camera, goggles, TX, RX and even a lipo to run it on for under £50) - works really well upto 1 KM away. Above, you can see the initial design, and I have now started on a build. As this thing develops I shall be updating and posting my progress.
The Hardware : What I have already to hand plus a few bits and bobs. The plan is to use :
* Basic PS2 Stamp to provide the processor (I got a few cheap of ebay)
* Propeller Servo Driver (Arduino has a very similar product, but I had this left over)
* 12 cheap 9g Servos ( I have 6 in my box, 6 on order at £1.15 each)
* Chassis - Acrylic and Aluminium (I am toying with the idea of some copper sheet cladding in later phases to give it a "steampunk" sort of look) * Propeller Servo Driver which I had left over (Arduino equivalent is only £16) * 12 V Lipo batteries I shall devise how to fit and develop the ultrasonics. FPV and later who knows what. Later Phases To be decided but I definitely fancy a rotating turret
02/02/16 update
Well, she's progressing really quite well - the speed of delivery from Hong-Kong being the limiting factor, but I want to make this baby dance b the end of February. Relatively few modifications to my design - moved the rear 35mm support post back a centimetre to allow battery space, and moved the lowe plate holse out a bit to give more room to rotation of servos, but apart from that the only change is to mount the ultrasonic further forward, and to put a flexible joint in between the first and secod rows of legs thus allowing it to rear up - see the new picture.
04/02/16 update
Updated the visio plans - I can provide the full set on request, but will wait until the project has finished before attaching here - 2 pics attached of the current design. Legs are now cut out of Acrylic thanks to my home made hot wire cutter (works really well !)
08/02/16 Update
Hooray ! - the long wait for my servos from china has ended - started now to create the leg housings - once I've finished this I will have most of the mechanics finished and can update my picture to give a real idea of the hexapod
17 Feb 2016 I'm quite pleased with the mechanics now - updated the picture with the legs installed - just need to finish the servo linkages and we should have this moving by the end of the weekend
03/03/2016 Update
Progress isn't at themoment - very happy with the new corrugated conduit from an aesthetic point of view, but now I discover that my servo driver, won't drive the SG90 Tower Mini Servos. It drives the 2 I got from AIrtec, but the 16 I got on line, it doesn;t want to know. I'm told I need to ramp down the voltage, though I'm suspicious that this won't work and I've also been told to introduce a 1KOhm resistor in the signal wire. Again I'm suspicious - so now the dilemma... throw away 16 servos, or throw away my Basic Stamp servo driver, move to Arduino or pololu and hope the servos will run. Any advice as to which wa yI shoudl go would be gratefully received.
08/03 -
Changed my tack - out goes teh stamp and PSCU driver, in with the Arduino Mega - hope this solves my servo issues
hexapod capable of climbing steps. Can operate as quad using front legs as claspers
- Actuators / output devices: T Pro SG90 servos
- CPU: Arduino Mega
- Power source: 7.2 V LI-ION 1500 mAh battery
- Programming language: Arduino ide
- Sensors / input devices: Ultra Sound
- Target environment: indoor on smooth surfaces
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/opabinia-steampunk-12-servo-hexapod