Tri-wheeled Omni-bot Update
This is as far as I've managed to get without the proper Rotacaster Omni-wheels on my main Omni-directional robot. The legs can be raised & lowered independently, to lift the body 150+mm above the floor. The 3x Ultrasonic Sensors appear to be working together and measures the distance to objects o.k.I'm now working on programming the behaviours and using the Playstation 2 Controller.
So far without the Rotacasters, I've been forced sit Omni-Bot on a large tin can as raising and lowering the legs pays havoc with the structure due to the fact normal wheels aren't meant to slide sideways. Accepting that minor issue, the action of the legs works well. I decided not to build some temporary omni wheels because of size restrictions and the fact I'd need a major redesign of the leg ends. It does spin in circles very efficiently at any height though!
My intention is to have it move autonomously around the room with the body about 20mm from the floor. When it detects an object it moves left & right to determine the objects width. If the object is less than 200mm wide it re-centres on the object and lifts itself up, measuring the objects height in the process to see if it can straddle it. If the object is too high/wide, it backs away, turns a few degrees and continues on randomly around the room.
"Well that's the intention anyway…. I'll see if my programming abilities are up to the standard of my imagination? There's always the Remote control if I fail!"
So far I've managed to consume:
- 3x NXT Servo Motors to drive wheels
- 3x Small PF M-Motors to operate the lifting mechanism (to be replaced with PF XL-Motors)
- 3x Ultrasonic Distance Sensors
- 1x Hitechnic IR-Transiever
- 6x RCX Type Touch Sensors (Leg Position Sensing)
- 1x RCX Touch Mux (My Design)
- 1x Mindsensor Sony PlayStation 2 Controller interface
- 1x 8884 Power Functions IR Receivers (I need 2)
- 1x Mindsensor Port Splitter.
I've just ordered 3x 8884 Power Functions IR Receivers, 2x 8882 Power Functions XL-Motors and few oth PF parts to add to the PF Accessory Box. This will allow me to independently raise and lower the legs/arms by using the PF XL-Motors instead of the PF M-Motors. It will increase the speed of the raising & lowering as I've had to do quite a bit of gearing down for it to work with the PF M-Motors. With the couple of PF XL-Motors I have the speed is increased by nearly 10 fold (The Joys of Planetary Gearing).
All up so far it weighs in at under 2Kg with the Extra Batteries to dive the PF stuff. Considering this, the PF M-Motors do a pretty good job. All be it slowly. With The PF XL-Motors it will still be under 2Kg.
The "Soccer-Bot" is on hold for this month, as I've spent more than my monthly allowance on the other Lego Parts mentioned above. I need to get a Infra-red Soccer Ball and Sensors to suite before I get the Soccer-Bots playing Soccer. It moves around reasonably well with make-shift Omni-wheels. I've had it locating a ball with a Ultrasonic Sensor & kicking it. All be it very unreliable though.