ROBOT PROJECT(S)

This page contains some limited info on some robotics projects from 2004

• ALPHA (Adaptive Layered Prototype Holonomic Apparatus)

 

    This is the initial phase of the mobility platform for ALPHA.

    This unit is built mostly from surplus components I had in my workshop.

    Pictures below show various stages of assembly and the drive motors.  

       

 

 

ALPHA AARDVARK ready for some mechanical testing

This unit uses surplus automotive window (or possibly windshield wiper) motors for driving the wheels.  These motors have a built in worm gear drive to achieve a speed reduction.  They run on 12 vdc and consume about 3 amps unloaded.  They have plenty of torque for this application.  Custom shims were necessary to mount the wheels to the shafts, but were easy to make from .030" aluminum sheet metal.  All of the metal work was custom made in my workshop.  Base is 3/4" plywood and top shelf is 3/8" plywood, supported on 3/8" threaded rods.  On the front top is mounted an old cordless screwdriver which hopefully can be used to drive a threaded rod to provide vertical motion to some sort of tool mount on the front of the unit.  Direction control is achieved through DPDT relays, speed control will be achieved via a MOSFET PWM control in the negative leg of the motor supply.  The use of relays for direction control does incur a power penalty over an H-bridge, but is cheap and easy.  Default (un-energized) position of the relays is forward.  Plan is to integrate PIC16F84 microcontroller(s) for controlling the mobility base.  Future plans are for motor current sensing to detect stall or excess load conditions.  Future layers will include various sensors and control systems.  This is only the mobility base, additional layers will be added on top.  Current weight of the unit is estimated at 50 lbs.  Unit will turn in place quite well and has considerable torque for the drivewheels.  Current cost of the project is about $100, this will go up considerably as sensors and control systems are added.  Currently this project is being funded totally out of my personal resources.  A small controller was added to this for some basic dead reckoning navigation demos, but alas the project has been now sitting on the shelf for a while due to other more pressing matters.  I hope to get back to this project in late 2007 or early 2008. 

                                       

Battery compartment rear view                                        Battery housing front, left drive wheel assy

 

Here is a small bot built around a modified RC car.  The controller here is a PIC16F84

Here is a robot called BETA built by Curtis Welborn, with a little help from me on some electronics issues. 

This unit uses a J-Stamp controller, and has 3 sonars, 3 IR sensors, and 4 whisker sensors along with

a pan-tilt head for the main sensor head.  It is very cool to watch it in action.