Al's Robotics....

INDEPENDENT WING CONTROL

Having solar panels give you virtually free energy is great but the only draw back is that it’s got to be sunny and the solar panels must point towards the sun.  But hang on a moment, our ship is not always going to be aligned with the sun.  So, we need to make the ship capable of aligning it's solar panels to the sun for optimum collection, regardless of the direction the boat is going.  

Photoresistor comparator test circuit

How can this be done?  We need some way of “seeing” where the sun is, then using that information to tell the panels where to point.  Ideally, this should be achieved automatically to free the crew and ensure accuracy.  Fortunately, thanks to electronics there are many different ways in which to measure light, or sunlight - usually by a photo reactive sensor, or photocell.  Provided we set up a suitable photocell such that it detects direction, we could then tell where the sun is.  But only a few sensors are reliable and rugged enough to be put on a ship that is going to be exposed to a harsh marine environment.

So, now that we can see where the sun is we need to be able to use this information to move the solar panels.  Obviously, we need a motor drive to move the panels.  For simplicity we are going to use a radio control type digital proportional servo.   But hang about, doesn't that use lots of power and we don’t want to be wasting power which we could be using to drive the boat.  So we need to make sure we are going to move the solar panels in the right direction first time.  To be sure we achieve this we will use dual sensors on each side of the ship, plus there will a scanning sensor mounted on the bridge of the ship.

All this data that we can get from the sensors is great but what do we do with it all.  Well, to start with we need to process the data first as the signals will be coming in various forms i.e. Digital and analogue.  Once this data is in side the control systems we can do some dare I say it mathematics.  This is were it all starts getting rather complicated.  

RISC Processor

The control system needs to be able toprocess millions of signals every second and determine what action it should take. To make things run even faster we are going to implement mutli processor functions.  Meaning that we will have several computer control systems to process the signals.  For all this computing power we will be using PICs from Microchip.  These are small yet highly powerful devices.  PICs are available with loads of onboard hardware functions such as USART PWM capture and so on.  I know it's all getting a bit technical, but sometimes you have to knuckle down to get  things done.  If the terms are a bit worrying, ignore the details for now - just hang in there for the overview.

A control system that can do all the calculations we want (work) is great, but sometimes your going to get conditions that you just don’t expect.  So it must have some form of override.  All the control systems are fitted with serial ports and can all talk to each other, like one fax machine to another, but should we need to take control we can log into the system and administrate the control of the solar panels.  This is called going to manual.

WATCH THIS SPACE AS THE PROJECT DEVELOPS TO A FULL BLOWN WORKING PROTOTYPE

COMPONENTS:

Light sensor: LDR

Sensor processor: microchip PIC comparator

Maths processor: microchip PIC

Serial port override: handheld device or laptop

Actuator drive: independently controlled by microchip PIC

Actuator feedback sensor: processed by microchip PIC

More information can be found at http://www.solarnavigator.net

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