Wasn't sure of the exact forum to post this but here seemed safest.
I've been lurking and reading through and I have some experience with things, enough to be dangerous. I like the capabilities of the arduino chip, the price, the opensource ability, did I mention price?
I'm planning an art project using a large robotic arm being controlled by a Haptic interface using potentiometers to mimic the artist's movement. The hand is just meant to create patterns in a Zen garden. This will later be adapted for a halloween project for a local center.
Here's the rub...
I'm using Series Wound motors converted to be Servos with encoders. They can achieve speeds in excess of 10000 RPM and 1000Amps at 14.4 volts. They need to use an H-bridge for reversing and Pot interface for use.
If I need to interface a PC that's fine but I expect to have to use one Arduino board per SWServo. My concern is the loads, temps and the limits of the Arduino system.
Basically the arduino is just a control device providing low level logic signals. So providing you have a motor controller that will handle this size of load the arduino will be able to control it just like anything else.
If however you are asking if you can cobble together a 15KW motor controller from a circuit you find on the net then the answer is :- please get real
That is a serious amount of power and you can't scale up a 1A motor control to do this.
No the motor controller is separate, I can imagine that some might make that mistake. I however am not implying that hehe.
I am not trying to supplement the motor controller, I'm actually hoping to skip it, send signals to the SWServo like to a DC motor and supply power externally.
(note: SW motors are servo convertable like DC motors and encoders can be attached.)
Sorry for the late edit
Or am I on the wrong track? I cannot use hydraulics and SW provides the best torque available.
Yes it must be 1000mA because you are not going to get 1000A from the mains in a house or even a block of flats. You don't need a 14KW servo motor to swing about a ground to air missile let alone a robot hand.
14KW is serious civil engineering requiring heavy lifting gear. Don't even thing about trying to make something like this.
1A on the other hand is well within the range of a hobbyist.
I have had a hard time controlling a 15A motor (stall current is more like 40A). 1000A is best left to erm I don't know, welders.
Otherwise if you do mean 1000 mA - then this is bread and butter stuff. Of course you will need some sort of controller between your motors and the Arduino still.
I was trying to think of something common and comparable, and the only I could think of would be the starter motor for a small truck's diesel engine.
Here, you might see many hundreds of amps, but for no more than a few seconds, otherwise the (very substantial and short) cables would overheat.
Even a petrol engined car's starter can draw a couple of hundred amps, but again, for a very short time.
Before the fervor and uproar ensues, I hope cooler, inventive heads prevail. I merely mention the amperage as a range from 400 - 1000 AMPS not mA. I need the Arduino to handle PWM of a single servo modified SW motor with H-Bridge to use in a 330 - 1800 arc for DOF placement. Can the arduino handle it?
As for the rest, I site the following real world examples -
--- Series Wound motors dominate in the National Electric Drag Racing Association (NEDRA). Most — if not all — electric powered drag race cars use SW motors. Maniac Mazda does wheelies and over 100 mph in a quarter mile drag race.
--- Series Wound Motors are used everyday in Clothes Washing machines with transmission gearing.
--- An electric motor conversion for a Kawasaki Motorcycle using a single 550A 60kW 84v SW Drive with Li-Ion battery packs for 100+mph speeds and through life of around 60+ miles or around 3 hours, depending on load and traffic.
--- Use of these SW systems in combat robot movement systems is ongoing as they render incredible hole speeds and length of grab in motion due to the torque. The torque of an Series Wound motor is proportional to the current squared whereas the torque of a Permanent Magnet motor is only proportional to the current. They use between 1 - 2 kW as well.
I fully realize the heating conditions and the general life of the motor. A serious cooling regimen will have to be put in place and the motors will have to be modified for stamina but generally when a problem occurs it is not the motor but the wiring, the bendix and the solenoid that suffers, depending on motor type.
I need the torque due to the end projects size and use. It is modeled on a skeletal dinosaur performance art design using hydraulics. That system uses a 2HP electric pump at 240VAC, 24,000lbs peak force at 2500PSI, 1.3 GPM at 2000 - 2500PSI with five (5) attached cylinders 3.5" bore with 6" stroke. Potentiometers are used for position feedback.
I'm doing similiar with an electric system using recycled materials whenever possible.
I've got to chime in here, it just seems like the wrong product for the job.
This kind of current will require single connectors that will cost far more than the Arduino. Safety is a huge issue. You have power levels far exceeding any average arc welder.
You need dedicated purpose built motor controls and redundant safety equipment.
I haven't been posting here lately, but I too have to chime in. Good god, what have you got planned? i'm more concerned as to how you have the money to do all this, let alone the safety precautions.
I need the Arduino to handle PWM of a single servo modified SW motor with H-Bridge to use in a 330 - 1800 arc for DOF placement. Can the arduino handle it?
This is essentially a meaningless question, like asking whether you can use your iPod in a car with a 300HP V8. When you are using even a 100A motor (which is in the realm of high-end electric remote control model cars and boats, or "battle robots"), the electronics (and even the wire) between the motor and its power components, and the microprocessor are more important than the characteristics of the microprocessor itself... The way you have worded your question(s) hint(s) at a degree of understanding that is likely to be insufficient for your project...
The same class of microcontroller (ATmegaXXX) used in arduino has been used as the controller for 20k+ RPM brushless motors with back-emf current sensing, so it's a pretty capable CPU. OTOH, it doesn't have the same class of DSP-like performance as some of the microcontrollers currently being specifically targeted toward motor control, so ... I'm not sure...
I suggest you start with the Open Source Motor Control project (Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos), which apparently controls some motors at up to 400A (surge. 160A continuous.) The people there probably have more clues about high-power motors than the people here. OSMC is apparently a price-leader per amp, hitting "only" about $400 for the 160A controller. I don't think that the "low cost" of arduino is going to be a big factor...
My concern is the loads, temps and the limits of the Arduino system. Can it handle it?
Just to skip a lot of pointless hanger flying, The arduino probably can develop its control signals (you need to be specific as to the type you need) using a standard 9v battery. Beyond that you will need to develop the hardware to impliment control of the high current hardware you apparently want to use. An arduino can start a 10,000hp diesel by energizing a transistor placed across the terminals of the start switch.
I should add that the Arduino software libraries are probably iffy for your application. AnalogRead() is slowish, and PWM is about 500Hz, both of which are probably not so good for a 10kRPM motor...
Would it be really dumb to ask why you need to replace a 2hp hydraulic pump with 1000A electric motor? I'm sure the base spec any motors you have looked at lack the required toque, however this is what gearboxes were invented for.
I should add that the Arduino software libraries are probably iffy for your application. AnalogRead() is slowish, and PWM is about 500Hz, both of which are probably not so good for a 10kRPM motor...
Agreed, the Arduino libraries are not ideal, but the ATmega is capable of running 8-bit PWM at much higher frequencies (i.e. 62.5kHz)
AnalogRead() isn't so good, but cranking the encoder signal upto a logic level, and pushing that into an Arduino Mega's 16 bit timers input capture would give reasonable resolution.
AFAIK, ordinary Arduino processors are qualified for -40°C to 85°C
I don't know of anyone has ever tested the rest of the components on an Arduino for those temperature ranges.
There are automotive ATmega parts qualified for -40°C to 125°C but I have no idea what on the board, if anything, is similarly qualified.
I suspect there will be some other fearsome issues though
