Hello all you smart people.
I own a Thomas skid steer loader and it has the conventional foot controls for the loader arm and bucket controls. Long story short, I absolutely hate them.
Having said that what I plan on doing is converting it over to an electric over hydraulic system using electrically controlled proportioning valves.
I'm going to 3D print new handles for it that incorporate Arduino dual axis joystick controls and then read the signal from those and send the required voltage to the solenoid valves with an Arduino.
The valves will need an infinitely variable voltage from 0 to 12V DC with an operating current of about 2 amps (3 amps max).
Incase it matters, the valves are basically just a coil that pulls on a mechanical spool valve with a spring return.
The power supply is strictly 12v DC (12 volt system from the skid steer) so no need for rectification.
I've looked a few ways to do it including op amps, voltage control ic's, mosfets etc, but thought I'd post the question on here and see what smarter people than myself might think is the best and simplest way to do it. I do think PWM is possible if that makes it easier.
That's a heavy machine capable to make substancial damage if the control system fails.
I have a master degree in electronics and computer design, 13 years of experience of designing heave indoor, high lifting, fork lift trucks, controlled the way You indicate.
There's a lot to consider, more then a lot.
The design must handle every possible cable failure at sensors. It calls for special sensors with a specific design.
The specially designed computer, "large Arduino", had to be tested against radio transmitter interference from Walkie Talkies ets. There are international rules named "The machine directive" stating it.
What if your machine sets off full speed due to a radio amateur is too close, or Your own phone?
It's defenately not a suitable "hobby project".
What is Your background regarding electronics and mechanical (hydrulic) design?
STMicroelectronics Application Note AN2689:
This application note provides guidelines on protecting automotive electronics from electrical hazards, focusing on design and component selection. Reading this will greatly enhance your understanding of automotive circuit protection. Read AN2689
Analog Devices: Automotive Electronics Design:
This article distills key insights into designing automotive electronics, offering practical advice for engineers. Read the article
Diodes Incorporated: Transient Voltage Suppression in Automotive:
Learn about techniques to protect automotive circuits from transient voltage, which is critical for ensuring reliable operation in harsh conditions. Read the article
AEC-100 Standards Webinar:
This webinar from Monolithic Power Systems provides a detailed overview of AEC standards, essential for understanding automotive electronics requirements. Watch the webinar
Understanding Automotive Electronics, An Engineering Perspective by William B. Ribbens:
This comprehensive book offers an in-depth look into automotive electronics from an engineering perspective, making it an invaluable resource. Access the book
These resources should provide a strong foundation for anyone involved in automotive electronics design. If you need further help or more resources, feel free to ask!
Thanks! I left the job I referred to 17 years ago but remember all travels around Europe when the local service organisation didn't coop.
One multiton truck accelerated when the driver pushed the brake! Healt and Safety threatend to stop every truck of our brand..
The explanation was inadequate motor cable fastening. One cable from the 20 kW inverter got the insulation damaged and one of the 3 phase cables made contact with the chassis, that must be free from any potentail, and that must be monitored!
It's just a home machine being run on the farm. As it is now the controls freeze up due to their inherent morse cable design. When I'm out pushing snow off my driveway after about half an hour the cables freeze up due to frozen moisture and then it becomes somewhat useless until I pull it into the shop and warm it up for a couple hours. If the control was to go full on all that would happen is it would go full travel to the end of the cylinder stroke and hit the hydraulic release pressure, at which time I could just shut down the machine or simply lift the controls lockout to disable it (I will retain that feature in this changeover). I'm only controlling the lift arms and the bucket with this, the drive will remain mechanical, as that system works great. I don't run this machine around any other people or have anyone in the direct vicinity of its range of motion.
PWM is much easier than varying analog voltages. Look at the BTS7960 motor driver breakout boards. They "claim" 10A (don't believe a word of it!!!) but they should be safe at 3A. I think 3A is about what the actuator I have connected to one stalls out at.
I got into reading the biography of R. G. LeTourneau - Wikipedia because of an offhand comment in a web forum a few years ago about some earth scrapers whose brakes didn't work unless the motor was at least at half-throttle. So going down a hill, you had to rev the engine to get the thing to stop!
Went down the rabbit hole of earthmoving equipment and ended up at an Amazon link to his biography. It was interesting if you can get past all the religious stuff.
Thanks. The environment, humidity, vibrations(!) are enemies to our inventions. The trucks I worked with sometimes ran in Freezers, minus 30 C. Some companies charged them inside the cold area and that worked at the best.
Customers driving the vehicles out into room temperature for charging faced condensation, then melting, and water causing all kinds of issues.
Arduinos, in general, are not certified for the use You tell about. Brake downs are likely happening in a too short time.
In the respect of safety issues, concider a truck mishap and running over a pet, a child, wife..... It's serious business even if it takes place on your private property.
I advice You to not go the Arduino way for this, the way You have described it.
You need a more serious attack of the problem.
Thanks for the link! That was a successful guy.
"My" company was Atlet, Sweden. The founder was Knut Jacobsson. They started in an apartment! Once they blew a hole in the ceiling, freeing a jammed piston. What the neighbour up there said I haven't heard...
He also launched new theories how to evaluate the economy of the company.
He got 5 children but only one really took action in the company. Not seeing the successor, the future, the company was sold to the Japs some 2007.
Ok good finally an answer to my actual question. Thanks cedarlakeinstruments! I will look into it.
Not sure why my post has attracted all the safety police when none of the other similar posts about controlling equipment have had any mention of it. Next time instead of posting all the background information I'll just stick the basic electronic details.
The BTS7960 is a solid device; I’ve run them at a little over 20 amps without any issues or noticeable heating. However, you must follow the BTS7960 datasheet carefully and ensure you have a reliable ground connection, as losing it can fry the part. Note: On the module, the power and logic grounds are connected together, so maintaining a solid ground is critical for proper operation.
It was very interesting. What I found really amusing is that he got his start doing road construction and he would build custom machinery for it. Never made any money at construction. Then a friend pointed out to him that he was more profitable making copies of his machines for other companies and maybe that was where he should focus!
I based my skepticism on the poor way that the module implements heatsinking: the vias that should be moving heat to the heatsink have soldermask over them instead of remaining bare. Good to hear that you had a reliable experience.
That said, for my application they worked fine, but I never went over 3A.
Being the the one in the union working for raising the salories for the members was a duty.
Engineers often make/create fantastic things. That's the soul/spirit in engineers. However they are really bad in argumenting for higher salories!
This man was a true engineer.....
Most proportional flow / pressure valves I worked with required proportional CURRENT control. Post a link to the datasheet or brand name and exact part number for the valve you plan to use.
