Motor Control With BS2 (Wheelchair Lift)
Crystalionx
Posts: 18
Motor Control - I am seeking to use the BS2 in order to start-up a 12VDC bi-directional (up and down) motor used for a wheelchair lift that does on the back of a car - it is a gift for my disabled father.· I have read about the H-Bridge and the motor mind - I cannot figure out if either of these devices actually turns on the motor or just controls its speed once it is turned on with the power switch.· My eventual goal is to construct a remote control unit to start up the wheelchair lift - using the RF digital system.· If I build the H-Bridge myself - will it turn on the motor of the wheelchair lift.· Also, where do I get the pBasic code to operate the H-Bridge?· Has any one done such a project before?
Post Edited By Moderator (Jon Williams (Parallax)) : 7/20/2005 12:02:09 AM GMT
Post Edited By Moderator (Jon Williams (Parallax)) : 7/20/2005 12:02:09 AM GMT
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bugg
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Boe-bot: $229
Toddler: $249
Learning Google is your friend: priceless
Post Edited (bugg) : 7/20/2005 12:57:02 AM GMT
bugg
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Boe-bot: $229
Toddler: $249
Learning Google is your friend: priceless
Post Edited (bugg) : 7/21/2005 12:51:25 AM GMT
If the "12VDC bi-directional (up and down) motor used for a wheelchair lift" is part of a "bolt-on package" which is ready to operate as soon as it's installed on the back of a car, then you MAY have very little work to do, as everything necessary to control the motor should be included in the package. Thus, no high current H-Bridge or heavy duty relay may be required. It really depends on the package, and how it is configured. A link to the web site for the company which makes it would be very helpful. If you can attach a copy of the documentation which comes with it, that too would be most helpful.
I'm going to go out on a limb with an educated guess, just based on many of these chair lift units that I've seen before. Most if not all have some sort of umbilical control cord with a set of push buttons on the end of it, contained in a pendant mounting for manual control of the motor. Generally the hand controls are labelled something like: RAISE, STOP, LOWER. There are a number of ways in which these buttons can be wired, but in most cases a parallel set of manual motor controls can exist rather easily and safely.
In the world of industrial motor control when such a dual control system exists or is designed, there is usually a selector switch associated with these controls, which will be labelled something like this: HAND, OFF, AUTOMATIC or if you prefer in this case, for a better overview for this particular application, the selector switch might read: HAND, OFF, REMOTE. There are numerous reasons for having such a selector switch, but the foremost reason is safety. That safety aspect will beome more clear in a moment.
All you will be doing is adding the REMOTE motor control station. Essentiallly (ignoring the RF wireless component, and the Stamp for a moment) you will have a simple SPDT or DPDT center off relay, which will take the place of the pendant mounted control buttons in the HAND motor control. The selector switch will prevent the two parallel control systems from interfering with one another, as only on can be in control at any given time. So too, the OFF position ensure that the controls can not be activated unless some overt act is performed; that being turning the switch either to the HAND or REMOTE position. If you choose to do so, some extra protection can be had by making the selector switch key activated rather than just by a lever or knob. This way ONLY authorized people (those with a key) can active EITHER of these systems, HAND or REMOTE. Yet another safety feature, at a mimimal cost.
Fast forwarding to the end of this design, the RF unit will control the Stamp, and the Stamp in turn will control the SPDT or DPDT relay mentioned above. It may sound terribly involved, but it's really not. Industrial control electricians put these systems together in a matter of an hour or so, and it sounds a lot worse than it really is. There are even standard wiring control circuits available, that are used for these types of motor control.
If this appeals to you, and you want to know more, let me know. Obviously this presumes that some type of appropriate motor control is supplied with this chair lift package.
Regards,
Bruce Bates
Post Edited (Bruce Bates) : 7/21/2005 6:00:29 PM GMT
You will probably end up driving some high power relays with something like a darlington driver. A good substitute for high power relays could be some starting solenoids.
A picture is worth a thousand words so if you can put up a schematic or anything else, I can certainly give you some guidance on this.
Regards,
Gerry
I don't know about anyone else but I cannot understand this reply. ??????
would help understand your situation.
If there are already a bunch of relays attached to the motor then you need to figure out what type of relays those are, if they are DC or AC, how much current needs to pass to trip them and if the are solid of magnetic. solids can handle a lot of punishment. anyway i have to go. if you can post a little more info would be helpful.
This thread/subject died/ossified more than 5 years ago.
Heh ...is it coincidenal you noticed??
(Your own join date is a scant few months after this threads posting......you recognized it?)
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