Re: Re: Whoooosh..thud..oh bugger

[Martin Howell <martin.howell@xxxxxxxxxxxx>]

Could do, Jaycar sell a module to do that, but I suspect it
wouldn't go down well with the other half.....

M

Paul Gale wrote:
> Excellent - looks good.
>
> One question though - are you going to have the star trek door whoosh
sound effect playing as it opens ? ;)
>
> Paul.
>
>
>
>> -----Original Message-----
>> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
>> Of Martin Howell
>> Sent: 11 April 2007 20:12
>> To: ukha_d@xxxxxxx
>> Subject: Re: [ukha_d] Re: Whoooosh..thud..oh bugger
>>
>> Funny you should ask...  Some pics and details are rather
>> hastily chucked together at
>>
>> wwww.grizelli.com/partition/partition.htm
>>
>> When the door is working properly, I'll add some moving
>> pictures as well, ooh er missus.  The drive is disconnected
>> at present as SWMBO can't seem to master the knack of taking
>> her finger off the switch before (rather than 3 seconds
>> after) the door hits the buffers at 40 mph, and I'm worried
>> that the whole thing might end up in the garden.
>>
>> Martin
>>
>> Paul Gale wrote:
>>> Any pictures yet?
>>>
>>> Would be interesting to see...
>>>
>>> Paul.
>>>
>>>
>>>> -----Original Message-----
>>>> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On
>> Behalf
>>>> Of Martin Howell
>>>> Sent: 11 April 2007 17:56
>>>> To: ukha_d@xxxxxxx
>>>> Subject: Re: [ukha_d] Re: Whoooosh..thud..oh bugger
>>>>
>>>> Thanks Simon, not as strange a suggestion as it might
seem.
>>>>   I originally planned a fully automated system, using a
>>>> controller devised by Rodney Hall (on this list, thanks
>>>> Rodney), but decided against it on the grounds that it
would
>>>> be pretty complex - IR beams to trigger both open and
close;
>>>> obstruction detection; manual overrides etc - and that it
>>>> would need too many fail-safes to stop it from squashing
>>>> people, and avoid getting Aunt Edna getting trapped in the
>>>> lounge for several days while we worked out what had gone
wrong.
>>>>
>>>> I'm sticking with the simple manual approach for now, with
a
>>>> series of micro switches to slow the door down for the
last
>>>> 6 inches of travel and to shut the power off before the
door
>>>> hits the stops, together with some cushioning of the cable
>>>> drive mechanism.  As a last resort (and with higher WAF),
I
>>>> could disconnect the drive completely and just add a
handle
>>>> on both sides, though there's still the problem of small
>>>> boys closing the door enthusiastically and forgetting to
>>>> move all their body parts out of the way...
>>>>
>>>> Martin
>>>>
>>>> Simon Pawson wrote:
>>>>> I tried this reply last night but haven't seen it
yet...
>>>>>
>>>>> Coming totally from a strange direction....
>>>>>
>>>>> could you do something with a reversing sensor system
for a car.
>> The
>>>> bar
>>>>> graph of LEDS could be converted to opto-isolators
driving relays
>>>> with
>>>>> build in resistors to slow the travel.
>>>>>
>>>>> Might be hard getting a reliable bounce if wall/frame
mounted.
>> Easier
>>>>> spotting the wall from the door but not so elegant.
Could be set up
>>>> as a
>>>>> safety measure as well. Child in the way stops (or
even beeps).
>>>>>
>>>>> Sorry just an odd thought - back to the merlot.
>>>>>
>>>>> Simon
>>>>>
>>>>>
>>>>> In message <461A91D0.8000200@xxxxxxx>, Martin
Howell
>>>>> <martin.howell@xxxxxxx> writes
>>>>>> Hmm, this unit from RS gives the 'soft start' I'm
looking
>>>>>> for, but not the 'soft stop, which is where the
real problem
>>>>>>  lies.  I agree with your analysis of the drive
train
>>>>>> issues, but I'm concerned that strengthening the
cables and
>>>>>> applying more tension will just move the force to
the next
>>>>>> weakest part of the drive - the cable fails at
present
>>>>>> because of a joint, inserted partly to prevent
breaking a
>>>>>> more difficult to fix part of the drive.  I'm
looking at a
>>>>>> more simplistic system of forcing a slow down at
each end of
>>>>>> the movement, watch this space to see if it works,
or if the
>>>>>> whole contraption bursts through the wall into the
garden :-)
>>>>>>
>>>>>> Martin
>>>>>>
>>>>>> David Cole wrote:
>>>>>>> Martin
>>>>>>>
>>>>>>> Sounds to me like you need a PWM (Pulse Width
Modulation) drive
>> to
>>>>>>> efficiently control the speed of the motor.
>>>>>>>
>>>>>>> Something along the lines of 510-1209 at RS
should do it, this
>>>> would
>>>>>>> give the acceleration and deceleration whilst
also limiting the
>>>>>>> current if the door jammed. Alternatively
google for PWM DC drive
>>>>>>> circuit
>>>>>>>
>>>>>>> You want to ensure that your drive train
(cables) are as stiff as
>>>>>>> possible, this is why industrial applications
usually use rack
>> and
>>>>>>> pinion drives. This may mean increasing the
diameter of the cable
>>>> to
>>>>>>> ensure that you don't have any stretch which
causes jerk. It
>> sounds
>>>>>>> like you have a lot of inertia in your system
it may help if you
>>>> add
>>>>>>> additional gearing which will reduce the
speed, increase the
>> torque
>>>>>>> but also decrease the amount of reflected
inertia seen by the
>>>> motor.
>>>>>>> Hope this helps
>>>>>>>
>>>>>>> Regards
>>>>>>>
>>>>>>> Dave
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>> --
>>>>>>
>>>>>>
>>>>>> Grizelli Associates Limited
>>>>>> IT Project Consultants
>>>>>> 2c Nethermoor Road, Middlezoy, Bridgwater, TA7 0PG
>>>>>> UK Company registration no. 2468872
>>>>>> VAT registration no. 713 1775 49
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>> --
>>>>
>>>>
>>>> Grizelli Associates Limited
>>>> IT Project Consultants
>>>> 2c Nethermoor Road, Middlezoy, Bridgwater, TA7 0PG
>>>> UK Company registration no. 2468872
>>>> VAT registration no. 713 1775 49
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>> --
>>
>>
>> Grizelli Associates Limited
>> IT Project Consultants
>> 2c Nethermoor Road, Middlezoy, Bridgwater, TA7 0PG
>> UK Company registration no. 2468872
>> VAT registration no. 713 1775 49
>>
>>
>>
>>
>>
>>
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--


Grizelli Associates Limited
IT Project Consultants
2c Nethermoor Road, Middlezoy, Bridgwater, TA7 0PG
UK Company registration no. 2468872
VAT registration no. 713 1775 49