Forward-looking CCTV for rowing

classic Classic list List threaded Threaded
100 messages Options
12345
Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Forward-looking CCTV for rowing

Hi folks - I'd like to ask the HBBR electronics experts for advice about a forward-looking video camera and a monitor so I can see where I'm going when rowing my fixed-seat skiff.

Age is steadily reducing the amount of twisting round that I can do. I've fiddled with mirrors, but I think video might be much better, and would also be handy on my bicycle.

The idea is to mount a camera on a small mast somewhere in the forward part of the skiff, and fit a reasonably-sized monitor on the thwart that's above my feet.

I initially thought of using a car reversing video system, but I think those cameras are too wide-angle, and I don't need LED illumination, which many of them have built-in. Cheap cameras and monitors seem to be easily available (e.g. on eBay), and it seems that it should be possible to put together a system quite cheaply. These are the initial parameters I'm thinking about:

- 12V system powered by a rechargeable battery to give (say) minimum 12-hour working.
- Camera with suitable lens (about 50 degree included angle?) or manually variable lens, waterproof. I don't know how to specify the camera, and I'd greatly appreciate some help with that. I see that some cameras have an SD slot for recording, which might be useful, but isn't the primary purpose.
- CCD monitor, presumably something like this one:
http://www.ebay.co.uk/itm/320931566727?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
Again, I'm not sure about the spec or indeed the screen size. The bigger the better, I suppose. Waterproof if possible.
- Budget... Well, say up to £100? Less if possible.

You will see that my ignorance about such matters is considerable! Any comments or advice would be most welcome.
Thanks,
Martin
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

The camera bit is pretty easy, a wide angle reversing camera would do the job well (I happen to have a spare one somewhere, too).

The real challenge is going to be getting hold of a good daylight viewable screen.  Even the very best LCD screens are poor when viewed out in the open on water, where the ambient light level will be pretty high.

I think you might be better at looking at adapting something like a head mounted display, if you can find one at a reasonable price.  I looked at doing this a while ago and concluded that a head band, with a small camera at the back and a eye-directed display pointing at one eye might work well, as you could alter the view by turning you head a little, which might be useful.

I'll go and do some digging around and see what I can find, as I know I noted some links to this sort of thing a year or so ago.

An alternative might be to look at changing to a front rowing system.  As it happens I built one of those a year or so ago that I've never got around to testing...................
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

In reply to this post by Martin C
Martin,

This is quite achievable - for example security cameras are small, cheap and cheerful these days. LCDs are coming down in price, driven by the the explosion in smart phone and tablet sales.

The biggest problem will be the environment, e.g. you expect it to work in the rain and most displays are not rated for use in the rain (however most security cameras are).

Also bright sunshine can be a problem - all screens reflect the sun to some extent so there will be times when you won't see any thing clearly.

Perhaps the solution is a plywood box tunnel, painted black internally, with perspex cover to protect the screen from sun and rain.

-Paul
Say NO to Brexit. Kick it into the long grass
Paul (admin) Paul (admin)
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

BTW: That display looks ideal - however it has no "IP-rating" which means it is not waterproof at all and may fail if it gets wet internally.
Say NO to Brexit. Kick it into the long grass
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

adminHBBR wrote
BTW: That display looks ideal - however it has no "IP-rating" which means it is not waterproof at all and may fail if it gets wet internally.
Somewhere I've got a near identical one, from a motor home reversing kit.  I can say with certainty that it's to all intents and purposes unviewable in bright daylight, unfortunately.

AFAIK, it's only the latest tablet and smartphone screens that seem to have enough contrast to be OK in daylight, but even some of those struggle a bit.  Virtually all of the cheap small monitors around use ordinary TFT LCD displays, that just don't have a good enough contrast range to be daylight viewable.

An OLED screen would probably be OK, but most still seem to be a bit too small for this job.
Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

Wow - quick responses! Thanks!

Ah... I had entirely missed the problem of daylight viewing of an LCD. Would putting it into a black 'tunnel', as suggested by Paul, be an option? Or maybe they are simply too dim.

The head-mounted option sounds possible if the equipment can be sourced, and I agree that it would be useful to be able to move it around. The only snag  being that the oarsman looks a bit weird with stuff strapped on his head... ('Do you think I've got eyes in the back of my head?'  - 'Well, yes, actually.')

Funnily enough I have just been looking at forward rowing as another possibility, and have sketched a simple 'reversing' mechanism that I could build (it would not allow feathering on the backstroke, but that's not vital in my view). The posh systems use a sliding seat as well, I see, and at least one of them allows rowing with the legs alone. But they are complicated and way too expensive for me... Unless I build a home-made version, of course. I would be interested to participate in trials of that option.

Martin

Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

Martin,

My forward rowing prototype is sitting gathering dust, and given the large number of projects I have on the go I'm not at all sure I'll ever get around to adding the finishing touches and trying it out.  Here are some photos of it:











It's designed to bolt to an outrigger, but could very easily be adapted to fit to something that fitted onto a gunwhale directly.



Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

That's fascinating, Jeremy... It's not unlike the system I've sketched myself, but you've got a much better reversing mechanism. I see that yours has the same fore-and-aft hinge axis to allow the blade to be raised and lowered, but I have sketched two meshing semicircular gears enclosed between two alloy plates to give the reversing action, whereas you've used a link tube and two plain bearings.

Two issues that seem important are the reduction of friction and slop in the reversing mechanism (your system looks very good from that point of view), and the bending loads that the mechanism has to endure as the blades are lifted. Your system puts quite large bending loads into the hinge-pins, I think...? I wonder whether there shouldn't be a second plate on top, so the hinge pins are supported at both ends...?

Anyway, it's extremely interesting.  It would be good to look at it - that is, provided you're not a vast distance from me (I'm in Gosport). Maybe, if you definitely aren't going to proceed with it, I could do some trials with it? It even looks as though your outrigger frame might drop straight into my Linnet, which has a flat floor in way of the rowlocks... Or I could make an outrigger frame to fit my boat. It seems not a bad idea to keep the loads out of the gunwales, which are not very substantial on the Linnet.

Incidentally, on the question of sunlight-visible LCD screens, I've found a couple of (expensive) commercial cycle rear-view video systems that claim to be available, but I'm not sure they have actually gone on sale yet. Maybe the LCD vision problem is holding them back. (The Owl 360 and one by Cerevellum).

Martin
 
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

I'm only just up the road from you, Martin, near Salisbury.  I could easily pop the bits in the back of the car and drop them off next time I'm down your way (my aged outlaws live in Chichester, so we head that way fairly often).

The horizontal pivots are stainless hollow pins running in oilite bronze bushes, the vertical pins are 10mm solid stainless, again running in oilite bronze bushes.  The reversing linkage uses stainless steel Rose joints, with bronze bushes, connected via 6082-T6 aluminium alloy straps top and bottom.  The oar looms are 1.5" diameter 6082-T6 alloy tube.

I'm pretty confident that the 10mm stainless pins will take the loads OK, as they are pretty well supported and the bending loads are fairly modest.  They are drilled and tapped at the upper ends, to take the screws that hold the retaining washers in place, so if they were found to flex a bit they could easily be strapped together with a plate.
Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

That's very generous, Jeremy - thanks! The specifications of your system sound very good indeed.  

If you're going in the Chichester direction it would be much easier for you if we met at Langstone SC, where my skiff is. The sailing club is is just on the right before the Hayling Bridge.

A slight complication, I now realise, is that I have managed to register myself twice on this forum, but I'm sure that either of me, Martin C or Martin Corrick, will respond promptly to any contact message.

Cheers,

Martin  
Chris Partridge Chris Partridge
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

In reply to this post by Martin C
Hi Martin,
The only mirror system that worked for me was the one on the Clovelly Scull, which positioned a convex rear view mirror from a car on a bipod in the middle of the boat, directly in front of and above the sculler's head. This gives a very good view forward and it isn't as confusing as a wing mirror.
BrianP BrianP
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

On the issue of day light viewable screens - my wife has a Kindle Reader and it is completely readable in strong daylight. It uses a completely different display, I am sure the techs here can explain. Can  Kindle show black and white pictures? Could it take a camera feed?

Thanks, Brian.
Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

In reply to this post by Chris Partridge
Chris - Yes, that does seem very possible... I recall seeing a photo of something like that, using what looked like a larger than normal mirror. I have experimented with a pair of motorcycle mirrors, but it seems that they would need to be somewhere above the rowlocks, and their support structure would get in the way of the oars. The fact that one sways forward and back obviously adds another dimension of difficulty to the problem.

Another thing I wondered about is the small cycle rear-view mirror that mounts on one's glasses or on a cycle helmet, but I have no experience of that.  In general I came to the conclusion that the most promising avenue was the video camera/LCD monitor, but of course I had forgotten the daylight viewing issue.

Incidentally, I was looking last night at 7 inch tablets, which might provide a daylight-viewable screen. There are cheapo ones from China at little more than £50, but of course they may not be very reliable.  

Jeremy's suggestion of forward rowing, and the obvious quality of the mechanism he has built, has re-interested me in that solution. Rowing is such a good way to get about, but it's such a pain that one has to be looking backwards! If one could develop a really good forward rowing system, isn't there a possibility of it catching on in a big way?

Martin

On 05/12/12 09:35, Chris Partridge [via UK HBBR Forum] wrote:
Hi Martin,
The only mirror system that worked for me was the one on the Clovelly Scull, which positioned a convex rear view mirror from a car on a bipod in the middle of the boat, directly in front of and above the sculler's head. This gives a very good view forward and it isn't as confusing as a wing mirror.


If you reply to this email, your message will be added to the discussion below:
http://uk-hbbr-forum.967333.n3.nabble.com/Forward-looking-CCTV-for-rowing-tp4025894p4025904.html
To unsubscribe from Forward-looking CCTV for rowing, click here.
NAML

Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

In reply to this post by BrianP
BrianP wrote
On the issue of day light viewable screens - my wife has a Kindle Reader and it is completely readable in strong daylight. It uses a completely different display, I am sure the techs here can explain. Can  Kindle show black and white pictures? Could it take a camera feed?

Thanks, Brian.
Unfortunately the "electronic ink" displays used in most ereaders can't show moving images well, as they have a very slow refresh rate.  They are very clear in bright light because they don't (usually) emit light (there are some with backlights now though). The other nice thing about these displays is that they only consume power when the display is actually being re-written, static images use no power at all when displayed.

They can display still images in shades of grey, but can't accept video, unfortunately.
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

In reply to this post by Martin C
Martin C wrote
Chris - Yes, that does seem very possible... I recall seeing a photo of
something like that, using what looked like a larger than normal mirror.
I have experimented with a pair of motorcycle mirrors, but it seems that
they would need to be somewhere above the rowlocks, and their support
structure would get in the way of the oars. The fact that one sways
forward and back obviously adds another dimension of difficulty to the
problem.

Another thing I wondered about is the small cycle rear-view mirror that
mounts on one's glasses or on a cycle helmet, but I have no experience
of that.  In general I came to the conclusion that the most promising
avenue was the video camera/LCD monitor, but of course I had forgotten
the daylight viewing issue.

Incidentally, I was looking last night at 7 inch tablets, which might
provide a daylight-viewable screen. There are cheapo ones from China at
little more than £50, but of course they may not be very reliable.

Jeremy's suggestion of forward rowing, and the obvious quality of the
mechanism he has built, has re-interested me in that solution. Rowing is
such a good way to get about, but it's such a pain that one has to be
looking backwards! If one could develop a really good forward rowing
system, isn't there a possibility of it catching on in a big way?

Martin
I tried the cycle mirror that clips to the side of my glasses but it doesn't really give a wide enough field of view to be useful.  I think the one Chris mentioned is a pretty big mirror with a slightly convex face, so that you get a nice wide angle view ahead.  The only problem with it is that it looks a bit odd, being so large and having to be mounted up above head height.

The funny thing is that designed and built that forward rowing system because I was really struggling to turn my head around (bit of arthritis in my neck).  After spending a few hours making it I sort of lost interest in rowing................

As soon as I know when I'm next likely to be down your neck of the woods I'll let you know.
tony waller tony waller
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

RE: Forward-looking CCTV for rowing

There’s one problem with forward-facing rowing systems that I have encountered when trying one : the rower’s CG moves towards the stern as the boat surges forward. The dinghy fitted with the system I used was about 10ft long and the porpoising motion was extreme. Tony

 

From: Jeremy [via UK HBBR Forum] [mailto:[hidden email]]
Sent: 05 December 2012 14:44
To: tony waller
Subject: Re: Forward-looking CCTV for rowing

 

Martin C wrote

Chris - Yes, that does seem very possible... I recall seeing a photo of
something like that, using what looked like a larger than normal mirror.
I have experimented with a pair of motorcycle mirrors, but it seems that
they would need to be somewhere above the rowlocks, and their support
structure would get in the way of the oars. The fact that one sways
forward and back obviously adds another dimension of difficulty to the
problem.

Another thing I wondered about is the small cycle rear-view mirror that
mounts on one's glasses or on a cycle helmet, but I have no experience
of that.  In general I came to the conclusion that the most promising
avenue was the video camera/LCD monitor, but of course I had forgotten
the daylight viewing issue.

Incidentally, I was looking last night at 7 inch tablets, which might
provide a daylight-viewable screen. There are cheapo ones from China at
little more than £50, but of course they may not be very reliable.

Jeremy's suggestion of forward rowing, and the obvious quality of the
mechanism he has built, has re-interested me in that solution. Rowing is
such a good way to get about, but it's such a pain that one has to be
looking backwards! If one could develop a really good forward rowing
system, isn't there a possibility of it catching on in a big way?

Martin

I tried the cycle mirror that clips to the side of my glasses but it doesn't really give a wide enough field of view to be useful.  I think the one Chris mentioned is a pretty big mirror with a slightly convex face, so that you get a nice wide angle view ahead.  The only problem with it is that it looks a bit odd, being so large and having to be mounted up above head height.

The funny thing is that designed and built that forward rowing system because I was really struggling to turn my head around (bit of arthritis in my neck).  After spending a few hours making it I sort of lost interest in rowing................

As soon as I know when I'm next likely to be down your neck of the woods I'll let you know.


If you reply to this email, your message will be added to the discussion below:

http://uk-hbbr-forum.967333.n3.nabble.com/Forward-looking-CCTV-for-rowing-tp4025894p4025908.html

To start a new topic under Technical/Eco Forum, email [hidden email]
To unsubscribe from UK HBBR Forum, click here.
NAML

Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

In reply to this post by Jeremy
Thanks for that, Jeremy.

I'm rather aware of being behind the game on these issues. I see that forward-facing rowing has been discussed already in Chris' rowing blog, for example:

http://rowingforpleasure.blogspot.co.uk/2010/04/this-extraordinary-mechanism-is-fine.html

And forward-rowing systems are commercially available. Perhaps their lack of success is due to the forward rower (or indeed pedaller or mirror-user, as Jeremy says) looking silly. The forward-rowing mechanism, all levers and angles, looks ungainly, rather like the pterodactyl, which seems to be reaching out to hang on to its own cranky wings. But this really just a perception; it would be perfectly fair to say that a person proceeding backwards in a rowing boat looks pretty silly too, were we not used to it.

If the forward-rowing mechanism were operated entirely by the legs, the rower holding on to a fixed crossbar with his or her hands, might it look less silly? I see that there is an American system which allows legs only: see http://www.frontrower.com/ But it looks even crankier than most - a great festoon of wires, levers and pulleys.

Martin
Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

I think your right, the resistance to adopting these systems is probably down to the natural conservatism of most boaty folk.  The idea goes back a long time, at least 100 years or more.  

One advantage of adding a linkage is that you can alter the relationship between the angle that the inboard part takes relative to the outward part.  I did a bit of modelling of oar movement, using some research that some of the universities that are heavily into rowing have done, and there is a clear need for the blade to accelerate from the catch to the release, with the propulsive force on the blade being kept fairly even for the whole stroke.  

For a fixed seat and conventional oars this seems to me to create a bit of a problem.  Leant forward for the catch the rower can't exert as much mechanical force on the handle as further into the stroke when the mechanical advantage is better (in terms of the relationship between muscles and limb angles).  Similarly, the force tails off towards the release as the blade is now moving quite fast and again it isn't as easy to deliver maximum force because of the angles.

To some extent you may be able to compensate for this by building in acceleration, so that at the catch the blade moves at a rate close to that of the handle movement (in angular terms) but by the release the blade is moving much faster.  The result seems to me to be a longer effective stroke, but I may well be talking complete rubbish................

Martin C Martin C
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

Yes... I think I see what you mean, Jeremy.

Thinking aloud, the links connecting the oar and the handle (for want of
a better term) are like the connecting rods of a steam engine, only they
are 'crossed over' - each end of a link is connected to the 'opposite
side' of an imaginary rotation circle. And it is a reciprocating system,
so the blade speed/acceleration on the backstroke will be the same as on
the power stroke.

The main variables seem to be:

The radius of rotation of the attachment point at each end of the
connecting link
The ratio between [distance between rotation centres] and [length of the
link between centres]
The relation between the radial start point (which must be before the
catch) and the radial finish point (i.e. the reversing point) during a
complete cycle

These variables appear to allow quite a number of different-shaped
velocity/acceleration curves as measured at the blade.

I guess that there are also a number of practical design requirements,
such as:

At normal boat speed the catch has to occur when the blade is travelling
pretty near zero velocity in relation to the water surface, and ditto
for the 'un-catch' (whatever that is called).
There will be an optimum speed for the rower's hands, variable to some
degree by altering the effective length of the 'handle' and/or the oar.
There will also be an optimum match of lever arms (oar to handle) for
the best ratio between blade force and blade velocity - the shorter the
handle, the faster the blade speed and the lower the force generated.

The geometry and mechanics of all this get quite complicated! Anybody
good at computer modelling?

Additionally, there is an over-arching question of whether the most
effective system is to reverse the blade action, as we have been
discussing, or to move the oar hinge point inboard, as in the Frontrower
system. The more I look at the Frontrower the more interesting it gets -
there are some good videos on the site, including a 90-yr-old rowing
happily. It looks very antique - all wood and wires - but evidently
works well. Yours for $2200...

Dammit, I must stop thinking about this and do some work!

Martin


Jeremy Jeremy
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: Forward-looking CCTV for rowing

I spent hours modelling the angle changes in AutoCAD before committing to the final design!  It proved to be pretty difficult to get the geometry right, much more difficult than I thought it would be.  One problem was getting the geometry such that you could fairly easily make the linkage go over-centre so that you could ship the oars (as shown in the third photo above), harder than it seemed at first, as the handles can't move through your body!
12345
Loading...