It has been a while since I have posted up, due to the fact that I felt like I was getting nowhere fast with the current project.
R2's periscope is a part that comes out of the dome and retracts back in - seen a couple of times in the movies, most notably on Dagobah, as R2 "swims" through the swamp after he falls off of Luke's X-Wing.
So - is this part "necessary" to the build - NO. Is it a very cool piece that will enhance the viewer's (and user's) experience - YES. It is nothing but droid-bling. Something to look at when you are tired or watching a white and blue trashcan drive around the room.
Why did this take so long ? There ware a lot of parts to make myself in this assembly. After the Periscope lighting was finished, it then came to mounting the Linear Actuator. The Linear Actuator was purchased from a member of Astromech.net second hand, and was the correct size and had an appropriate amount of travel for this application. This is one of those parts that one can buy "off the shelf" and modify to work for a specific R2 related project .... with a little work. There is talk on the boards of a couple of members working up kits for periscope lifters, but nothing has become reality in the past 6 months.
This particular linear actuator can be found here :
http://www.firgelliauto.com/product_info.php?cPath=118&products_id=257
Firgelli Automation is the company, and they make track actuators and tube actuators. The tube actuators are the more familiar units - think of a lift gate on a truck bed or trunk lift mechanism on a car. The tube actuators are more like pistons or hydraulic actuators. These would be great for this project IF there was enough room inside the dome for the unit. The track actuator has a screw lift that moves a mount up and down the shaft. Even this unit is quite large. It stands 10" tall but only offers 5" of travel.
I won't bore you with all of the details and trial and error that went into mounting this on the dome plate, but it was not easy. The alignment of the mechanism is critical, as the periscope "head" needs to travel in and out of one of the pie panels on top of R2's dome. Little to no clearance and less margin of error mean that the actuator needs to be positioned perfectly in order for the unit to raise and lower without getting caught up on the dome opening.
Here are a few shots of the mounting of the actuator and the periscope.
The periscope is mounted on a piece of 1-1/4" PVC pipe to add a little height, and to get the cool posts exposed after it has been lifted out of the dome.
As I stated before, the glide path of the actuator has to be exact every time it is raised or lowered. The dome plate is rather flexible, and this caused the periscope to wobble and lean as it made it's short 5" trip. I used some 80-20 aluminum (basically uber-cool erector set like material for big boys) to create a stabilizer mount for the actuator.
Here is a pretty good shot of the stabilizer attached to the top of the actuator. You will notice that the top edges of the arch are rounded off, this allows the top of the dome to clear the assembly.
Here is the motor on the actuator. The mount for the riser is shown here as well. The periscope will mount on the aluminum spire.
Periscope and PVC riser being glued together with JB Weld. No more craptastic tape to hold the two pieces together.
Yet another hacked-up cutting board was installed on the arch to offer mounting points for the electronic goodies inside the dome.
In the picture below, bottom center is the slip ring connector board. This was previously mounted on one of the spokes of the dome plate. On the right of the board is a 12 channel RF receiver. This allows 12 channels of relays to be triggered by a wireless remote.
The idea was to have a single button used to raise the periscope and another to lower the periscope, as this particular RF board did not offer reverse polarity within a single relay pot. A little searching on the interwebs showed how to hook up one of these unite to achieve the forward and reverse motion with separate buttons. OK - it was a LOT of searching, and more trial and error... and some blue smoke here and there before I got it hooked up properly. Most of the "help" available on the internet is written as if the reader has some kind of knowledge about the unit. Unfortunately, I am not that guy. Terms like Comm, Normal Open, Normal Closed, Latched Mode, Toggle Mode and Momentary Mode were all but unknown to me before I read up on the topic.
The individual relays correspond to buttons on the remote, but were not numbered in any way. A little multimeter probing allowed me to identify the correct numbers. Relays #1 and #2 are hooked up, but the final working scheme is on relays #7 and #8. Basically, the relays are wired with shared positive and negative wire leads from the main power - BUT the poles are reversed to pass a reverse polarity signal based on two buttons. The center pole is used to attach the positive and negative lead of the actuator motor. Pressing button #7 sends a positive signal to the actuator, causing it to raise. Pressing button #8 sends a negative (or reversed polarity signal) to the motor which sends it down. the linear actuator has built in limit switches that stop the signal when it reaches the top and bottom of the travel.
All of these relays will require their own power, so I set up a distribution strip to split out the 12V signal from the slip ring board.
Here is a video of the unit in action - sans Dome.
All in all, the frustration over the past couple of weeks is well worth it.
Tomorrow, I plan on re-installing the lights within the periscope and get the lights wired to a button on the remote. I will also finalize the position of the actuator with the dome on, so it will clear the opening in the pie panel.
I have to get some pictures up of some of the new aluminum goodies I received last week as well !
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