Building Robonova-1

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horatio

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發表於 2007-10-8 21:37 |只看該作者 |倒序瀏覽

Robonova-1 humanoid robot kit from Korean RC-servo company Hitec was introduced to the Japanese market a year after KHR-1 humanoid robot kit was first launched from competitor company Kondo. Between July 2004 through the end of 2005, Kondo sold over 3500 units of KHR-1 out of which it is estimated that not more than a couple of hundred units were sold outside of Japan and Korea.
Hitec engineers were very much inspired by KHR-1 to the extent that many of the Robonova-1 building blocks seem to be almost identical to its rival. Nevertheless, Robonova-1 is an evolution from KHR-1. It is easier to build, its software is more comprehensive, and it looks and feels a bit less like a bunch of servos hacked together by some aluminum brackets.
Robonova comes in a very nicely planned and finished box about 30x40x10cm weighing about 2.5kg. The CE logo appears on the side of the box. This is an indication of one major evolution from Kondo's KHR-1. It means that Hitec have taken the European market seriously and expect to sell many hundreds of units in the European Community. The CE certification process can cost several thousand Euros/Dollars, it can be done outside of Europe, it can imply the destruction of several units of the product, it can imply changing of some components or manufacturing process of components and it is essential for any company wanting to wholesale in EC market. CE requirements for a mechanical and electronic product that comes in kit form, which is not intended to be used by children under 14, can be a bit vague. It would imply compliance with radio frequency emission regulations, refrained use of certain toxic materials, covering of any exposed electrical or electronic components and maybe ensuring that sufficiently smooth parts are used on the outside parts of the item. The CE logo means that the importer and seller of the item can produce on demand, some papers describing what kind of tests have been conducted to the product and show that sufficient care has been taken to ensure safe use of the item as instructed. If someone gets hurt from use of the product as directed, although Europe has not yet adopted the American suing culture culture, one may have a more difficult time claiming damages from the importer if the product has really undergone CE certification.

As you can see, the items in the kit are neatly packed and easily identifiable against the inventory list in the manual. The kit comes with a remote control like RoboSapien and the keys can obviously be mapped to pre-programmed movement sequences. This is an European kit and it comes with a separate box containing the battery charger. More about this in the following pages.

The screws come inside about 15 little marked plastic bags. There are supposedly just the right number of screws , washers and bolts to build the robot and a small bag with some extras just in case. Don't know if it was a mistake in the manual, the fault of the people who assembled the box or our construction but we were left with extras. In the early 70's it was fashionably geek (so i heard) to completely disassemble your portable Sony radio just to understand how it works. Whenever you reassembled it back, you'd be left with spare parts although the reconstructed radio would still work. It was then theorized that if you repeat this process enough times, you eventually end up with two radios.

Even though this kit is certainly not for his age group, I summoned the help of my 11 year old brother in the construction of the robot with the hope that it will get him interested in robotics. Most of the work revolves around inserting and and later extracting and re-inserting about 200 screws.
Each servo is marked with a number ranging from 1-12. There are a total of 16 HSR-8498HB2 servos. Number 2 and 4 appear on 3 servos each. The differences between the servo boxes is in their casing and right/left symmetry.

FeetThe first step in the book was building the robot's feet.

BTW: The kit comes with a CD containing the color version PDF of the black&white paper manual. In retrospective, it would have been a good idea to use that PDF and a laptop rather than that bad B&W photocopy. You can find the PDF manual on http://robonova.de (try this link).

The naming convention for items used throughout the manual is somewhat cryptic and the asymmetric pictures of left/right side of the robot are a bit confusing. This ensures that you make at least a couple of mistakes throughout the construction. We eventually only spotted two mistakes, both of them related to screw names showing up in the manual as "PH/T 2.6x4mm bolts" and on the plastic bag sticker as "PH/M 2.6x4".
The servo hones have numbers 1-8 in a clockwise order. These are used to align the servo so that optimal degree of freedom (DOF) is obtained. One small trick that Hitec added to make things easier is a little knob at the back of the servo hone that aligns the servo hone to the servo box in only one possible way.

This means one less place to make mistakes when aligning the servo hones as instructed.

LegsThe next step was to construct the brackets that will serve to connect the leg servos together. Unlike with KHR-1 where these brackets are all identical, Robonova has top/bottom brackets distinguished by the height of their "side flanges".

Some screws had to be extracted from the servos and then re-inserted with the brackets.

So far pretty straightforward. Most parts have their asymmetry which helps distinguish between left and right. Some of the parts have an external and internal part distinguished by the smoothness of their cut edges.

Arms & ChestThe robonova comes with plastic hands which makes it a bit more Votoms like.

12 more and the chest is assembled.

It's starting to look like the real deal..

Here's one place where we used the usual PH/T 2x4 Screws (130 supplied) when we should have used the PH/T 2x5 Screws. At some stage we were left with no more PH/T 2x4 Screws and had to go through the manual page by page looking for where we used them instead of some other ones. In the end we were left with 4 extras..

Here he is standing with his wires all messy. Making him look pretty is what we'll do in the next couple of hours.

Head, Wires & ControllerGetting the little board with the led light into the head and then screwing the head onto the shoulder bracket was a bit of a challenge. In fact, we left these 4 screws half way because the amount of force required to get them all the way in was counterintuitive and since they are not seen anyway.. however, after the head-shoulder attachment saga, and attaching the two to the chest, we realized that two screws that attach the shoulder bracket to the chest, were left out. it meant dismantling the head again and looking ahead into the manual, at the work ahead of making all the wires look pretty, a quick executive decision was made to abandon two missing screws for the time being.

A special hole was created by the Robonova engineers to allow a screw-driver into the chest in order to attach the front panel with yet another PH/T 2x4mm screw. A magnetized screw driver was very helpful for this job.

How exciting! Robonova's body is complete. The process taught us one important lesson. It made us look in a different way at the many electronic devices and gadgets around the house. For the first time we kind of got a feeling of what it meant to work in one of those Chinese factories you read about where people get paid $1/day to screw, solder, weld and knit thousands of pieces of plastic, metal and cloths together. These $1/day workers, that are the substitute for expensive automation robots, are what allows us to enjoy modern commodity technology at ridiculously low prices.

Thanks to my experience with building the KHR-1, I didn't follow the instructions manual and tied all the wires neatly into place before actually switching on the robot to see if the servos were connected properly.
When the robot is switched on, it immediately gets into a standing initial position. There were two problems I encountered. The first problem was that half the servos didn't light up. These digital servos become very sturdy in their orientation when electricity is passed through them. The 9kg/cm torque that you see in the specs applies not only when the servo is turning but also when it is standing still. Hence when the right side of the robot's didn't show any objection to change, it was obvious that the servos were not connected to the controller board properly. The picture on the right is taken from the manual and for whatever reason I thought that the letter S stands for signal and hence the orientation of the connector is the same for left and right side servos. Wrong was I. The orientation of the connector on the right is 180° to its mate on the left and this makes sense if you look at the writings on the PCB where it depicts the position of the GND pin.
Once the connectors were turned all the motors buzzed. The Robonova servos buzz a bit quieter than the ICS784ICS servos that I have building the KHR-1.
The second problem was that the left foot turned into a crooked looking position (as in the picture above). This was a result of not following the instructions properly and setting the servo hone numbers to the wrong orientation.
OK, now that we are sure that the wires are connected properly to the controller board and that the basic orientation of all the servos is ok (calibration is obviously needed but the basic stand is almost perfect), we can get to the daunting task of tying the wires together neatly.

Here the objective was to somehow shove 3 of the long wires close to the controller board into the chest cavity. Seemed like an irritating challenge at the time as it involved unscrewing the controller board but it was done and the results are shown below if you skip a few pictures.

The rest of the work, probably 25% of the total amount, was about making the wires look pretty.

In the picture below you can see how the wires are tied together by cable ties.

The back cover in the pictures below is opened by loosening 4 screws. You can also see how some cables are tucked underneath the controller board.

There's also a transparent protective plastic cover for the unused top pins. Like with the KHR-1 where the whole back cover had to be hand-machined (with scissors) to snug the cables together, this plastic bit had to be scissored into shape in order to fit cozily onto the board and underneath the cool looking back cover.

Here's the pretty guy with the back cover.

TestingThe battery enters into Robonova's nether-region. A nice touch was the rubber protector that stops the battery cord from getting torn by the rough aluminum edges. Here's something I bet was probably required for the CE approval.

The European Robonova comes with a very generous Multicharger set. Not only does it have all the standard electricity plugs, but it also has the ability to connect to a car cigarette lighter socket (also available in American-Airlines business-class seats, though insisting on bringing your robot on board may get you delayed at security..).

The charger also has an indicator that shows when the charging is complete.

Charging takes about an hour and the three software systems RoboBASIC, RoboScript and RoboRemocon were downloaded from http://robonova.de and installed.
The first thing to be done with the software is actually setting the default controller type with the RoboBASIC software menu. Set → Controller Type → MR-C3024 Serial
The second thing is calibrating the robot's Zero Position. Again, using the menu you select Compile → Set Zero Point and the following screen appears. Pressing on the little red and blue arrows moves the robot's servos in real-time. You start buy pressing READ which takes the current values into the PC, play around with the arrows and then press WRITE which will set this position as Zero Position.

The final step of this initial introduction with Robonova was to run a couple of programs and see the robot do cool stuff. For some reason the using roboBasic with one of the many motion sequences available on the CD, didn't work the first time. So we used the roboScript and the robot did its thing with panache.

This was a short summary of our 7 hour adventure that spread over 4 evenings building the robot and documenting the process. Robonova is certainly an evolution from KHR-1 but KHR-1 still has it's Japanese charm an honorary position of being the first to market (in fact it won an excellence award in February 2006).
Robonova-1 and KHR-1 are not intended to be used by children under 14. The aluminum brackets attached to 9kg/cm servos can easily cause harm to a child's fingers if proper care is not taken to prevent fingers entering in the robot's way.
Over the weeks to come, I'll be spending time learning how to program it and try to make it climb some stairs cause I haven't seen any videos of Robonova or KHR-1 climbing stairs. So this challenge should be fun to conquer and I'll post the results on the RoboSavvy forum.