|
Post by donburch on Aug 28, 2006 22:15:54 GMT 10
It was the Carpet Rover and Pololu base which pushed me into making my own chassis. My Parallax BoE controller will drive modified servos (A$23 each), so I really just want a chassis for attaching the components. I think Carpet Rover looks cool, but what is it ? A sheet of Acrylic plastic with rounded corners, and a couple of right-angle mounting brackets for the motors. And the Pololu base is sold for A$55 for just a flat pre-cut acrylic base without motors. So expensive for something so simple ! So first step was to use a CD as a base, and next I'll get some Acrylic and a Dremmel and make my own bigger chassis.
|
|
|
Post by donburch on Aug 11, 2006 7:43:37 GMT 10
Yes, it was the comments that modified servos are not designed for continuous operation and so good for only about 100 hours which stared me wondering why they are advocated so often. The Parallax BoE can connect 4 servos, so they use servos; whereas the Arrick ARobot's controller board provides 4 servos and 2 "powerful output"s so they use a motor (and a servo for steering). I guess it comes down to BoE being a general purpose educational controller (with BoE-bot being but one of many "experiments") vs. ARobot is designed with heavy duty components specifically as a mobile robot. I do however prefer the idea of controlling 2 drive motors directly, rather than 1 drive motor and one steering servo, because I expect that it gives more control over the unit with more accurate movements and minimal turning circle. At RoboCup Junior competition yesterday I noticed some of the line following robots jerking wildly back and forth; and wondered if it was (a) lack of fine motor control, (b) using only one sensor, or (c) inexperienced programming. OK, c is a given for primary school students ;-) You may gather that I'm seriously thinking of the ARobot to get mobile - but I just can't budget A$459 for what is essentially just a sheet of metal, a motor, a servo and some sensors ... and if Abe Howell can build a robot in a CD case, then can I ?
|
|
|
Post by donburch on Aug 8, 2006 22:10:44 GMT 10
I have noticed quite a few websites describing autonomous wheeled robot bases advocate using servos modified for continuous turning.
In my very limited understanding, a servo is a motor with electronics (to accept digital (PWM) pulses, and turn them into fairly precise amounts of motor movement) and mechanical stops to prevent more than 180degrees movement.
So then we modify the servo by removing the mechanical stops and disabling the feedback part of the electronics ... turning it effectively into a stepper motor.
I get the impression that H-bridge is the electronic circuit to control a plain motor. I haven't looked into this yet, so please excuse my flawed knowledge.
So my question is ... for an autonomous robot which will be controlled by sensors (so presumably doesn't require precise motor control), is a modified servo, stepper, or H-bridge and motor going to be more economical ? Is there any other significant advantage to the modified servo (or other method) ?
|
|
|
Post by donburch on Aug 28, 2006 22:22:37 GMT 10
Maybe this should be re-titled "Where did all the current conversations go ?".
At first glance I thought the board must have crashed and been restored from a 2004 backup database !!!
It seems that the movement action was enough to bump the moved threads to the top of the list, and the latest posts in "General" got pushed to page 2 !
Dingo, is it possible to re-sort the General Board by Date of Last Post ?
|
|
|
Post by donburch on Aug 27, 2006 8:54:57 GMT 10
Fact of life is there are endless options out there (and you could probably spend the rest of your life weighing up the options) and no 1 option is the best option for every project. Amen ! Actually I'm not so sure. The Basic Stamp 2 (which admittedly I chose for it tutorial course material, not for its processing power) and several of the other common microcontrollers are only 8-bit processors. Actually less powerful than the Motorola 6800 and Intel 8080 from 25 years ago. And PBASIC is so ... well, so basic ! Because I would like to get to realtime video processing, I anticipate needing at least PC speed, memory, and programming tools. But I get the impression that none of the robotics controllers are so powerful. Well I guess that's because most embedded devices are much simpler; and that engineers would rather start from scratch than reuse existing program code ;-) That's where I see a robotics club being of most value, providing many "friends" who can suggest and help with many different platforms. Looks good. I guess other States will follow suit shortly when they see how useful the mentoring program is. Is your students robotics project related to RoboCup Junior or totally independent ? I know the RoboCup Junior students have to prove that their entries are (mostly) their own work. I can imagine that your mentoring gets them started, and the next year they would be in a good position to enter RoboCup by themselves. Thanks, emzed, for taking the time to reply to all my questions !
|
|
|
Post by donburch on Aug 25, 2006 19:59:47 GMT 10
I use google to search for anyone else out there that has done or is doing something similar to any project i think i might tackle. I guess this is the most common approach for anyone who has heard of google. But it requires that you already know what you want to do. When I decided to start, I was looking for suggestions of where to start, appropriate to my background. I've come across it, and I'm of two minds. Some ideas are cool, but a lot are simply cookoo ! Of course, that's only my personal opinion ;D Agreed ... for people into AVR platform. But it's not the only platform available, and it may not be the best for any particular project. Of course it's much more effective to choose a powerful, flexible and cheap platform (is that too much to ask) and avoid duplicating the learning curve for each project. Wow! Where do you work ? Who organises the Mentoring program ? Do they have a website or brochure ? If you work in robotics, I guess that you got the job from Uni, where you probably did engineering and mechatronics ? What happened to the other students ? Enough jobs for all ? Are the ones not working in robotics still doing it as a hobby ? When will I stop firing off questions ?
|
|
|
Post by donburch on Aug 23, 2006 22:24:39 GMT 10
There was a local Brisbane Group that is all but defunct now. ... As for names, I always like the officialdom of a 'SIG' (Special Interest Group) Are you thinking of the Aust. Computer Society's Brisbane Robotics SIG (http://robotsig.org/) ? I'm currently trying to join the ACS myself, but I wouldn't want to limit any hobby club to 'ACS-approved IT professionals' only. My current questions are on the lines of ... - what happened to the previous club members ? - why did the previous club stagnate ? - what do we have to do differently / better to avoid the same fate ? [Edit] Sorry, that sounds negative. I just don't want to have all the effort of setting up a club "wasted" because it isn't sustainable. My current thinking is to start an Australian Amateur Robotics Association covering ALL robotics enthusiasts ALL across Australia. Membership will be open to anyone, however it will initially focus on those enthusiasts not adequately represented by the existing educational, academic and industrial robotics communities. First priority will be setting up an online community. An online forum is available 24/7 from everywhere (with an internet connection), all members can contribute and participate, forums can be made to suit members interests. Also private forums can be used for the clubs administration - polls in a private committee forum can be used for decisionmaking replacing the need for physical committee meetings - making a truly national or international club practical. Members are encouraged to organise local/regional meetings under the association’s umbrella. The important thing is that any meetings will be additional to the main association activities, and that members who are unable to attend meetings (because of distance, working hours, or other reason) are not effectively excluded – as is the case with most existing clubs. Competitions will provide a series of achievable challenges through which novices can learn, practice and improve; and so should be a secondary goal of the association. [/edit]
|
|
|
Post by donburch on Aug 23, 2006 21:56:14 GMT 10
I'm getting rather obsessed with the idea of starting a robotics club ... Been thinking more about starting a club ... Rather than starting a club in one location only (and thereby limiting the potential membership) it makes sense for it to be an Aust-wide club, and use website / forum / blogs to build an online community. Sooner or later, members will organise local/regional meetings under the association’s umbrella. The important thing is that any meetings will be additional to the main association activities, and that members who are unable to attend meetings (because of distance, working hours, or other reason) are not effectively excluded – as is the case with most existing clubs. Competitions will provide a series of achievable challenges through which novices can learn, practice and improve; and so should be a secondary goal of the association. But hang on, what about the existing websites, forums and blogs (such as this one) ? Why should another one be required ? Am I looking in the wrong place ? Or are robotics enthusiasts really anti-social introverts ? Or maybe they are getting plenty of community involvement through international clubs/forums/newsgroups, probably focussed on their preferred hardware/software platform of choice ? Am I going round in circles ? Yes I am ! But I'm thinking of putting up notices around the RoboCup Junior national finals next nonth, since that's the only robotics event I'm aware of in the rest of this year ... which will require some advance planning.
|
|
|
Post by donburch on Aug 23, 2006 0:13:12 GMT 10
My gosh, that was quick, emzed ! I have noticed that posts on this forum get plenty of views, even though there aren't many new posts or replies.
I'm in Sydney (Chatswood on the north shore).
I guess most Ausssie robotics hobbyists (there must be a better name than that) are either isolated loners, or they are involved with overseas/international clubs/forums/newsgroups, probably specific to their platform(s) of choice.
What robotics clubs are you in ? What websites, discussion forums, etc do you frequent ?
Any other ideas on how to contact other local roboticists ?
Sorry, I'm getting rather obsessed with the idea of starting a robotics club ... but I don't want to waste my time if there's no need or interest. Actually I'm rather disappointed that this forum is so inactive, since I believe that a web-based community would be the best way to run a club these days.
|
|
|
Post by donburch on Aug 22, 2006 23:31:50 GMT 10
There are currently well established Educational and Academic robotics competitions (RoboCup Junior and RoboCup), and presumably forums and communication channels. There are also Associations for the (industrial) Robotics industry.
However I have been unable find any club or association in Australia for adult robotics hobbyists. There are several clubs in USA which have been going over 20 years (e.g. Seattle Robotics Society).
What robotics clubs, websites and online ‘meetings’ are available ?
What do other Aussie robotics hobbyists do ?
|
|
|
Post by donburch on Sept 16, 2006 14:28:03 GMT 10
Venue changed to the Scientia building (officially "G19 John Niland Scientia" on the UNSW map). Parking is free during the weekend - enter from Gate 11 off Botany Rd.
Popped in earlier with my son and friends, and the quality was certainly higher than the NSW competition.
Unfortunately someone (not wearing and official identification) stated that Adults are not allowed to view the Rescue competition, and after lunch my son and friends weren't interested to go back and watch any more, so we just came home.
No results yet (20 Sept) on the Robo Cup website
|
|
|
Post by donburch on Aug 28, 2006 22:23:52 GMT 10
bump
|
|
|
Post by donburch on Aug 11, 2006 23:01:18 GMT 10
If you're not familiar with RoboCup Junior, it is a robotics competition for Primary and Secondary students, with 3 competitions available. Firstly I'll say that I only saw a couple of robots that did not use the Lego RCX brick. Very appropriate for schools, as the hardware is all matched, allowing them to get results very quickly, and that builds enthusiasm. " Dance" is probably the easiest category, with lots of first-time competitors, particularly from Primary schools. Competitors can pre-program a dance routine into their bots. Additional points are awarded for bot decorating, and the competitors may interact with the bot during the dance. Plenty of opportunity for creativity ... so I was a little disappointed that most of the dances I saw appeared to be just random movements and spinning around. Also the bots all looked very small out in the middle of the dance floor ... giving me some ideas to shake up the dance competition. Pity I'm about 30 years too old to compete ;-) " Rescue" is basically line-following. One thing I noticed particularly was the way some bots jerked from side to side. Maybe this was lack of fine motor control, from only having one sensor (so having to make bigger sweeps), or just inexperienced programming. The highlight for me is the Soccer competition, probably because it is the most active, and requires most sophisticated programming. Each team fields 2 robots (usually a "srtiker" and a "goalie") and the objective is to kick a ball into the opposing goal. Not at all as easy as it sounds. First you have to find the ball. For this the bots need Infra-Red (IR) sensors, since the ball contains IR emitters. Having found the ball and got to it, you then have to aim in the direction of the opposing goal, and kick. I noticed that many of the teams had obviously learnt from last years Australian winner (from Queensland) with lots of similar designs including the reverse motor to roll the ball back to the bot, enabling the robot to 'dribble' the ball. A few of the bots just spun around in the same place, and many seemed to be wandering aimlesly. I wonder if this is due to a lack of practice games while developing the robots. I would certainly recommend each school who is competing in rescue or soccer to purchase (or make for soccer) a playing field, and practice on it well before the competition day.
|
|
|
Post by donburch on Aug 11, 2006 13:43:19 GMT 10
I went to the RoboCup Junior NSW competition yesterday. Great to see so many kids getting involved and having fun. Just wish I wasn't too old to enter I will be taking my son and his friend to the Australian finals competition next month. If you're in Sydney I suggest you take a look ... Their website doesn't mention spectators, but there was no charge. Part of my motivation for thinking about starting a robotics club is to run similar competitions, as a way of providing challenges.
|
|
|
Post by donburch on Aug 11, 2006 6:39:10 GMT 10
Hi Bones,
RoboRealm doesn't even need live video ... you can process still images such as JPEGs to play around with the different filters. Because it's so interactive I think it would be a great tool for working out which filters would be best, even if someone is not going to use a windows PC in the final bot.
Sorry it sounds like an advert, but I'm just so enthusiastic to find a package that's free and easy to use - where I was anticipating months (if not years) trying to learn the theory and mathematics to be able to understand and use the free (academic) code libaries.
|
|