Post by thread:[PIC]: Toy cars for robots?

Hey! One I can answer. Not a ton of detail on my page yet, but: http://www.reedonline.com/brian/robot/bedlam/ is mine with an F877 on the ICD demo board. It's a Radio Shack Bedlam, currently in closeout. They have a replacement tread vehicle that looks more like a tank (Bedlam is a kind of buggy). Should be $30 (or less) but you may have to call around to find one. Open it at the store and inspect that it wasn't a return item (check cleanliness). Battery was like $18 + charger $10. I had to do a little channel re-wiring to use the existing H-bridge circuits, and one may put out a little more current, explaining a bit of a veer to the right for now. Or the veer may be my fault (marginal resistor vals in my opto isolator circuit). Software could compensate if I can't solve it in H/W. Another option: forget the included H-bridges and install matching bridges. 2 for the treads, add a third for bi-dir control of the left / right wheel carriage. I don't have a bottom photo so you'll havta see a Bedlam to get the idea. It's very cool and sturdy. The new tank model has a hard plastic tread made of dozens of links, it looks very fragile... the bedlam has a rubber loop that I probably couldn't break in my bare hands. Small advantage to the "Sentinel Tank": it comes with a rotating turret, which I think reverses direction each use. My phase 2 is about complete. I have one pre-programmed motion cycle, and I'll probably add a couple more. It's using an interrupt-based time-slice multitasker, ready for phase 3... adding sensors. - Bri R -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Ellen Spertus wrote: >Has anyone adapted motorized toy cars to be controlled by a PIC or other >microcontroller? I'd welcome any pointers. > Ellen, The illustrious "Wiz" did it: http://www.wizard.org/gadget.html Also, Tom Handley did it - and he may be lurking around about piclist somewheres. I think a major problem Tom found is that the basic off the shelf RC toy car runs a little too fast to make a good robot, and has to be geared down substantially. You can find lots of info by doing a directed search on google.com. If you are looking for specific design info, I have a bunch of robotics links that are fairly well categorized: http://www.oricomtech.com/emerge6.htm#Work2 best regards, - dan michaels ===================== -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Two thoughts on this area. First, there are higher end cars than the Radio Shack one that might be easier to deal with. The servos for steering and the electronic speed controls are driven by a pulse between 1mSec and 2mSec. Pretty easy with a controller. As someone said, they are fast and questionable for a robot. There are some monster trucks that are geared down like the clodbuster. You can find out more about this from: http://www.towerhobbies.com Also, I keep finding those all plastic kiddie cars at garage sales for $10-$50. These can move about 80lbs (made for 1-2 young kids) These are geared way down with lots of torque, come with the batteries and charger. You might want to trash the car since there is no frame to work from. Once you lose the chassis, the size could be made reasonable. I've always thought this would be fun to make a beer cooler that followed me around. I could be the envy of everyone at the beach. -- Steve Nordhauser Director of New Product Development Imaging Systems IEM Corp. 60 Fourth Ave. Albany, NY 12202-1924 digitalKILLspamnycap.rr.com http://www.iem.net Phone: (518) 449-5504x21 Fax: (518) 449-5567 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Also, I keep finding those all plastic kiddie cars at garage sales for $10-$50. > These can move about 80lbs (made for 1-2 young kids) These are geared > way down with lots of torque, come with the batteries and charger. You might > want to trash the car since there is no frame to work from. Once you lose the > chassis, the size could be made reasonable. I've always thought this would be > fun to make a beer cooler that followed me around. I could be the envy of > everyone at the beach. > I saw one of these on sale at a local supermarket just after Christmas and bought it with the intention of changing it into a robot. Having bought the thing I lost the incentive to modify it. A Fire Engine just running around aimlessly seemed boring. However, the battery compartment under the seat is just the right size for a can of beer. The battery can be moved to the cab where the electronics can also be installed. The vehicle follows you around and when you remove the cold beer, it goes off and gets another one. Thanks for the idea Steve. This is the equivalent of the Emergency Medical Hologram Mobile Emitter. Up until now Cold Beer delivery has required I stay within arms length of the Garden Railway. ;-) Regards Chris -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

>Once you lose the chassis, the size could be made reasonable. >I've always thought this would be fun to make a beer cooler >that followed me around. I could be the envy of >everyone at the beach. I once had a lecturer at Polytech who was threatening to make a robot that followed him around shouting "hey wait for me". I think what he suggested doing was to have a belt with a heap of IR LED's around it (probably a dozen or so would be sufficient) pulsed at a rate the robot could recognise and follow. I do not know how he intended to have the robot keep from crashing into him and knocking him over. The only trouble with this scheme for your fridge is the sunlight at the beach would probably saturate the IR receiver unless you could work out some form of attenuator using photographic filters or some such that the robot could switch in automatically if it found the receiving photodiodes saturated. Even more impressive would be to lie on the beach and the robot to have enough speech recognition capability that when you turned to it and said "another beer please" it opened the fridge door with one arm and reached in and handed you a beer with the other arm:) 'Course it would only understand your voice :)) -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Ellen, sorry for the late reply but I've been busy and it's been hard to keep up here... Dan and I kind of started at the same time and compared many notes here in this forum. Please check the archives for the subject line beginning with "PIC Robot Update" for more info on my current efforts. I started with a RadioShack R/C car and the first problem I encountered was the gear ratio as Dan has mentioned. That, and the mechanical `slop' in the gears. While they do have a tank model, I had a racing car... It's important to define what you want your robot to do. In my case, I wanted a technology `test-bed' to try a variety of sensors. It was to be confined to roaming rooms in my house. Going into this, I realized I wanted a dual drive so I can basically turn in small spaces. I thought a about using treads but cat hairs on the carpet would have been a problem. Since I already had this RS car, and it only had rear wheel drive and front wheel steering, I thought I would experiment with motor control and a basic bumper switch. The turning radius was about 2ft... After wasting way too much time analyzing the RC car's receiver and `crude' H-Bridge, I designed my own motor driver and interface. While this worked well, there was still a problem with a high speed motor and low-torque gears. I tried several combinations of PWM frequency and duty cycle but it was not really what I was looking for. However, I did manage to add bumper switches and it was able to climb around the thick-braided carpets in my house. Overall, it was good experience. They do have a tank model and someone else mentioned Tower Hobbies for more expensive vehicles with a low gear ratio, but I strongly suggest taking a hard look at doing it from scratch. Tamiya makes an excellent series of gear boxes that are normally used in a lot of the R/C models and toys that you see. I ended up using their Worm Gear Box HE. It cost around $10. My current `bot' uses a dual drive Tamiya Worm Gear Box HE. with front wheel drive and a castor wheel with bearings in the rear. It's built on a 9x6" aluminum base with a similar upper deck. So far, I've got a rather fancy power management scheme that supplies the dual Tamiya motors, the CPU, and the sensors. There are front bumper `whiskers' and IR sensors that look left and right. I've been testing the Vector 2X Compass on a wooden platform to eliminate stray fields. I expect to integrate that with the bot this month. I'll be adding ultrasonic ranging, mounted on a standard RC servo to build-up an acoustical description of the environment. I'm also looking at light and sound sensors. I also have VoiceDirect364 which I have already interface to a PIC but want to add to this project. Since I made good use of the lower deck for motor control, power supplies, and the CPU, I have plenty of room on the upper deck. BTW, my little bot is controlled by a 16F877 so far but I may add a Lattice CPLD to expand the capability. - Tom Ellen Spertus wrote: >Has anyone adapted motorized toy cars to be controlled by a PIC or other >microcontroller? I'd welcome any pointers. Dan Michaels wrote: >Also, Tom Handley did it - and he may be lurking around about piclist >somewheres. I think a major problem Tom found is that the basic off the >shelf RC toy car runs a little too fast to make a good robot, and has >to be geared down substantially. ------------------------------------------------------------------------ Tom Handley New Age Communications Since '75 before "New Age" and no one around here is waiting for UFOs ;-) -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

This is an awesome topic! I'd love to have a beer cooler follow me around. However the actual task of creating a mobile platform that could successfully follow me around (and as someone said, not smack into me or anything else) through an unknown environment is, for me at least, impossible... I made a couple of Stamp-based Radio Shack toy car platforms a couple of years back, and as long as you don't have very high expectations it's great fun. As far as gearing, etc., I think the hardware is the least of your worries... Bruce Cannon Silicon Crucible (510) 787-6870 1228 Ceres ST Crockett CA 94525 Remember: electronics is changing your world...for good! -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads