Shoutbox |
Loki Off The Shelf Advanced Robotic PlatformFrom GizmoGarden
[edit] "Ideas Great and Half Baked"[edit] How to build your own advanced robotic platform with off the shelf components
[edit] abstract - work in progress
|
| Hello? What's this at the end of the high current motor? | 
|
| There is the root of at least some of my problems - a 24 volt brake, not energizing it will cause it the brake to engage and my circuitry to heat-up |
| We'll have to remove it. Don't throw it away, we can use it for another project! I'll add it to that huge pile of junk hiding in my basement. ;P | 
|
[edit] create your own h-bridges
 | I created my own H-bridge circuits with 4 mosfets to deal with the high current of the wheelchair motors. What I didn't do is create overload protection. Another fatal flaw: It did not dawn on me, the high pitched whine of the pre-existing circuitry was pulse width modulation PWM. My control circuitry just simply turned the bridge on and off. Turning the bridge from on to off created a large spike in current and voltage. This fried the gate of the mosfet. Of course it fries in a state that the platform goes full speed forward with one wheel. It smashed a small cabinet and hit a concrete wall in my basement. After hitting the wall, the motors stalled and this dumped lots of current into my H-bridge (ala flambé). |
[edit] how to power a computer on a mobile bot
| The little Pico 12V to ATX power converter. Very clever little design, used in car manufacturers now to put MicroATX sized computers and smaller in your vehicle. |  |
 | Here is the little Pico working with Der Werker :) |
[edit] power log
2 marine batteries wheelchair wired in series for 24 V, 1 onboard recharger for the marine batteries, 1 12 V AGM battery for electronics (currently wired in parallel with one of the marine batteries to get the benefit of being recharged), recharger currently is plugged in.
| date | voltage | recharger | temperature | notes |
|---|---|---|---|---|
| 04/16 8:00 PM | 11.7 | 4 Amps! | Low | after 3 days of running the fan constantly! |
| 04/17 12:00 AM | 11.9 | 3.75 Amps! | Low | unplugged the fan - cpu hopefully has overheat protection (don't try this at home) |
| 04/17 8:00 AM | 12.1 | 3.75 Amps! | High 54 C running motion 49 C idle | unplugged the fan - cpu hopefully has overheat protection (don't try this at home) |
| 04/24 10:14 PM | 11.57 | 0.0 Amps! | High 30 C / 86 F running motion | fan is on - somehow its determined the end of a charging cycle - don't know how - hooked up small neck motor |
| 04/25 7:00 AM | 11.3 connected to marine batter#2 disconnected 7.0 v YIKES! | 0.0 Amps! | 42 C 107.6 F and climbing ! | Loki was brain dead this morning. I disconnected the fan ,however , the drive would still not spin up completely. The mainboard would power on. This would show within the brain system the drive is the biggest power draw - at least on boot up. I put the fan back on. I could not get the system to boot - the drive appeared not to be getting enough power at 7 volts (the measured Werker voltage - duh), at yet the recharger failed to kick in. After taking several voltage test, I came to the conclusion that the recharge checks to see if battery #1 and battery #2 in series are about 24 v. What had happened is I connected the computer, fan, and drive to battery #2. Occasionally, the system would recharge - but recharge both batteries at the same rate. Since battery #2 was the only one sustaining a load, this caused the batteries to get charged unevenly. Battery #2 is @ 10.8 volts and Battery #1 is @ 13.56 volts. I since switched the computer, drive and fan to battery #1, but not without incident! It turns out I had some H-bridges still connected and the difference in voltage between the computer ground and battery #1 ground was 13.56 volts ! That could have messed things up in a big smoky way. All the more reason to isolate the 2 systems electronics / mechanical through opto-isolators etc. |
Celsius to Fahrenheit: (1.8*deg C)+32
[edit] following needs to be organized
- first attempt was to integrate with the existing circuitry - i identified some mosfets however - there was a substantial number of "safety" circuitry which would shutdown the mosfet.
- i attempted to remove this unfortunately, i destroyed all the mosfets in the process
- next i made my own high powered h bridge with <<part numbers>>
- starting and stopping the large motors was something of a challenge - there was no pwm initially and stops & starts would destroy the mosfets - i should have realized that the chair had a pwm circuit for control.
- smaller motors are much more forgiving
- you don't want to change a large motor direction
- i searched the web for motor controller circuits, until i ran across osmc - which was inspirational !
- its important that you document!
- here i mapped out the control and power lines for the wheelchair
wheelchair power circuit
- here i mapped out the control and power lines for the wheelchair
- another thing i had to deal with, was electric brakes on the motors, again one of the safety features of the wheelchair. I ended up removing them.
- I thought I would just need the 12v to power the drive (I was wrong)
[edit] modularity modularity modularity
If your robot is modular, it will give you plenty of freedom in changing its design and purpose. When you want to turn your 4 wheeling ATV bot into a submersible, modularity will help you get there. Common motor interfaces, standard driver circuits, modular software all help in providing basic building blocks for your grand design. If your basic blocks are common or standard, it allows you to quickly build what you want. Here, Frits Lyneborg uses the omni-purpose paint stick to whip together a robot in record breaking time (Skiwalker).
[edit] parts list
<<todo get picts - table>>
[edit] hardware
| item | function | source | cost |
|---|---|---|---|
| Jelly Extra Large Wheel Chair base | Mobile Base | Craigslist | $200 |
| 12v 18Ah AGM Battery | Power supply for all electronics | Batteries Plus | $50 |
| Pentium III 730 Mhz | Brain | Dumpster | $0 donated |
| National Instruments PCI-DIO 96 digital input output card | Controller | Ebay | $50 |
| Airlink MIMO extended range PCI network card | Communications | Frys | $30 |
| 2 X H-Bridge Motor Controller | Controller | RobotPower | $160 |
| pico PSU 120 | 120 watt 12v input DC - DC ATX Power supply | iTuner Networks Corporation | $49.95 |
| DIY LIDAR | Distance Sensor | Open Source LIDAR | $5 |
[edit] software
| item | function | source | cost |
|---|---|---|---|
| Linux Kernel 2.6.20 | Kernel | http://www.kernel.org | $0 |
| Fedora Core 8 | OS Distro | http://fedoraproject.org/ | $0 |
| Comedi Driver | DIO Driver | http://www.comedi.org | $0 |
| Festival | Speech Synthesis | http://festvox.org/festival/ | $0 |
| OSROS | Open Source Robotic Operating System | Robotic cerebellum | $0 |
[edit] comedi
Comedi is a set
- whenever comedi_dio_config is used to config - it reset that bit COMEDI_OUTPUT/COMEDI_INPUT
modprobe ni_pcidio comedi_config /dev/comedi0 ni_pcidio
| block 1 | | block 2 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
| |
|
[edit] block diagram
[edit] hardware
The hardware diagram shows a discarded pc or mac at its core. A DIO card is used to interface with various hardware. 
[edit] software
Basic block diagram. Java was chosen as the core language to support as wide a range of operating systems as possible. A simple JNI interface is created which allows direct hardware and memory reading and writing. The Web 2.0 interface allows any HTTP client an opportunity to interface with the robot. 
[edit] comedi initialization
modprobe ni_pcidio comedi_config /dev/comedi0 ni_pcidio cd /garden/trunk/cpp/comedi ./check
[edit] parallel port initialization
- module makefile reference
- unloading and loading
rmmod parport_pc rmmod parport cd /garden/trunk/cpp/captain/ insmod ./skeleton.ko mknod -m 666 /dev/skeleton c 32 0 modprobe ppdev
[edit] motion initialization
motion -n motion -c /usr/local/etc/motion_01.conf -n
[edit] code drop
chown -R tomcat:tomcat /usr/share/tomcat5
[edit] open cv
/usr/local/share/opencv/
[edit] 3com homeconnect
raw = 320 x 240 channel = 3 interleaved 8 bits
[edit] microsoft camera on linux
changelog cutlog.py Etoms gspca_core.c license Makefile.kld Pixart Sonix Sunplus-jpeg utils Conexant decoder gspca_build gspca.h Makefile Mars-Semi READ_AND_INSTALL Sunplus Transvision Vimicro [root@loki gspcav1-20071224]# ./configure -bash: ./configure: No such file or directory [root@loki gspcav1-20071224]# make make -C /lib/modules/`uname -r`/build SUBDIRS=/download/gspcav1-20071224 CC=cc modules make[1]: Entering directory `/usr/src/kernels/2.6.23.1-42.fc8-i686' CC [M] /download/gspcav1-20071224/gspca_core.o CC [M] /download/gspcav1-20071224/decoder/gspcadecoder.o LD [M] /download/gspcav1-20071224/gspca.o Building modules, stage 2. MODPOST 1 modules CC /download/gspcav1-20071224/gspca.mod.o LD [M] /download/gspcav1-20071224/gspca.ko make[1]: Leaving directory `/usr/src/kernels/2.6.23.1-42.fc8-i686' [root@loki gspcav1-20071224]# make install mkdir -p /lib/modules/`uname -r`/kernel/drivers/usb/media/ rm -f /lib/modules/`uname -r`/kernel/drivers/usb/media/spca5xx.ko rm -f /lib/modules/`uname -r`/kernel/drivers/media/video/gspca.ko install -c -m 0644 gspca.ko /lib/modules/`uname -r`/kernel/drivers/usb/media/ /sbin/depmod -ae [root@loki gspcav1-20071224]# ls /dev/vid* /dev/video /dev/video0 /dev/video1 [root@loki gspcav1-20071224]# modprobe -v gspca insmod /lib/modules/2.6.23.1-42.fc8/kernel/drivers/usb/media/gspca.ko [root@loki gspcav1-20071224]# ls /dev/vid* /dev/video /dev/video0 /dev/video1 /dev/video2 [root@loki gspcav1-20071224]#
[edit] gwt messages
| Object | Values | Frequency |
| Status | active | inactive | unauthenticated | often |
| PilotRoster | list of names and stati | often |
| Sensors | data | unknown |
| Heading | unknown | |
| PolledSensorData | unknown | |
| MappingDisplayAread | unknown | |
| SystemMessages | unknown | |
| StepperLocation | often | |
| CommandConfirmation | often |
[edit] todo
- splice cpu fan in with 12 v system so it does not pull its power off the board (and through the ATX Pico)
- put in an emergency stop / kill switch following DARPA designs (rc and physical)
- integrate electronics battery with onboard recharger - parallel with one of the marine batteries
