The final computing system design has been completed and differs substantially from the initial study.
Kambara is intended to be an autonomous underwater vehicle, its primary control computing will be carried onboard. This and the nature of the experiments we would like to perform lead to some design requirements.
· The processor should provide adequate processing capacity for simultaneous filtering, servo control, vision computation, and communication.
· There is a strong preference for the VxWorks
operating system.
· The computing system and card cage must fit within the upper pressure cylinder, 25cm diameter and 46cm length.
· The computing enclosure should be able withstand high-frequency vibration and occasional shock loads (from thrusters), greater shock loads will probably be experienced in transport (design for 10G).
· There are 5 brushed DC motors with power amplifiers driven by PWM signals, so at least 5 PWM output channels are required. A sixth channel could be used to control light levels.
· The AUV will carry at least two matched color NTSC cameras as two color and one color with integral pan/tilt, so 3 channels of video digitizing will be required.
· At least 2 serial communication, RS-232, lines (for compass and pan/tilt) are needed and 4 lines are preferred.
· At least 9 digital signal lines (16 preferred) are required: camera controls (6), temperature (2), and water leakage.
· At least 16 A/D channels are required (16+ preferred) at 12 bits resolution: tachometers (5), accelerometers (3), gyros (3), inclinometers (3), pressure (1), and battery voltage (1). No more than 6 channels may prefer greater than 12 bits resolution. Some channels may require/prefer optical isolation.
· No D/A channels are required.
· The component selection should attempt to minimize power draw on batteries.
Physical size and compatibility with the VxWorks operating system seem to be dominant constraints in selecting components.
The computing system must fit inside the AUVs upper enclosure: 25cm diameter by 460cm length. This diameter is too small for a 6U card cage (unless at most three cards are mounted with frontplates facing up, a possibility) and too small for a typical PCI motherboard, although a narrow passive PCI motherboard may fit.
Cards in the 3U form-factor, both CompactPCI and VME, will fit.
Cards of the PC/104 standard will fit.
The choice of VxWorks as the operating system constrains the available options. There are no PC/104 single board computers supporting VxWorks as yet. Similarly, many available 3U VME boards (for example from Matrix and Force ) do not support VxWorks.
We are left with 3U CompactPCI or a narrow PCI motherboard.
There are three processor boards in CompactPCI 3U which seem suitable Gespac, PEP, and Ziatech.
Eurotechdoes not support VxWorks.
OR has standard PC BIOS.
|
Make
|
Model
|
Processor
|
Clock
|
Features
|
VxWorks
|
Price ($A)
|
|
Eurotech
|
ETH0996
|
Pentium/
AMD K5
|
166Mhz
|
64M DRAM,
2 serial ports
|
Unknown
|
|
|
Pentium MMX
|
233MHz
|
64M DRAM, 4M Flash, 2 serial
ports,
10bT Ethernet (driver extra),
IDE, KBD
|
Yes
(PC BIOS)
|
$3010
+$550
|
||
|
Pentium
|
200MHz
|
64M DRAM,
80M Flash,
VGA, SCSI-2,
4 serial ports, 2 parallel
ports,
2 USB ports |
Probably
|
$5516
|
||
|
CP310
|
Pentium
|
166MHz
|
64M DRAM, 1M Flash, 2 IDE,
KBD,
2 serial ports,
9 digital I/O
|
Yes
(PC BIOS)
|
$7157
|
|
|
ZT 6500
|
Pentium
|
200MHz
|
48M DRAM, 4M Flash, 2 serial
ports, 1 parallel port,
24 digital I/O
|
Maybe (6/98)
|
$4677
+BSP
|
General Micro Systems, Concurrent Technologies, Matrix and Force were also studied by did not provide CompactPCI, Pentium-based single-board computers.
Video digitizers in the CompactPCI 3U format.
|
Make
|
Model
|
Inputs
|
Features
|
VxWorks
|
Price ($A)
|
|
PCX200
|
1 (4)
|
Eventually
|
$1153
|
||
|
CP335
|
2
|
70M/sec
|
Unknown
|
$3970
|
All seem to be based on the Brooktree Bt848 chip.
There are very few dedicated motion control boards which still produce PWM output directly (due to changes in the basic chip sets). There are several PC/104 motion control boards based on the LM629 chip which produce PWM output. There are two IP mezzanine boards based on the LM629 chip and one board based on an Altera chip which produce PWM output.
|
Make
|
Model
|
Chip
|
Axes
|
Features
|
VxWorks
|
Price
|
|
50A (double IP)
|
Altera
|
4
|
S-profile, encoder input,
digital I/O
|
Maybe
|
||
|
29A
|
LM629
|
2
|
Encoder input
|
Maybe
|
||
|
IP-629Servo-2
|
LM629
|
2
|
3 TTL,
Encoder input
|
Yes
|
Gespac makes CompactPCI boards, Greenspring makes IP modules.
|
Make
|
Model
|
Channels
|
Resolution
|
Input
|
Features
|
VxWorks
|
Price
|
|
PCIADC-32
|
32 (16)
|
14-bits
|
+/-10V @
0-20mA
|
Unknown
|
|||
|
IP-ADIO (double IP)
|
16 (8 diff)
|
13-bits
|
+/-10V
|
2 D/A
68 I/0
2 clocks
|
Unknown
|
||
|
IP-16ADC
|
16 (8 diff)
|
16-bits
|
+/-10V,
0-10V,
+/- 5V,
0-5V
|
Voltage protection
|
Yes
|
||
|
IP-AD16SS
|
16
|
16-bit
|
+/- 10V
|
Yes
|
|||
|
IP-OptoAD16
|
16 (8 diff)
|
16-bit
|
+/-10V,
0-10V
|
Optical Isolation
|
Yes
|
|
Make
|
Model
|
Channels
|
Features
|
VxWorks
|
Price
|
|
PCICIO-12
|
12/4
|
Unknown
|
|||
|
IP-Digital24
|
24
|
2 Interrupts
|
Unknown
|
||
|
IP-Digital48
|
48
|
8 Interrupts
2 Timers
|
Unknown
|
||
|
IP-OptoOutput
|
16
|
Optical Isolation
|
Yes
|
||
|
IP-OptoInput
|
16
|
Optical Isolation
|
Yes
|
|
Make
|
Model
|
Channels
|
Protocols
|
Features
|
VxWorks
|
Price
|
|
IP-Serial
|
2
|
EIA-232
EIA-422
|
Unknown
|
|||
|
IP-Octal 232
|
8
|
EIA-232
|
8TTL Inputs
|
Unknown
|
||
|
IP-OctalOpto
(double-IP) |
8
|
EIA-232, EIA-422
|
Optical Isolation
|
Unknown
|
Mezzanine (IP) card carriers in the CompactPCI 3U format all carry two IPs.
|
Make
|
Model
|
IPs
|
Features
|
VxWorks
|
Price
|
|
PCIIPC-1
|
2
|
Yes
|
|||
|
CSIPC
|
2
|
DSP available
|
Maybe
|
||
|
CPC100
|
2
|
Maybe
|
The critical feature of the enclosure is its ability to fit within the cylindrical pressure vessel. At least five slots will be required. No power supply is needed since the backplane will be powered by batteries (with DC/DC conversion to 5 volts or 3.3 volts as needed).
|
Make
|
Model
|
Slot
|
Width
|
Height
|
Depth
|
Diagonal
|
Price
|
|
Elma
|
Type 11
|
6
|
21.3cm
|
3U
|
16.0cm
|
25.1cm
|
$405
|
|
Vector
|
Vector-Pac
CCK 26-36-03
|
4
|
18.8cm
|
3U
|
12.7cm
|
23.7cm
|
$450
|
|
Zero
|
CPCI6S160ST
|
6
|
17.7cm
|
13.3cm
|
20.7cm
|
22.7cm
|
$450
|
The possibility of mounting an laptop computer inside Kambara was considered as this would provide a number of useful features, like Ethernet support and an integral hard disk. There are challenges/unknowns in running VxWorks (or a suitable multi-tasking operating system), interfacing the various devices including PWM signal production, and integrating high-rate video digitizing.
Advantech
makes a ruggedized PCI system, the IPC
6806, that fits within our enclosure. This backplane is passive and
thus requires a processor board occupying one of the 5 slots. An advantage
of such system might be that IP Carrier boards will hold 4 IP modules.
A much larger selection of video framegrabbers are available.
A ruggedized PCI system may be worth further investigation. After an initial look it seems unlikely that such a system could be configured running the VxWorks operating system, neither processor boards nor framegrabbers are available, yet.
Is it worth dropping VxWorks and picking a new operating system to configure a ruggedized PCI system?
Given the trade study thus far, the following computing
system was proposed:
A CompactPCI system comprised of the Gespac PCISYS-57, ImageNation PCX200, and three Gespac PCIIPC-1 boards carrying three IP-629Servo-2, one IP-16ADC, one IP-Digital24, and one IP-Serial (all from Greenspring), mounted in a Zero CPCI6S160ST 6-slot 3U card cage.
Given feedback from reviewers (primarily that a 68332
module should be considered to decode encoder signals and generate PWM
for the motors) the proposed design was mdivled to replace the LM629 based
servos with a single Motorola 68332 chip in an IndustryPack. To ease
compatibility between the Motorola chip and the main procesor a PowerPC
solution for the main processor was sought, along with appropriate operating
system architecture extensions.
The final computing system design is:
A CompactPCI system comprised of the Force CPCI-3740 (PowerPC 740 chip), ImageNation PCX200, and two Greenspring CPCI100 boards carrying one IP-68332, one IP-ADIO, and one IP-Serial (all from Greenspring), mounted in a Zero CPCI6S160ST 6-slot 3U card cage. Ethernet is provided by a Force 100bTX PMC module.
Many thanks to Bob Edwards of the Department of Engineering, Australian National University and Dan Christian and Hans Thomas of NASA Ames Research Center for their review, comments, and suggestions.