FasTrak
Fastrak is a 3D electromagnetic tracking system from Polhemus. When Fastrak was announced, it was Polhemus' top end system, until Liberty was announced.
Fastrak is an AC electromagnetic tracking system.[1] The FASTRAK consists of a System Electronics Unit (SEU), one to four receivers, a single transmitter, a power supply and a power cord. The system is capable of operating at any of four discrete carrier frequencies. Different carrier frequencies allow operation of up to four FASTRAKs simultaneously and in close proximity to one another.[2]
Fastrak is a time-multiplexed system, rather than a frequency multiplexed system like the Model 1.
It is a 6DOF tracking system, meaning it tracks position and rotation.[3]
The price was about $6000.[3]
Polhemus Fastrak was developed based on a redesign of Polhemus' Isotrak product.[4]
FastTrak was used in some VPL systems. It was also used in the first generation Virtuality systems.[5]
Fastrak behaves as a transmitter on RS-232, therefore a null modem cable is required.[2]
SpecificationsEdit
These are the specifications for one of the Fastrak systems.[6]
- 6 Degrees-of-Freedom.
- 1-4 Sensors.
- Update rate 120 Hz (divided by number of sensors).[3]
- Position Coverage: specified accuracy when standard receivers are located within 30 inches (76 cm) of the TX2 transmitter.
- Static Accuracy 0.03 in. (0.08 cm) RMS for the X, Y, or Z receiver position, and 0.15° RMS for receiver orientation.
- Resolution 0.0002 inches/inch of range (0.0005 cms/cm of range), and .025°.
- Latency 4.0 milliseconds.[3]
The transmitters for Fastrak are compatible with other Polhemus systems: Patriot, FastSCAN, and Liberty.
ComponentsEdit
The SEU's circuit board is made using entirely through-hole construction.
- Multiple PMI SSM2017P preamplifiers
- DIP ROMs that hold device firmware
Fastrak uses a 5-pin DIN connector as its power connector.
The optional stylus is a pencil-like device that acts as a 3D tracked sensor. It has a switch built in that acts similar to a mouse button.
VersionsEdit
The original Polhemus Fastrak is a white and gray box with an IEEE-488 connector.
An updated Fastrak is the same box with a USB connector. This version, released around 2002, allows the user to connect a stylus into any of the four receiver ports compared to the old FASTRAK design which required a stylus be connected to port one only.[2]
There is a third, updated, later version of the Fastrak with a USB connector and a different case, but otherwise the unit is about the same size. This version has a trapezoid case that is not white and gray.
FrequenciesEdit
A FASTRAK may be configured with any one of four discrete carrier frequencies:
- Frequency 1: 8013 Hz
- Frequency 2: 10016 Hz
- Frequency 3: 12019 Hz (Standard)
- Frequency 4: 13022 Hz
OperationEdit
Fastrak operates using command letters.
The letter is sent over the serial connection.
This is the same general process as the previous 3Space Tracker systems, but some letters are not the same.[7]
Some command letters are the same on later units like Patriot and Viper.
Command letters: A, R, B, b, control-K, F, control-Y, P, C, c, U, u, control-S, control-Q, v, x, V, e, f, I, O, S, l, H, N, G, D, d, r, y, W, X, Q, o, T.
A Alignment Reference Define Alignment Frame from Host
R Reset Alignment Reset Alignment Reference Frame
B Boresight Define Boresight
b Unboresight Reset Boresight
control-K Save Operational Save System Configuration State
F Enable ASCII Output Set ASCII Data Format Format
control-Y Re-initialize System System Reset
P Single Record Send Record Transmission
C Continuous Print Set Continuous Output Xmit Mode
c Disable Continuous Printing Set Non-continuous Xmit Mode
U Set Unit Inches Set Inches Unit
u Metric Conversion Set Centimeter Units Units
control-S Suspend Data Suspend Xmission Xmission (X/OFF)
control-Q Resume Data Resume Xmission Xmission (X/ON)
v Attitude Filter Attitude Filter Parameters Parameters
x Position Filter Position Filter Parameters Parameters
V Position Operation- Define Envelope al Envelope
Cmnd Ltr Fastrak Title Tracker Title
e Define Stylus Button Run Digitizer
Function Mode
f Enable Binary Set Binary Data Output Format Format
I Define Increment Define Increment
O Output Data List Define Output List
S System Status System Status
l Active Station State Station Acti vate/Deactivate
H Hemisphere of Define Hemi- Operation sphere from Host
N Define Tip Offsets Define Tip Offsets
G Boresight Reference Angles
D Enable Fixed Metal Compensation
d Disable Fixed Metal Compensation
r Transmitter Mounting Frame
y Set Synchronization Mode
W Reset System to Defaults
X Configuration Control Data
Q Angular Operational Envelope
o Set Output Port
T Built-In-Test Information
ReferencesEdit
- ↑ "FASTRAK". https://www.vrealities.com/products/magnetic/fastrak.
- ↑ 2.0 2.1 2.2 "Fastrak User Manual". http://www.cis.rit.edu/pelz/lab/documentation/manuals/polhemus_fastrak/Fastrak_2002_rev_C.pdf.
- ↑ 3.0 3.1 3.2 3.3 "Virtual Reality Platform". https://sed.inrialpes.fr/ARCHIVE/PRV/CATALOG/moca.html.
- ↑ "ADA314134". https://apps.dtic.mil/sti/tr/pdf/ADA314134.pdf.
- ↑ http://web.archive.org/web/20160801042252/http://vrtifacts.com/setup-a-fastrack-fast/
- ↑ https://www.imaging.psu.edu/facilities/human-electrophysiology/3d-motion-tracking-system-polhemus
- ↑ https://www.cis.rit.edu/people/faculty/pelz/lab/documentation/manuals/polhemus_fastrak/Fastrak_1993_rev_F.pdf