NIGHTSIGHT Pan and Tilt
NIGHTSIGHT Pan and Tilt
4.0 Vision Statement
FIGURE 6.a If you only look straight ahead...
FIGURE 6.b ...you aren't getting the whole picture.
TABLE 1. Functional Requirements: These requirements indicate what
the device must do.
------------------------------------------------------------------------
Requirement Quantity Rationale
------------------------------------------------------------------------
Field of Regard The original requirement was to
Pan: Infinite pan +/- 170 deg. After interviewing
Tilt: +45 deg, users, we realized that it would be
-22.5 deg a significant advantage for the user
to pan infinitely. The tilt is driven
by the need to scan the top of
buildings and for looking down into
the water for maritime applications.
Angular Velocity User's indicated that this was the
Pan: 48 deg/sec quickest speed necessary for most
Tilt: 6 deg/sec applications. Our testing has verified
that this speed is adequate, but if
possible, we will try to exceed it.
Positional +/- 2 deg The original requirement was less
Accuracy: than 1 deg. After testing, we realized
that since the sight has a field of
vision of 28 deg by 18 deg, 2 deg
accuracy would be more than sufficient.
Stability 8 lbs is the weight of the current
Static: +/- 8 lbs NightSight design. Because the
Dynamic: +/- 4 g camera will be mounted on a patrol
car in certain applications, it
will be subjected to loads from high
speed chases, off-road, conditions,
and automobile accidents.
These adverse conditions drove
the high dynamic stability.
------------------------------------------------------------------------
FIGURE 7. Field of Regard
FIGURE 8. Closed Loop Feedback
TABLE 2. Physical Requirements: These requirements indicate
how the mechanism accomplishes the functions.
------------------------------------------------------------------
Requirements Quantity Rationale
------------------------------------------------------------------
Weight < = 6 lbs This mechanism will be mounted
in a variety of locations and
situations. In order to insure the
sight and mechanism are portable,
the weight must be minimized.
Size The current sight design is 7
Height: 4 inches inches tall. In Canada, some clear
Pan Base: 8 inches ances are only 11 inches above the
Tilt Diameter: 12 inches height of the police cars, so the
mechanism must be 4 inches tall or
less. The pan and tilt diameters are
driven by constrained spaces the
sight must operate in and the
desire to keep it portable.
Input Voltage 9-16 volts Car batteries output within this
DC voltage range.
Power The vehicles that will mount this
Consumption type of device also must power
Slew: < = 16 watts other electrical devices. The power
Steady State: < = 6 watts used by our mechanism must be
minimized.
Weatherproof Our design will be subject to very
difficult external conditions, from
ocean salt to car washes.The internal
components must be protected.
Flexible Mount The mechanism must be mounted
on many different platforms
------------------------------------------------------------------
FIGURE 9. Pan and Tilt Size Limitations
TABLE 3. External RequirementsThese requirements indicate
how the mechanism accomplishes the functions.
-------------------------------------------------------------------------
Requirement Rationale
-------------------------------------------------------------------------
Manufacturability Current projections call for production runs of
10,000 or more devices. The device should be
designed for mass assembly.
Ergonomic Control Police typically operate alone. The control
Interface interface should not impair the officer's
ability to operate the vehicle
Maintenance Typical users; police, coast guard, and security
guards do not perform their own maintenance.
Our design should require no user-level
maintenance (i.e. lubrication, calibration).
Easily Detachable Users should be able to detach the entire mechanism
quickly so that they can secure it or switch it
to different vehicles, boats, etc.
Intuitive Feedback Users will not be able to confirm the orientation
of the sight by checking their surroundings during
limited visibility conditions. Our design must give
the user simple, accurate positional feedback.
-------------------------------------------------------------------------
TABLE 4. Environmental Requirements
----------------------------------------------------------------------
Requirements Quantity Rationale
----------------------------------------------------------------------
Safety No device There is no reason the user should
induced be injured during operation of this
injuries mechanism. Furthermore, the device
must be secured such that it will not
strike persons in an accident
Operating Temp. -40 deg to Cold weather in Calgary
70 deg C Hot sun in Pheonix
Storage Temp. -40 deg to Cold weather in Ottawa
105 deg C Parked in sun in Huston
Altitude 0 ft. to The device may be transported in cargo
40,000 ft. planes that are not pressurized.
Shock Endurance 20 g half Accident conditions
sine wave
pulses
Noise 40 db 40 db is the noise level in a typical
"living room" situation. Low
noise level is important to users in
surveillance situations.
----------------------------------------------------------------------
TABLE 5. Constraints
------------------------------------------------------------------------
Constraint Rationale
------------------------------------------------------------------------
Cost < = $300 at production Cost is very restrictive and will be a
rate of 10,000 units driving factor in design of mechanism
and materials.
Final design is due to This date is non-negotiable. All design,
sponsor on May 19, 1994. manufacture, assembly, testing, and
documentation must be complete.
The budget for this project This amount is all-inclusive. It includes
is $10,000. travel, hardware, shop time, manufacture,
assembly, testing, and documentation.
NIGHTSIGHT design can Hughes expended significant time and
not be altered money into their current design. Our
mechanism must not necessitate any
changes to its current design.
------------------------------------------------------------------------
TABLE 6. Opportunities
--------------------------------------------------------------------------
Opportunity Rationale
--------------------------------------------------------------------------
Design a flexible The potential users vary a great deal in
mechanism that will terms of needs. The mechanism designed
meet the needs of for the roof of a car may be designed
various users. much differently than one for maritime
applications. We will design for the most
stringent needs, maritime, so that our
design will meet or exceed the desires of
all users.
Preserve or accentuate Our sponsor has invested a great deal of
the aesthetics of the time and money into the appearance of
NightSight the NightSight. Our design will not
detract from this appearance and, if
possible, will improve it.
Use plastics to the Initial tests and calculations indicate that
maximum extent for the housing and some of the gears can be
the mechanism manufactured from plastic. This will
minimize our cost and weight.
Design the mechanism By using plastics, the opportunity to
for snap-fit assembly design snap-fit components is available.
This will minimize manufacture costs.
--------------------------------------------------------------------------
6.0 Design Process