PI Engineering:
Design Project Proposal
Ryan Boak
Douglas Gobeski
Justin King
Mike Priebe
Dan Raphael
Mark Rogers
Rebecca Wahmhoff
Bryan Witherspoon
Introduction
The overall objective is to simulate the feel of a boat’s pilot house. To do this a simulator
will be connected to software to provide realistic feedback to an operator. The operator, in turn,
will control a series of gauges and the steering shaft to return input into the software program to
allow the simulator a realistic response. This requires a group of different parts working as a
whole to simulate the overall response. The steering shaft, the motion platform, the gauges and
the compass all must work together with the software program to provide the ambience of a real
boat house. In addition, a pilot house must be built to complete the overall feel.
The Motion Platform
Spacing of the Bellows
One of the critical factors of the motion platform
will be the spacing of the bellows. Since the cabin of the
ship simulator is more massive than the airplane simulator
for which the motion platform is currently set up, it is
possible that the bellows will have to be spaced out relative
to the pivot point in order to accommodate the extra
weight. Spacing the bellows will require modification of the motion platform and should only be
done if necessary. However, by doing so, the simulated cabin’s motion will be sacrificed.
In order to determine if the bellows need to be further spaced, the distributed mass of the
cabin will need to be estimated, and calculations will need to be performed to determine if the
bellows in their current configuration will be able to support it. If not, similar calculations will
be performed to determine the optimal position of the bellows.
Pivot Point
The pivot point of the motion platform is one of the main factors affecting the realism of
its motion. To be as realistic as possible, the pivot point should be at the same distance from the
cabin in the simulator as the center of gravity of the ship is from the cabin. However, since
space is a design constraint, this will not be possible. Thus, the motion of the ship simulator will
not be exactly like the ship that it’s simulating. Moving the pivot point away from under the
position of the simulator operator’s feet will give a more realistic feel. The pivot point can be
moved by moving the entire motion platform’s location, by modifying the motion platform, or
both. Modification of the motion platform should be avoided if possible.
Balancing Masses
Since most of the weight on the ship simulator will be concentrated at the front, balancing
masses will need to be located in the rear of the simulator. These added masses will allow to
motion platform to move in a balanced and stable manner. Calculations will need to be
performed to determine the moment (force*distance) that the weight at the front of the cabin
creates about the pivot point, and mass will need to added at the back to create an equal and
opposite moment.
The Gauge and Compass
Typically, modern watercraft display thrust, fuel, electrical, and other important
information on a display connected to an onboard computer. To recreate a more “vintage” feel,
the Soo River Belle, and her simulator, will be outfitted with modern analog gauges. A general
purpose analog gauge will be created using a DC gear motor, a position sensor, some LEDs for
color effects, and a small microcontroller.
Figure A shows the connections that the gauge
will have. A backup, “always-on” Vdd connection
Wire
Vdd
Gnd
will be used to keep power to the microcontroller so it
Backup Vdd
can properly shut down when the gauge is turned off. Signal
Light
The signal connection will contain a DC voltage
USB
between 0 and 5V that will control the needle position. A light
will be used to turn on or off the lights.
Description
12V DC
Ground
12V DC
Needle Position Voltage
LED Enable
5-pin USB Connection
connection
Figure A
The gauge will be easily customizable. A USB interface will allow the microcontroller to
be reprogrammed, enabling the user to modify light patterns, or the range of motion of the
needle. In addition, the faceplate of the gauge will be easy to remove and replace, allowing for
customized faceplates.
The needle position will be closely monitored using the microcontroller, and a capacitive
position sensor, which will be provided by PI Engineering. The sensor will be attached to the
shaft of the motor, and will provide a DC voltage to the microcontroller. The microcontroller
will then compare the feedback voltage with the external signal voltage, and make adjustments
as necessary.
The gauge will have several red, green and blue LEDs mounted at the bottom of the
casing. The LEDs will be controlled by the microcontroller, which will control each color
separately. The microcontroller will also be able to control the LEDs based on the needle’s
position.
While the Soo River Belle will have as many as 40 different gauges, it is not feasible to
create each and every gauge for this simulator, as a lot of miscellaneous data is not even taken
into account in Virtual Sailor. We will, however, attempt to build these gauges for the most
basic readings, including a tachometer for each engine, and rudder position. Other gauges may
be added if time permits.
We will use the actual compass from the Soo River Belle to display the ship’s heading in
the simulator. We will accomplish this by using the same hardware as the gauge, but we will
attach a strong magnet to the shaft of the motor, then mount the entire assembly directly
underneath the compass. As the magnet turns, the compass will follow its magnetic field rather
than the earth’s magnetic field. Properly calibrating this device will allow the Virtual Sailor
program to accurately display the ships heading on the compass.
A digital-to-analog device will be used to send analog signals to the gauges and the
compass, using data sent to it from Virtual Sailor. PI Engineering will provide us with the
device, or a suitable one will be recommended and purchased.
The Steering
The primary means of input to the simulator will be the steering wheel. Since the user
will have almost constant interaction with the steering wheel, it is important that it work
properly.
The steering wheel has to be free-spinning until it reaches the “locks” at the clockwise
and counterclockwise extremes of its rotation. It also has to provide position information to the
Virtual Sailor simulation software.
To accomplish this, a chain drive will be used to connect the output from the steering
shaft to a hydraulic pump. The hydraulic pump will pump hydraulic fluid through a closed
system consisting of the pump and two hydraulic cylinders. Since the steering wheel has to
move through four revolutions between the “lock” positions, the system has to be designed to
make the hydraulic cylinders reach their maximum displacements at the points where the “locks”
are supposed to be. To accomplish this, the design must address the gear ratio between the
steering shaft and the pump, the displacements per revolution of the pump, and the capacities of
the cylinders.
Additionally, it may be necessary to create a compound train by adding a second shaft
and associated bearings and extra chain. This will be done if the necessary gearing ratio requires
the use of sprockets that are too large to be housed inside the helm stand.
The position information will be obtained by using a potentiometer that is attached to the
steering shaft.
The Software
To coordinate all the different parts, the gauge, the compass, the motion platform and the
response to the steering a software program will be used. The software program that will be used
for the graphical ship interface will be Virtual Sailor. The software will take inputs from the
ShipDriver Consumer Product. The team will have to build a hardware-to-software interface to
accommodate this since the Virtual Sailor software does not know how to read signals from the
ShipDriver. The software will take user inputs from the controls and use these inputs to drive the
ship in the simulation. The software will accurately update the ship’s path through the simulated
environment. An output interface will also have to be devised in order for the software to
interact with the hardware. The software will have to send a signal to the platform/gauges
simultaneously and in real-time. The hardware will then interpret the signal appropriately.
The software supports UDP for real-time connectivity with hardware. Currently, the
software uses key strokes from the keyboard and on screen mouse clicks for ship control. This
will have to be modified in order for the simulator to be able to read inputs from a ship control
module. Below is a screenshot from the Virtual Sailor software. The boat pictured is similar to
the boat we will be simulating.
Taken from http://www.hangsim.com/vs/boats.php?dzone=ship.
The Pilot House
Finally, to give a complete sense of actually being in a pilot house the cabin will
be constructed onto the motion platform to give the observers onboard perspective of a normal
ship captains experience. The cabin must be large enough to comfortably hold one to two people
inside the cabin in addition to the helm stand console with any other electronic devices that will
be on the moveable platform. The pilot house will be the last major item constructed and will
generally be designed around the other items and components to accommodate their design and
constraints.
The mock-up of the pilot house will be entirely enclosed to test the physical room and
comfort when underway in various conditions. All four sides (port, starboard, stern, and bow)
will have vertical walls including a ceiling. By totaling enclosing all the walls on the passengers,
the entire cabin may give a claustrophobic feel to the ship to some guests, which is desired for
the realism of the project. The back of the platform will have a hinged door and will serve as the
entrance and exit to the platform. The door should be able to close and not lock, in case of any
type of emergency should happen it will allow easy access from inside or out.
As illustrated in the picture, the bow walls will be slightly angled to one another and also
the walls will taper outwards. Each wall panel will have rectangular windows to limit the
viewing perspective of the captain in all directions. The bow wall windows will have vertically
placed computer screens displaying the open waters on the screen acting as the main navigation
window for the guests onboard.
The entire pilot house will be created with plywood and other inexpensive materials.
Approximately ½” plywood will be used to limit the weight applied to the platform and should
be thick enough to be structurally safe. Each wall panel will be built and assembled
independently to allow quick transportation, storage, and disassembly of the project. To create a
quick assembly and disassembly of a large project like this one, the walls will be joined with
nuts, bolts, and washers rather than permanent connects like adhesives or nails. L-brackets and
angled brackets will be bolted to the plywood walls and connect to an adjacent wall or structure
for the cabins structure and stability.
The mock-up pilot house is meant to be a simple addition to the simulator that will add
characteristic and realism to the project. The cabin is not to be complex in design, just to
demonstrate to spectators inside the cabin or out on the exhibit floor the experience one can have
on a real tugboat. Again the project is meant to demonstrate the fun and excitement of the marine
industry.