The design process is complex and requires extensive planning. The
entire project can be compromised if problems are not found early in the design
stage. It is important to identify possible issues within the project early in
the design process to minimize risk of project failure and to avoid unnecessary
costs and delays. A systems engineer’s responsibility is to manage the entire
project. He will define derivative requirements based on customer needs and specifications.
He will solve conflicts arising between the design teams and select the
appropriate solutions. He will be responsible for the final product approval,
launch, and support. It is a tremendous task, which can only be accomplished
with careful planning, constant monitoring, and critical decision making.
The system engineer will have to take the role of mediator to
solve conflicts between the two design teams. Sometimes the solution will
require both teams to modify their systems in order to achieve a functioning
end product (Loewen, 2013).
The current scenario describes the situation when an UAS system
was built overweight. A major contributing factor to this issue is that the
guidance, navigation, control and payload delivery system were all purchased
from an outside vendor. This resulted in both systems going over their allotted
weight budgets. This resulted in the inability of the UAS to carry a sufficient
weight to spray a certain amount of fertilizer over the specified area without
cutting into the fuel margin.
The customer is already expecting the UAS to meet certain
performance requirements. Therefore, changing the system’s spraying capacity or
range will potentially result in the customer cancelling its order and the entire
project may be compromised. Therefore, we need to decide how we can change the
UAS to accommodate the customers’ requirements and still be within the weight
budget.
What are your
considerations?
The primary focus in the systems engineering process are the
project requirements. The entire project is focused on transforming the requirements
into final product. The main idea is to fulfill these requirements within the
constraints: limited resources, limited time, limited weight, etc. (Department of Defense [DoD],
2001). The requirement-based design is an approach which can be used to
maintain “quality control” of the project and ensure that design team efforts
match what the UAS must accomplish (Loewen, 2013). For this particular project
it is important to consider the following:
1. We cannot cut fuel margin, since it will compromise the safety
of the system and also reduce its range. Although, it may be possible to modify
the power system to be more fuel efficient in order to provide longer endurance
with the same fuel amount. However, this may result in significant increase in project
cost and time required to complete the process.
2. We can custom design the payload delivery system and/or
navigation, control, and guidance system. However, this option will also result
in extra costs and time delays. However, certain modification may allow a decrease
in size and weight of each system and, therefore, decrease overall gross weight
of the UAS.
One solution is to modify the payload delivery (spraying) system
by installing a pressurized fluid reservoir instead of electric motor driven
pump. The pressurized spraying system will eliminate the need and weight of the
motor, the pump and its wiring and hardware. This modification will also lower
the overall power requirements for the UAS and save fuel. The reservoir would
be filled and then pre-charged with compressed air to deliver the spray under
pressure. Another solution is to modify the navigation, control, and guidance
system by placing some required navigation and guidance subsystems in the
ground control station (GCS) instead directly on the vehicle. It will also save
weight and free up the extra space onboard.
3. We could find a different vendor for these system. It is
possible to replace the control/navigation and guidance system with lighter
off-the-shelf equipment. However, the availability may not be certain. Another
concern is the safety and quality of the off-the-shelf products. Before making
a commitment to purchase a system from the outside vendors, it imperative to
review and verify its safety and quality characteristics.
4. We could increase a size of the UAS platform itself, this would
allow it to house the existing systems.
5. We could incorporate lighter composite materials to help reduce
the overall weight of the UAS.
6. We could compensate for weight increase by reducing the weight
of other systems? For example, if we eliminate any redundant equipment, the UAS
weight will be decreased. However, it is important to maintain certain level of
redundancy to maintain operational safety.
What are your
priorities?
First of all, we have to keep in mind the customer requirements.
The entire project should be focused on creating a UAS, which will be able to
carry out the customer specified mission. Another priority is to achieve the
finished product within budget and with the time constraints. A quick time-
to-market is another important consideration. Delays in production may hinder
project success and allow competition to step in. Quality of the product is
another priority. The product should be designed to be easily supported after
release and throughout its lifecycle. It should be easy to maintain and, and if
necessary, upgrade. Of course safety
should also be a major priority. Although, some may believe that since the
system is unmanned, the levels of safety are not as important as with manned
systems. However, it is imperative to keep in mind the safety aspect for UAS,
considering that the vehicle may overfly populated areas and could easily
become a hazard to personnel on the ground.
The systems engineer deals with solving conflicts between the
design teams. The phase-gate approach can be used in systems development. This
includes a periodic review of each system. The design team cannot continue past
a certain point in the design process unless the corresponding review has been
satisfactory completed. The review can be formal or informal (peer) review.
Projects executed in a phase gate model have three main fundamentals:
deliverables, criteria and outputs (Innotas, n.d.). Another
important aspect to consider is traceability throughout the entire project.
Traceability will ensure that each team is accountable for its design and this will
allow the designers to trace their steps back to mistakes (Loewen, 2013).
There are several steps in managing conflict:
1. Explore the reasons for the conflict.
2. Find an alternate resolution for the disagreement.
3. Choose the most appropriate solution.
4. Implement the solution.
5. Evaluate the solution (Rainey, n.d.).
This steps can be applied to any conflict. In this particular
case, the system engineer will have to serve as the “mediator” between teams
and recommend the best resolution.
What do you think about
the future prospects for the “next generation, enhanced” version of the system
as a result of your approach?
It is important to keep in mind future missions for designed UAS.
Maybe the customer requirements will change and an even larger spaying capacity
will be required. It is also possible that a customer will add additional
payload systems into the UAS, such as sensor and cameras for crop evaluation
and monitoring. In this case, increasing size of the vehicle may be
advantageous at this stage to allow for a larger payload capability in the
future. Incorporating a modular design could be beneficial for future
applications as well. It will allow the incorporation of “next generation”
payloads without redesigning the UAS.
References
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