System Architecture Selection for a Package Delivery UAV#
Step 1: Define Physical Requirements#
Extract from System Requirements#
Package Dimensions: Support packages up to 9 x 6 x 2 inches, compatible with most lightweight consumer goods.
Payload capacity: 2.5 kg.
MTOW: 25 kilos.
Footprint: 2m x 2m.
Ceiling: 122 m (400 ft) AGL.
Autonomy: 10 km per delivery.
Navigation: GPS-based with collision avoidance.
Noise levels: Below 65 dB to comply with urban regulations.
Reliability: maintain a system uptime of 99.95%.
Package drop accuracy:
Within 1.0 m of the destination mark.
Maximum load on package:
2g
Accuracy:
Achieve a delivery accuracy rate of 99.9% ensuring packages are delivered to the correct location.
Consider Environmental Factors#
Operating environment:
Constrained urban areas (capacity to maneuver amogn buildings with different heights and with ledges, such as balconies).
Open spaces in rural areas.
Weather:
Heavy winds (resitance up to 20-25 km/h) and light rain resistance.
Moderate wind in rural environment.
Operating temperatures ranging from -20°C to 40°C.
Meneuvrability: take-off and landing in small and constrained spaces
Regulatory Compliance#
Adherence to local aviation regulations (e.g., FAA, EASA).
Adherance to regulations from environmental agencies (noise).
Adherance to local regulations managing rural and urban integration of UAV’s.
Adherence to EASA regulations: Compliance with EU Regulation 2019/947 and 2019/945.
U-Space participation: Integration with U-Space services for traffic management and airspace deconfliction.
Restricted airspace compliance: Avoidance of no-fly zones like airports and military zones.
Privacy compliance: Adherence to GDPR regarding data handling and privacy (unauthorised collection of personal data).
Aviation Authority Regulations: Compliance with FAA Part 107, EASA regulations, including registration, airworthiness certification, and remote pilot licensing.
Operational Requirements: Adherence to flight restrictions, altitude limits, visual line of sight rules, and night operation regulations.
Safety Standards: Compliance with DO-178C software certification, redundancy requirements, and fail-safe system implementations.
Privacy Laws: Following data protection regulations, camera usage restrictions, and personal property protection laws.
Security Requirements: Implementation of anti-tampering measures, cybersecurity protocols, and secure communication standards.
Emergency Protocols: Compliance with mandatory safety features, emergency landing procedures, and incident reporting requirements.
Documentation: Maintaining flight logs, maintenance records, and operator certifications as required by regulatory bodies.
Step 2: Identify Candidate Architectures#
List Possible Architectures#
Quadrotor UAV:
Good payload lifting capabilities.
Highly agile with vertical takeoff/landing capabilities.
Package delivery method:
Cable drop.
Parachute.
Low altitude drop.
High altutude drop.
Vertical landing (user takes the package from the drone when it is in “safe mode”, that is harmless for the user)(dangerous option due to third parties manipulating the drone).
Fixed-wing UAV:
Good endurance and cruise speed performances.
Blended wing architecture.
Limited in vertical takeoff/landing.
Package delivery method:
Parachute.
Mother + minidrones system: the FW UAV acts as a “mother” hub by releasing small, multirotor mini-UAV for precise package delivery.
Hybrid-VTOL UAV:
Combines the best qualities of the above architectures (horizontal and vertical flight).
Possible configuration with tilting rotors.
Package delivery method:
All of the above.
Consider Technology Readiness#
Quadrotor UAV:
Robust readiness.
Simple architecture.
Cable system technology might be difficult to find in state-of-the-art.
Proven technology for payload lifting in tight environments.
Because the multiple rotors, it generates significant noise.
Fixed-wing UAV:
Robust readiness.
Limited for constrained environments.
Good noise impact: quiet operation, minimal disturbance to urban communities.
Hybrid-VTOL UAV:
Still an emerging architecture/technology.
Readiness depends on payload size.
Energy source#
Batteries (fix) - Good energy density (compared to supercapacitors), wide availability, slow charging performance.
Batteries (removable) - Same as before. Slow charging performance is not a constraint.
Supercapacitors - Quick charging capacities but low energy density (emerging technology)
Solar panels - Eco-friendly and ideal for long-duration operations in areas with consistent sunlight. However, they have low power output and depend heavily on weather conditions, limiting practical use for most UAVs.
Hydrogen fuel cells - Promising for extended endurance with high energy density and faster refueling compared to batteries. Still in early adoption stages, with higher costs and system complexity.
Ground cable alimentation - Offers unlimited operational time by providing continuous power. However, it restricts range and mobility, making it suitable only for fixed or close-range missions.
Step 3: Establish Evaluation Criteria#
Operational Suitability#
Scenarios - The most constrained scenario is the urban delivery, where the major constraints are noise level and safety of operations.
Quadrotor UAV - Autonomy and range suitable for urban areas. Good vertical flight capability. Cable delivery represents less danger and permits delivery in crowded or difficult access places. Landing delivery option is dangerous and not suitable since it implies the manipulation of the drone by the user taking the package (risk of drone turning on during the manipulation: undesired take-off position after package recovery, hardware incidents, etc.). Delivery via dropping system is suitable for remote areas where the drone can descend down to a suitable heigh (even land vertically) and drop the package. No suitable for crowded places where the drone could represent a risk when flying at low altitudes.
Fixed-wing UAV - Great range capability for extra-urban areas. Good cruise velocity translates to fast delivery. Delivery system not precise due to uncapability to hover and not suitable for crowded areas (risk of collision package falling into a pedestrian).
Hybrid-VTOL UAV - Good range and delivery speed, capacity to hover (suitable for rural and urban areas). Delivery architecture can be variable.
Performance Metrics#
Payload capacity 2.5 kg.
Range of at least 10 km.
MTOW 25 kg.
Reliability: maintain a system uptime of 99.95%.
Speed:
10-20 km/h for safe urban navigation.
Up to 80 km/h in unconstrained zones.
Operational footprint 2m x 2m.
Drop accuracy:
1m from the drop zone.
Environmental Compatibility#
Noise:
Low noise to minimise disturbance.
Noise levels below 65 dB at 25 m.
Emissions:
Electric propulsion to produce zero direct emissions.
Impact of operations:
Mitigate impact on local wildlife.
Avoid flight paths that can disrupt natural habitats.
No environmental damages.
Constraints Compliance#
Meet environmental and regulatory standards for UAV.
Safety: redundant systems and fail-safes.
Step 4: Perform Trade-Off Analysis#
Quantitative Assessment#
Architecture |
Payload Capacity |
Range |
Maneuverability |
Noise |
Technology Readiness |
Package delivery modularity and precision |
|---|---|---|---|---|---|---|
Mutlirotor |
High |
Moderate |
High |
High |
High |
High |
Fixed-wing UAV |
Moderate |
High |
Low |
Low |
High |
High |
Hybrid-VTOL UAV |
High |
High |
High |
High |
Moderate |
Low |
Qualitative Assessment#
Fixed-Wing - Complex in urban environments, poor maneuverability and high limitations in delivery operations. Best fits rural area for long range missions. It is the best known technology for drones so far, hence the costs will be lower. Other cons of this architecture are the higher maintenance complexity and the limited scalability for delivery operations.
Multirotor - High agility, simple maintenance, ideal for constrained areas and precision delivery but limited in range of operations. It shows an excellent urban adaptability, an high sclability according to a large spectrum of operations, simpler maintenance requirements, and a strong commercial support ecosystem.
Hybrid VTOL - Promising but may introduce complexity and higher costs, generally have larger size trhan multirotor and technology is the least developed one between the models taken into consideration. Therefore the development risk is higher. The maintenance is more complex. this architecture has the pros of both the multirotor and FW configuration; hence it has a really good operational flexibility.
Step 5: Eliminate Unsuitable Concepts#
Threshold Criteria#
Must support 2.5 kg payload
Must allow vertical takeoff/landing.
Relatively good delivery precision.
Safe and suitable urban delivery (maximum payload load of 2g).
Feasibility Assessment (list of discarded solutions along with the corresponing reasons)#
Fixed-Wing:
Eliminated due to poor maneuverability in constrained spaces and not ideal delivery option.
Hybrid-VTOL:
Eliminated due to high complexity and costs.
Eliminated due to low readiness.
Hybrid-VTOL (tilting rotors):
Eliminated due to high complexity and costs.
Eliminated due to higher risk.
Eliminated due to low readiness.
Multirotor (landing):
Eliminated due to unsafe delivery option (it adds randomness to the success rate of the mission).
The drone could be damaged during landing.
Multirotor with ground cable alimentation:
Eliminated due to its working impossibility in constrained environments like urban areas.
Parachute:
Discarded for not having enough precision when delivering a package.
Discarded because unfeasible in complex urban environments.
Fuel cells:
Discarded due to safety reasons.
Solar panels:
Discarded because too dependent on the weather and because they require extra maintenance.
Step 6: Select Best Architecture (Qualitatively)#
Selected Architecture (list of the selected architectures)#
Multirotor UAV powered by batteries and solar panels - Selected for its high agility, proven technology, and suitability for constrained environments. It is also a technology that allows to meet delivery requirements and safety. Powered by rechargable batteries for their reliability and solar panels for higher energy efficiency.
Multirotor UAV with cable - Selected for its high agility, proven technology, and suitability for constrained environments. The delivery system with the cable, despite adding complexity to the system, is safe and permits deliveries in all desired areas (urban, crowded, rural), as long as the range is respected.
Multirotor UAV with swappable batteries and landing - All the advantages seen before. The batteries are swapped at the station between an operation and another. The delivery by landing, in order to make the operation simpler and easier.
Multirotor UAV with batteries and low altitude drop - All the advantages seen before. The low-altitude drop maximizes precision in urban context, avoiding complex scenarios as take-off in hostile environment.
Multirotor UAV OR Hybrid VTOL with minidrones- All the advantages seen before. “Also, possiibliity of reduce rotors number to reduce noise”. The distribution method relying on mini-drones guarantees high maneuverability and the ability to deliver in constrained spaces; good delivery gentelness. Less constrained with weather conditioones when compared with the multirotor + cable methood.
Multirotor UAV with direct mounting - For payload integration, direct mounting offers simplicity, reliability, and reduced weight but comes with limited payload flexibility and a higher center of gravity. In contrast, a cable-based system reduces rotor wash and enables flexible payload delivery, though it introduces wind sensitivity and more complex control dynamics. Parachute seems like a choice as the immediate reduce weight after drop off the package, however, The parachute method has high uncertainty when dropping, also potential makes more waste. As long as we had the Multirotor as the best choice, the direct mounting can reduce the structure weight and avoid the waste like of the parachute.
Hybrid VTOL + Batteries + Cable or mini-drone
Multirotor with landing (energy sourge not specified)
Validation Feasibility#
Technical: Meets payload, range, and endurance requirements with zero-emissions electric propulsion.
Regulatory: Compliant with EASA regulations and U-Space integration.
Operational: Reliable and manufacturable with minimal setup, adaptable to various environments.
Limitation of landing delivery: final user must provide a suitable landing surface. rational and regulatory requirements (to be checked for the cable delivery system).
Technology is reliable.
Practical, manufacturable, and maintainable with current technology.