33 UAV Energy-Aware Mission Planning

33.1 Start Simple

Start with a mission that moves, loses energy, and changes its radio path while it works. In UAV Energy-Aware Mission Planning, the practical question is what the aircraft must sense, relay, decide, and prove before the flight or network role is safe enough to trust.

The mathematical gist. A 22.2 V, 10.0 Ah pack holds 222 Wh at nameplate, but a 20% reserve leaves 177.6 Wh for planned work. With 40 mΩ internal resistance, 25 A cruise causes 1.00 V sag while a 45 A climb causes 1.80 V, leaving 20.4 V and less cutoff headroom. After a two-week gap at 2% monthly self-discharge, about 9,899 mAh remains. Mission planning must check both stored energy and the worst-current segment.

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Before worked Numbers: A Catalog-Typical Mapping-Drone Pack, inspect Figure to compare “balance connector” with “main power leads”. Their juxtaposition makes A LiPo pack like this is the physical source of the voltage sag in the Worked Numbers panel above: on a catalog-typical 6S, 22.2 V pack with 40 mOhm internal resistance, the 45 A climb segment sags the terminal voltage by 1.80 V (8.11%), nearly double the 25 A cruise segment’s 1.00 V (4.50%) sag. Photo: RC Lipo battery, CC BY-SA 3.0 visible.

Read Figure from “balance connector” to “main power leads”. Taken together, “balance connector” and “main power leads” express A LiPo pack like this is the physical source of the voltage sag in the Worked Numbers panel above: on a catalog-typical 6S, 22.2 V pack with 40 mOhm internal resistance, the 45 A climb segment sags the terminal voltage by 1.80 V (8.11%), nearly double the 25 A cruise segment’s 1.00 V (4.50%) sag. Photo: RC Lipo battery, CC BY-SA 3.0. For worked Numbers: A Catalog-Typical Mapping-Drone Pack, the observed relationship between “balance connector” and “main power leads” is evidence that “balance connector” carries into the next decision.

33.2 Learning Objectives

By the end of this chapter, you will be able to:

• Build a UAV energy budget from measured pack, route, payload, dwell-time, climb, and return records.
• Separate usable mission energy from reserve energy and return-to-home energy.
• Explain why the farthest reachable point, not just the final waypoint, controls the return reserve.
• Choose energy-aware route adjustments without hiding safety, payload, or data-collection trade-offs.
• Create a traceable mission record that supports repeatable improvement across flights.

33.3 Protect Reserve Before Work

If you only need the operating rule, this layer is enough: plan the required mission, protect return reserve from the worst active point, then add optional work only when measured records leave enough margin.

Before protect Reserve Before Work, inspect Figure to compare "Update logs" with "handoff options". Their juxtaposition makes energy-aware planning accepts, trims, splits, or returns from measured energy records, route estimates, reserve gates, live checks, and post-flight updates visible.

Read Figure from "Update logs" to "handoff options". Taken together, "Update logs" and "handoff options" express energy-aware planning accepts, trims, splits, or returns from measured energy records, route estimates, reserve gates, live checks, and post-flight updates. For protect Reserve Before Work, the observed relationship between "Update logs" and "handoff options" is evidence that "Update logs" carries into the next decision.

Mobile summary: Protect return reserve first; optional work only stays in scope while measured energy, route, payload, weather, and fallback records still pass.

33.4 Roof Inspection Scope Record

For the roof-inspection example, the record should make the scope decision obvious to the next operator: what must be collected, what can be skipped, and which gate protects return.

33.5 Under the Hood: Why Energy Debt Hides

Energy plans fail when several small costs are treated as harmless extras. The controller may still show a healthy percentage while the mission has already spent the margin needed for return or handoff.

• Dwell debt: hover, slow passes, photo retries, and weak-link retransmission turn time-on-task into propulsion and payload cost.
• Route debt: detours, repeated climbs, wind exposure, and a farthest active point can dominate the final waypoint distance.
• Payload debt: sensors, radios, compute, gimbals, lighting, storage, and live transfer modes change both draw and duration.
• Fallback debt: waiting too long to skip, split, hand off, loiter, or recall can spend the reserve that made fallback possible.

33.6 Prerequisites

Revisit these chapters if the terms are unfamiliar:

• UAV Trajectory Control: bounded path adjustments and feedback loops.
• UAV Network Topologies: gateway exits, relay patterns, and physical link records.
• UAV Swarm Coordination: role handoff and task ownership.
• FANET Fundamentals: aerial ad hoc links and routing choices.

33.7 How This Chapter Fits

Trajectory control asks how the aircraft should move. Energy-aware mission planning asks whether the aircraft should keep accepting that motion plan. It sits between mission design and in-flight control: the planner sets the budget and reserve gates, while the controller checks those gates whenever route, link, weather, payload, or safety records change.

The overview depth layer shows the energy-aware planning loop that anchors mission scope, measured energy records, route estimate, reserve gates, execution with live checks, and post-flight updates.

33.8 Energy Budget Record

An energy plan should be written as a record, not as a single remaining-battery number. The record separates what the mission is allowed to spend from what must remain available for return, uncertainty, and fallback.

Let $E_m$ be mission energy, $E_t$ transit, $E_d$ dwell, $E_c$ climb, $E_p$ payload, $E_{ctrl}$ control overhead, $E_{ret}$ return, $E_u$ uncertainty, and $E_{res}$ protected reserve.

$E_m = E_t + E_d + E_c + E_p + E_{ctrl}$

$E_{req} = E_m + E_{ret} + E_u + E_{res}$

The plan is acceptable only when the measured usable pack energy is greater than the required energy for the current mission scope. If the inequality is close, the correct action is not to hope that the battery lasts. Reduce the mission, change the route, split the flight, or hand off work.

Before energy Budget Record, inspect Figure 33.1 to compare “transit” with “Protect”. Their juxtaposition makes UAV energy budget record showing measured battery state, derating records, mission loads, return requirement, reserve gate, and decision outcome visible.

Read Figure 33.1 from “transit” to “Protect”. Taken together, “transit” and “Protect” express UAV energy budget record showing measured battery state, derating records, mission loads, return requirement, reserve gate, and decision outcome. For energy Budget Record, the observed relationship between “transit” and “Protect” is evidence that “transit” carries into the next decision.

33.9 Reserve Gates

Reserve gates convert an energy estimate into a decision. They prevent the mission from spending return energy on optional work.

1. Launch gate: the aircraft does not launch unless the route, reserve, return, and uncertainty budget all pass.
2. Segment gate: each new segment must leave enough energy to return from the worst reachable point after the segment starts.
3. Dwell gate: hovering, slow passes, repeated photos, and link retries have a time limit tied to the energy budget.
4. Scope gate: low-priority tasks are skipped before the return gate is threatened.
5. Return gate: the aircraft returns or hands off when the current reserve is no longer enough for safe continuation.
6. Post-flight gate: the measured energy use updates the next planning record.

Before reserve Gates, inspect Figure 33.2 to compare “Launch gate” with “recall before”. Their juxtaposition makes UAV route reserve gates showing launch, segment, dwell, scope, return, and post-flight update checks along a mission route visible.

Read Figure 33.2 from “Launch gate” to “recall before”. Taken together, “Launch gate” and “recall before” express UAV route reserve gates showing launch, segment, dwell, scope, return, and post-flight update checks along a mission route. For reserve Gates, the observed relationship between “Launch gate” and “recall before” is evidence that “Launch gate” carries into the next decision.

33.10 Route Planning Decisions

Energy-aware routing is not just shortest-path routing. A shorter route can still be worse when it forces repeated climbs, slow passes in poor wind, long hover periods, or weak-link retries.

33.11 Worked Example: Inspection Mission Scope

Consider a roof-inspection mission with five waypoints, two photo dwell points, and one optional thermal sweep. The planning team has recent measured logs from the same airframe and payload. The numbers below are not universal platform values; they are the team’s measured planning inputs for this specific setup.

The important learning point is the decision structure. The team does not ask, “Can the UAV probably finish?” It asks:

1. What energy records are measured rather than assumed?
2. Which tasks are mandatory, optional, or handoff candidates?
3. Which segment contains the worst return demand?
4. Which gate will shorten the mission before return reserve is spent?
5. What post-flight data will update the next plan?

33.12 UAV-WSN Data Collection

In UAV-assisted wireless sensor networks, the aircraft may act as a data mule, temporary gateway, or emergency collector. Energy planning must balance route efficiency with data urgency.

33.13 Common Pitfalls

33.14 Readiness Checklist

Before a mission is accepted, verify these items:

33.15 Concept Relationships

33.16 Interactive Checks

33.17 Summary

Energy-aware mission planning is the discipline of deciding what a UAV is allowed to attempt with its current battery, route, payload, weather, and fallback records. The central habit is to separate mission energy, return energy, uncertainty, and reserve instead of collapsing them into one remaining-battery number. The safest plans protect return feasibility from every active point, place optional work behind scope gates, and use post-flight logs to improve the next plan.

33.18 See Also

33.19 What’s Next

33.20 Key Takeaway

UAV energy planning must reserve capacity for flight, sensing, communication, return-to-home, and contingencies. A route that consumes the safety margin is not operationally viable.