Topic 3 — Task Allocation, Role Assignment & Distributed Planning
Assigning the right tasks to the right robots is a cornerstone of effective multi-agent systems. This topic presents core strategies for distributing work among a team, planning as a group, and ensuring robust execution even as the environment and available agents change.
3.1 Assignment Models
How do robots decide who does what?
Auction-Based Allocation
- Robots broadcast available tasks and bid based on cost (distance, time, capability).
- Highest/lowest bid wins, all robots update their assignments accordingly.
- Useful for decentralized, dynamic teams.
Leader Election
- One robot (elected via protocol, e.g. Bully algorithm) organizes and hands out tasks.
- Only used when centralization is temporarily advantageous or failover is needed.
- Robustness: If the leader fails, another is elected.
Graph Partitioning/Splitting
- Map divided into regions/subtasks, assigned by dividing a graphical representation (e.g., Voronoi partitioning, nearest neighbor, coverage maps).
- Great for spatially-structured missions.
Diagram: Auction-Based Task Allocation Flow
+----------------+
| Task Request |
+--------+-------+
|
Robots submit Bids
|
+--------v--------+
| Auctioneer |
+--------+--------+
|
Assign task to winning robot
|
+--------v--------+
| Winner does |
| task, others |
| re-bid/remain |
+-----------------+
3.2 Planning as a Group
Negotiation and fallback
- Robots can negotiate ownership ("I'm closest, I'll do it!") or request help.
- If a robot becomes incapacitated, tasks are dynamically transferred.
- Subtasks may have dependencies: robots must communicate about what must happen first and next.
Protocols for distributed planning
- Often implemented as distributed consensus (task logs, distributed locks), or lighter-weight, decentralized heuristics (assignment based on most recent/frequent user, etc.).
3.3 Load Balancing & Efficiency
- Shortest path assignment: Minimize travel/time across the team.
- Energy vs time trade-off: Decide whether to balance robot battery use or minimize total mission time.
- Dynamic redistribution: If a robot's progress stalls, incomplete tasks are re-broadcast and reassigned.
Lab: Simulated Auction-Based Distributed Task Assignment
Goal: Simulate a fleet of robots negotiating task assignment in simulation using auction/market protocols.
Tasks:
- Set up 2+ robots in Gazebo/Isaac Sim, each with a basic task queue (mock delivery/inspection/search jobs).
- Implement a simple auctioneer node (central or rotating):
- Announces new jobs.
- Robots compute bids (distance to site, time, or random weight for demonstration).
- Auctioneer assigns job to best bidder; others rebid for remaining jobs.
- Introduce dropout/failure: one robot drops out; observe that tasks are re-auctioned and assigned to remaining robots.
- Log:
- Assignment sequence.
- Bids per robot.
- Task completion vs dropped/failed tasks.
Deliverables:
- Auction/election node code and launch configs.
- Task queue/bidding logic logs or visualization.
- Short report on efficiency, robustness, and recovery behavior.
Summary
Effective distributed task allocation and planning are what allow multi-robot teams to be more than "just many single robots." These algorithms enable scale, resilience, and workload optimization—fueling mission performance in warehouses, search/rescue, and dynamic human-robot teaming.