Marine robotics · interactive classroom lab

Cooperative path following · 2–5 vehicles

Compare independent line-of-sight guidance, independent virtual targets, and coordinated virtual targets. Give each robot a different path, configure wingmen or leader–followers, and disturb one vehicle to reveal why path following alone is not formation keeping.

Version 4 · VT speed & sine phase shift · offline

1 · Experiment setup

Path edits restart · Speed adjustments apply live
Playback 3× VT speed U₀ [m/s] 1.55 Coordination gain 1.0
Retained commanded speed 50%

2 · Vehicle paths and formation slots

Path and formation parameters are independent.

Sine x-shift: moves the waveform horizontally (positive values shift peaks right). It is not the same as a wingman’s desired lag. VT pace ×: multiplies the global target speed for one robot and can be adjusted during a run; formation coordination may override the resulting free-running pace.

3 · Live top-down simulation

t = 0.0 s / 110 s

Error histories

Vehicle x-station (green) · target x-station (amber) · vehicle–target distance (blue)
Green and amber show fleet progress-synchronization errors. Blue shows vehicle-to-target positional RMS, a separate measure of local convergence. Disturbances at 18 s; optional communication loss at 58 s.

Instructor's 3-minute demonstration

1. Turn speed-limit fault OFF. Use coordinated VT with “Track actual virtual target.” Watch blue vehicle-to-target error converge near zero while the formation metrics do their own work.

2. Choose the “Keep lookahead gap” objective: the target retains an approximately 9.5 m x-station lead; the blue Euclidean distance also depends on path shape. Reset, restore target tracking, then enable the 18 s speed-limit fault to demonstrate residual error under constraints.

3. While running, adjust VT speed U₀. When it exceeds achievable vehicle speed, tracking error increases. Change just one vehicle’s VT pace factor; compare independent and coordinated VT. Then try the shifted sine preset.

Concepts to discuss

Wingman: a slot specifies both its desired lane (lateral offset) and its desired path-station delay behind the leader. Select “Matched wingmen” for a formation on similarly shaped paths.

Leader–follower: select “Leader–followers.” Each robot aims for a different delay on a common route. This is not collision avoidance: the separation metric uses vehicle points and contains no hull geometry.

Different paths: assign individual straight, sine, or curved routes. Change each sine wave’s x-shift and notice how shifting a path differs from requesting an along-path formation lag. Progress synchronizes x-stations—not Euclidean separations. Export CSV for analysis.