Past, Present, and Future of Aerial Robotic Manipulators

A structured review of aerial manipulators, from helicopters and standard multirotors to multidirectional-thrust vehicles carrying various arms. It classifies platforms by thrust properties (uni-directional, multidirectional, fully actuated, over-actuated, omnidirectional) and covers tools and arm morphologies, compliance, cooperation, teleoperation, perception and planning. Applications include contact inspection of tanks, pipes, bridges and plants and valve operation, and the stated challenges are endurance, safety, accuracy under wind, and reliable autonomy.

Key findings

• Positioning accuracy should be below about 10% of the manipulator's reach; platforms above 25 kg should be avoided
• Visual markers gave better than 5 mm accuracy at 0.7 m, while UWB localization gave about 0.5 m
• Marker-free ICP localization had 0.11-0.21 m RMS error at tens of metres
• Future challenges: flight time/BVLOS, interaction safety, accuracy under wind, reliable autonomy

Limitations

• Review; few direct comparisons of NDT measurement quality
• Ultrasonic thickness measurement and power lines are not singled out in the body