Here is comparison of latching systems. The different prototypes for roboat and other models from the community. The comparison is applied in all three stages of the latching process: homing, docking and garaging.
Autonomous latching system. funnel / funnel / genderless gripper / adaptive funnel.
This step utilizes a tracking system to assist in guiding the AUV into the dock. This system is activated once the AUV is within a close range of distance to the docking station.
Ideally we should have an accurate sensor (≤40mm) that can detect the target from far away (≤1500m), work outdoors and with minimal cost.
GUIDING | ACCURACY (mm) | DISTANCE (m) | SENSOR | COST | POWER (W) | TEST |
Camera-AprilTag | ±10mm | 2m | Camera | $100 | In/Outdoors | |
Magnetic | ±50mm | 0.3m | Magnetic field | $10 | --- | Indoors |
Electro-Magnetic | ±50mm | 0.3m | Magnetic field | $20 | Indoors | |
IR sensors | ±50mm | 1m | IR Photodiodes | $10 | Indoors | |
Indoors GPS | ±50mm | 10m | Ultrasound | $400 | Indoors | |
Outdoors GPS | ±50mm | 1000m | RTK | $9876 | --- | |
IR camera | ±50mm | 0.5m | IR Camera | $500 | Indoors | |
Lidar | ±100mm | 100m | VLP16 | $6000 | In/Outdoors |
Table 1. Guiding methods for latching a roboat.
Docking specifically refers to joining the AUV to a static docking station.
DOCKING | GENDER | TOLERANCE (m) | ACTUATORS | POWER | TEST |
Magnetic | Yes | 20mm (Magnetic field) | --- | --- | Indoors |
Electromagnets | Genderless | 10mm (Magnetic field) | 1 per electromagnet | Indoors | |
Arms | Yes | V-shape 200mm | 2 per arm | In/Outdoors | |
Funnel | Yes | 80mm (adjustable) | 1 per funnel | Indoors | |
Gripper | Genderless | (200mm) Arm length | 1 per gripper | In/Outdoors | |
Stinger | Yes | --- | 2 per set | --- |
Table 2. Docking methods for latching a roboat.
The garaging refers to how the vehicle is locked, securing its position. In this context, the locking mechanism can be as simple as a hook, or a more elaborated system that involve active devices, such as motorized-screws.
GARAGING | STRENGTH | JOINT TYPE | ACTUATORS | POWER | TEST |
Magnetic | LOW (70N) - magnetic field | Rigid | --- | --- | Indoors |
Electromagnets | LOW (70N) - magnetic field | Rigid | 1 per electromagnet | 2-100 W while latched | Indoors |
Push and lock | High - Physical lock | Spherical | 1 actuator for lock/unlock | 0.5 W per operation | In/Outdoors |
Motorized funnel | High - Physical lock | Spherical | 1 actuator for lock/unlock | 0.5 W per operation | In/Outdoors |
Adaptive funnel | High - Physical lock | Spherical / Rigid | 1 actuator for lock/unlock + 1 or 2 for ams | 0.5 W per operation | Indoors |
Gripper | High - Physical lock | Cylindrical pair | 1 per gripper | 0.5 W per operation | In/Outdoors |
Stinger | High - Physical lock | Cylindrical pair | 2 actuators | 0.5 W per operation | --- |
Table 3. Garaging methods for latching a roboat.