Two Numbers Make the Decision: 15 kg and 40 kg
The AS2 has a 15 kg walking payload against the B2's 40 kg. The gap widens further on standing capacity: 65 kg against 120 kg. Walking payload is the figure that decides matters in the field, because the robot does its job while moving. Weigh the sensor package you intend to carry: if a thermal camera, gas sensor, spare battery and mounting hardware together exceed 15 kg, the AS2 is already out. Unitree's ready-made payloads and the carrying limits of each version are collected in our Unitree industrial packages guide.
Body and Agility
The AS2 measures 720 × 378 × 457 mm at 20 kg. The B2 measures 1098 × 450 × 645 mm at 60 kg. The AS2's smaller body is an advantage in narrow corridors, covered car parks and between machinery, where the B2 can run into turning-radius and height problems. In exchange, the B2 clears terrain the AS2 cannot, with a 45 degree slope, a 40 cm step and jumps beyond 1.6 m against the AS2's 40 degrees and 25 cm. The B2 is also faster, at over 6 m/s against over 5 m/s.
Ingress Protection: The Quiet but Decisive Difference
The AS2 is IP54, the B2 IP67. That single line settles the choice on its own in most projects. IP54 covers dust protection and resistance to splashing, which suits semi-open areas and in-facility work. IP67 means dust-tight and able to withstand temporary immersion: inspection in the rain, muddy construction sites, production areas that get washed down. Where the mission is continuously outdoors, there is in practice no option other than the B2. The operating range is slightly wider too, at -20 to 55 degrees against -20 to 50.
Energy and Endurance
The AS2 runs for over 4 hours unloaded on a 648 Wh (15,000 mAh) battery. The B2 runs for over 5 hours unloaded and over 4 hours with a 20 kg load on a 2250 Wh (45 Ah, 58 V) battery. The critical detail is that second figure: even under load, the B2 matches the AS2's unloaded endurance. On long, loaded inspection shifts that difference directly sets how many battery swaps you make per day. Joint torque differs sharply as well, at 95 N·m against 360 N·m.
Which One to Buy
In-facility and semi-open site inspection, narrow passages, a sensor package under 15 kg and a few hours of rounds a day: the AS2. Continuous outdoor work, rain and dust, equipment above 20 kg, long shifts and demanding terrain: the B2. If range is your priority, the wheeled-legged versions open a separate class: the AS2-W offers over 30 km. To weigh the B2 against the light class instead, see our Go2 and B2 comparison.