Survey: using momentum beyond the motor torque limit

Whether swinging, a countermovement or pumping lets Pupper do what its motors cannot do slowly. Momentum moves the torque demand into short peaks rather than lowering it, and on hardware such skills have failed on electrical and thermal limits; on Pupper's model a countermovement never raised a jump.

• A countermovement, the dip before a jump, adds nothing when the motor has no internal state: the push-off starts from the same state as a squat jump from the same depth. It pays through a spring
• On hardware the limit is usually electrical: an A1 jump policy trained with a plain torque clip demanded about 30 V from a 21.5 V pack and about 3,750 W from a 1,290 W battery, and failed
• Pupper has no torque problem in slow motion: every static posture needs at most 2.31 N·m, the four-leg stance at most 0.58. A scripted squat jump lifts the centre of mass 0.150 m with the training model's flat 3 N·m clip and 0.114 m with the GIM4305's torque–speed figures at 20 V; a countermovement never raised it, in 9 of 9 paired runs
• Found along the way: the robot's ROS 2 simulator capped every joint at about 1.37 N·m. Since 2026-10-26 it uses the motor's joint-side constants on the pack's 20 V by default
• Proposed: measure how much torque a skill needs when the controller may use momentum, as a torque-limit sweep of one recipe trained free and trained slow, with self-righting as the first skill