  The potential of Martian lava tubes for resource extraction and habitat
sheltering highlights the need for robots capable to undertake the grueling
task of their exploration. Driven by this motivation, in this work we introduce
a legged robot system optimized for jumping in the low gravity of Mars,
designed with leg configurations adaptable to both bipedal and quadrupedal
systems. This design utilizes torque-controlled actuators coupled with springs
for high-power jumping, robust locomotion, and an energy-efficient resting
pose. Key design features include a 5-bar mechanism as leg concept, combined
with springs connected by a high-strength cord. The selected 5-bar link lengths
and spring stiffness were optimized for maximizing the jump height in Martian
gravity and realized as a robot leg. Two such legs combined with a compact body
allowed jump testing of a bipedal prototype. The robot is 0.472 m tall and
weighs 7.9 kg. Jump testing with significant safety margins resulted in a
measured jump height of 1.141 m in Earth's gravity, while a total of 4 jumping
experiments are presented. Simulations utilizing the full motor torque and
kinematic limits of the design resulted in a maximum possible jump height of
1.52 m in Earth's gravity and 3.63 m in Mars' gravity, highlighting the
versatility of jumping as a form of locomotion and overcoming obstacles in
lower gravity.
