Research questionHow does actively regulated spinal compliance trade off quadruped bounding speed against energy use?Quadruped bounding requires coordinating trunk motion with leg dynamics, while active compliance may increase speed at the cost of additional energy. The design challenge is determining whether the speed benefit justifies that energetic cost. Latest papersRecent research connected to this question, newest first.SPARC: Spine with Prismatic And Revolute Compliance for Faster Quadrupedal BoundingThe evidence concerns SPARC, a 1.26-kg, 3-DoF sagittal spine with tunable task-space stiffness and damping, integrated into an 8-DoF quadruped. It compares impedance-controlled compliance, position control near a fixed pose, and a rigid spine across 97 bounding trials, with benchtop tests of commanded versus fitted axial stiffness. The results report speeds of 1.029, 0.769, and 0.673 m/s respectively, and higher electrical cost of transport at matched speed for impedance-controlled SPARC than for the rigid spine.research paper · Sep 3, 2026