# Marc Raibert > 1949– · Roboticist, Founder of Boston Dynamics > > **Recorded contribution:** Founded Boston Dynamics; legged locomotion; dynamic balance robots ## How to use this dossier Read for a causal chain, not a hero story: inherited problem → contribution → mechanism → downstream capability → limit. Then close the page and complete the reconstruction exercise from memory. ## 1. Historical orientation Marc Raibert (born 1949) is a roboticist who developed dynamic legged locomotion at Carnegie Mellon and MIT and founded Boston Dynamics. Earlier robots often tried to maintain static balance at every instant; Raibert's hopping machines treated running as controlled falling, using feedback to regulate vertical energy, forward speed, and body attitude across repeated stance and flight phases. Boston Dynamics extended dynamic control with sophisticated mechanisms, perception, optimization, and large engineering teams. Raibert's historical contribution is a control decomposition and experimental culture, not sole authorship of every later robot or a claim that machines move exactly like animals. ## 2. The problem inherited Static walking methods were slow and brittle, while running and hopping require recovery from underactuated flight and brief ground contact. ## 3. The central contribution Raibert demonstrated that simple feedback laws organized around an alternating spring-like gait can stabilize dynamic one-, two-, and four-legged machines. ## 4. Reconstruct the mechanism 1. Model locomotion as alternating flight and stance phases with the leg behaving approximately like a spring. 2. Control hopping height by adjusting leg thrust or stored energy during stance. 3. Control forward speed by choosing foot placement relative to the projected center of mass. 4. Control body attitude with hip torque and repeat the feedback cycle after every sensed contact and flight state. ## 5. What changed downstream - Dynamic balance enabled faster, more robust legged robots over uneven terrain. - Raibert's laboratory trained a lineage of researchers in experimental locomotion and control. - Boston Dynamics made highly dynamic robots visible in industrial, research, and public contexts. ## 6. Attribution, limits, and uncertainty - Modern Boston Dynamics systems are large multidisciplinary team achievements with mechanisms beyond Raibert's early controllers. - Demonstration videos do not reveal reliability, energy, maintenance, autonomy, payload, or operating constraints. - Military, policing, workplace, privacy, and animal-comparison narratives require separate ethical analysis. ## 7. Reconstruction lab Simulate a one-dimensional spring–mass hopper with an energy controller, then add horizontal foot placement. Perturb velocity and terrain height, plot recovery, and list the sensing/model assumptions hidden by the simulation. ## 8. Evidence trail - [Legged Robots That Balance](https://mitpress.mit.edu/9780262681193/legged-robots-that-balance/) — MIT Press - [Marc Raibert](https://bostondynamics.com/about/) — Boston Dynamics --- *Research checked 2026-08-09. Dates, roles, and claims about living people are historical snapshots. Linked sources remain the authority; this dossier is original instructional synthesis.*