 MIT Cheetah robot

The MIT Cheetah robot is an electrically actuated quadrupedal robot research platform used to investigate dynamic legged locomotion and control. Specific demonstrations must be identified by version and experiment. In the primary MIT account of a 2015 running-jump demonstration, onboard Lidar estimated obstacle height and distance, software adjusted the approach strides, and a subsequent calculation selected the jumping action.^[ref]

The experiment connects perception to physical contact. Detecting an obstacle does not by itself establish a feasible jump: the machine must reach a suitable takeoff state and supply forces within its motor and ground-contact constraints. Computation is performed while the robot approaches the obstacle, so available decision time is also a physical constraint.

An original ballistic approximation illustrates one requirement. If the center of mass must rise $\Delta h$ after takeoff, with gravity the only vertical force during flight, its launch velocity must satisfyFor $\Delta h=0.20\mathrm{m}$, this is about $1.98m/s$. If the vertical velocity starts at zero and that change is generated over $0.10\mathrm{s}$ of contact, vertical impulse balance givesThese values are illustrative requirements for the stated center-of-mass model, not measured MIT parameters. Foot clearance, body orientation, leg motion and landing cannot be inferred from this one vertical calculation.

The primary report describes tests on both a treadmill and an indoor track. The available approach distance differed, and the reported clearance success differed as well. This makes the observation conditional on apparatus and trial conditions rather than a universal performance figure.^[ref]

The scientific value of the platform is that a proposed controller has to close the loop through actual motors, contacts and sensor estimates. Successful trials demonstrate a capability in the tested conditions; robustness to other surfaces, disturbances or obstacles requires additional experiments.