Abstract-This paper presents the design principles for highly efficient legged robots, the implementation of the principles in the design of the MIT Cheetah, and the analysis of the high-speed trotting experimental results. The design principles were derived by analyzing three major energy-loss mechanisms in locomotion: heat losses from the actuators, friction losses in transmission, and the interaction losses caused by the interface between the system and the environment. Four design principles that minimize these losses are discussed: employment of high torque density motors, energy regenerative electronic system, low loss transmission, and a low leg inertia. These principles were implemented in the design of the MIT Cheetah; the major design features are large gap diameter motors, regenerative electric motor drivers, single-stage low gear transmission, dual coaxial motors with composite legs, and the differential actuated spine. The experimental results of fast trotting are presented; the 33kg robot runs at 22 km/h (6 m/s). The total power consumption from the battery pack was 973 watts and resulted in a total cost of transport of 0.5, which rivals running animals' at the same scale. The 76% of total energy consumption is attributed to heat loss from the motor, and the 24% is used in mechanical work, which is dissipated as interaction loss as well as friction losses at the joint and transmission.

A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low power electronic systems. The energy is transduced through the use of a variable capacitor. Using microelectromechanical systems (MEMS) technology, such a device has been designed for the system. A low-power controller IC has been fabricated in a 0.6-m CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce 8 W of usable power. In addition to the fabricated programmable controller, an ultra low-power delay locked loop (DLL)-based system capable of autonomously achieving a steady-state lock to the vibration frequency is described.

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A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) technology. A low-power controller IC has been fabricated in a 0.6pm CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce SpW of usable power.