High-speed bounding with the MIT Cheetah 2: Control design and experiments

Abstract

This paper presents the design and implementation of a bounding controller for the MIT Cheetah 2 and its experimental results. The paper introduces the architecture of the controller along with the functional roles of its subcomponents. The application of impulse scaling provides feedforward force profiles that automatically adapt across a wide range of speeds. A discrete gait pattern stabilizer maintains the footfall sequence and timing. Continuous feedback is layered to manage balance during the stance phase. Stable hybrid limit cycles are exhibited in simulation using simplified models, and are further validated in untethered three-dimensional bounding experiments. Experiments are conducted both indoors and outdoors on various man-made and natural terrains. The control framework is shown to provide stable bounding in the hardware, at speeds of up to 6.4 m/s and with a minimum total cost of transport of 0.47. These results are unprecedented accomplishments in terms of efficiency and speed in untethered experimental quadruped machines.

Design and experimental implementation of a quasi-direct-drive leg for optimized jumping

“…In contrast, MIT Cheetah [13] has relatively larger linkage length, hence motor speed is not the bottleneck for creating dynamic motions.…”

“…Recently, a new actuator design strategy utilizing a high-torque density electromagnetic actuator and low-gear-ratio gearbox has been introduced by a few researchers [4] (proprioceptive actuator design) [11] (quasi-direct-drive actuator). This design successfully balances between requirements for transparent transmission and high torque generation, providing an actuator design for dynamic robots that achieved diverse dynamic motions including jumping over obstacles [12] and high-speed running [13].…”

Fast and Continuous Foothold Adaptation for Dynamic Locomotion Through CNNs

“…L EGGED platforms have recently gained increasing attention, motivated by the versatility that these machines can offer over a wide variety of terrain and tasks. Quadrupeds in particular are able to perform robust locomotion in the form of statically [1], [2] and dynamically [3], [4] stable gaits. In parallel, sensor fusion techniques have evolved to overcome the harsh conditions typical of field operations on legged machines [5], to provide effective pose and velocity estimates for planning [6], control, and mapping [7], [8].…”

Advances in real‐world applications for legged robots

“…Despite all the advances throughout the DRC, the locomotion performance of humanoid robots is still far behind the performance of multilegged robots in terms of speed, energetic efficiency, and obstacle negotiation skills. Examples of multilegged robots with greater locomotion capabilities include HyQ (Semini et al, ) and its successor HyQ2Max (Semini et al, ), MIT’s Cheetah (Seok et al, ) and Cheetah II (Park, Wensing, & Kim, ), ETH’s StarlETH (Hutter et al, ). Boston Dynamics’ Spot and SpotMini robot, a direct successor to Big Dog (Raibert, Blankespoor, Nelson, & Playter, ) show impressive results of which unfortunately no scientific publications are available.…”