Design and control of a planar bipedal robot ERNIE with parallel knee compliance

Abstract

This paper presents the development of the planar bipedal robot ERNIE as well as numerical and experimental studies of the influence of parallel knee joint compliance on the energetic efficiency of walking in ERNIE. ERNIE has 5 links-a torso, two femurs and two tibias-and is configured to walk on a treadmill so that it can walk indefinitely in a confined space. Springs can be attached across the knee joints in parallel with the knee actuators. The hybrid zero dynamics framework serves as the basis for control of ERNIE's walking. In the investigation of the effects of compliance on the energetic efficiency of walking, four cases were studied: one without springs and three with springs of different stiffnesses and preloads. It was found that for low-speed walking, the addition of soft springs may be used to increase Electronic supplementary material The online version of this article (http://dx.energetic efficiency, while stiffer springs decrease the energetic efficiency. For high-speed walking, the addition of either soft or stiff springs increases the energetic efficiency of walking, while stiffer springs improve the energetic efficiency more than do softer springs.

Maneuver based design of a passive-assist device for augmenting linear motion drives

“…One way more energy can be saved is if the maneuver and PAD are designed together. Significant research has gone into the simultaneous optimization of springs and gait designs in walking robots [18], [24]. These works demonstrate the potential advantages of simultaneous maneuver and spring optimization including the performance of simultaneous optimization vs sequential optimization [24].…”

“…Applications for static balancing include industrial robots [14], [15], exoskeletons [16], [17], as well as non-robotic devices including an architect's desk lamp and a garage door assembly. Parallel springs can also be used to capture and release kinetic energy to make walking robots more efficient [18]. Static balancing only considers the weight distribution and kinematics of the system.…”

Natural dynamics modification for energy efficiency: A data-driven parallel compliance design method

“…The same cost function is used in [14] to optimize the knee compliance of bipedal robot. Other cost functions, such as torque square ( [17]), are also used for compliance design.…”

“…In both bipedal and quadrupedal systems, leg compliance can absorb ground impacts and help to use the energy for stable locomotion ( [13]). In bipedal robots, adding parallel compliance to knee joints can result in energy efficiency ( [14]). Recent researches show that compliance in spinal joint of a quadruped can lead to better behavior ( [1], [15], and [16]).…”

Velocity disturbance rejection for planar bipeds walking with HZD-based control

“…Generating the heuristics based on simulations of a simplified model grounds the rules in theory rather than an ad-hoc approach. This paper designs and experimentally validates such a heuristic-based controller for the five-link biped ERNIE [17] in Fig. 1, whose physical parameters with curved feet installed [18] are listed in Table I. II.…”