Passive dynamic walking with flat feet and ankle compliance

Robotica ◽  
2009 ◽  
Vol 28 (3) ◽  
pp. 413-425 ◽  
Author(s):  
Qining Wang ◽  
Yan Huang ◽  
Long Wang

SUMMARYThis paper presents a bipedal locomotion model for passive dynamic walking with flat feet and compliant ankles. The two-dimensional seven-link model extends the simplest walking model with the addition of hip actuation, knee joints, flat feet and torsional springs based compliance on ankle joints, concerning heel-strike and toe-strike transitions, to achieve adaptive bipedal locomotion on level ground with controllable walking speed. We investigate the effects of foot geometric parameters and ankles stiffness on bipedal walking. The model achieves satisfactory walking results not only on even ground but also on uneven terrain with no active control and on different walking velocities. In addition, from the view of stability, there is an optimal foot-ankle ratio of the passivity-based walker. The results can be used to explore further understanding of bipedal walking, and help the design of future intelligent ankle-foot prosthesis and passivity-based robot prototypes towards more practical uses.

Robotica ◽  
2010 ◽  
Vol 29 (3) ◽  
pp. 351-365 ◽  
Author(s):  
Fumihiko Asano ◽  
Zhi-Wei Luo

SUMMARYAchieving energy-efficient and high-speed dynamic walking has become one of the main subjects of research in the area of robotic biped locomotion, and passive dynamic walking has attracted a great deal of attention as a solution to this. It is empirically known that the convex curve of the foot, which characterizes passive–dynamic walkers, has an important effect on increasing the walking speed.This paper mainly discusses our investigations into the driving mechanism for compass-like biped robots and the rolling effect of semicircular feet. We first analyze the mechanism for a planar fully actuated compass-like biped model to clarify the importance of ankle-joint torque by introducing a generalized virtual-gravity concept. A planar underactuated biped model with semicircular feet is then introduced and we demonstrate that virtual passive dynamic walking only by hip-joint torque can be accomplished based on the rolling effect. We then compare the rolling effect with a flat feet model through linear approximation, and show that the rolling effect is equivalent to virtual ankle-joint torque. Throughout this paper, we provide novel insights into how zero-moment-point-free robots can generate a dynamic bipedal gait.


Author(s):  
Kazi Rushdi ◽  
Derek Koop ◽  
Christine Q. Wu

Passive dynamic walking is a gait developed, partially or in whole, by the energy provided by gravity. An improved kneed bipedal walking mechanism was designed and built to study passive gait patterns. The first aim of this study is to determine if testing a passive dynamic biped walker on a ramp is equivalent to testing on a treadmill. Based on the small difference between the gait patterns measured on the two test platforms, testing on a treadmill is equivalent to testing on a ramp. Measurement of the gait parameters were then conducted on the treadmill to evaluate the effects of the treadmill angle of inclination, mass distribution of the biped, treadmill belt speed and length of flat feet. Our experimental results are presented and compared with previous experimental and simulation results. Research on passive dynamic bipedal walking helps to develop an understanding of walking mechanics. Moreover, experimental passive dynamic walking results provide information to validate mathematical models of passive dynamic walking.


Robotica ◽  
2011 ◽  
Vol 30 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Yan Huang ◽  
Qining Wang ◽  
Baojun Chen ◽  
Guangming Xie ◽  
Long Wang

SUMMARYThis paper presents a seven-link dynamic walking model that is more close to human beings than other passivity-based dynamic walking models. We add hip actuation, upper body, flat feet, and ankle joints with torsional springs to the model. Walking sequence of flat-feet walkers has several substreams, which forms bipedal walking with dynamic series of phases. We investigate the effects of ankle stiffness on gait selection and evaluate different gaits in walking velocity, efficiency, and stability. Experimental results indicate that ankle stiffness plays different roles in different gaits and the gaits, which are more close to human walking with moderate speed, achieve better motion characteristics.


2005 ◽  
Vol 02 (04) ◽  
pp. 459-478 ◽  
Author(s):  
MARTIJN WISSE

One of the main challenges in the design of human-like walking robots (useful for service or entertainment applications as well as the study of human locomotion) is to obtain dynamic locomotion, as opposed to the static form of locomotion demonstrated by most of the current prototypes. A promising concept is the idea of passive dynamic walking; even completely unactuated and uncontrolled mechanisms can perform a stable gait when walking down a shallow slope. This concept enables the construction of dynamically walking prototypes that are simpler yet more natural in their motions than the static bipeds. This paper presents three additions to the concept of passive dynamic walking. First, hip actuation is added to increase the fore-aft stability and to provide power to the system, removing the need for a downhill floor. Second, a bisecting hip mechanism is introduced to allow the addition of a passive upper body without compromising the simplicity, efficiency and naturalness of the concept of passive dynamic walking. Third, skateboard-like ankle joints are implemented to provide 3D stability. These ankles couple the unstable sideways lean motion to yaw (steering), a kinematic coupling which provides sideways stability when walking with sufficient forward velocity. The three additions are investigated both with elementary simulation models and with prototype experiments. All three prototypes demonstrate an uncannily natural and stable gait while requiring only two foot switches and three on/off actuators.


Robotica ◽  
2004 ◽  
Vol 22 (3) ◽  
pp. 251-262 ◽  
Author(s):  
Q. Wu ◽  
N. Sabet

A two-straight-legged walking mechanism with flat feet is designed and built to study the passive dynamic gait. It is shown that the mechanism having flat feet can exhibit passive dynamic walking as those with curved feet, but the walking efficiency is significantly lower. It is also shown that the balancing mass and its orientation are effective for controlling side-to-side rocking and yaw, which have significant effects on steady walking. The effects of various parameters on the gait patterns are also studied. lt is shown that changes in the ramp angle have the most dominant effect on the gait pattern as compared with the changes in the hip mass, ramp surface friction and size of the flat feet. More specifically, as the ramp angle increases, the step length increases while the range of the side-to side rocking angle decreases and the step length dictates the walking speed and the gravitational power. Another finding, is that adding a hip mass improves the walking efficiency by allowing the mechanism to walk on a flatter ramp. This research enables us to gain a better understanding of the mechanics of walking. Such an understanding will have a direct impact on better design of prostheses and on the active control aspects of bipedal robots.


2005 ◽  
pp. 787-800 ◽  
Author(s):  
Daan G.E. Hobbelen ◽  
Martijn Wisse

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