Analysis of fast bipedal walking using mechanism of actively controlled wobbling mass

In this study, a novel approach was developed to achieve fast bipedal walking by using an actively controlled wobbling mass. Bipedal robots capable of achieving energy efficient limit cycle walking have been developed, and researchers have studied methods to increase their walking speed. When humans walk, their arm swinging is coordinated with the walking phases, generating a regular symmetrical motion about the torso. The bipedal robots with a wobbling mass in the torso mimicked the arm swinging by the proposed control method. We demonstrated that the proposed method is capable of increasing the bipedal walking speed

Parametric excitation-based inverse bending gait generation

In a gait generation method based on the parametric excitation principle, appropriate motion of the center of mass restores kinetic energy lost by heel strike. The motion is realized by bending and stretching a swing-leg regardless of bending direction. In this paper, we first show that inverse bending restores more mechanical energy than forward bending, and then propose a parametric excitation-based inverse bending gait for a kneed biped robot, which improves gait efficiency of parametric excitation walking

A novel mathematical formulation for predicting symmetric passive bipedal walking motion with unbalanced masses

Commercial prosthetic feet weigh about 25% of their equivalent physiological counterparts. The human body is able to overcome the walking asymmetry resulting from this mass imbalance by exerting more energy. It is hypothesised that the passive walking dynamics coupled with roll-over shapes has potential to suggest energy efficient walking solutions. A two link passive walking kinematic model has been proposed to study the gait pattern with unbalanced leg masses. An optimal roll-over shape for the prosthetic foot that minimises the asymmetry in the inter-leg angle and the step period is determined. The proposed mathematical formulation provides insights into the variation of step length and inter-leg angle with respect to the position and location of the centres for mass of both prosthetic and physiological legs

Design and control of a soccer-playing humanoid robot

Master'sMASTER OF ENGINEERIN

The Effect on Postural Balance as a Result of Different Types of Golf-Specific Footwear Over an Extended Duration

The sport of golf is increasingly popular within the United States, with an estimated 35 million participants worldwide. To be successful, the golf swing, regarded as a difficult biomechanical motion to accomplish, needs to be accurate and powerful. A proper swing incorporates a weight shift from the rear foot to the leading foot, which indicates that balance is crucial to maintain. The purpose of this study was to examine the effect of golf-specific footwear on static balance over an extended duration in order to relate it to golf performance. Twelve recreationally trained males (age: 23.4±2.2 years; height: 181.5±9.0cm; mass 95.8±18.6 kg) with no history of injuries or disorders participated in the study. The study lasted about four days, which included a familiarization day, and experimental days lasting around four hours each. Static balance was assessed by equilibrium scores using the NeuroCom Equitest Sensory Organizational Test (EO, EC, EOSRV, EOSRP). The conditions were counterbalanced prior to the start of the experimental days, which included a dress shoe style (DS), a minimalist shoe style (MIN), and a tennis shoe style (TS), with a barefoot condition (BF) as the control variable. A predetermined alpha level of 0.05 was used, and results were analyzed using a 4x5 repeated measures ANOVA [4 footwear conditions (BF, DS, MIN, TS) x 5 measurement times (pre, 60, 120, 180, 240)]. There was a significant interaction, within the EC condition, detected at the three-hour mark, where the DS condition indicated an impairment in balance control compared to the BF condition. However, there was no indication of significance among the golf-specific footwear. This expresses the fact that may have the ability to choose golf-specific footwear according to preference without worrying about static balance detriments

System Identification of Bipedal Locomotion in Robots and Humans

The ability to perform a healthy walking gait can be altered in numerous cases due to gait disorder related pathologies. The latter could lead to partial or complete mobility loss, which affects the patients’ quality of life. Wearable exoskeletons and active prosthetics have been considered as a key component to remedy this mobility loss. The control of such devices knows numerous challenges that are yet to be addressed. As opposed to fixed trajectories control, real-time adaptive reference generation control is likely to provide the wearer with more intent control over the powered device. We propose a novel gait pattern generator for the control of such devices, taking advantage of the inter-joint coordination in the human gait. Our proposed method puts the user in the control loop as it maps the motion of healthy limbs to that of the affected one. To design such control strategy, it is critical to understand the dynamics behind bipedal walking. We begin by studying the simple compass gait walker. We examine the well-known Virtual Constraints method of controlling bipedal robots in the image of the compass gait. In addition, we provide both the mechanical and control design of an affordable research platform for bipedal dynamic walking. We then extend the concept of virtual constraints to human locomotion, where we investigate the accuracy of predicting lower limb joints angular position and velocity from the motion of the other limbs. Data from nine healthy subjects performing specific locomotion tasks were collected and are made available online. A successful prediction of the hip, knee, and ankle joints was achieved in different scenarios. It was also found that the motion of the cane alone has sufficient information to help predict good trajectories for the lower limb in stairs ascent. Better estimates were obtained using additional information from arm joints. We also explored the prediction of knee and ankle trajectories from the motion of the hip joints

Stability analysis and control for bipedal locomotion using energy methods

In this thesis, we investigate the stability of limit cycles of passive dynamic walking. The formation process of the limit cycles is approached from the view of energy interaction. We introduce for the first time the notion of the energy portrait analysis originated from the phase portrait. The energy plane is spanned by the total energy of the system and its derivative, and different energy trajectories represent the energy portrait in the plane. One of the advantages of this method is that the stability of the limit cycles can be easily shown in a 2D plane regardless of the dimension of the system. The energy portrait of passive dynamic walking reveals that the limit cycles are formed by the interaction between energy loss and energy gain during each cycle, and they are equal at equilibria in the energy plane. In addition, the energy portrait is exploited to examine the existence of semi-passive limit cycles generated using the energy supply only at the take-off phase. It is shown that the energy interaction at the ground contact compensates for the energy supply, which makes the total energy invariant yielding limit cycles. This result means that new limit cycles can be generated according to the energy supply without changing the ground slope, and level ground walking, whose energy gain at the contact phase is always zero, can be achieved without actuation during the swing phase. We design multiple switching controllers by virtue of this property to increase the basin of attraction. Multiple limit cycles are linearized using the Poincare map method, and the feedback gains are computed taking into account the robustness and actuator saturation. Once a trajectory diverges from a basin of attraction, we switch the current controller to one that includes the trajectory in its basin of attraction. Numerical simulations confirm that a set of limit cycles can be used to increase the basin of attraction further by switching the controllers one after another. To enhance our knowledge of the limit cycles, we performed sophisticated simulations and found all stable and unstable limit cycles from the various ground slopes not only for the symmetric legs but also for the unequal legs that cause gait asymmetries. As a result, we present a novel classification of the passive limit cycles showing six distinct groups that are consecutive and cyclical

Energetics of an Inertia Coupled and Simple Rimless Wheel

It has been shown by others that it is theoretically possible for a walking robot to achieve a perfectly efficient gait. The simplest model capable of highly efficient walking motions is the Inertial Coupled Rimless (ICR) Wheel. To examine the dynamics of the ICR wheel, two related studies were done. To determine the lowest energy cost for the ICR wheel we examined one mechanism of energy loss, non-elastic deformation of the elastic elements. Quasi-static experimental tension tests determined that the minimal energy loss for our system was 8:4x10�4 Joules per cycle. A more realistic, high frequency test, showed that the energy loss increased by a factor of 9.16. The ICR wheel walks down a ramp which is assumed to be very at. But no surface in reality can be perfectly at. For a more realistic study, rough terrain is introduced to the ramp. To better understand the dynamics of the motion of the ICR wheel, a simple rimless (SR) wheel is examined on a ramp with roughness. The roughness of the ground is randomly generated but bounded in magnitude. The minimum angle of inclination required for a rimless wheel to walk down both smooth and rough ramps is determined. For the rimless wheel we examined with 5 legs, the minimum slope required for a rough surface is 12.4% higher than that required for a smooth surface, and for 10 legs, the minimum slope for a rough surface is 40.83% higher than the smooth surface. This work has formed the foundation for the design of an energy efficient walking robot and has given insight into its behavior over rough terrain

Endurance running and the evolution of Homo.

Striding bipedalism is a key derived behaviour of hominids that possibly originated soon after the divergence of the chimpanzee and human lineages. Although bipedal gaits include walking and running, running is generally considered to have played no major role in human evolution because humans, like apes, are poor sprinters compared to most quadrupeds. Here we assess how well humans perform at sustained long-distance running, and review the physiological and anatomical bases of endurance running capabilities in humans and other mammals. Judged by several criteria, humans perform remarkably well at endurance running, thanks to a diverse array of features, many of which leave traces in the skeleton. The fossil evidence of these features suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years ago, and may have been instrumental in the evolution of the human body form. M ost research on the evolution of human locomotion has focused on walking. There are a few indications that the earliest-known hominids were bipeds 1,2 , and there is abundant fossil evidence that australopithecines habitually walked by at least 4.4 million years (Myr) ago However, although humans are comparatively poor sprinters, they also engage in a different type of running, endurance running (ER), defined as running many kilometres over extended time periods using aerobic metabolism. Although not extensively studied in non-humans, ER is unique to humans among primates, and uncommon among quadrupedal mammals other than social carnivores (such as dogs and hyenas) and migratory ungulates (such as wildebeest and horses) How well do humans run long distances? In considering human running, it helps to start from the perspective of the basic biomechanical differences that distinguish running and walking gaits in all mammals, including human bipeds. These differences are well characterized. Walking uses an 'inverted pendulum' in which the centre of mass vaults over a relatively extended leg during the stance phase, efficiently exchanging potential and kinetic energy out-of-phase with every ste