Robotic Hopper Using Phase Oscillator Controller

New, Philip; Wheeler, Chase; Sugar, Thomas G.

doi:10.1115/detc2014-34188

Cited by 7 publications

(5 citation statements)

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“…This work was originally started by Holgate 1 and has now been shown to work for hip exoskeletons, oscillating backpacks, and hopping robots. [2][3][4] Similar work is being developed by Gregg and his research team. 5,6 A. Jan Ijspeert et al, [7][8][9][10] also use a phase-based method to control the motion of an elbow orthosis.…”

Section: Introductionmentioning

confidence: 94%

Phase controller outperforms impedance controller for a hip exoskeleton

Sugar¹,

Redkar²,

Hollander³

2020

MOJABB

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Developing controllers for exoskeletons has many challenging requirements: one of which is creating a torque command based on measured human data that that is in phase with the user (in-synchrony with the human gait). We show that the hip torque for walking gait can be modeled using a phase angle based on hip angular position and velocity. This model is superior to a standard impedance model based on inertia, damping, and stiffness parameters because the phase model uses less parameters and they change linearly with varying speed and weight. The controller has been tested on ten subjects (weighing from 68 to 118kg) wearing the hip exoskeleton walking at speeds from 0.7 to 1.8m/s in outdoor environments.

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Section: Introductionmentioning

confidence: 94%

Phase controller outperforms impedance controller for a hip exoskeleton

Sugar¹,

Redkar²,

Hollander³

2020

MOJABB

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“…A sinusoidal joint trajectory is the simplest form that meets these properties and is the core of Phase Oscillators. Due to their simplicity, Phase Oscillators are extensively used in robotic applications [17][18][19][20]. Moreover, implementing Phase Oscillators using dynamical systems, such as Hopf and Van Der Pol oscillators [21], offers us stable limit cycles with advantageous properties such as smooth convergence behavior; see [22] for application in swimming robots.…”

Section: Related Workmentioning

confidence: 99%

Adaptive Natural Oscillator to exploit natural dynamics for energy efficiency

Khoramshahi

Nasiri

Shushtari

et al. 2017

Robotics and Autonomous Systems

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We present a novel adaptive oscillator, called Adaptive Natural Oscillator (ANO), to exploit the natural dynamics of a given robotic system. This tool is built upon the Adaptive Frequency Oscillator (AFO), and it can be used as a pattern generator in robotic applications such as locomotion systems. In contrast to AFO, that adapts to the frequency of an external signal, ANO adapts the frequency of reference trajectory to the natural dynamics of the given system. In this work, we prove that, in linear systems, ANO converges to the system's natural frequency. Furthermore, we show that this tool exploits the natural dynamics for energy efficiency through minimization of actuator effort. This property makes ANO an appealing tool for energy consumption reduction in cyclic tasks; especially in legged systems. We also extend the proposed adaptation mechanism to high dimensional and general cases; such as n-DOF manipulators. In addition, by investigating a hopper leg in simulation, we show the efficacy of ANO in face of dynamical discontinuities; such as those inherent in legged locomotion. Furthermore, we apply ANO to a simulated compliant robotic manipulator performing a periodic task where the energy consumption is drastically reduced. Finally, the experimental results on a 1-DOF compliant joint show that our adaptive oscillator, despite all practical uncertainties and deviations from theoretical models, exploits the natural dynamics and reduces the energy consumption.

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“…Acceleration and position signal of subject walking on treadmill at 3mph showing that the human"s COM position can be assumed to be sinusoidal By assuming the vertical motion of the trunk to be sinusoidal, position, , velocity, ̇ , and acceleration, ̈ , can be defined in the same way as in the previous modeling shown in equations 3.2 -3.4. Using Working Model 2D, a dynamics simulation software, a human with mass, , can be modeled as a 2nd order system mass-spring-damper system with a linear actuator creating the trunk"s sinusoidal motion [16]- [20]. A back pack can be modeled by adding a mass, , pinned to the trunk, as seen in Figure 10.…”

Section: Pogo Principlesmentioning

confidence: 99%

Load Carrying Assistance Device Pogo Suit

Redkar¹

2016

IJRA

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<span>Wearable robots including exoskeletons, powered prosthetics, and powered orthotics must add energy to the person at an appropriate time to enhance, augment, or supplement human performance. Adding energy while not being in sync with the user can dramatically hurt performance. Many human tasks such as walking, running, and hopping are repeating or cyclic tasks and a robot can add energy in sync with the repeating pattern for assistance. A method has been developed to add energy at the appropriate time to the repeating limit cycle based on a phase oscillator. The phase oscillator eliminates time from the forcing function which is based purely on the motion of the user. This approach has been simulated, implemented and tested in a robotic backpack which facilitates carrying heavy loads. The device oscillates the load of the backpack, based on the motion of the user, in order to add energy at the correct time and thus reduce the amount of energy required for walking with a heavy load. Models were developed in Working Model 2-D, a dynamics simulation software, in conjunction with MATLAB to verify theory and test control methods. The control system developed is robust and has successfully operated on different users, each with their own different and distinct gait. The results of experimental testing validated the corresponding models.</span>

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Robotic Hopper Using Phase Oscillator Controller

Cited by 7 publications

References 0 publications

Phase controller outperforms impedance controller for a hip exoskeleton

Phase controller outperforms impedance controller for a hip exoskeleton

Adaptive Natural Oscillator to exploit natural dynamics for energy efficiency

Load Carrying Assistance Device Pogo Suit

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