Adaptive control of a one-legged hopping robot through dynamically embedded spring-loaded inverted pendulum template
Author
Uyanık, İsmail
Advisor
Morgül, Ömer
Date
2011Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Practical realization of model-based dynamic legged behaviors is substantially
more challenging than statically stable behaviors due to their heavy dependence
on second-order system dynamics. This problem is further aggravated by the dif-
ficulty of accurately measuring or estimating dynamic parameters such as spring
and damping constants for associated models and the fact that such parameters
are prone to change in time due to heavy use and associated material fatigue.
In the first part of this thesis, we present an on-line, model-based adaptive control
method for running with a planar spring-mass hopper based on a once-per-step
parameter correction scheme. Our method can be used both as a system identifi-
cation tool to determine possibly time-varying spring and damping constants of a
miscalibrated system, or as an adaptive controller that can eliminate steady-state
tracking errors through appropriate adjustments on dynamic system parameters.
We use Spring-Loaded Inverted Pendulum (SLIP) model, which is the mostly
used, effective and accurate descriptive tool for running animals of different sizes
and morphologies, to evaluate our algorithm. We present systematic simulation
studies to show that our method can successfully accomplish both accurate tracking
and system identification tasks on this model. Additionally, we extend our
simulations to Torque-Actuated Dissipative Spring-Loaded Inverted Pendulum
(TD-SLIP) model towards its implementation on an actual robot platform.
In the second part of the thesis, we present the design and construction of a onelegged
hopping robot we built to test the practical applicability of our adaptive
control algorithm. We summarize the mechanical, electronics and software design
of our robot as well as the performed system identification studies to calibrate the
unknown system parameters. Finally, we investigate the robot’s motion achieved
by a simple torque-actuated open loop controller.
Keywords
Spring-Mass HopperAdaptive Control
System Identification
Legged Locomotion
Spring-Loaded Inverted Pendulum (SLIP)
Hybrid System