5,046 research outputs found
Robust Control Theory Based Performance Investigation of an Inverted Pendulum System using Simulink
In this paper, the performance of inverted pendulum have been Investigated using robust control theory. The robust controllers
used in this paper are H∞ Loop Shaping Design Using Glover McFarlane Method and mixed H∞ Loop Shaping Controllers.
The mathematical model of Inverted Pendulum, a DC motor, Cart and Cart driving mechanism have been done successfully.
Comparison of an inverted pendulum with H∞ Loop Shaping Design Using Glover McFarlane Method and H∞ Loop Shaping
Controllers for a control target deviation of an angle from vertical of the inverted pendulum using two input signals (step and
impulse). The simulation result shows that the inverted pendulum with mixed H∞ Loop Shaping Controller to have a small rise
time, settling time and percentage overshoot in the step response and having a good response in the impulse response too.
Finally the inverted pendulum with mixed H∞ Loop Shaping Controller shows the best performance in the overall simulation
result
Feedback control of unsupported standing in paraplegia. Part I: optimal control approach
This is the first of a pair of papers which describe an investigation into the feasibility of providing artificial balance to paraplegics using electrical stimulation of the paralyzed muscles. By bracing the body above the shanks, only stimulation of the plantarflexors is necessary. This arrangement prevents any influence from the intact neuromuscular system above the spinal cord lesion. Here, the authors extend the design of the controllers to a nested-loop LQG (linear quadratic Gaussian) stimulation controller which has ankle moment feedback (inner loops) and inverted pendulum angle feedback (outer loop). Each control loop is tuned by two parameters, the control weighting and an observer rise-time, which together determine the behavior. The nested structure was chosen because it is robust, despite changes in the muscle properties (fatigue) and interference from spasticity
A validation of mobile sensing actigraphy devices for generating a biomechanical model of posture
Mobile sensing actigraphy was tested and validated as a modality for computing dynamic posturography. Twelve healthy volunteer subjects (6 male) were administered risperidone and assessed for postural stability using a NeuroCom® Balance Master system and BioSensics® mobile sensors at baseline, 2 hours, 6 hours, and 24 hours post-dose. A strong positive correlation was shown between BioSensics and Balance Master systems in a modified Sensory Organization Task, with Pearson’s r = 0.76, p < 0.001 on composite equilibrium scores. Strong to moderate correlations during the same task showed r = 0.48, p < 0.001 to r = 0.74, p < 0.001. Mobile sensing actigraphy may be a viable alternative to force plate posturography in assessing drug-induced postural instability
Feedback control of unsupported standing in paraplegia. Part II: experimental results
For pt. I see ibid., vol. 5, no. 4, p. 331-40 (1997). This is the second of a pair of papers which describe an investigation into the feasibility of providing artificial balance to paraplegics using electrical stimulation of the paralyzed muscles. By bracing the body above the shanks, only stimulation of the plantar flexors is necessary. This arrangement prevents any influence from the intact neuromuscular system above the spinal cord lesion. Here, the authors present experimental results from intact and paraplegic subjects
Imprecise dynamic walking with time-projection control
We present a new walking foot-placement controller based on 3LP, a 3D model
of bipedal walking that is composed of three pendulums to simulate falling,
swing and torso dynamics. Taking advantage of linear equations and closed-form
solutions of the 3LP model, our proposed controller projects intermediate
states of the biped back to the beginning of the phase for which a discrete LQR
controller is designed. After the projection, a proper control policy is
generated by this LQR controller and used at the intermediate time. This
control paradigm reacts to disturbances immediately and includes rules to
account for swing dynamics and leg-retraction. We apply it to a simulated Atlas
robot in position-control, always commanded to perform in-place walking. The
stance hip joint in our robot keeps the torso upright to let the robot
naturally fall, and the swing hip joint tracks the desired footstep location.
Combined with simple Center of Pressure (CoP) damping rules in the low-level
controller, our foot-placement enables the robot to recover from strong pushes
and produce periodic walking gaits when subject to persistent sources of
disturbance, externally or internally. These gaits are imprecise, i.e.,
emergent from asymmetry sources rather than precisely imposing a desired
velocity to the robot. Also in extreme conditions, restricting linearity
assumptions of the 3LP model are often violated, but the system remains robust
in our simulations. An extensive analysis of closed-loop eigenvalues, viable
regions and sensitivity to push timings further demonstrate the strengths of
our simple controller
- …