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. 2009 Dec;31(10):1244-54.
doi: 10.1016/j.medengphy.2009.08.002. Epub 2009 Sep 4.

Real-time model based electrical powered wheelchair control

Hongwu Wang  1 , Benjamin Salatin, Garrett G Grindle, Dan Ding, Rory A Cooper
Affiliations

Real-time model based electrical powered wheelchair control

Hongwu Wang et al. Med Eng Phys. 2009 Dec.

Abstract

The purpose of this study was to evaluate the effects of three different control methods on driving speed variation and wheel slip of an electric-powered wheelchair (EPW). A kinematic model as well as 3D dynamic model was developed to control the velocity and traction of the wheelchair. A smart wheelchair platform was designed and built with a computerized controller and encoders to record wheel speeds and to detect the slip. A model based, a proportional-integral-derivative (PID) and an open-loop controller were applied with the EPW driving on four different surfaces at three specified speeds. The speed errors, variation, rise time, settling time and slip coefficient were calculated and compared for a speed step-response input. Experimental results showed that model based control performed best on all surfaces across the speeds.

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Figures

Figure 1
Figure 1
Conceptual model of a wheelchair on an inclined surface with cross slope
Figure 2
Figure 2
wheelchair axis systems on a slope showing OAP as the slope surface, C represents the wheelchair, α (up/downhill slope of surface) and β (side slope of surface) associated with the surface, γ (slope along line of EPW motion) and φ (cross-slope to EPW motion) associated with the wheelchair, and the EPW direction θ
Figure 3
Figure 3
Mathematical representatives of different views of a wheelchair on a slope
Figure 4
Figure 4
Open-loop and closed-loop control systems for the model based control of a wheelchair
Figure 5
Figure 5
the smart wheelchair platform used in this experiment
Figure 6
Figure 6
Five difference surfaces on which the experiment was conducted.
Figure 7
Figure 7
A example figure of two driving wheels and caster speeds with different controllers applied at low and high speeds on a grass surface.
Figure 8
Figure 8
Slip coefficients of three controllers with the wheelchair driving on grass at 2 m/s.
Figure 9
Figure 9
Wheelchair performances with three controllers at three different speeds.
Figure 9
Figure 9
Wheelchair performances with three controllers at three different speeds.
Figure 9
Figure 9
Wheelchair performances with three controllers at three different speeds.
Figure 9
Figure 9
Wheelchair performances with three controllers at three different speeds.
Figure 9
Figure 9
Wheelchair performances with three controllers at three different speeds.
Figure 10
Figure 10
Wheelchair performances with three controllers on five different surfaces
Figure 10
Figure 10
Wheelchair performances with three controllers on five different surfaces
Figure 10
Figure 10
Wheelchair performances with three controllers on five different surfaces
Figure 10
Figure 10
Wheelchair performances with three controllers on five different surfaces
Figure 10
Figure 10
Wheelchair performances with three controllers on five different surfaces
Figure 11
Figure 11
Slip measurements with three different controllers: open loop, PID and model based control
See this image and copyright information in PMC

References

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