26-03-2012, 01:20 PM
An Embedded Control System for Intelligent Wheelchair
[attachment=18952]
INTRODUCTION
intelligent robots are currently developed to help disabled
and handicapped people at a high speed, and will be a
certain key area in the next 10 years. Since the average age
in our society is increasing notably in recent years (Huaqing
He et al, 2003), the number of people with severe motion
impairments is increasing. The expenditure for health care
and nursing is becoming a big burden for our society. On the
other hand, the nursing staff is continuously reduced by the
government and health authority in order to cut the cost.
Therefore individual healthcare is becoming more expensive
than before and people with medium and lower income are
unable to afford such service.
HARDWARE STRUCTURE
A. Mechanical structure of iWheelchair
Fig. 1 shows the mechanical structure of iWheelchair,
which is similar to a commercial power chair and is driven
by its two differentially-driven wheels. In order to deal with
uncertainty in the real world, it is equipped with 8 ultrasonic
sensors for obstacle avoidance.. Instead of using an x86
CPU and Windows operating system, a DSP (digital signal
processor) based embedded control system is developed for
the iWheelChair. The hardware architecture of the controller
B. Architecture of control module
A DSP chip TMS320LF2407 (Heping Liu et al, 2002)
from TI Corp is used as the core processor of the control
module. Note that all the circuits for iWheelchair control are
integrated on a single board.
Environment information processing
In this module, ultrasonic sensor readings are processed
and then the corresponding mode is set. Considering that the
maximal detecting range of the ultrasonic sensors is 2m, the
space around iWheelchair is divided into 4 modes according
to the distance from the wheelchair, which are No-obstacle
mode (above 2m), Detected mode (1m~2m), Approaching
mode (50cm~1m), and Stop mode (0~50cm). More
specifically, we have
IV. EXPERIMENTAL RESULTS
To test the effectiveness of the developed system, an
experiment is designed for iWheelchair. An obstacle is put
in the center of the room, as shown in Fig. 5(a). When the
user is driving the iWheelchair toward the obstacle and the
distance between iWheelchair and the obstacle is in a range
of 2m, the controller of iWheelchair is set to Detected mode
(the maximal speed is 0.8m/s) automatically, as shown in
Fig. 5(b). When iWheelchair is approaching to the obstacle,
V. CONCLUSION
This paper describes the hardware architecture and
control strategy of a newly developed intelligent wheelchair,
iWheelchair. Based on the DSP techniques, the controller of
iWheelchair is quite compact and has a good performance
and real-time response. Our iWheelChair has a high
performance-price ratio and is competitive in the
commercial market.
[attachment=18952]
INTRODUCTION
intelligent robots are currently developed to help disabled
and handicapped people at a high speed, and will be a
certain key area in the next 10 years. Since the average age
in our society is increasing notably in recent years (Huaqing
He et al, 2003), the number of people with severe motion
impairments is increasing. The expenditure for health care
and nursing is becoming a big burden for our society. On the
other hand, the nursing staff is continuously reduced by the
government and health authority in order to cut the cost.
Therefore individual healthcare is becoming more expensive
than before and people with medium and lower income are
unable to afford such service.
HARDWARE STRUCTURE
A. Mechanical structure of iWheelchair
Fig. 1 shows the mechanical structure of iWheelchair,
which is similar to a commercial power chair and is driven
by its two differentially-driven wheels. In order to deal with
uncertainty in the real world, it is equipped with 8 ultrasonic
sensors for obstacle avoidance.. Instead of using an x86
CPU and Windows operating system, a DSP (digital signal
processor) based embedded control system is developed for
the iWheelChair. The hardware architecture of the controller
B. Architecture of control module
A DSP chip TMS320LF2407 (Heping Liu et al, 2002)
from TI Corp is used as the core processor of the control
module. Note that all the circuits for iWheelchair control are
integrated on a single board.
Environment information processing
In this module, ultrasonic sensor readings are processed
and then the corresponding mode is set. Considering that the
maximal detecting range of the ultrasonic sensors is 2m, the
space around iWheelchair is divided into 4 modes according
to the distance from the wheelchair, which are No-obstacle
mode (above 2m), Detected mode (1m~2m), Approaching
mode (50cm~1m), and Stop mode (0~50cm). More
specifically, we have
IV. EXPERIMENTAL RESULTS
To test the effectiveness of the developed system, an
experiment is designed for iWheelchair. An obstacle is put
in the center of the room, as shown in Fig. 5(a). When the
user is driving the iWheelchair toward the obstacle and the
distance between iWheelchair and the obstacle is in a range
of 2m, the controller of iWheelchair is set to Detected mode
(the maximal speed is 0.8m/s) automatically, as shown in
Fig. 5(b). When iWheelchair is approaching to the obstacle,
V. CONCLUSION
This paper describes the hardware architecture and
control strategy of a newly developed intelligent wheelchair,
iWheelchair. Based on the DSP techniques, the controller of
iWheelchair is quite compact and has a good performance
and real-time response. Our iWheelChair has a high
performance-price ratio and is competitive in the
commercial market.