The matched spectrum and correlation characteristics are both important to realize the multichannel ultrasonic sensors working together. The spectrum matching can make full use of the bandwidth of the ultrasonic ranging system, and the good correlation characteristic can eliminate crosstalk among multichannel ultrasonic sensors triggering simultaneously. Linear frequency modulation (LFM) excita...

It is essential to supply electrical power continuously to mobile robots to keep moving. We studied how to make a mobile robot return to a recharging station autonomously by using specially designed ultrasonic sensors when a battery is low. A principle to calculate location and rotation angle of a mobile robot from recharging station was suggested. An anisotropic ultrasonic sensor system, we ca...

The electric wheelchair for handicapped is used to improve the displacement of disabled persons. An automatic navigation system is needed to ensure greater autonomy and security for the disabled person. Automatic control system is added to a manual control for autonomous displacement. Initial system composed of two DC motors installed at the rear of used electric wheelchair, power module for th...

Electronic canopy characterization is an important issue in tree crop management. Ultrasonic and optical sensors are the most used for this purpose. The objective of this work was to assess the performance of an ultrasonic sensor under laboratory and field conditions in order to provide reliable estimations of distance measurements to apple tree canopies. To this purpose, a methodology has been...

Interference between sensors is a serious problem when ultrasonic sensor arrays are used to monitor and to explore the environment. In ultrasonic sensor arrays operating in the pulse-echo mode, the transmitters usually are excited serially by time division multiplexing. The repetition rate of the entire system is limited by the time of flight (TOF) of the pulses. For in-room applications, the T...

The spectrum matching and correlation characteristic are both important in the multiple-user ultrasonic ranging system. As people know, an ultrasonic ranging system, which has a bell-shaped magnitude spectrum, acts like a band-pass filter. If the spectrum of the excitation signal does not match that of the ultrasonic ranging system, some of energy cannot be transmitted by the ultrasonic system....

This paper introduces error eliminating rapid ultrasonic firing (EERUF), a new method for firing multiple ultrasonic sensors in mobile robot applications. EERUF allows ultrasonic sensors to fire at rates that are five to ten times faster than those customary in conventional applications. This is possible because EERUF reduces the number of erroneous readings due to ultrasonic noise by one to tw...

In this study, we have evaluated the ability of ultrasonic sensors to produce guidance signals for greenhouse application robots. First, one high-quality ultrasonic sensor was selected and some basic experiments were carried out. Experimental results showed that with predetermined internal parameters, the accuracy of the selected sensor was good for distances between 15 and 215 cm and angles be...