Abstract
This article discusses a concept for developing a vision-based sensing system for measuring the velocity of an object which is based on the concept of apparent size. Objects at a finite distance from the eye look smaller than their real dimension. Movement of the object causes to change in its apparent size. In this work a mathematical relation is obtained which relates infinitesimal change in apparent size to the infinitesimal change in spatial coordinates of the object in the form of an ordinary differential equation. A mechanical device is fabricated for measuring the apparent size. Then by knowing the change in apparent size due to motion, change in displacement is calculated. Experiments were conducted to measure the average velocity of regular shaped object based on the change in its apparent size due to its motion. The average magnitude of error between average velocity calculated from the change in apparent size through the equation and from the actual displacement is about 2% and it is varying in between 0% and 5%. Results show the possibility to develop a vision sensor system to measure the velocity of objects by using high-speed cameras when the real size of the object is known and also it may be possible to develop vision velocity sensors for mobile robot applications.
Highlights
Sensors play a key role in the mechatronic and robotic systems [1]
Velocity is one of the important physical quantities which has to be continuously measured in various mechanical systems such as robotic systems
Various sensors are available as internal (Encoders, LVDT (Linear Variable Differential Transformer), Tachometer, Hall effect sensor and etc.) and external (Proximity, Microwave, Ultrasonic, Vision sensors and etc.) sensors for positioning and velocity measurement in mechanical systems [2]
Summary
Sensors play a key role in the mechatronic and robotic systems [1]. Velocity is one of the important physical quantities which has to be continuously measured in various mechanical systems such as robotic systems. An end effectors position and velocity have to be continuously monitored for the successful operation of the robot [2,3]. Various sensors are available as internal (Encoders, LVDT (Linear Variable Differential Transformer), Tachometer, Hall effect sensor and etc.) and external (Proximity, Microwave, Ultrasonic, Vision sensors and etc.) sensors for positioning and velocity measurement in mechanical systems [2]. We describe a concept to develop a vision-based sensing system for measuring the velocity of the objects which is based on the apparent size of a moving object
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