Afocal Optical Flow Sensor for Reducing Vertical Height Sensitivity in Indoor Robot Localization and Navigation

Abstract

This paper introduces a novel afocal optical flow sensor (OFS) system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length) system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively.

Optical Mouse Sensor for Eye Blink Detection and Pupil Tracking: Application in a Low-Cost Eye-Controlled Pointing Device

“…The optical mouse sensors, which were originally designed as the computer's mouse main sensor, are widely used in many scenarios to estimate the relative displacement of the surface under the sensor [34][35][36][37][38]. In [38], it was used to estimate the translation of the eye analyzing the scleral surface.…”

Optical Flow Sensor/INS/Magnetometer Integrated Navigation System for MAV in GPS-Denied Environment

“…Due to the drawbacks of GPS and INS, lots of novel navigation devices have been studied. For example, optical flow sensor has been proved which can provide reliable velocity and position information when applied for robot localization or navigation [10,11]. Optical flow techniques are motivated by bird and insect flights which are used to solve the navigation problem.…”

Optic-flow based car-like robot operating in a 5-decade light level range

“…Several approaches based on visual odometry have therefore been recently developed, using standard cameras [3], [4] and optical-mouse sensors [5], [6] as well as custom-made optic flow (OF) sensors [7], [8]. In particular, applications using downward-facing visual sensors have been widely used to estimate the velocity and the distance traveled, since the visual patterns and light conditions encountered are more uniform, and they make it possible to use visual sensors such as optical mice.…”

“…Solutions based on custom laser or LED-lighted OF sensors, such as those presented in [7], [8], have been developed in order to reduce the sensitivity to height and improve the performances while traveling over terrains of various kinds, but no tests were run by these authors under various lighting conditions and under the robot's normal driving conditions. Several versions of Local Motion Sensors (LMSs) providing alternative solutions to standard visual sensors have been developed at our laboratory [9]- [12] to obtain 1-D OF measurements in various velocity and luminosity ranges, using methods based on findings obtained on the fly's visual system [13].…”