Ultrasonic Sensor Ring Research Articles

Dynamic Motion Planning for Autonomous Wheeled Robot using Minimum Fuzzy Rule based Controller with Avoidance of Moving Obstacles

In this article, the Minimum Fuzzy Rule-Based (MFRB) sensor-actuator controller has designed for dynamic motion planning of a differential drive wheeled robot among the moving, non-moving obstacles and goal in two-dimensional environments. The ring of ultrasonic sensors and infrared sensors have been attached on the front side, left side, and right side of the wheeled robot, which detects the moving obstacles, as well as non-moving obstacles in any environment. This proposed MFRB sensor-actuator controller helps the wheeled robot to move safely in a different scenario. The onboard sensor interpretation data are fed as input to the MFRB controller, and the MFRB controller provides the Pulse Width Modulation (PWM) based wheel velocity commands to both the left and right motors of a wheeled robot. In the numerical simulation and experiment, we have taken one condition that the speed of wheels of the differential drive wheeled robot is at least more than or equal to the rate of the moving obstacles and the moving goal. The numerical simulations are performed through a MATLAB graphical user interface (GUI), and we have used the differential drive wheeled robot to conduct experiments. The presented numerical simulation and experimental results illustrate that the MFRB controller operated wheeled robot has successfully avoided the stationary and non- stationary obstacles in various scenarios.

Semi-autonomous mobility assistance for power wheelchair users navigating crowded environments.

Power wheelchair users suffering from cognitive or physical impairment often face difficulties in maneuvering their wheelchairs through crowded environments. Currently, users need to be continuously aware of all traffic around them to actively avoid all collisions. This is an especially difficult task since many wheelchair users are unable to accurately view or perceive their surroundings. Additionally, imprecise joystick control, slowed reaction time, or imperfect interpretation of the environment can lead to unintended collisions with objects in the environment. This work looks to augment user's input with data gathered from an ultrasonic sensor ring to prevent accidental collisions. Using data gathered from the sensors, we detect objects within a certain radius of the chair. This sensor information is combined with the user input from a joystick to generate a potential field description for the intended motion of the wheelchair. An optimal motion vector is calculated which works to avoid collision with obstacles. Ultimately, this control method reduces the cognitive load on the user and enables them to navigate complex environments by providing simple and/or imprecise input to the system.

중첩 초음파 센서 링의 장애물 탐지 성능 지표 비교 분석

This paper presents a comparative analysis on three different types of performance indices of obstacle detection for an overlapped ultrasonic sensor ring. Due to beam overlap, the entire sensing zone of each ultrasonic sensor can be divided into three smaller sensing subzones, which leads to significant reduction of positional uncertainty in obstacle detection. First, the positional uncertainty in obstacle detection is expressed in terms of the area of a sensing subzone, and type 1 performance index is then defined as the area ratio of side and center sensing subzones. Second, based on the area of a sensing subzone, type 2 performance index is defined taking into account the size of the entire range of obstacle detection as well as the degree of the positional uncertainty in obstacle detection. Third, the positional uncertainty in obstacle detection is now expressed in terms of the length of the uncertainty arc spanning a sensing subzone, and type 3 performance index is then defined as the average value of the uncertainty arc lengths over the entire range of obstacle detection. Fourth, using a commercial low directivity ultrasonic sensor, the changes of three different performance indices depending on the parameter of an overlapped ultrasonic sensor ring are examined and compared.

고분해능 장애물 탐지를 위한 중첩 초음파 센서 링의 최적 설계

This paper presents the optimal design of an overlapped ultrasonic sensor ring for high resolution obstacle detection of an autonomous mobile robot. It is assumed that a set of low directivity ultrasonic sensors of the same type are arranged along a circle of nonzero radius at a regular spacing with their beams overlapped. First, taking into account the dead angle region, the entire range of obstacle detection is determined with reference to the center of an overlapped ultrasonic sensor ring. Second, the optimal design index of an overlapped ultrasonic sensor ring is defined as the area closeness of three sensing subzones resulting from beam overlap. Third, the lower and upper bounds on the number of ultrasonic sensors are derived, which can guarantee minimal beam overlap and also avoid excessive beam overlap among adjacent ultrasonic sensors. Fourth, employing a commercial low directivity ultrasonic sensor, an optimal design example of an overlapped ultrasonic sensor ring is given along with the ultrasonic sensor ring prototype mounted on top of a mobile robot. Finally, some experimental results using our prototype ultrasonic sensor ring are given to demonstrate the validity and performance of an optimally overlapped ultrasonic sensor ring for high resolution obstacle detection.

Optimally overlapped ultrasonic sensor ring design for minimal positional uncertainty in obstacle detection

This paper presents the optimal overlapping arrangement of a circular array of ultrasonic sensors for minimal positional uncertainty in obstacle detection. First, it is shown that beam overlap among three adjacent ultrasonic sensors leads to significant reduction of positional uncertainty. Second, the positional uncertainty of an overlapped ultrasonic sensor ring is compared to a single ultrasonic sensor in terms of a collision-free region with obstacles. Third, the optimal design index for an overlapped ultrasonic sensor ring is defined as the area closest between the non-overlapped and overlapped sensing sub-zones. Fourth, using commercial low directivity ultrasonic sensors, an optimally overlapped ultrasonic sensor ring is given along with its prototype installed on top of a mobile robot. Finally, experimental results are given to demonstrate the validity and performance of our overlapped ultrasonic sensor ring prototype.

ALEF: An autonomous vehicle which learns basic skills and constructs maps for navigation

Abstract This paper introduces a control system for a mobile robot which provides learning for two essential kinds of knowledge representation: internal world models and internal abstract concepts. Concretely, learning methods are applied to evolve basic skills (goal oriented driving and collision avoidance) and to generate maps of the environment, even if the mobile robot acts in an a-priori unknown environment and no external navigation aids (like beacons) are used. Results of experiments are presented performed with a real mobile robot equipped with simple and inaccurate sensors (a ring of ultrasonic sensors and goniometers on the wheel axles).

Echolocation — From range to outline segments

A ring of ultrasonic sensors mounted on a mobile robot is used to map a room. The sensors are modelled with an arc model: the object causing the reflection lies on an arc with radius equal to the range and arc angle equal to twice the beam angle. By fusing sensing with motion, a surface is displayed as a sequence of arcs. In this paper, the algorithm for obtaining outline segments from the arcs is presented.