Small Autonomous Mobile Robot Research Articles

Design, Fabrication, and Experimental Investigation of Screw Auger Type Feed Mechanism for a Robotic Wheat Drill

Highlights An auger-type feed mechanism was designed for a robotic wheat drill, and a laboratory investigation was carried out. To avoid seed blockage, the recommended screw auger pitch must be at least 150% of the maximum seed dimension. The performance of the feed mechanism was influenced by auger speed, vibration, and slope. This study delivered a bulk feed mechanism for wheat drilling, which can be easily scaled and adopted by small autonomous vehicles or mobile robots. Abstract. Cultivating the arable, highly sloped hills and uneven terrain is challenging and unsafe with large agricultural machines. Therefore, a fleet of small autonomous ground vehicles (AGVs) was proposed to farm sloped or uneven terrain. The fleets need a robotic grain drill to operate on varying slopes, and the success of the fleet depends on the performance of the robotic seeder or grain drill. The feed mechanism is the heart of the seeder, and its design and performance influence the plant population and crop yield. In this study, we designed and fabricated an auger-type feed mechanism for robotic wheat drilling. Feed mechanisms with augers having three different pitches were developed as per the ASABE standards. The developed feed mechanism was investigated in a laboratory setup for flow rate and flow uniformity in accordance with ISO standards. The predictor variables were auger type (pitch), auger rotational speed, vibration, and slope. The auger flow rate for flat slopes was a linear function of auger speed and varied from 30 g/min to 170 g/min. The coefficient of variation (CV) for the flow rate ranged from 2% to 10%. The CV was within acceptable limits, which was an excellent indicator of the bulk feed mechanism's flow uniformity. The performance of the feed mechanism was influenced by vibration and slope. However, the auger flow rate remained constant for vibration frequencies of 0, 6, and 14 Hz, suggesting that the feed mechanism was vibration-proof and could tolerate the vibration frequency up to 14 Hz. The flat, downhill (descending), and uphill (ascending) slope levels did not affect the feed mechanism performance. However, the side slopes (right and left slope) significantly affected the feed mechanism flow rate but did not affect the flow uniformity. The study also developed a feed mechanism for a sloped-ground prototype seeder, which can be easily scaled and adopted by small autonomous vehicles or mobile robots. Keywords: Flow rate, Flow uniformity, Multi-robot, Robotic seed drill, Screw auger, Seed rate.

A Modular Real-Time Fieldbus Architecture for Mobile Robotic Platforms

The design and construction of complex and reconfigurable embedded systems such as small autonomous mobile robots is a challenging task that involves the selection, interfacing, and programming of a large number of sensors and actuators. Facilitating this tedious process requires modularity and extensibility both in hardware and software components. In this paper, we introduce the universal robot bus (URB), a real-time fieldbus architecture that facilitates rapid integration of heterogeneous sensor and actuator nodes to a central processing unit (CPU) while providing a software abstraction that eliminates complications arising from the lack of hardware homogeneity. Motivated by our primary application area of mobile robotics, URB is designed to be very lightweight and efficient, with real-time support for Recommended Standard (RS) 232 or universal serial bus connections to a central computer and inter-integrated circuit (I <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> C), controller area network, or RS485 bus connections to embedded nodes. It supports automatic synchronization of data acquisition across multiple nodes, provides high data bandwidth at low deterministic latencies, and includes flexible libraries for modular software development both for local nodes and the CPU. This paper describes the design of the URB architecture, provides a careful experimental characterization of its performance, and demonstrates its utility in the context of its deployment in a legged robot platform.

Development of a Low Cost High Speed Stereo Vision System for Embeded Use Using CMOS Imagers and DSP

We developped a low cost high speed stereo vision system for embeded use using CMOS imagers on the market and TI DSP(Digital Signal Processor) board that can capture subframe images in shorter period than video rate. Because the proposed system is small, low enegy consumption and low cost, it is suitable for embeded use or small autonomous mobile robot. Some experiments demonstrate that this vision system can capture 96[pixel]×96[pixel] image in 1[ms] period and detect the target position and track the target in 3[ms] period.

Preservation and Utilization of Reinforcement Learning Robot's Strategies Using Probablistic Networks

Reinforcement learning (RL) has been proven to be a promising approach to behavior acquisition of an autonomous robot. However, it holds the unwanted character of over-fitting such that a RL robot often loses its stable behavior to a change occurred in an environment after successful learning. To overcome this problem, we propose the mechanism for a robot that transforms an implicit knowledge collected as a result of RL into the form of a probabilistic network model as an explicit knowledge and preserves it for future use. We expects that a robot tends to show more robust behavior against various changes in an environment with the increase of the knowledges. The computer simulations are conducted to illustrate the effectiveness of the proposed knowledge collecting mechanism. The physical experiments with a small autonomous mobile robot called Khepera are also examined to validate the effectiveness of the proposed method.

A sound localizer for reverberant environments

This paper proposes an intelligent acoustic sensor able to localize sound sources in acoustic environments with strong reverberation. The proposed system is inspired on the precedence effect used by the human auditory system and uses only two acoustic sensors. It implements a modified version of the algorithm proposed by (Huang etal. 1999a) that uses the precedence effect in order to achieve robust sound localization even in reverberant environments. The system was tested on a small autonomous mobile robot programmed to chase an arbitrary sound source. Several experiments were carried out to characterize its performance. Other possible applications of the system are, for example, the automatic orientation of a directional microphone or a video camera to a direction of interest, e.g. toward an interacting human, or an intruder in a protected area.

AAAI Hosts the national botball tournament

Botball is a national program in which teams of middle and high school students design, build, and program small autonomous mobile robots to compete in a highly charged interactive (but non-destructive) tournament. Botball students learn to program in c, construct feedback and control loops, create electromechanical systems, and integrate it all together while they work on a team. Botball takes place in regional tournaments across the country and culminates in a National Botball Tournament traditionally hosted by the American Association for Artificial Intelligence at its annual conference. This program puts reusable equipment into schools and, at the Botball Teacher Workshops, trains teachers in robotics and the integration of robotics into their curriculum. Botball appeals to a wide variety of students and brings out the best in each, challenging them to solve real-world problems in a dynamic environment at their own level.

Faster learning of control parameters through sharing experiences of autonomous mobile robots

This paper describes a learning algorithm for small autonomous mobile robots based on sets of fuzzy automata. The task of the robots is to learn how to avoid obstacles reactively. The approach presented here is one in which two robots learn simultaneously. with the experiences of each robot being passed onto the other. It is shown that this sharing of experiences results in a faster and more repeatable learning of the robots' behavioural parameters when compared with individual learning.

Barbaneta - A Modular Autonomous Vehicle

This paper presents a small autonomous mobile robot designed and implemented by the authors. The vehicle is modular, in the sense that new functionalities may be added if needed. Therefore, it can be used as a testbed for research and development on autonomous mobile robots. An open architecture was designed and implemented to allow the integration of the different modules. Three modules were implemented in the current stage: motor controllers, guidance control loop and ball catcher/selector. These allow the vehicle to follow an optical track and recover the track if it is suddenly interrupted (using retroreflectors), while collecting and discriminating billiard balls of different colors placed along the path.