Development of a collision avoidance system for a videoconferencing robot

Abstract

The work presented in this paper is about the development of a collision avoidance sys- tem for a mobile telepresence robot developed by the company Gira􏰢 technologies AB. The robot is designed to extend the length of time elderly can stay in their homes before requiring full-time sta􏰢ed care. The collision avoidance system is needed to help the user to avoid running in to objects or down a stairway. The design must be capable of being implemented at low cost, and should not look overtly "robotic" as this would not result in an appealing industrial design.

Herein, di􏰢erent techniques are presented and analyzed to 􏰣nd the best suitable solu- tion for the robot. In particular a lot of work is done in taking measurements to 􏰣nd the right characteristics for the sensors according di􏰢erent mounting angles, di􏰢erent objects and distances. A solution is chosen and calculations are made to 􏰣nd the best positions to place the sensors to get the best results.

A complete solution is presented and implemented in the current system and tested to work as expected.

Introduction

Collision avoidance systems are commonly used in diferent robot solutions to help an autonomous or remotely controlled robot to navigate through an area with diferent ob- stacles. In areas where obstacles are generally time-invarient, sensors often are used to create a map over the area that the robot later can navigate by. If the robot is going to be used in a dynamic area, especially if it is going to interact with people, it need a way to easily update the environment around itself to be able to avoid obstacles or stairways.

Gira􏰢 technologies AB is commercializing a remotely controlled videoconferencing robot for elder care known as the Gira􏰢. The task for this project is to design a collision avoid- ance system for the Gira􏰢. At this time safety is completely dependent on the skill of the person operating the Gira􏰢 and has no sensors at all helping the user. There are two main actions by the user that can cause harm to humans, the interior, or the robot itself. These actions are driving the robot over a precipice like a stairway and driving into obstacles at high speed.

There are several di􏰢erent solutions to create a collision avoidance system and in this report we are trying to 􏰣nd the best suitable solution for the Gira􏰢. Common techniques to locate objects are to use IR, ultrasonic, laser, vision or a combination of techniques. All the di􏰢erent possibilities mentioned are discussed in this report. Due to the require- ments from the company some of the solutions are rejected early on, but the solutions that ful􏰣ll the requirements are processed and the most suitable solution is selected for the Gira􏰢. The report also explains the basics of all techniques that are mentioned and the construction of a fully working system. The system is also integrated with the current hardware and software and fully tested to work properly.

The work is divided in-to three parts:

∙ First, a background about the di􏰢erent techniques that are possible for our use is presented. The main goal is to ful􏰣ll the requirements that are stated by Gira􏰢 technologies AB.

∙ Second, is to test di􏰢erent solutions to determine which system best suits the re- quirements and perform tests that will determine the pros and cons of each sensor system

∙ Finally, integrate the complete system with current hardware and perform tests to verify that the system works properly.

Patrik Björkman pbn05003@student.mdh.se Lars Odens Hedman los05001@student.mdh.se

January 12, 2010

School of Innovation, Design and Engineering (IDT) Mälardalen University, Västerås, Sweden

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