Advance Modeling of a Skid-Steering Mobile Robot for Remote ...

1.1 The Pioneer 3-AT Robot 7tween itself and the server is disrupted for a set time interval. As soon as the connectionactivity is restored ARCOS resumes robot’s motion. Our Pioneer 3-AT robot contains three,hot-swappable, seven ampere-hour, 12 volts direct-current (VDC), sealed lead/acid batteries(total of 252 watt-hours) capable of running the robot continuously with a range betweentwo and three hours, even if due to usage at the end battery life decreased of 20% − 30%.The platform has been extended for interior, human filled, unstructured spaces by adding thefollowing hardware components (Figure 1.1(b)):• Lenovo PowerPC laptop with extended battery (almost four hours expiration)• lightweight extruded aluminum framing to position the laptop at waist height relativeto standing humans• Logitech USB camera with Pan Tilt Zoom capabilities (pan ∈ [−90 o , +90 o ] and tilt ∈[−30 o , +30 o ]) positioned at chest height relative to standing humans• horizontal wheels and bumpers designed to allow safe operation in the target environment.The laptop is connected to the robot via an USB serial connection whose end is pluggedinto the RS-232 port. The laptop runs the client side of the ARCOS that waits and forwardscommands to the robot via serial communication. The laptop also runs custom developedsoftware that waits and forwards commands to control the camera parameters.In the previous thesis [9], an iPhone running the AlterEgo application was employed forthe remote user workstation. AlterEgo is an Objective-C/C application to interpret gesturesperformed by an operator. It sends a TCP packets through the Internet to reach the clientside of ARCOS which is waiting for that packet. These packets contain commands for eitherthe mobile robot or for the pan-tilt camera. After error checking, the laptop computer willforward the commands either to the mobile robot or to the camera for implementation.¨Safe operation¨ in the target environment is defined by the inability of the robot to damageitself or its environment during operation. It specifically does not imply that the robotnever contacts objects in its environment other than the floor. The robot has a parallel portwhose pins trigger some behaviors, and in particular we use those pins to temporarily stoppingrobot motion. The robot is equipped with a front and a rear bumper. When the robotfrontally or posteriorly hits an object straight on the robot temporarily stopped. Conversely,