Stability and dynamic analysis of a service robot

A Remote Operated SErvice robot (ROSE) is built to assist elderly people in health care. The use of technology to assist the elderly and disabled is desirable to ease the burden on the decreasing working population in the Netherlands and all over Europe. In this report the stability of the ROSE robot is investigated. The reason behind this is that the robot has to operate safely. Safe operation is a requirement because if the robot becomes unstable, it can easily injure people or the robot itself. Four complementary approaches are used to investigate the stability of the robot. The analyses consist of the half car model to investigate the suspension forces on the robot’s suspension, a static stability analysis to draw conclusions about the stability of the robot, a Zero Moment Point (ZMP) analysis to investigate the effect of arm movements on the stability of the complete robot, and a SimMechanics model to visualize the robot’s stability. The half car model shows that the maximum suspension forces are very high. Because of these high forces the wheelmodules which are attached to the mobile platform have to be redesigned. The result of the static stability analysis is that the angle of the parallelogram mechanism has to be restricted when the arms are stretched and loaded with the maximum load. The ZMP analysis gives several restrictions on the movements of the robot arms. Furthermore the ZMP analysis show that a static analysis is sufficient when the average velocity of the end effector of the robot arm is sufficiently low. The results of the static and ZMP analysis can be implemented in the robot’s software. This prevents the robot from tipping over. An extended SimMechanics model can be exported to the real robot, where it can be used to implement additional features, for example collision avoidance.