Moment-Height Tip-Over Measure for Stability Analysis of Mobile Robotic Systems

Mobile machines equipped with manipulator arm(s) are being increasingly used in a variety of areas of industry. When these mobile utilities perform fast maneuvers, move over rough terrain, manipulate heavy work pieces, or interact large wrenches with their environment, they may go unstable and overturn. Therefore, safety and efficiency of such systems can be improved with a reliable stability recognition metric. For on-line applications, such tip-over stability measure should be computationally simple which makes its presentation a challenging task. In this study, various dynamic stability measures are investigated and compared with each other in terms of their reliability and computational complexity. Then, a new reliable and efficient metric named as moment-height stability (MHS) measure is introduced for mobile manipulators. The proposed metric is a physically meaningful and reliable measure while it contains low computational burden. The MHS measure can be exploited successfully for wheeled mobile manipulators containing single or multiple arms. Besides, by some minor modifications the MHS measure can be also employed for the case of legged locomotion. Also, the proposed MHS measure may be extended for the case of suspended mobile manipulator on rough terrains. Several case studies are presented to reveal the effectiveness of the new MHS measure compared to the main previous measures