A MEASURE OF STABILITY FOR MOBILE MANIPULATORS WITH APPLICATION TO HEAVY-DUTY HYDRAULIC MACHINES

This paper describes the development of a suitable algorithm to comput e the potential of tipping-over for vehicles that carry manipulators. The energy method developed by Messuri and Klein (1985) is extended he re to quantitatively reflect the effect of forces and moments arising front the manipulation of the implement. The amount of the impact ener gy that can be sustained by the vehicle without tipping-over, about ea ch edge of potential overturning is computed. First, the instantaneous onset of instability configuration of the machine about the edge is d etermined by constructing an equilibrium plane. Next, the work done by all acting forces and moments when the machine is virtually brought t o this unstable stance from the current state, is calculated. This,cor k is the indication of the proximity of the machine to tipping-over ar ound that edge. The application of this study is directed at industria l mobile machines that carry human-operated hydraulic manipulators. Th e algorithm is therefore used to study the stability of an excavator b ased log-loader. Simulation studies clearly show the importance of ine rtial loads in determining the stability of such machines.