We propose a model-based control framework for

multi-arm manipulation of a rigid object subject to external

disturbances. The control framework, based on projected inverse

dynamics, decomposes the control law into constrained

and unconstrained subspaces. Unconstrained components accomplish

the motion task with a desired 6-DOF Cartesian

impedance behaviour against external disturbances. Meanwhile,

the constrained component enforces contact and friction constraints

by optimising for contact forces within the constrained

subspace. External disturbances are explicitly compensated for

without using force/torque sensors at the contact points. The

approach is evaluated on a dual-arm platform manipulating a

rigid object while coping with unknown object dynamics and

human interaction.