In real-world object manipulation scenarios, multiple mobile manipulator systems may suffer from disturbances and asynchrony, leading to excessive interaction forces and causing object damage or emergency stops. This paper presents a novel distributed motion control approach aimed at reducing these unnecessary interaction forces. The control strategy only utilizes force information without the need for global position and velocity information. Disturbances are corrected through compensatory movements of the manipulators. Besides, the asymmetric, non-uniform, and time-varying communication delays between robots are also considered. The stability of the control law is rigorously proven by the Lyapunov theorem. Subsequently, the efficacy of the proposed control law is validated through simulations and experiments of collaborative object transportation by two robots. Experimental results demonstrate the effectiveness of the proposed control law in reducing interaction forces during object manipulation.
