Active capsule endoscopy is becoming a research hotspot in recent years. We design an active capsule robot (capsubot) with the vibrational mode. The internal force-static friction control strategy which is used in the capsubot is effective in rigid environment but not in viscoelastic environment. A particular viscoelastic material whose parameters are confirmed is set to the viscoelastic environment. We suppose that it is a periodic damped oscillation system when the capsubot make a free vibration in the environment. We propose a new control strategy whose principle is similar to a swing in the environment. The simulation results show that the new strategy is effective.