In an Intelligent Assist Device (IAD), the human operator is assisted by the power of the servo drives as well as intelligence from this device. Because of the power actuation, the ergonomic injury of the operator using the device can be reduced. A force transducer provides a convenient way for the operator to generate control command by a simple "push to move" intuition. Therefore, there is minimum required training for using an IAD. Collision of payload with obstacles has always been a major problem in using a lift assist device. Collision might cause damage to the work piece, lift device and sometimes result in operator injury. All these occurrences will significantly increase the total production cost. In this work, a modified collision-avoidance scheme has been proposed, and it has been proven stable both analytically and experimentally. An artificial attractive well is also explored in this research to guide an operator to approach a target along a preferred path. Stability proof is provided and experimental results are given.