A remote manipulator for forestry operation

The remote manipulator described consists of two arms: a 3-DOF main lifting arm (aerial device), and a 6-DOF robot manipulator (treejib) mounted at the upper end of the aerial device. Each arm is single-joint rate controlled, with the reference joint rate being proportional to the corresponding joint displacement of a corresponding hand controller. Both controllers are kinematically equivalent to each of the two arms. Two of the treejib joints are instrumented for position feedback, and the corresponding hand controller joints are motorized and also position controlled. This ensures that no excessive force is exerted on the tool during contact with the branches. The system is of a master-slave rate controlled force reflective type. The design presented has novel features such as a quick connect-disconnect coupler for hydraulic tools and a force reflective master in a form of a small kinematic replica of the slave. The system has been extensively field tested. The results were very promising, however several modifications to the basic concept used to automate the specific operations are necessary. >