An Untra-Accurate High-Speed Six DOF Manipulator

Dual-axis linear motors (i.e., Sawyer motors) are utilized in various manufacturing applications such as electronics industry for assembly, packaging, lead bonding, and wafer probing. In these applications, additional degrees of freedom are attained by using other types of motors and mechanisms (e.g., geared motors or lead screws). Inherently, these additional mechanisms degrade the overall performance of the system and various motor technologies need to be employed to design a four to six degree of freedom (DOF) manipulation system (four being common for many packaging and assembly operations).

We have considered the use of Sawyer motors to design a direct drive six DOF manipulator. Many 6 DOF industrial manipulators have been built by various groups and companies. The unique features of the proposed 6 DOF manipulator are that it is direct drive, uses a single motor technology, has a large work space, is high speed, and is capable of achieving high positional resolution. We have performed detailed kinematic and dynamic modeling for this type of manipulators. Furthermore, we carried out a kinematic optimization to maximize the manipulator workspace. The advocated six degree-of-freedom positioning system is a tripod structure with inextensible limbs actuated at the base by two dimensional linear stepper motors (although other types of actuators may be utilized). The proposed manipulator achieves large range of motion in all the six degrees of freedom. Furthermore, high resolution and high speed motion may be achieved in all axes. A picture of our tripod manipulator is given below.