This work describes a hierarchically structured geometric database in an off-line robot programming system. The data structure contains the numerical definition of the frame variables, as well as an indicator of the respective reference frames. Moreover, the physical relations between the objects in the environment are included. The database is implemented such that it continuously reflects the actual structure of the environment. As a result, all calculations of the frame locations are carried out automatically. Moreover, the programming system is capable to autonomously updating the numerical information after changes in the environment. Making this database the heart of a robot programming system greatly simplifies the off-line programming of complex robot tasks, like f.i. assembly tasks.

Automated methods are developed to classify a robot's kinematic type and select an appropriate library inverse-kinematic solution based on this classification. These methods automatically generate DenavitHartenberg joint frame parameters, given any frame representation that can mathematically be represented as a homogeneous transformation.

To reduce the number of closed-form inverse-kinematics solutions required for a broad class of serial robots, additional methods account for differences in robot zero state, base frame location, and joint polarity. Further generalization results from using joint frame decoupling to map lower degree-of-freedom robots into the inverse-kinematics solutions of higher degree-offreedom robots.

An off-line programming station for a robotised welding cell is presented. In this context the choice of a kinematic inversion method applied to the simulation of robots is discussed.

A direct inversion method is developed in the case of 5-axes robots of plane geometry and for a task presenting a symmetry of revolution. It uses the geometry of the tool and of the robot and vectorial calculations very well adapted to this particular case. The results presented validate the choice of this method for a specialised programming environment.

This paper presents a new calibration method for industrial robots. The calibration method is based on a combination of inclinometer and LVDT measurements and is very simple to use. The inclinometers measure the deviation from the gravity direction of a measurement rod and the LVDT sensor measures the length of the rod. The inclinometers can be used without any pre-calibration and the whole equipment is inexpensive, portable and robust.

For off-line programming to work, systematic methods must be developed to account for non-ideal performance of the parts and devices in the manufacturing cell. Although much of the literature focuses on robot inaccuracy, this paper considers practical methods for the tool control frame (TCF) calibration and rigid-body compensation required to close the inverse kinematics loop for target driven tasks.

In contrast to contemporary estimation methods, a closed-form, easily automated, solution is introduced for calibrating the position and orientation (pose) of orthogonal end-effectors when the distal robot joint is revolute. This paper also considers methods for measuring and compensating the small rigid-body perturbations that result from non-repeatable part delivery systems or from geometric distortion. These methods are designed to eliminate rθ error from the rigid-body prediction and can be conducted in real-time. Without accurate TCF calibration and rigid-body compensation, even the most accurate robot will fail to complete an off-line programmed task if the task tolerances are stringent.