Approximating Cartesian free-form curve path in SCARA robot joint space using clothoid curves

• Main Author: Moreno, Mary Anne E.
• Format: text
• Language: English
• Published: Animo Repository 2003
• Subjects: Path analysis; Approximation theory; Interpolation; Curves; Computer simulation; Robots > Programming
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/3047
• Institution: De La Salle University

A method for approximating Cartesian free-form curve path in SCARA robot joint space using clothoid curves is presented. Path Approximation is done by taking sample points on the curve path in Cartersian space and converting these to their corresponding joint coordinates by applying inverse kinematics. Then, interpolation of the joint space coordinates by piecewise clothoid curve segments followed. The clothoid curves correspond to the approximated curve path in joint space. Forward kinematics was then applied to the approximated curve in joint space to generate its corresponding curve in Cartesian space. The performance of the approximation algorithm was compared with linear interpolation and cubic spline interpolation. Numerical integration was used to estimate the area under a curve. The error between the ideal and approximated curves was taken by computing for the percentage error between the area of the ideal curve and that of the approximated curve. Simulation results showed that approximation using linear interpolation produced the worst approximations, giving large percentage errors, especially when two to five segments were used. Approximation using cubic spline interpolation and clothoid interpolation produced more accurate results visually and in terms of the percentage errors even with two to four segments although there are cases where clothoid interpolation did not produce accurate results. As the number of segments used in the interpolation was increased, all three interpolation methods produced better results.