2. Image-based Control Convergence issues CMPUT 610 Winter 2001 Martin Jagersand

3. Notes: Please hand in project proposal on Thu. See me if there are any problems. Some on-line search engines for papers: – http://www.cora.whizbang.com/ http://www.cora.whizbang.com/ – http://citeseer.nj.nec.com/cs http://citeseer.nj.nec.com/cs

4. Recall: Visual Servoing Observed features: Motor variables: Local linear model:

5. Recall again: Visual Servoing Steps 1. Solve: 2. Update and move: 3. Read actual visual move 4. Update Jacobian:

6. Recall again: Visual Servoing Steps 1. Solve: 2. Update and move: 3. Read actual visual move 4. Update Jacobian:

7. How to specify a visual task?

8. Visual specifications Point to Point task “error”: Why 16 elements?

9. Visual specifications 2 Point to Line Line:

10. Parallel Composition example E ( y ) = wrench y - y 47 25 y (y  y ) 8 3 4 6 1 2 (plus e.p. checks)

11. Serial Composition Solving whole real tasks Task primitive/”link” 1. Acceptable initial (visual) conditions 2. Visual or Motor constraints to be maintained 3. Final desired condition Task =

12. “Natural” primitive links 1. Transportation Coarse primitive for large movements <= 3DOF control of object centroid Robust to disturbances 2. Fine Manipulation – For high precision control of both position and orientation – 6DOF control based on several object features

13. Example: Pick and place type of movement 3. Alignment??? To match transport final to fine manipulation initial conditions

14. More primitives 4. Guarded move – Move along some direction until an external contraint (e.g. contact) is satisfied. 5. Open loop movements: When object is obscured Or ballistic fast movements Note can be done based on previously estimated Jacobians

15. Solving the puzzle…

16. Summary Servoing alone does not solve whole tasks – Parallel composition: Stacking of visual constraints to be simultaneously satisfied – Serial composition: Linking together several small movements into a chain of continuous movements

17. Convergence? Convex function? Convex domain? Convergent method?