Description:
While serial robots are known for their versatility in applications, larger workspace, simpler modeling and control, they have certain disadvantages like limited precision, lower stiffness and poor dynamic characteristics in general. A parallel robot can offer higher stiffness, speed, accuracy and payload capacity, at the downside of a reduced workspace and a more complex geometry that needs careful analysis and control. To bring the best of the two worlds, parallel submechanism modules can be connected in series to achieve a series-parallel hybrid robot with better dynamic characteristics and larger workspace. Such a design philosophy is being used in several robots not only at DFKI (for e.g., Mantis, Charlie, Recupera Exoskeleton, RH5 humanoid etc.) but also around the world, for e.g. Lola (TUM), Valkyrie (NASA), THOR (Virginia Tech.) etc.These robots inherit the complexity of both serial and parallel architectures. Hence, solving their kinematics and dynamics is challenging because they are subjected to additional geometric loop closure constraints. Most approaches in multi-body dynamics adopt numerical resolution of these constraints for the sake of generality but may suffer from inaccuracy and performance issues. They also do not exploit the modularity in robot design. Further, closed loop systems can have variable mobility, different assembly modes and can impose redundant constraints on the equations of motion which deteriorates the quality of many multi-body dynamics solvers. Very often only a local view to the system behavior is possible. Hence, it is interesting for geometers or kinematics researchers, to study the analytical solutions to geometric problems associated with a specific type of parallel mechanism and their importance over numerical solutions is irrefutable. Techniques such as screw theory, computational algebraic geometry, elimination and continuation methods are popular in this domain. But this domain specific knowledge is often underrepresented in the design of model based kinematics ...
Publisher:
Universität Bremen ; Fachbereich 03: Mathematik/Informatik (FB 03)
Contributors:
Kirchner, Frank ; Mueller, Andreas
Year of Publication:
2019-11-15
Document Type:
Dissertation ; doctoralThesis ; [Doctoral and postdoctoral thesis]
Subjects:
geometry ; kinematics ; dynamics ; control ; series-parallel hybrid robots ; parallel robots ; parallel kinematic machines ; 000 ; 000 Computer science ; knowledge and systems ; ddc:000
Rights:
info:eu-repo/semantics/openAccess
Content Provider:
Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen)
