As the Light Weight Robot (LWR) is a highly integrated system of mechanical and electronic components collaboration between electronic and mechanical design from the start is essential.
At project start the basic design of integrating the controllers and power converters in the joints was determined as well as communication and supply concepts and power distribution. In the design process of the joints and links permanent interaction between mechanical and electrical design was necessary to achieve a high integration level. First board size and shape are defined according to various requirements, such as
This close interaction can only be performed using interchange modules between the different design applications as CAD and PCB layout software in several iteration loops.
Finite Element Analysis
Light-weight robot concept
A robot with a load-to-weight ration similar to that of the human arm (1:1) is the design goal. The usage of Harmonic Drive gears, of motors with high power density and of light materials, as well as a consequent light-weight oriented mechanical design are key issues in reaching this goal.
The effects of the inherent flexibility which appears mainly in the joints (effects such as vibrations or absolute positioning errors of the tip), are compensated using additional sensors in model based control structures.
In addition to usual motor position sensing, the link side position and the joint torque are measured in each joint.
Especially the joint torque sensor plays a key in this context, being used for: