The multisensory concept
Our approach in designing a new generation of multisensory light-weight robots is an integral one. To be more specific: the new sensor and actuator generations developed in the last years do not only show up a high degree of electronic and processor integration, but also a fully modular hard- and software structure. Analog conditioning, power supply and digital preprocessing are typical subsystem modules of this kind.
The main sensory developments finished with these criteria have been in the last years:
- compliant, optically measuring force-torque-sensor for assembly operations.
In a more compact form these sensory systems were integrated inside plastic hollow balls, thus generating 6-degree of freedom handcontrollers (the DLR control balls).The SpaceMouse is the most recent licence product based on these ideas.
- stiff strain-gauge based 6-component force-torque-sensor systems.
- miniaturized triangulation based laser range finders.
- integrated inductive joint-torque-sensor for our leight-weight-robot.
In order to demonstrate the multisensory design concept, these types of sensors have been integrated into the multisensory DLR-gripper, which contains 15 sensory components and - to our knowledge - is it the most complex robot gripper built so far (more than 1,000 miniaturized electronic and about 400 mechanical components).
Light-weight actuator and drive systems
The motor concept
Both the DLR-gripper and the joint drives of our light-weight robot make use of the same motor concept based on our own redesign of commercially available two-phase stepping motors of the ESCAP type. These motors were basically attractive for our light-weight goals because they show up
- very low rotor inertia (flat disc)
- small size, low weight (1,5 N) but relatively high torque (0,33 Nm), the rotor permanent magnets being integrated into a rare earth disc with large pdiameter
- high positioning accuracy (25 pole pairs).
All modern robot control approaches are based on commanding joint torques. Due to friction etc. this is not feasible with standard robots today. Thus we have developed an inductive torque-measurement system that may be seen as an integral part of the gearing system. The implementation of appropriate nonlinear joint torque feedback laws is in preparation.