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Human Augmentation Technology (HAT)
By means of force/motion scaling using mechanical systems, it is
possible to augment (or at least supplement) the capabilities of an
operator. This technology is called Human Augmentation and may be used
in a variety of application domains ranging from battlefield operations
(similar to exoskeletons) to stroke patient therapy/rehabiliation.
HAT Demonstrations
The following demonstrations are based on HAT and have been implemented
using our in-house operational software (OSCAR). The same applications have
been tested on two different types of manipulators (modular and monolithic
systems) thus demonstrating the generality and extensibility of our software.
The modular system used is the powercubes from Amtec and the monolithic system
is the FANUC M6iB-6S.
Payload Assist Demo (PowerCube Robot) :
In this demo the modular manipulator's (Powercube) end-effector behaves
like an inertia. This could be used to do force-scaling for human augmentation.
This same application can be used to create a master
manipulator for a teleoperation system. End-effector forces are mapped to
differential motions in cartesian directions. This application also aids in
ensuring the correctness of the frame transformations from sensor frame to the
task/world frame and can thus be used to verify frame transformations for a
force-controlled application.
 Payload
Assist Demo (FANUC M6iB-6S) [~4MB] : In this
demo the above application was implemented on a standard commercially available
industrial robot (FANUC M6iB-6S).
 Virtual
Spring Demo : In this demo the modular manipulator's
(Powercube) end-effector emulates a spring. A delta controller was
used to develop this application. The advantage of such programmable
compliance is that we could change the behaviour of the end-effector on the fly
depending on the task. The compliances can be different in different directions
too. Also, the dynamic behavior of the end-effector can now be programmed as a
combination of the above two modes, inertia and spring.
 Human Robot Interaction
Demo (~21 MB, 1:07 min) : In this demo, The force assist
application was reconfigured so that a modular manipulator could
assist a therapist in teaching a pre-planned path. Robots are increasingly
being used for therapeutic applications. Once the path has been taught, the
manipulator can be run at various speeds depending on the therapy needs. Such
an application helps stroke patients regain their motor functionality.
Contact Control
Transition from free space motion to constrained space motion can excite
undesirable bouncing actions depending on the approach velocities and surface
characteristics. The strategy followed for contact control was to execute
guarded motion immediately after contact is established. Contact is sensed by
monitoring the force signal derivative, after ensuring that this signal is
'clean'. A velocity based control was implemented using the following
law.
Contact Control Demonstrations
 Force
Regulation Demo : A force regulation task (target force =
3 lbs) with a compliant environment is shown in this video. The approach
velocity used was 5 mm/s.
Active Force Control
Most industrial robots are used in the position control mode with little
knowledge about the forces of interaction between the manipulator and its
environment. However, the need to incorporate force sensing and active force
control is being felt in the robot industry and force control has already been
implemented for some applications such as assembly and deburring. The
following videos show some demonstrations we developed using OSCAR to
implement force-compliant mechanical finishing. The integrated system consists
of a ATI F/T sensor, FANUC M6iB-6S industrial robot, and a stepper-motor
controlled wire brush. The software libraries used to develop this application
were Open Motion API from FANUC and OSCAR by UTRRG.
Active Force Control Demonstrations
Force Controlled Finishing of Planar Part
[~23MB] : This movie demonstrates a force
controlled finishing operation using the FANUC M6iB-6S industrial manipulator
operating on a steel planar surface using a steel
wirebrush. The controller used in this demo was a PD force controller.
 Force
Controlled Finishing of Spherical Part [~13 MB] :
This movie demonstrates a force controlled finishing operation using the FANUC
M6iB industrial manipulator operating on a sphericalsteel
surface using a steel wirebrush. The controller used in this demo was a PD
force controller. Following are the links to movies that show the GUI an
operator would use to teach trajectory points, input force controller
parameters, launch the force controller application, and display the process
statistics.
Generalized Impedance Control of Redundant Manipulators
Impedance Control achieves force control and motion tracking in
the same direction by specifying a programmable dynamic response between the
manipulator end-effector and the environment. For details, refer [Pholsiri et
al, 2003] in the publications
section.
Impedance Control Simulations
Compliant Control Saw-Cutting : In this demo a 10DOF redundant
manipulator is used to execute a saw cutting task while optimizing one or more
performance criteria.
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