Hari Das

The CLARAty architecture for robotic autonomy

This paper presents an overview of a newly developed Coupled Layer Architecture for Robotic Autonomy (CLARAty), which is designed for improving the modularity of system software while more tightly coupling the interaction of autonomy and controls. First, we frame the problem by briefly reviewing previous work in the field and describing the impediments and constraints that been encountered. Then we describe why a fresh approach to the topic is warranted, and introduce our new two-tiered design as an evolutionary modification of the conventional three-level robotics architecture. The new design features a tight coupling of the planner and executive in one Decision Layer, which interacts with a separate Functional Layer at all levels of system granularity. The Functional Layer is an object-oriented software hierarchy that provides basic capabilities of system operation, resource prediction, state estimation, and status reporting. The Decision Layer utilizes these capabilities of the Functional Layer to achieve goals by expanding, ordering, initiating and terminating activities. Both declarative and procedural planning methods are used in this process. Current efforts are targeted at implementing an initial version of this architecture on our research Mars rover platforms, Rocky 7 and 8. In addition, we are working with the NASA robotics and autonomy communities to expand the scope and participation in this architecture, moving toward a flight implementation in the 2007 time-frame.

Evaluation of a Telerobotic System to Assist Surgeons in Microsurgery

A tool was developed that assists surgeons in manipulating surgical instruments more precisely than is possible manually. The tool is a telemanipulator that scales down the surgeons hand motion and filters tremor in the motion. The signals measured from the surgeons hand are transformed and used to drive a six-degrees-of-freedom robot to position the surgical instrument mounted on its tip. A pilot study comparing the performance of the telemanipulator system against manual instrument positioning was conducted at the University of Southern California School of Medicine. The results show that a telerobotic tool can improve the performance of a microsurgeon by increasing the precision with which he can position surgical instruments, but this is achieved at the cost of increased time in performing the task. We believe that this technology will extend the capabilities of microsurgeons and allow more surgeons to perform highly skilled procedures currently performed only by the best surgeons. It will also enable performance of new surgical procedures that are beyond the capabilities of even the most skilled surgeons.

Dexterity-enhanced telerobotic microsurgery

A telerobotic platform developed in a collaboration between NASA-JPL and MicroDexterity Systems, Inc (MDS) is described in this paper. The lightweight, compact 6 dof master-slave system is precise to better than 10 microns and can cover a workspace greater than 400 cubic centimeters. Current capabilities of the system include manual position control with augmented shared control modes and automatic modes of control of the robot. Simulated force feedback on the master device has been implemented and plans are to integrate force reflection from the slave end effector and evaluate the performance improvements enabled by the telerobot in simulated microsurgical tasks. The telerobot was used in a recent demonstration of a simulated eye microsurgical procedure.

Robot-assisted microsurgery: a feasibility study in the rat.

OBJECTIVETelerobotic surgery is a novel technology that can improve a surgeon’s manual dexterity as well as the results achieved with microsurgical procedures. METHODSA prototype Robot-Assisted MicroSurgery (RAMS) microdexterity enhancement system developed by the Jet Propulsion Laboratory and MicroDexterity Systems, Inc., was tested in 10 rats. Carotid arteriotomies were created and closed using either the RAMS system or conventional microsurgical techniques. The time required, the technical quality (vessel patency and suture line integrity), the error rate, and subjective difficulty were compared. RESULTSAll procedures were successfully completed using the RAMS system to manipulate the vessel but not to hold the needle or place the sutures. The precision, technical quality, and error rate of telerobotic surgery were similar to those of conventional techniques. However, the use of the RAMS system was associated with a twofold increase in the length of the procedure. CONCLUSIONSurgery using a microdexterity enhancement system, or RAMS prototype, is feasible. With further development, such as a stereotelevisualization and haptic feedback system, this system could be used for telerobotic surgery in neurosurgical practice.

Operator performance with alternative manual control modes in teleoperation

Recent experiments conducted at the Jet Propulsion Laboratory (JPL) comparing alternative manual control modes using the JPL Advanced Teleoperator (ATOP) System are described in this paper. Of particular interest were control modes that provide force reflection to the operator. The task selected for the experiment is a portion of the Solar Maximum Satellite Repair (SMSR) procedure we developed to demonstrate the repair of the Solar Maximum Satellite with teleoperators. SMSR had been successfully performed by NASA astronauts in 1984 and it was selected as a task to demonstrate the ATOP system capability for space applications. The seven manual control modes evaluated in the experiment are combinations of manual position or resolved motion rate control with alternative control schemes for force reflection and remote manipulator compliance. Performance measures used were task completion times, average force and torque exerted during the execution of the task, and cumulative force and torque exerted. The results were statistically analyzed and they show that, in general, force reflection significantly improves operator performance and indicate that a specific force-reflecting scheme may yield the best performance among the control modes we tested. Also, our experiment showed that, for the selected task, the position control modes were preferable to the rate control modes and slave manipulator compliance reduced task interaction forces and torques.

A New Robot for High Dexterity Microsurgery

We report the development of a new six degree-of-freedom (d.o.f.) manipulator. This robot and its task-space controls enable relative tip positioning to better than 25 microns over a singularity-free work volume exceeding 20 cubic centimeters. By virtue of an innovative cable drive design, the robot has zero backlash in five joints and can sustain full extent loads of over three pounds. The robot is applicable to both fine motion manipulation of microsurgical tools and also dexterous handling of larger powered devices for minimally invasive surgery. Our current development emphasis is a teleoperated system for dexterity-enhanced microsurgeries; we believe the new robot will also have useful applications in computer assisted surgeries, e.g. image-guided therapies. In this brief paper, we outline the robot mechanical design, controls implementation, and preliminary evaluations. Our accompanying oral presentation includes a five minute videotape that illustrates engineering laboratory results achieved to date.

Toward developing reusable software components for robotic applications

We present an overview of the CLARAty architecture which aims at developing reusable software components for robotic systems. These components are to support autonomy software which plans and schedules robot activities. CLARAty modifies the conventional 3-level robotic architecture into a 2-layered design: the functional layer and the decision layer. The former provides a representation of the system components and an implementation of their functionalities. The latter is the decision-making engine that drives the former. It globally reasons about the goals, system resources, and system state. The functional layer is composed of a set of interrelated object-oriented hierarchies consisting of active and passive objects that represent the system abstraction levels. We present an overview of the design of the functional layer. It is decomposed into a set of reusable core components and a set of extended components that adapt the reusable set to different hardware implementations. The reusable components provide interface definitions and implementations of basic functionality, provide local executive capabilities, manage local resources, and support decision layer queries.

Towards a training methodology for skilled teleoperation

A novel approach to the design of training methodologies or programs for operators in man-machine systems and its application to the training of skilled human teleoperators is described. This approach requires that training goals are separated into four distinct categories: the maximization of performance consistency or reliability for critical tasks, the maximization of positive transfer between learned and new tasks, the minimization of the effects of internal operator states (e.g. fatigue, stress, workload), and the minimization of the effects of situational uncertainty or anomaly on performance. Being different from one another in fundamental ways these categories or goals entail the development and application of different training techniques. The paper reports the development of training procedures for achieving the first goal, that of performance consistency, for skilled teleoperators. This part methodology was evaluated against the training practices commonly used in the field, and was found to enhance the learning, hence promote the acquisition of performance consistency, of a challenging and realistic satellite servicing task. >

Telerobotics for microsurgery

A telerobotic workstation for microsurgery has been developed that enables scaling down motions and filtering tremor in a surgeons hand. The system is compact and light-weight and has the potential for improving the performance of all surgeons and enabling the development of new surgical procedures currently limited by the dexterity of even the most skilful surgeons.

Teleoperated Satellite Repair Experiments

In this paper, we focus on the role and im- portance of experiments in the development of tele- operation systems. Experiments conducted in the JPL Advanced Teleoperation Laboratory and les- sons we have learned from them are described. We also describe novel procedures and techniques that facilitate the conduct of experiments and these are presented in this paper. Also reported are problems faced in a laboratory that develops new teleoperation technology while concurrently validating the tech- nology with experiments.