Modular Telerobot Task Execution System

The Modular Telerobot Task Execution System (MOTES) remote site telerobotics control system provides for supervised autonomy, shared control, and teleoperation control of space robots. MOTES is implemented in the JPL Supervisory Telerobotics (STELER) laboratory initially for control of a 7 degree of freedom redundant arm. MOTES was developed as a prototype system for space telerobotics applications and therefore its design addresses expected constraints of a flight system, e.g., it is implemented in the Ada programming language and it provides data-driven execution.

MOTES was designed to provide maximum capability with minimized computational resources. Capability is maximized by providing simultaneous control based upon various real and virtual sensors. The permutations of the behaviors of the various control modules provides the wide range of capabilities of the system. The desired behavior of each module is specified via command parameters from the local site which are issued by the remote site command interpreter. The result of all the modules is the desired emergent command execution. Monitors determine when to stop motion and the Dispatcher transitions the system between commands, either to next expected commands, or to reactive commands. This approach provides a wide range of capability without the need for reprogramming the remote control system.

The Communication Module handles communication with the local site system. It places new commands into the Task Command Queue and returns status and data. The Dispatcher Module controls the transition between execution states by checking the status of the various modules and specifying the appropriate commands and parameters to the various modules via shared memory. The Sensor Modules provide sensor data processing. The Control Modules provide the control associated with the various real and virtual motion sources. Each Control module generates a task space motion command. The Fusion Module merges the motion commands of the various Control modules into task space motion commands for the manipulators and other physical devices. The Task to Joint Map Module maps the task space command of the Fusion Module to the actuator space of the physical devices. The Device Drivers Modules communicate with the physical devices to send the actuator space commands and receive status data. The Monitor Modules provide monitoring of the status of execution for both intended termination conditions and unintended error conditions.

The MOTES system has been used for various satellite servicing type tasks in the laboratory such as grasping, door opening, and insertion and removal operations.

More details can be found in

Paul G. Backes, Mark K. Long and Robot D. Steele. "The Modular Telerobot Task Execution System For Space Telerobotics." In Proceedings IEEE International Conference on Robotics and Automation, pages 524-530, Atlanta, Georgia, May 1993.

Point of Contact:
Paul G. Backes,
Mail Stop 198-219
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
818-354-3850
Paul.G.Backes@jpl.nasa.gov

Mark K. Long,
Mail Stop 198-219
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
818-354-9050
Mark.K.Long@jpl.nasa.gov

Robert D. Steele
Mail Stop 198-219
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena, CA 91109
818-354-4847
steele@telerobotics.jpl.nasa.gov

Telerobotics Program page

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Last updated: May 10, 1996