The Phoenix Robotic Arm (RA) is a 2.4-m long arm mounted on the Phoenix Mars lander. It has three joints.  The shoulder joint, where the RA is attached to the lander deck, has two degrees of freedom: motion in azimuth and elevation.  The elbow and wrist joints each have one degree of freedom allowing further motions in elevation.  Attached to the RA are: a scoop, a Thermal and Electrical Conductivity Probe (TECP), and the Robotic Arm Camera (RAC).  The RA was designed to acquire samples of martian soil, dig trenches to uncover subsurface ice, modify the terrain close to the lander, and serve as a means to insert the TECP into the soil.  The scoop has a drill bit on its back; after rasping icy soil, a series of RA motions was often used to send the material to the front of the scoop.  Both the scoop and TECP were mounted on the wrist joint of the arm.  Motor currents, link lengths, and joint positions of the RA were used to determine the force the RA exerted during its motions and the position of the scoop during these motions.  This information was useful in monitoring the safety of the instrument and has the science return of allowing analysis of soil properties at the landing site.

Instrument Overview
  ===================
    The Phoenix Robotic Arm (RA) is a 2.4-m long arm mounted on the Phoenix
    Mars lander. It has three joints.  The shoulder joint, where the RA is
    attached to the lander deck, has two degrees of freedom: motion in
    azimuth and elevation.  The elbow and wrist joints each have one degree
    of freedom allowing further motions in elevation.  Attached to the RA
    are: a scoop, a Thermal and Electrical Conductivity Probe (TECP), and
    the Robotic Arm Camera (RAC).  The RA was designed to acquire samples of
    martian soil, dig trenches to uncover subsurface ice, modify the terrain
    close to the lander, and serve as a means to insert the TECP into the
    soil.  The scoop has a drill bit on its back; after rasping icy soil, a
    series of RA motions was often used to send the material to the front of
    the scoop.  Both the scoop and TECP were mounted on the wrist joint of
    the arm.  Motor currents, link lengths, and joint positions of the RA
    were used to determine the force the RA exerted during its motions and
    the position of the scoop during these motions.  This information was
    useful in monitoring the safety of the instrument and has the science
    return of allowing analysis of soil properties at the landing site.
    For more details, see Bonitz et al. 2008 [BONITZETAL2008], Arvidson et
    al. 2009 [ARVIDSONETAL2009], and Shaw et al. 2009 [SHAWETAL2009].
 
  Scientific Objectives
  =====================
    The science objectives of the RA are the following: (1) Collect soil
    samples from various depths and locations relative to polygonal
    landforms.  Deliver these samples to onboard instruments. (2) Uncover
    subsurface ice. (3) Obtain vertical (and in some cases horizontal)
    profiles of data relevant to scoop - soil interactions (e.g. during
    scraping and excavation).  This data can be used to determine physical
    properties of the soil (e.g. soil cohesion). (4) Expose trench walls to
    aid in determining the presence/absence of fine-scale soil/ice layering.
    (5) Position the RAC for viewing of various targets in the workspace and
    below the lander deck. (6)Place the TECP in soil targets of interest;
    also place it at various heights in the air for relative humidity
    measurement. (7) Support any science investigations that require force
    to be applied (e.g. moving a rock, pressing down on soil surfaces). (8)
    Rasp icy soil for delivery to on-deck instruments.
 
  Calibration
  ===========
    The RA was calibrated both in the field (Death Valley, January 2000) and
    in the Payload Interoperability Testbed (PIT).  Calibration of the RA's
    ability to position itself accurately and then measure its position was
    conducted by commanding a series of movements and using a laser tracker
    for a second position measurement.  Calibration of rasp cutting torque
    was conducted with a dynamometer for measurement of output torque and
    force; this was done for the range of expected temperatures. See Bonitz
    et al. 2008 [BONITZETAL2008].  Position was repeatedly
    calibrated during mission operations.  Maximum force limits were also
    reset frequently during the mission.
 
  Operational Considerations
  ==========================
    The quality of the data was affected by the characteristics of the
    surface.  The data was collected at higher temporal resolution on sols
    when the spacecraft was expected to be able to send higher data volume
    to Earth.
 
 Electronics
  ===========
    The RA is controlled by two circuit boards located in the lander's
    Payload Electronics Box (PEB).  These circuit boards are responsible for
    power conditioning, motor and heater drivers, motor and heater current,
    motor and temperature sensor voltages, potentiometer voltage conversion,
    and joint encoder counting.  Another board on the PEB controls rasp
    current.  The PEB also provides sensor monitoring and command execution
    for joint movement and heater and rasp function.  The PEB is responsible
    for communication with the lander's Command and Data Handling computer.
    See Bonitz et al. 2008 [BONITZETAL2008] for more information.
 
  Location
  =================
    The instrument operated in the northern plains of Mars (68.22N, 234.25E
    areocentric; [HEETETAL2009]).  The test instrument operated at the
    University of Arizona, Tucson, Arizona, USA.
 
  Operational Modes
  =================
    The RA employed variable frequencies of data collection.  Maximum force
    limits were also variable.
 
  Subsystems
  ==========
    The RA consists of the following subsystems: (1) links (e.g. upper and
    lower arm), (2) joint actuators, potentiometers, and encoders (3) scoop
    with rasp and two blades, (4) temperature sensors, (5) TECP, and (6)
    RAC.
 
  Measured Parameters
  ===================
    Measured parameters include: time of observation, position of scoop at
    time of observation, and forces exerted at time of observation.

Changed logical_identifier from ra__phx to ra.phx

ROBOTIC ARM for PHX

ATMOSPHERIC STRUCTURE EXPERIMENT for PHX

METEOROLOGY SUITE, LIDAR for PHX

MECA ATOMIC FORCE MICROSCOPE for PHX

MECA COMMON ELECTRONICS for PHX

MECA THERMAL AND ELECTRICAL CONDUCTIVITY PROBE for PHX

MECA WET CHEMISTRY LABORATORY for PHX

METEOROLOGY SUITE, PRESSURE & TEMPERATURE for PHX

MECA OPTICAL MICROSCOPE for PHX

ROBOTIC ARM CAMERA for PHX

SURFACE STEREO IMAGER for PHX

THERMAL EVOLVED GAS ANALYZER for PHX

TELLTALE for PHX

PHOENIX

NAIF ID 499

Mars

Phoenix Robotic Arm

Description

Identifier (LID)

Version