---------------------------- history of changes ------------------------------------------
- 09-28-2004 mjg version 1
- 10-10-2004 mjg version 2,
-                add history of changes box,
-                new allowed values for ABS_THROTTLE and ABS_STEERING,
-                add note that all fields sent with each msg,
-                improve description of ACCELERATION, HEADING and RADIUS
-                new fields --> STOP_AFTER_TIME and STOP_AFTER_DIST
-                improved notes at bottom of message layout
------------------------------------------------------------------------------------------

Pilot to Vehicle_Control Interface (version 2)

Header_Info
  Message_Type.................."PILOT_TO_VC    "
  Message_Type_Version.........."0002"
  Message_Date.................."yyyymmdd"     // e.g. 20041010
  Message_Time.................."hhmmssmmm"    // gmt -- e.g. 161012123
  Message_Sending_Program......."PILOT   "
  Message_Seq..................."001"
  Message_Body_Config..........."S"      // array[35] (15 byte data_type,12 byte data)
                                         // 1 byte left over
  Message_Body_Length..........."000946"


Field_Info
*** the fields below are sent with EVERY message, though some may be NULL

Data_Type              | description
-----------------------+----------------------------------------------------
ABS_THROTTLE           | numeric, (-511 to +511) and -999
                       | absolute throttle position
                       | -511 = full break
                       | +0   = neither break nor throttle
                       | +511 = full throttle
                       | -999 = null (ignore)
-----------------------+----------------------------------------------------
ABS_STEERING           | numeric, (-511 to +511) and -999
                       | absolute steering wheel position
                       | -511 = full left turn position
                       | +0   = straight ahead position
                       | +511 = full right turn position
                       | -999 = null (ignore)
-----------------------+----------------------------------------------------
SPEED                  | numeric, (+0.0 to +60.0) and -999
                       | target speed (then maintain)
                       | mph (mile per hour)
                       | -999 = null (ignore)
-----------------------+----------------------------------------------------
ACCELERATION           | numeric, (+0.0 to +88.0) and -999
                       | rate at which SPEED should be attained
                       | feet per second squared
                       | *** used with SPEED
                       | -999 = null (if SPEED present then use default
                       |              else ignore)
-----------------------+----------------------------------------------------
HEADING                | numeric, (-180.0 to +180.0) and -999
                       | relative heading change
                       | negative values = turn to the left
                       |     (then go straight)
                       | positive values = turn to the right
                       |     (then go straight)
                       | degrees
                       | *** A sequence of steering changes is likely
                       |     required to attain the new heading
                       | *** At the end of said steering changes it is
                       |     likely that the abs_steering position will
                       |     be at (or near) zero
                       | -999 = null (ignore)
-----------------------+----------------------------------------------------
RADIUS                 | numeric, (0.0 - 200.0) and -999
                       | radius of turn (rate at which HEADING should
                       | be attained)
                       | feet
                       | *** used with HEADING
                       | -999 = null (if HEADING present then use default
                       |              else ignore)
-----------------------+----------------------------------------------------
STOP_AFTER_TIME        | numeric, (0.1- 30.0) and -999
                       | if no new message is received before this time
                       | elapses, stop the vehicle and await new messages
                       | seconds
                       | -999 = null (see notes below)
-----------------------+----------------------------------------------------
STOP_AFTER_DIST        | numeric, (0.1- 50.0) and -999
                       | if no new message is received before this distance
                       | has been traveled, stop and await new messages
                       | feet
                       | -999 = null (see notes below)
-----------------------+----------------------------------------------------

** 27 data slots open

Notes:
(1) if neither STOP_AFTER field is present then STOP_AFTER_TIME = 5.0
(2) ABS_THROTTLE (if not null) takes priority over SPEED
(3) ABS_STEERING (if not null) takes priority over HEADING
(4) use of the word "present" above means not null
(5) layout (at present) does not include fields needed beyond prototype