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GbxNovatelAcfr
[Libraries, C++, Linux, Hardware Drivers]

ACFR driver for a Novatel(SPAN) system. More...

ACFR driver for a Novatel(SPAN) system.

NovatelSPAN is a proprietary Novatel navigation system. It minimally consists out of a Novatel OEMV GPS receiver (OEM4 receivers should be compatible). If combined with an IMU, a SPAN system can provide an INS navigation solution at high rate (up to 100Hz). The driver initializes the hardware and reports navigation data continuously.

for a full list of functions see gbxnovatelacfr

Tested Hardware
Specific devices this driver has been tested with:

Header file
#include <gbxnovatelacfr/driver.h>

Style
See http://orca-robotics.sourceforge.net/orca/orca_doc_style.html
Copyright
Mathew Ridley, Ben Upcroft, Michael Moser
Responsible Developer
Michael Moser
License
LGPL
Dependencies.
libGbxSerialAcfr, GbxUtilAcfr
Example
See test/test.cpp for a full blown usage-example and test/example.readme on how to compile the test program.

To run the test program (defaults: /dev/ttyS0, 115200 bps, ...) call it without parameters. 

$ gbxnovatelacfrtest

If you want to change things, get a short usage description: 

$ gbxnovatelacfrtest -h

The test program reports back all messages received from the driver and prints out the data fields for each message (in verbose mode).

Minimal Example
This example (no error checking for clarity, but fully functional) shows the driver's intended usage: 

#include <gbxnovatelacfr/driver.h>
#include <cstdlib>
#include <iostream>
#include <memory>
#include <vector>

namespace gna = gbxnovatelacfr;

int main(void){

    // create a valid configuration
    std::vector<double> imuToGpsOffset(3,0.0); // made up; this MUST be correct for real work (see gbxnovatelacfr::Config::imuToGpsOffset_)
    gna::SimpleConfig sCfg(std::string("/dev/ttyS0"), 115200, std::string("IMU_HG1700_AG11"), imuToGpsOffset);
    gna::Config cfg(sCfg);

    // create the driver
    gna::Driver driver(cfg);

    while(0){
        // read from the driver
        std::auto_ptr<gna::GenericData > generic = driver.read();

        // figure out what type of data we got
        switch(generic->type()){
            case gna::InsPva:
                {
                    // process data
                    gna::InsPvaData *data = dynamic_cast<gna::InsPvaData *>(generic.get());
                    std::cout << data->toString() << "\n";
                }
                break;
            case gna::BestGpsPos:
                {
                    // process data
                    gna::BestGpsPosData *data = dynamic_cast<gna::BestGpsPosData *>(generic.get());
                    std::cout << data->toString() << "\n";
                }
                break;
            case gna::BestGpsVel:
                {
                    // process data
                    gna::BestGpsVelData *data = dynamic_cast<gna::BestGpsVelData *>(generic.get());
                    std::cout << data->toString() << "\n";
                }
                break;
            case gna::RawImu:
                {
                    // process data
                    gna::RawImuData *data = dynamic_cast<gna::RawImuData *>(generic.get());
                    std::cout << data->toString() << "\n";
                }
                break;
            default:
                if(0 == generic.get()){
                    std::cout << "Got NULL message!\n";
                }
                else{
                    std::cout << "Got unknown message!\n";
                    std::cout << generic->toString() << "\n"; // yes this works, since toString() is a member of the base class
                }
                break;
        }
    }

    return EXIT_SUCCESS;
}

References
This driver was programmed based on the protocol/message descriptions in Novatel's manuals, it does not contain any code from Novatel. The main source for information was:

The following sources have also been helpful:

Limitations
  • This is a Linux-only implementation (because of the serial library and the system-calls for timestamps, this might change in the future, particularly if there is user-demand)
  • Only supports a subset of the messages a NovatelSPAN system can provide, this can be extended, but only if there is demand.
  • The binary parser currently works on little endian architectures (e.g. x86) only. This is checked at run-time.
  • Driver currently treats the hardware as data-source only, communication _to_ the hardware is possible only during initialization.
  • Driver does limited checking if configuring the receiver was successful/as-intended:
    • Driver checks for 'ack' for commands, reports 'no-ack' and retries
    • This detects malformed commands _only_
    • The receiver (and hence the driver) will accept commands to e.g. setup an IMU, even if no IMU is present
  • Driver does not deal with persistent storage:
    • It is possible to make settings persistent between sessions (receiver command 'saveconfig'). Our driver does not use this command, but it could have been used manually.
    • There are cases where persistent settings could interfere with normal operation of the driver. This is particularly likely to happen when the hardware is shared between projects. There is no easy way to test for this, and the current implementation ignores the problem completely (the user is always right).
    • Workaround: To make sure that there are no lingering persistent settings, use the receiver's 'freset' command to bring it back to factory-defaults. The driver itself does not do this, on the grounds that it also might delete settings that were made persistent with good reason and purpose. If you are sharing equipment, check with everybody involved, before you use this approach.

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