merged

The merged movement sensor model is an abstraction that combines data from multiple movement sensors. This allows you to aggregate the API methods supported by multiple sensors into a singular sensor client.

This is especially useful if you want to get readings of position and orientation or linear and angular velocity at the same time, which are normally separately supported and returned by GPS or IMU models, respectively.

To reduce velocity error when your machine is using the navigation service, aggregate Position() from a GPS and Orientation() from an IMU movement sensor in a merged model.

Configure a navigation service to use your merged sensor to navigate.

Before configuring a merged movement sensor, configure each movement sensor you want to merge as an individual component according to its model’s configuration instructions. Reference the name you configure for each individual component in the merged sensor’s configuration attributes:

{
  "components": [
    {
      "name": "<your-sensor-name>",
      "model": "merged",
      "api": "rdk:component:movement_sensor",
      "attributes": {
        "position": ["<your-gps-sensor-name-1>", "<your-gps-sensor-name-2>"],
        "orientation": ["<your-imu-sensor-name-1>"],
        "compass_heading": ["<your-gps-sensor-name-1>"],
        "angular_velocity": ["<your-imu-sensor-name-1>"],
        "linear_velocity": ["<your-gps-sensor-name-1>"],
        "linear_acceleration": ["<your-accelerometer-sensor-name-1>"]
      },
      "depends_on": []
    }
  ]
}

// { "components": [ { ... },
{
  "name": "<your-sensor-name>",
  "model": "merged",
  "api": "rdk:component:movement_sensor",
  "attributes": {
    "position": ["gps1"],
    "orientation": ["imu-wit"],
    "compass_heading": ["gps1"],
    "angular_velocity": ["imu-wit", "mpu6050"],
    "linear_velocity": ["gps1"],
    "linear_acceleration": ["adxl345"]
  },
  "depends_on": []
}

Attributes

Configure an array of the name of each movement sensor you want to add to your machine as a merged resource in the attributes of the merged movement sensor model:

  • The name of each attribute represents the Property that the particular movement sensor supports, or the type of reading or measurement that it takes.
  • Get the properties supported by each model from its model configuration documentation, or by calling GetProperties() on the sensor.
  • Put the name of each movement sensor into the attribute array for the type of reading it supports. You can use the same sensor for multiple attributes if it supports multiple properties.
NameTypeRequired?Description
positionarrayDependent on Readings Type SupportedThe name of the movement sensor you want to merge, if it reads position.
orientationarrayDependent on Readings Type SupportedThe name of the movement sensor you want to merge, if it reads orientation.
compass_headingarrayDependent on Readings Type SupportedThe name of the movement sensor you want to merge, if it reads compass heading position.
linear_velocityarrayDependent on Readings Type SupportedThe name of the movement sensor you want to merge, if it reads linear velocity.
angular_velocityarrayDependent on Readings Type SupportedThe name of the movement sensor you want to merge, if it reads angular velocity.
linear_accelerationarrayDependent on Readings Type SupportedThe name of the movement sensor you want to merge, if it reads linear acceleration

Note that only one sensor from each array can be used to retrieve each type of reading. Your machine uses the first sensor in the array that has implemented the relevant API method in its model and does not raise an error at runtime. For instance, in the JSON Example above, if both "imu-wit" and "mpu6050" support returning angular_velocity, "mpu6050" is only used to read angular velocity on the machine if "imu-wit" returns an error at runtime.