Introduction
This post will be a serial post to explain the develop of autonomous robot which will be recovered and deployed by an autonomous helicopter.
Motivation
To take environmental measurements in difficult access zones, we propose develop a autonomous robot which will be deployed by a helicopter. When the robot has finished his mission, the robot must be retrieved by the same helicopter which will receive the location from the robot. This location will be calculated with a Wireless Network Sensor (WSN). Moreover we will develop a ground station to receive telemetry and the measurement which the robot took. Those measurements will be taken for the robot and others WSN nodes in that location. The ground station will be able to add waypoint to the mission before it finishes.
Context
This project belongs to PLANET project which belongs the 7º Marco Program. The main objective of PLANET project is the design, development and validation of an integrated platform to enable the deployment, operation and maintenance of large-scale/complex systems of heterogeneous networked Cooperating Objects, including Wireless Sensor and Actuator Networks and mobile objects. The platform will support optimal and adaptive deployment and operation by means of mobile cooperating objects, i.e. vehicles, networked with static nodes. The platform will be validated in two complementary scenarios: the monitoring of the Donyana Biological Reserve with very high ecological value and very sensitive to the impact of pollution, and the highly automated airfield scenario in which security plays an important role and where wireless communication and cooperative techniques pose significant challenges.
The main task of the robot will be calculate his localization to be able to be found and retrieved for the helicopter. A good GPS is very heavy to the restrictions of the robot in size and weight so the error of GPS of the smartphone will be huge to be useful. Finally to calculate a good measurement of the localization we use a WSN which gives a measurement with a error of centimeters.
Sensor network
A sensor network is composed of a large number of sensor nodes, which are densely deployed either inside the phenomenon or very close to it. The position of sensor nodes need not be engineered or pre-determined. This allows random deployment in inaccessible terrains or disaster relief operations. Sensor nodes are fitted with an on-board processor. Instead of sending the raw data to the nodes responsible for the fusion, sensor nodes use their processing abilities to locally carry out simple computations and transmit only the required and partially processed data.
The above described features ensure a wide range of applications for sensor networks. Some of the application areas are health, military, and security. Realization of these and other sensor network applications require wireless ad hoc networking techniques. Although many protocols and algorithms have been proposed for traditional wireless ad hoc networks, they are not well suited for the unique features and application requirements of sensor networks.
- The number of sensor nodes in a sensor network can be several orders of magnitude higher than the nodes in an ad hoc network.
- Sensor nodes are densely deployed.
- Sensor nodes are prone to failures.
- The topology of a sensor network changes very frequently.
- Sensor nodes mainly use broadcast communication paradigm whereas most ad hoc networks are based on point-to-point communications.
- Sensor nodes are limited in power, computational capacities, and memory.
- Sensor nodes may not have global identification (ID) because of the large amount of overhead and large number of sensors.
Requirements
To the design of the autonomous robot, we must comply with the next restrictions which imposes the project.
- The weight must be reduced because the helicopter can not lift 1.5 kg
- The network used for communication should be at the frequency of 5 GHz to not interfere with control of the helicopter.
- The location must be very precise. The location is sent to the helicopter should not be in error by more than 2 meters. The helicopter will fly to the position and seek the robot sent within two meters from that position. The location by GPS when not by differential GPS has an error of 5-10 meters. You must use a WSN for the location.
- The autonomous robot should consider moving over rough terrain and be robust enough to be deployed from a helicopter.
- The mobile robot must keep a two-dimensional code at a certain distance from the center of gravity. The helicopter will recognize this code using image processing in real time from the air. Later, this informacián betray the position and orientation of the center of gravity of the robot to pick it up.
Next Chapters
In the next posts…
- Hardware description: this post will describe the main parts of the robot, besides of the decisions to solve of the project’s restrictions.
- Software description: this post will describe the intern work and the algorithms which execute in the smartphone.
- Experiments and conclusions, this post will show the experiments in the National Park Of Doñana, in addition the experiments during the development the robot.