During the development of the robot, likewise in the process of finding a name for it, we always proceeded with a healthy portion of humour. This is how the wordplay EnteB (pronounced in German) came about, which contains the name of our school.

The most important components of the EnteB will be described in detail here. Additionally, the complete course of the game will be explained. In the following video you will find all the functions the EnteB needs to get over the mountain.

  • Specifications
  • Motors and encoder
  • Battery
  • Photodiode OPT 101
  • Permanent magnets
  • Printed circuit board

Specifications

Size:160x160x160 mm
Weight:2.6 kg
Used material:aluminium, steel

 

 

motors

Three identical motors are being used for the robot’s movement. The motors consist of four main components. The encoder, the gearbox and the dc-motor were sponsored threefold by the company “Faulhaber”.

Encoder: The encoder allows accurate positioning by counting the number of rotations performed by the motor. You will find the datasheet here.
Gearbox: With a translation ratio of 1:100, the epicyclic gearing ensures the necessary torque. You will find the datasheet here.
Motor: 12V dc-motor. You will find the datasheet here.
Winch: The cable is coiled onto the cable winch.

Current Power:10 Watt
Translation Ratio:1:100
Output Torque:   1 Nm
Output Rate of Rotation:30 min-1
Total Length:   110 mm

 

 

Actuonix servomotor

The linear servomotor is needed to retract and drive out the coupling plate. The linear servomotor was sponsored by NTB. For more information, you will find the datasheet here.

Extension length:50 mm
Force on pull/pressure:60 N

 

 

Turnigy nano-tech battery

The battery was provided by NTB. The battery lasts at maximum load for up to 11 minutes. For more information, you will find the battery’s datasheet here.

Voltage:11.1 V
Capacity:1300 mAh
Size: 70x34x22 mm

Photodiode OPT 101

For the positioning of the platform, which is equipped with a red LED, two photodiodes are attached on the bottom of the robot. Additionally, these possess a red-light filter to avoid interference from external light sources. The datasheet of the photodiodes you will find here and for the optional red-light filter here.

Permanent magnets

On the extendable coupling plate four permanent magnets are to be found. To balance out the inaccuracies of the coupling’s position, the partner robot also has the identical magnets. So that the magnets attract each other, they are oppositely poled on their respective positions. For more information about the block magnets Neodym (Q-15-15-03 N), you will find the datasheet here.

Printed circuit board

On the printed circuit board there are various components, which are essential for operating the robot. The microcontroller MPC 555, which is so to speak the brain of the robot, is a part of the components. The microcontroller is the interface to the information technology and can independently perform specific tasks.

There are two voltage converters on the printed circuit board so that the microcontroller can be provided with the necessary voltage. These reduce the 12V voltage of the battery to 5V and 3.3V respectively.

For the motor control, two motor drivers are provided. With one motor driver two dc-motors can be controlled. The operating mode of the motors is sign-magnitude.

The user interface has five pushbuttons and three toggle switches. The operational status indicator and the monitoring indicator is carried out by nine small green LED’s. Both photodiodes are also connected through the printed circuit plate to the microprocessor. For the communication between the two robots there is a WiFi module. Further information about the WiFi module, you will find here.

Procedure

For a successful completion of the task, the procedure is divided in four steps.

Step 1: Approaching position, where
the search begins (Image 1)

After the robot is placed and the ropes are tightened by the team, the robot approaches a defined, saved position, from where it can begin the search for the platform where it should land. It reaches this by winding up the ropes on two sides. The position lies centred on the half of the field on which the robot will be, around 20 cm above ground.

Step 2: Platform search (Image 2)

If step 1 is completed successfully, the robot begins its search. By means of two photodiodes it can localise the position of the platform, if the platform is located on the same side of the field. In order to do this, the robot approaches the six possible platform positions and detects the intensity of light at each position. At the position where the intensity is the highest, thats where the platform is located. This position is then saved and the search result is transmitted via WiFi to the partner robot.

Step 3: Approaching the coupling position & coupling with the partner robot (Image 3)

When the search process is completed, the robot goes to the arranged coupling position. As soon as both robots are at the coupling position, they extend their coupling plates. The robots connect with the permanent magnets, which are on the plates. The connection is verified through the triggering of the pressure sensor on the plate. Now both robots retract their plates at the same time and the robot that doesn’t have the platform on its side of the field unwinds all three ropes. The robots are now amongst themselves and are ready for landing.

Step 4: Landing (Image 4&5)

The stored position from step 2 will now be approached horizontally. As soon as the robots are above the platform, they land together and the game has successfully been completed.