Our robot - iTower

  • Specifications
  • Motors
  • Accumulators
  • Sensors
  • LCD
  • Printed circuit boards

Our robot moves on rolls which fit into the spaces on the LEGO plates. The housing of the robot is made of steel and aluminium. Rolls, gripper and tower-lock are made of plastic, they were produced using a 3D printer.
The rear wall serves as the print holder, the battery, which supplies everything with power, is located below the robot.


Size: 160x160x160 mm

Weight:  2.3 kg


DC-Motor by Faulhaber


Three identical motors were used for the robot's running gear, the linear axis displacement and the lifting movement. These consist of 3 individual parts: The motor itself, an encoder and a gearbox
Faulhaber sponsored these engines. 


Power:  8.5 Watt

Torque ratio: 1:66

Rotation Speed: 8'100 rpm






A servo motor, model HS-55, from HiTEC was used for the tower-lock.

Dimension: 23.8x12.6x24.0 mm

Torque: 12 Ncm


The gripper is opened and closed with a servo motor, model HS-5065MG, from HiTEC.

Dimension: 23.6x11.6x24.0 mm

Torque: 18 Ncm

Turnigy nano-tech

The batteries were provided by NTB.

The datasheet for the accumulators can be found here.



Voltage: 11.1V

Capacity: 1'300mAh

Dimenstion: 70x34x22mm

3 roller limit switches were used as sensors.
The sensors are meant to indicate whether the robot hit something at the front, the linear unit has reached the rear end, or if the gripper has been fully raised.

An LCD was used to output the status. It can display the status of the WLAN connection or the sensors, predefined errors can be read out. With a button on the print you can switch between the individual displays.


Two PCB's were created, one control and one power PCB. The MPC555 microcontroller is mounted on the control board.

The WLAN module is powered with 3.3V, the microcontroller as well as the servomotors with 5V. Each listed component has its own voltage regulator. The DC motors are connected to the 12V voltage supplied by the accumulator.

The DC motors of the running gear and the linear axis displacement run on sign-magnitude mode, while the motor for the lifting movement is set to locked anti-phase. There are 2 motor drivers on the PCB.

For operating the robot there are 1 main switch for turning it on and off and 3 buttons, one of which is responsible for a hard reset, on the PCB. Monitoring is ensured by 8 LEDs. 4 LEDs are for checking the power supply, the remaining LEDs are for the status output of the program.

In addition, there is an LCD on the robot, which is intended to provide some basic information.

There is also a WLAN module on the print, which enables communication with the partner robot, whereby the construction process can be controlled.



Operational sequence

Playfield with lighthouse
Sequence of the construction process
  • 1 Initialisation
  • 2 Orientation
  • 3&4 Building process
  • 5 Placing

After the robot has been placed and switched on, it starts to check its functions, the motors are tested for example. Then the identification of the partner robot takes place, which is visually displayed.

As soon as the partner robot sends the signal that it is ready, initialization is complete and the construction process can be started.

First the robot moves forward until it hits the tip of the tower. With the help of the gripper, it picks up the tip and positions it on itself.

As soon as the top of the tower has been picked up, the robot moves back until the building position has been taken. This completes the orientation process. 

There are two different variants of the partner robot for the construction process. Team 06's robot will first pick up all stones and store them in an internal magazine until they are handed over, whereas Team 05's robot picks up and hands over each stone individually.

The partner robot will approach our robot to transfer a stone, which is placed directly on the robot. Our robot will then lower the top of the tower onto this stone and press it twice. Then the lowest stone is grabbed and the robot awaits the signal for the handover of the next stone.

This process is repeated until the required tower height is reached.

As soon as the required tower height is reached, we send a signal to the partner robot that it is to move away. The tower is then moved in front of the robot, lowered and our robot moves backwards. The building process is finished.