**2.1. Robot model description**

The mobile robot used in this project is the robotic platform called NI LabVIEW robotics Starter Kit®, described in [8], also known as DaNI 2.0, developed by NI. This mobile robot was designed to develop and run algorithms in real time for autonomous system applications and can be programmed on two different languages: LabView or C.

Each wheel of the robot is connected to a DC motor which provides the traction force and stabilization wheel for balancing the robot; the kinematic model and the representation of robot position used in this work is the same as the one presented in [5]. The sbRIO-9632 card

**2.2. Robotic arm with LEGO MINDSTORM NXT 2.0**

robots of this kind.

**2.3. Analysis of the gearbox**

down. Each motor is finally fixed to the gear train.

shows the 3D design of the gear train implemented.

dance with the desired speed ratios, which will be explained below.

number of teeth of a gear, respectively, both parameters are directly related as:

the number of teeth required to provide a given angular velocity. If the rate *Z1*

The Lego Mindstorm is a programmable robotic kit developed by Lego® and introduced for the first time in September 1998. The kit Lego Mindstorm NXT 2.0 provides basic pieces to construct mini-prototypes of robots by means of the assembly of mechanic plastic parts such as wheels, gears and bricks, among others, and electromechanic parts such as motors and different kind of sensors; finally, the robot prototype is programmed in an interactive way. The robots constructed using the Lego Mindstorm kit can simulate the same functionalities as real

Design and Implementation of a Demonstrative Palletizer Robot with Navigation…

http://dx.doi.org/10.5772/intechopen.72872

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The robotic arm assembled for this project has a degree of freedom; its design is based on a parallel mechanism, and its motion is restricted only to vertical movements (up and down). The NXT brick is the central unit processing for programming robot task using LabVIEW Robotics which is the same graphical language used for programming the mobile robot

The mechanical design of the robotic arm is based on a parallelogram arm (four bars) [11] and an arrangement of gear wheels (called gear train) [12] to transmit turning force and to provide a degree of freedom. The four-bar mechanism consists of two vertical bars of 8 cm in height and two horizontal bars of 6 cm in length. To implement our parallelogram arm, the four-bar mechanism is implemented twice, one for each servomotor used to move the arm up and

A 3D model in Solidworks® [13] of the different ratios of used gears is shown in **Figure 2**. Note that different ratios are used for drive transmission and for the moving arm in accor-

The number of teeth on the gear is the most important parameter during gearbox design, because the speed of a final gear train only depends on this parameter, with 24 and 36 teeth being the most common sizes used. With *n* and *Z* being the desired angular velocity and the

*n*<sup>1</sup> *Z*<sup>1</sup> = *n*<sup>2</sup> *Z*<sup>2</sup> (1)

where index *i* represents the motor (*i = 1*) and the driven (*i = 2*) gear. This equation provides

1, the speed will be reduced. In our case, the gearbox uses eight gears, and we consider Z<sup>1</sup> = 8 teeth for gears 1, 3 and 5, and Z<sup>2</sup> = 24 for gears 2, 4 and 6, yielding a ratio of *1/3*. The last two gears 7 and 8 are considered as *Z1* = 16 and *Z2* = 36, respectively, with a ratio of 4/9. **Figure 3**

Another important parameter during gear train design is the relation between power supply and torque of the servomotor. The Lego servomotor datasheet establishes that

*/Z2*

is less than

DaNI. The communication between the NXT module and the PC is via Bluetooth.

**Figure 1.** Global strategy for palletizer robot moves a box from place A to place B.

was developed by NI and contains a real-time processor which serves as a main control unit for the robot [10]. In addition, this platform includes a field-programmable gate array (FPGA) Xilinx Spartan-3 which is a reconfigurable device that executes programmed tasks in real time, that is, the active response of the system to external events. For this FPGA, a higher level of programming is possible using the NI LabVIEW® robotics software, which is a graphical language. Programming languages like C, C++ or Java could also be used.

This mobile robot is programmed using an efficient algorithm to cover a trajectory that takes it to the box that needs palletizing. The aim is to illustrate the function of a box palletizer robot in industry. Yet, at this stage, it is only a prototype to show basic functions not involving heavy weights as those handled by an industrial robot.
