## 1 Introduction
Thus, it is very important to start teaching science, technology, engineering and mathematics (STEM) concepts involving robotics as soon as possible. In this sense, when students reach a higher education level, they can focus on the specific high-level concepts of robotics such as intelligent robotics, swarm robotics, autonomous vehicular network robotics, among others, to prepare them with the required skills for future jobs. [PERSON] [6] indicates that University 4.0 is needed to prepare students for the Fourth Industrial Revolution. An integrated digital learning model is proposed by [PERSON] [6] using the study by [PERSON] et al. [7] as a basis. This is composed of three areas: Communication and Creativity, Critical thinking and Problem Solving, and Responsibility, and robotics is involved in this approach. Thus, the goal of this study is to develop a low-cost collaborative robotic arm with 6 degrees of freedom to be applied to laboratory teaching-learning activities within the scope of the curricular units of engineering courses. Additionally, it may be used to support research activities in the scope of projects, and even to test its suitability for other types of applications in industry or services outside the educational context. In particular, the use of the robotic arm developed within the scope of curricular units of robotics is an added bonus for students, giving them the opportunity to develop their practical work and enrich their practical knowledge. On the other hand, applications in research projects can be varied, but specifically, they are associated with robotization projects of agricultural tasks, such as picking fallen fruit from the ground. Picking fallen fruit automatically has several direct and indirect impacts, especially for peach, which is an endogenous fruit product of the region [11]. There are many robot solutions on the market and under development forvarious applications. These robots are selected or designed considering fundamental parameters such as payload, repeatability, and reach. From the low-cost solutions existing in the literature, [PERSON] et al. [12] proposed a HydraX robot printed with PETG filament, with 6 degrees of freedom, a payload of 4 kg, repeatability of \(\pm\)0.01 mm, and a length of up to 550 mm. [PERSON] et al. [13] proposed an anthropomorphic robot with a variable rigid link, with 3 degrees of freedom and joints moved by stepper motor (NEMA 17). The authors of [14] proposed WE-R2, 4 of 6 degrees of freedom, printed with a PLA filament and with joints moved by stepper motor (NEMA17). [PERSON] et al. [15] proposed the robot SCARA with a double arm and 9 degrees of freedom, which can support a weight of 5 kg in each arm. [PERSON] et al. [16] proposed the humanoid robot (LWH) with 8 degrees of freedom, with an aluminum structure, 810 mm reach, supporting a weight of 3.5 kg. [PERSON] et al. [17] proposed a robotic arm with recyclable materials for payload of 1.5 kg, with 6 degrees of freedom. [PERSON] et al. [18] proposed a robotic arm with guidance based on computer vision with 4 degrees of freedom. [PERSON] et al. [19] proposed a soft robotic arm made from a lightweight nylon fabric coated with a thermoplastic polyurethane, total weight of 2 kg and 4 degrees of freedom. All solutions presented above are controlled by microcontrollers (Arduino, ESP32 or PIC), with structures made of filament (Polylactic acid-PLA or Polyethylene Terephthalate Glycol-PETG) or aluminum, and some have a user interface via MATLAB. To carry out this study, SolidWorks software was used to model and modify the structure of the robotic arm, and subsequently, a filament of a 3D printer was used to print the parts. To move the robotic arm, stepper motors were used with an encoder attached. This control is performed through ESP32 microcontrollers, which are directly handled through an interface program in MATLAB.