Robotics is a hot topic of discussion on blogs, online technical journals, and industry trade magazines. Design News has covered a variety of robotic applications and systems for its readers over the years. In keeping with this highly visible and mainstream subject, Design News readers will find this robotic arm that can be operated using a desktop PC, notebook computer, Android phone, or tablet of interest. Global Specialties, a manufacturer of test equipment and electronics prototyping and training tools, has developed a desktop robotic arm that can be programmed in C or operated by a computer-based teach pendant, a keypad, Android mobile phone, or tablet. The robotic arm has expandable operating controls features and can easily be modified using external sensors or other electronic interfacing circuits.
The Global Specialties Model R700 Vector Robotic Arm. (Source: Global Specialties)
R700 Vector Robotic Arm Basic Components
The R700 Vector Robotic Arm is built from a multitude of electronic and electromechanical components. The manual that comes with the robotic arm provides component details and how they are used with the mechatronics machine. The robotic arm comprises several subsections or units that provide articulating movement or Degrees of Freedom (DoF) for the programmable electronics and electromechanical system.
The R700 Vector Robotic Arm Block Diagram consists of several basic subsection components that make up the overall mechatronics system. (Source: Don Wilcher)
Here’s the explanation of the components that make up the R700 Vector Robotic Arm.
The power supply provides the necessary electrical voltage to operate the electronics and electromechanical components of the R700 Vector Robotic Arm. The robotic arm can operate from a power supply ranging from 9V DC to 14V DC at 3A to 4A. The R700 Vector Robotic Arm system is supplied with an AC adapter meeting the power supply requirements listed.
Human engagement with the robotic arm by way of Teach Pendant interaction, keypad, and actuator control is managed by the logic controller. The main processing component for the R700 machine is the Atmel ATMEGA64 8-bit microcontroller. The ATMEGA64 microcontroller has a processing operating speed of 16MIPs (million instructions per second) based on a clock frequency of 16MHz. Memory capabilities of 64KB Flash ROM, 4KB SRAM, and 2KB of EEPROM allow sophisticated robotic tasks to be executed easily and effectively. Programming tasks can be implemented using the popular C- language and the WinAVR/avr-gcc coding toolchain or the computer-based teach pendant.
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In addition to C instruction processing capabilities of the R700 Vector Robotic Arm, the ATMEGA64 microcontroller is responsible for operating the six servo motors. The six port pins of the ATMEGA64 microcontroller provide the PCM (pulse coded modulation) control signals for providing robotics servo motors’ angular rotation. To prevent over extension of the robotic arms’ mechanical appendages, there are servo sensing amplifiers that measure the current flowing through the motors’ windings. The servo motor current sensing is accomplished using dual precision Texas Instruments TLC27M2CD operational amplifiers.
The Atmel ATMEGA64 8- bit microcontroller provides drive capability for the R700 robotic arm servo motors. (Source: Global Specialties)
Upon reaching a critical current threshold value, the circuit shuts off the servo motors. Shutting off the current prevents damage to the electronics and the motors. Current sensing and control of the servo motors are accomplished with the following electronic circuit.
Current sensing of the six R700 robotic arm servo motors is accomplished by dual-precision operational amplifiers (TLC27M2CD) manufactured by Texas Instruments. (Source: Global Specialties)
The actuators provide six DoF for the R700 robotic arm. The actuators or servo motors allow six articulating mechanical movements for a variety of pick-and-place robotic tasks. The actuators are partitioned into two weight categories: 0.20g and 56g. The motors’ torque values consist of 3.2kg-cm and 13kg-cm respectively. Also, there is a torque clutch mechanism used in the robot’s end effector to disengage the power when grasping objects. This disengaging device prevents damaging the servo motors.
Six servo motors (actuators) provide six Degrees of Freedom for the R700 robotic arm. The torque clutch is used to disengage the power during grasping tasks. (Source: Global Specialties)
The teach pendant allows the robotic arm to be controlled remotely by the operator. Also, the robotic arm can be programmed manually by moving and recording the actuator’s movements. A script is logged by the teach pendant for the actuator’s positional movement. Once recorded, the logged movements can be played back and observed on the robotic arm. Actuator-logged movements can also be fine adjusted either by changing the recorded data point or capturing a new script.
The Robotic Arm Control (RAC) Teach Pendant allows programming the actuators’ movement through recorded scripts. (Source: Don Wilcher)
In addition, wireless control of the robot can be accomplished by using WiFi, RF, and Bluetooth modules. The wireless modules easily mount to the PCB located in the robotic arm’s base. The installation instructions are provided in the manual. Global Specialties has provided software examples for evaluating the wireless modules, as a well as an Android app for operating the robotic arm with a smartphone.
There are a variety of wireless and in circuit programming modules for operating the R700 robotic arm using a keypad, desktop PC, notebook computer, Android smartphone, or tablet. (Source: Global Specialties)
A small robotics lab for exploring AI and manufacturing concepts can easily be setup using the cost-effective R700 Vector robotic arm system. Additional information on pricing, wireless modules, keypad, circuit schematic diagrams, and example software can be obtained from Global Specialties website.
Don Wilcher is a passionate teacher of electronics technology and an electrical engineer with 26 years of industrial experience. He’s worked on industrial robotics systems, automotive electronic modules/systems, and embedded wireless controls for small consumer appliances. He’s also a book author, writing DIY project books on electronics and robotics technologies.