Machnical Design
"Z(H)ERO"
This week we are tasked with the Group assignment to actuate and automate your machine and to document the group project and your individual contribution My contrubution to the group was very minimal but having amazing friends in the group who knew what they were doing helped me learn. Arefin and Rutvij took the lead as they worked with interfacing and eletronics of the machine. Unlike previous years, this time the machine week was much later than before, hence Input, Output and interfacing weeks had already been completed This enabled a better understanding of what Arefin and Rutvij were doing while Rohan was making arm in acryllic and getting it laser cut ready when the eletronics part is done. My primary focus this week was to design the end effector but due to time limitations we decided to not make the end effector so I was helping around I had the oppurtunity to grab lots of new concept.
For robots like the 3D arm, kinematics are an integral part.
Kinematics:
Kinematics is a branch of classical mechanics that describes the motion of points, bodies (objects), and systems of bodies (groups of objects) without considering the mass of each or the forces that caused the motion. Kinematics can be further separated into two major parts:Forward Kinematics
Forward Kinematic, or the easier of the two.... they give the position of the end effector based on the individual relative position of the joints.Reverse Kinematics
Reverse Kinematics, or the harder of the two... they give the relative position of the joints based on the position of the end effector The robot’s arm must adjust each joint’s angle in order to move its hand over to the position. This is quite the opposite - here, we start with a given position and want to know how to rotate each segment of the arm. It turns out that this is much harder than the forward case. And whenever something is hard to solve, there are usually several different approaches available for solving that problem. For inverse kinematics, there are three of them: The algebraic approach: This basically works by solving (super complex) matrix equations. The geometric approach: The idea is to combine knowledge about the robotic arm’s geometry with suitable trigonometric formulas. The numeric approach: Take a guess and look how far we are off. Move one or more segments to locally minimize the error. Repeat. Rohan did a rough calculation of the kinematics, to solve the reverse kinematics we need t=to calculate the D-H parameters, i.e. the Denavit–Hartenberg parameters This video helps to get a more clear understanding of the D-H parametersElectronics and Softwares
Komal and Kamlesh went with the software named as GRBL Gru, this is a software used for X-Y plotters following the schematic as shown below for testing.
Now we are going to operate it via programming language, Before going to this we are complete the electronics part,
Here for movement in X, Y, Z axis we used three stepper motor called NEMA 34.
The electronic wiring and motor connection and driver assembly we did together,
For controlling the motor we used TB6600 stepper driver with RAMPS shield board of Arduino Mega 2560.
We used three motor NEMA 34 + TB6600 Driver+ RAMPS 1.4+Arduino Mega 2560
For controlling the motor, We used Marlin Firmware for controlling the stepper motor as redial degree instead of co-ordinate system. Marlin is working with Python GUI/Processing GUI or JAVA GUI. Arefin used Pronterface (Windows Based) GUI for controlling the Stepper motor. These are all new to me but it was quite fun to learn how these softwares worked
Final Works
After two weeks of intense team work, we finally managed to get our three axis robot to this point
Personal contrubutions
For me, my main work assignment during the team assignment division was the designing the end effector and during the second week, I had the oppurtunity to be able to assist the team members working on different aspects of the work, I got to learn lots of new concepts and also play assistive roles to my team.