RobotArm project...briefly history...

The robotarm project has been started many years ago. Went on building to finish it, recently. The arm has 6 degrees of freedom and an endeffector. The different joint are moved by steppermotors and the gripper by a DC-motor. Gearcombinations are used to get a nice and smooth transmission from motors to joints.

The Interface between robot-arm and pc is done by an ISA-slot with a bunch of 82c55a IO-peripherals on it. May sound a bit "old-skool" but they are easy, proven and easy to programm! Future projects will be done with more sophisticated “techniques” like a Raspberry PI module used as an I/O-module controlled by USB. My ISA-pcb is complete DIY, build from “zero”.

The electronics are partly DIY and partly read-modules. In the beginning it was all DIY: built by using electronic components like ic’s and discrete components. Nowadays, complete modules are very affordable.

The software is written in Turbo Pascal 7.0. but for this purpose it’s very nice, most of the programm concist of mathematics! As userinterface there’s the pc-keyboard and my DIY: QuadStick. 4 gamecontrollers in 1, connected to the ISA-pcb!Allready got a nice piece of software made in Delphi. As the robotarm is a mechnical structure, the software is allmost complete filled with mathematic parts. One part is called kinematics

A robot is mostly controlled by software but you can do it manualy by  using a keyboard or an other so called human-machine-interface, HMI.

So, after long time, the project is going to finish...that's means the mechanical and electronic part. I have to continue creating the software. 


Take a quick tour on youtube! Much more video's to come!


UPDATE NOVEMBER 2016

Recently, I started to work with microcontrollers, in this case the 2560 Arduino Boards.

For programming these, I use mikroPascal. On the pc, I'm using allready Lazarus.

Wanna getn rid off using the pc's ISA-slot for contact to the world outside the computer.

With the microcontroller, easely an RS232 connection ( bi-directional ) can be established.


UPDATE NOVEMBER 2016

robotarm


More to come...

interface

My first DIY ISA-slot IO-pcb was not that good, so had to build a better one. I call it ISA2.0:



On the pcb are 2 82c55a chip’s. Each has 24 configurable I/O-lines. The chip’s can also configured in different modes. For chipselecting and addressing 2 74hc138 are used. With a jumper the basic-adress is set. On the pcb are some LED-bargraph’s, they give an easy and quick overview of the incoming signals like endswitches. The connection to the robot is done by 5 times a 10-pin connector and 1 16-pin connector.

ISA may look old-fashioned but the IO-rate is about +330.000 commands per second! That will do perfect! Each command is one read- or write-instruction. When starting my software the 82c88a chip's will be set in the right IO-mode and the IO-lines will be dedicated as written in the setup-file of my programm. The setup-file can be accesed by notepad or a simmular programm.

The pcb is completely DIY! That means there are no lanes at the bottomside of the pcb. Had to wire it by using tiny wires. Powerlines are done with regular insulated copper wires 0,08mm2. The wires for the digital lines are done with very small insulated cupper wires, as shown in the close-up above. The number of pins is about ( chip’s + bargrap’s + connectors + “the rest” ) is about 240! So you get an idea of the cable-spaghetti. Watch the clos-up, it gives an indication of the tiny wires...

electronics

Eachone of the 6 bi-polair steppermotors and the DC-grippermotor has it's own driver. TB6560-based drivers for the bigger steppermotors and A4988-based fot the smaller steppermotors. The gripper is driven by a small H-bridge chip. First, all was build on DIY-pcb's. Pcb containing TB6560-based drivers:


The DIP-switches are to set settings as microsteps, torque etc. I choose not to set these by software, 'cause they need to be set only once. Later, this pcb has been replaced by complete TB650-based modules. 


More to come...

software


More to come...

kinematics


More to come...

HMI

Of course, you want to controll a robot arm manualy. That's more fun! You need a so called humane-machine-interface, HMI. This can be a joystick. I’ve created a HMI consists of 4 mini joystick from a gameconsole. I called mine the QuadStick:


Each of the joystick is an analog one, but configured as a digital one. Later, it will be configured analog, using ADC’s, analog to digital convertors. Each stick can point into each direction and has a push-button inside.