The guys at Totem sent me a sample of their robotic arm to review (link points to the mechanical version without the electronics). The version I received contains several Totem Bus modules to drive the arm.
It is described on their web page as an “easy and fun to assemble mechanical parts together with 4 motors makes an agile 3 degrees of freedom robotic arm with a gripper, two elbows and ability to rotate 180° around platform axis“.
Little mechanical issue
In the proces of building up the mechanics I found a little problem, that I will describe here. When you have a look at the picture on the right, you will see the three hole bracket that is recommended in the booklet (picture #8) to mount the pivoting table on the base (picture #13). It’s laying on top of the constructing.
When that bracket is installed, I could not get the thread of the 12 mm bolt to grip in the motor, this bolt under these conditions is just not long enough. So I had to replace the three hole bracket with a shorter, two hole version. Then I had the bolt go in that way (look under the tip of the little screw driver). The construction seems secure now, in the sense that the pivoting table is fastened to the base.
Mechanical part finished
After some fiddling, the mechanical part is now finished and sitting on my desk:
Totem bus modules
As I mentioned, this version contains a couple of bus modules. Here’s a picture of three modules with their base boards.
The base boards (white ones on the left) take care of power and communication to all of the function boards. Apart from that the bottom one (with the two larger black squares) has Bluetooth capabilities, so it can be paired with a phone or computer.
The function boards are the PCB’s on the right, from top to bottom: A board to control three servo’s; a board to control two servo’s and a DC motor; and the third one is a power board for the servo functions.
The little one is a separate connector that, as far as I can tell, is used to connect the DC motor for the gripper.
A picture of the boards, built and connected:
The software for iOS, Android, Linux and Mac is still in development stage; I’m invited to participate in the beta development, but don’t have enough time at this point. I’ll enroll and participate when time allows.
Last but not least, the guys with Totem were kind enough to send me one of their T-shirts ?:
To be continued…