Daily Archives: December 14, 2011

Robot’s hardware: Summary

General

By now we have completed the series of posts describing the “hardware” of our robot. Here is what we have covered.

If there is anything regarding the hardware of the robot that should be explained in more detail – feel free to ask in the comments.

The Budget

General

To finalize the story of our hardware development, let me show you the budget, i.e. the money we spent on building the robot in the table below. There are two numbers for each expense. The “nominal price” denotes the approximate minimum amount of money one should expect to spend on a particular item. The “we paid” price denotes the actual amount we had to pay. It is nearly always different from the nominal price for two reasons:

  • In some things, such as the smartphone and CNC manufacturing we got help from the sponsors (Nokia, Tööstusplast, Tartu University Institute of Technology and the Robotics club of the University of Tartu). Thus, we spent less than the nominal price.
  • For other things, we spent more either because we bought back-up items (you never know when something is going to burn so this is always a good idea) or because we did not know exactly which particular option we would need and had to try different options.

I might have forgotten or left out something, but the table below should give a reasonable impression of a minimal expense sheet for a robot like Telliskivi. The prices are in euros.

Item Nominal price We paid Remarks
Electronics (275.00 | 325.73)
Miscellaneous (55.00 | 37.28)
Sockets, pinheaders, buttons, etc 15 18.18
LiPo 3-cell battery 30 0 Provided by the Robotics club
Battery voltage converter circuit 10 19.10
Main PCB & motors (140.00 | 217.70)
Main (motor control) PCB 35 0 Provided by the Robotics club
Motor drivers 30 45.80
Motors 60 122.20 We ordered two pairs, just in case
Wheels, wheel mounting hubs, motor mounting brackets 15 49.70 In the end we did not use the wheels nor the motor brackets. We did need two sets of wheel tires and mounting hubs.
Coilgun (50.00 | 39.60)
Coilgun PCB 35 0 Provided by the Robotics club
Capacitor with mount 5 9.60 We bought two, just in case
Coilgun wire 10 30.00 We tried several options
Bluetooth module (30.00 | 31.15)
BlueSMIRF Silver 30 31.15
Mechanics (130.00 | 114.34)
Nuts and bolts, spacers, rubber bands, springs, ball bearings, grease, … 30 92.52
Sheet plastic and CNC cutting 50 14.07 Tööstusplast sponsored most of the manufacturing. The “nominal price” is an optimistic guess.
Sheet aluminium and laser cutting 50 7.75 Metec sponsored most of the manufacturing. The “nominal price” is an optimistic guess. The “we paid” price includes the price for restoring a lathe and a drill broken by us.
Other (0.00 | 105.51)
Postage and taxes on stuff ordered from Pololu and Proto-pic 0 105.51
Total: 405 545.58
+ Nokia N9 600 0 Provided by Nokia
Grand Total: 1005 545.58

Let me summarize this to those of you not interested in detailed numbers.

  • If you are willing to make a similar robot, be prepared to spend at least 400 euros. Out of those, you will spend about 100 on raw materials and manufacturing, 100 on microcontrollers and PCBs, 100 on “large” components (motors, capacitors, battery) and 100 on all kinds of nuts, bolts, connectors and wires. If you plan to order stuff from abroad, prepare another 100 for shipping and taxes.
  • You might easily end up spending at least twice the nominal amount on some articles either for experimenting or for safeguarding against failures on the last moment. This can double your numbers up to 1000 euros.

If you now include expenses on junkfood, transport and the sleepless nights spent by the four team members making and programming the robot, you’ll see that participation in Robotex is, in fact, a very expensive project (for a student, at least). But it’s worth it none the less!