UPDATE: Checkout my BOM and cost breakdown here.
I have spent the last few years considering the design of biped robots primarily for research purposes. The Robot Academy, https://robotacademy.net.au/ , was a big help in this effort. I took both classes back in 2015 and thoroughly enjoyed them.
A couple of days ago an article showed up in my inbox about a great open-source initiative, https://open-dynamic-robot-initiative.github.io/, with a well-developed quadruped called Solo 8. They have plans to leverage this design into an open-source biped with point feet. Consistent with what I have been trying to model over the last couple of years. The name alone piques my interest.
I am going to build their open-source biped model. They used selective laser sintering and high-detail stereolithography. I might try desktop filament printers. Unfortunately, I am an accountant so my natural reaction is to calculate the Open Dynamic Robot Initiatives cost to build.
Cost of the 3D Printed Parts
The cost of the 3D Printed Leg Structures from https://www.3dsystems.com/ :
| Biped Leg | Cost | Qty | Ext Cost $ |
| lower_leg_solid | 84.00 | 2.00 | 168.00 |
| stopper_upper_leg_base | 46.00 | 2.00 | 92.00 |
| stopper_upper_leg_cover | 47.00 | 2.00 | 94.00 |
| stopper_upper_lower_leg_base | 47.00 | 2.00 | 94.00 |
| stopper_upper_lower_leg_cover | 47.00 | 2.00 | 94.00 |
| upper_leg_shell_base | 86.00 | 2.00 | 172.00 |
| upper_leg_shell_cover | 60.00 | 2.00 | 120.00 |
| hip_fe_structure_right_side_cover | 64.00 | 2.00 | 128.00 |
| hip_fe_structure_right_side_base | 66.00 | 2.00 | 132.00 |
| hip_aa_structure_right_side_cover | 63.00 | 2.00 | 126.00 |
| hip_aa_structure_right_side_base | 66.00 | 2.00 | 132.00 |
| Cost | $1,352.00 |
While the above costs do not include the body, I believe those could be readily printed by a desktop printer.
Cost of Actuator Hardware
The cost of the actuator hardware from various manufacturers ( I did not price miscellaneous wiring):
| Part Name | Qty | DoF | Cost | Ext $ |
| T-Motor Antigravity 4004 300kV | 1 | 6 | 72.95 | 437.70 |
| Encoder Broadcom AEDT-9810-Z00 | 1 | 6 | 29.46 | 176.76 |
| Codewheel for Encoder AEDT-9810-Z00 | 1 | 6 | 29.56 | 177.38 |
| Timing Belt Conti Synchroflex AT3 GEN III, width: 4mm / length: 150mm / 50 teeth, Timing belt first stage | 1 | 6 | 6.16 | 36.94 |
| Timing Belt Conti Synchroflex AT3 GEN III, width: 6mm / length: 201mm / 67 teeth, Timing belt second stage | 1 | 6 | 9.65 | 57.88 |
| Bearing Output Shaft, 32mm x 25mm x 4mm | 2 | 6 | 13.85 | 166.20 |
| Bearing Motor Shaft and Center Shaft, 8mm x 4mm x 2mm | 3 | 6 | 6.26 | 112.68 |
| Bearing Timing Belt Tensioner, 7mm x 3mm x 3mm | 2 | 6 | 6.85 | 82.20 |
| Encoder Codewheel PWB Mount | 1 | 6 | 61.00 | 366.00 |
| Timing Belt Tensioner Roller 10mm (SLA) | 2 | 6 | 51.00 | 612.00 |
| Motor Shaft | 1 | 6 | 25.00 | 150.00 |
| Motor Pulley – AT3 T30 | 1 | 6 | 50.00 | 300.00 |
| Transmission Pulley AT3 T30 Output | 1 | 6 | 85.00 | 510.00 |
| Fasteners Encoder, M3 x 16 Philipps Flat Head Screw | 2 | 6 | NQ | 0.00 |
| Fasteners Motor, M3 x 5 Flat Head Screw | 4 | 6 | NQ | 0.00 |
| Fasteners Timing Belt Tensioner, M3 x 10 Flat Head Screw | 2 | 6 | NQ | 0.00 |
| Washers Timing Belt Tensioner, M2,5 Washer | 2 | 6 | NQ | 0.00 |
| Helical Insert Output Shaft, Helicoil M3 x 6 | 2 | 6 | 0.90 | 10.81 |
| Motor Phase Connectors 2mm gold | 3 | 6 | NQ | 0.00 |
| Reely RE-1373188 | 6 | NQ | 0.00 | |
| Motor Phase Wires | 3 | 6 | NQ | 0.00 |
| LiY 0.50 mm² black | 6 | NQ | 0.00 | |
| Encoder Connector | 1 | 6 | NQ | 0.00 |
| Hirose DF13 Socket 5 Pin | 6 | NQ | 0.00 | |
| Encoder Connector Crimp Terminals | 5 | 6 | NQ | 0.00 |
| Encoder Wires | 5 | 6 | NQ | 0.00 |
| LifY 0.14 mm² | 6 | NQ | 0.00 | |
| Total | $3,197 |
Cost of Custom Electronics and IMU
The remaining electronics are priced as follows:
| Part Name | Qty | Cost | Ext $ |
| Master Board (Custom) | 1 | 158 | 158 |
| BLMC Board (Custom) | 3 | 163 | 489 |
| IMU (3DM-CX5-25 AHRS) | 1 | 1,215 | 1,215 |
| Total | $1,862 |
So, in total, we are at about $6,400 USD before incidentals, maybe $7,000 after.
UPDATED: 12/20/2020
UPDATED: 2/5/2022