A high speed and high torque robotic actuator using low-cost brushless motors, custom controller, 3D printed parts and bearings.
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Repaired Pack and go file for SEA leg
x-zip-compressed - 28.52 MB - 04/24/2019 at 16:48
PSOC4 Project files Hardware and software (code) files More CAN comms and move instructions
x-zip-compressed - 1.76 MB - 10/23/2018 at 16:28
Full Tail CAD Files Inventor Pack and Go
x-zip-compressed - 21.73 MB - 10/21/2018 at 17:40
Full Tail Step Files
stp - 3.93 MB - 10/21/2018 at 16:28
Full Leg (with SAE) Step files
stp - 5.83 MB - 10/21/2018 at 16:23
Before Cycloidal Gearboxes, I research Concentric Magneti Gearboxes.
I made an improvement on the current design by drastically reducing the flux path length and hence increasing the torque handling ability.
standard flux path
New flux path
More development on Cycloidal Gearboxes
240:1 reduction ratio
Before I settled on Cycloidal gearboxs I did some other experiments
Boards got delivered from JLC PCB. Ordered on Monday night, arrived in Australia on Monday morning.
10x 4 layer boards + Shipping = AU$35.75
Internal Power planes were checked and all seamed fine. Next time I will order gold boards.
Via hole centering is slightly better than the last boards I had made at PCBWay.
Surface finish is not as good, but I think I ordered a better finish last time.
Silkscreen is clear and much better aligned.
I am happy with the boards.
I populated the board by hand using a soldering iron, solder and solder wick.
I will order a stencil next time or just get JLC to populate the PCB. I may still order a stencil for the remaining boards.
I took two nights to populate and 90% test the boards.
Motor is running from this board, so the follwoing are working
Next to test
Smaller form factor with on-board magnetic encoder
1KW Peak 8S (34V @ 30A)
JLC just completed PCB manufacture (DHL shipping 4-5days)
PSOC4 SOC (CY8C4247AZI-L485)
Smart MOSFET Driver DRV8305 with three Current sensors
6x SIR638ADP-T1-RE3 40V 0.88 mOhms PowerPAK SO-8
3x 1mOhms with Kelvin Terminals
Centre Mounted AS5147 (or AS5047/48) Absolute Magnetic Encoder 14-Bit
5V @ 600mA Regulator
MOSFET Temperature Monitor
External Temperature Sensor Connector
I2C Qwiic (For OLED Display)
External SPI (single/Dual) Absolute Encoder Connector
2x Servo Outputs or 2x Analog Inputs
4 spare IO
Back of Board
Strip of Ceramics or two Electros
Tightly couple Half Bridge
The Cypress PSOC4 Controllers are not very common in the maker community. As I would like more makers to be able to use/modify/improve this Actuator, I am designing an Arduino version. It will be based around the MKR Zero with the SAM D21.
Earlier I got the Centered Aligned PWM working for controlling the MOSFETs for driving the Brushless motor. Next was the SPI for reading the Magnetic Absolute encoders for the motor and joint positions. The SPI on the SAMD21 only has a single buffer which is not time efficient for this application. It does have a DMA on the SPI which is much more complex but the most efficient for operation. The problem is that it is not a standard feature for the Arduino system.
I started with the following information.
Now the Adafruit Zero DMA library makes it too easy
and can now be installed by the standard Arduino IDE --> Sketch --> Include Library --> Manage Libraries
It also support Interrupts "dma_callback" to tell when the transfer has completed.
Visual Studio and C# in .Net was used to write a simple test program. An X,Y foot position is generated, converted to hip and knee angles using Inverse Kinematics and sent to the serial to CAN converter (spare PSOC actuator controller). These packets are addressed to the two robot actuators to move to the required position. A second mode just returns Joint positions.
I have modified the base robot actuator to make it into a full robot leg for a quadruped. It has a parallel linkage with springs and 2 robot Actuators. This means that the spring direction changes from rotation to almost vertically linear when the leg is in the standard walking positions. Different strength springs can be swapped for testing, with the aim to store energy at the end of a jump cycle and use it for the next jump. It will also be used for efficient walking/running.
Everything rotates around the same joint, for the centre joint, described from top to bottom of the drawing.
1x Brushless motor with extended shaft (6mm Silver Steel)
1x Custom Brushless Controller Board
2x AS5147 Absolute Position Boards
2x 6mm x 2.5mm Diametric Neodymium Magnet
12x 3D printed parts
16x 5x8x2.5 bearings
2x 6809 Bearings
8x 3mm dia x 30mm Silver Steel shaft
26 (or 13) 3/32" x 28mm Silver Steel shaft
26 (or 13) 1/8" x 16mm Brass tube (thin wall)
24x M3 bolts
10x M2 Bolts
3x PZT screws
1x M6 thin wall washer
1x 2mm dia x 11mm Silver Steel shaft
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