Posts by Ryan
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Alvaro Villoslada, Pololu customer, made this impressive open-source 3D-printable hand prothesis. Each finger uses a 1000:1 Micro Metal Gearmotor HP 6V with Extended Motor Shaft to wind a fishing line—acting as a tendon—onto a spool. A magnetic encoder attached to each motor enables closed-loop control, and the motors are driven by DRV8838 DC motor driver carriers. An RC hobby servo controls the thumb position. Alvaro uses a Teensy 3.1 microcontroller to monitor the encoders and control the actuators, and he built a user interface in Python for controlling the hand from a computer.
For CAD files, detailed instructions and more pictures and videos, see the Hackaday project page.
MCHobby, a Pololu distributor, translated the Pololu Zumo Shield for Arduino User’s Guide to French as the Guide utilisateur du Robot Zumo Pololu (2MB pdf)! They describe it in French as “Un guide complet pour assembler, utiliser et exploiter rapidement votre Robot Zumo (version 0.1)”. If you’d like to see more translations like this, please let them you know that you enjoyed it and support them by buying from their shop.
We are now offering two new NEMA 17-size pancake bipolar stepper motors from Sanyo, each featuring an integrated high-resolution quadrature encoder and home channel for absolute positioning.
|Stepper motor||Steps per revolution||Current rating (per coil)||Voltage rating||Resistance (per coil)||Holding torque|
|#2279 42×31.5mm||200||1 A||5.4 V||5.4 Ω||1.9 kg-cm (26 oz-in)|
|#2278 42×24.5mm||200||1 A||3.5 V||3.5 Ω||800 g-cm (12 oz-in)|
The integrated quadrature encoder operates from 5 V and has a resolution of 1000 P/R, which allows for 4000 counts per revolution (CPR) of the output shaft when counting both edges (i.e. rising and falling) of both channels (i.e. A and B). In addition to the A and B channel outputs, the encoder has a home channel, Z, that pulses once per revolution and can be used for absolute positioning. The encoder also has outputs for the inverse of A, B, and Z. A 15 cm (6″) encoder cable is included.
We’ve replaced our original 12 V 1 A wall power adapter with a lighter, smaller version. This UL-listed 12 W, “wall wart”-style switching power adapter supplies up to 1 A at a regulated 12 VDC. The AC adapter works with input voltages of 100 to 240 VAC and has a 1.5 m (5 ft) DC power cord that is terminated by a center-positive, 5.5 × 2.1 mm barrel connector.
Forum member jwatte posted about a robot he made for the RoboGames MechWarfare 2017 competition. The goal is to build a walking robot that tries to hit an opponent’s pressure sensors with airsoft pellets or melee weapons. The robots walk around in a scaled-down cityscape field. Autonomous operation and teleoperation are allowed, but teleoperators must view the field from cameras mounted on the robot.
The mech uses a few Pololu voltage regulators: a 3.3 V, 1 A step-down regulator D24V10F3 powers a Xbee-Pro 900 XSC S3B wireless transciever and the laser pointer, a 6 V, 500 mA step-down voltage regulator D24V5F6 powers an OpenCM 9.04A robot logic board, and a adjustable step-down regulator D24V6ALV powers a 5.8 GHz wireless camera. A 250:1 Micro Metal Gearmotor LP 6V drives the plastic BB agitator that feeds the airsoft gun. The wiring harnesses used a lot of our pre-crimped wires.
For more details including a system block diagram see the forum post.
We added the FEETECH Mini Servo FT1117M to our expanding RC servo selection.This miniature-sized servo has a stall torque of 50 oz-in (3.5 kg-cm) and a speed of 0.11 sec/60° at 6 V. The pinion gear is plastic, but the rest of the gear train consists of all metal gears, allowing this servo to deliver the kind of speed and torque typically associated with larger servos.
Comparison to the Power HD 1711MG mini servo
This servo is a lower-cost alternative to the 1711MG from Power HD, which has nearly identical dimensions and performance. The two servos should be generally interchangeable for most applications. The picture below shows both the FT1117M and the 1711MG side by side:
Expect more new FEETECH servos in the coming weeks!
The RoboClaw 2x60A motor controller (V5) we’ve been carrying has been replaced by the new RoboClaw 2x60A Motor Controller (V6). This powerful motor controller can drive two brushed DC motors with 60 A continuously at voltages from 6 V to 34 V, and it allows for peak currents up to 120 A. Version six adds a protective aluminum plate to the board bottom and ports for connecting optional cooling fans that are controlled based on the board temperature.
RoboClaw 2×60A Motor Controller (V6), bottom view.
The RoboClaw motor controllers from Ion Motion Control can control a pair of brushed DC motors using USB serial, TTL serial, RC, or analog inputs. Integrated dual quadrature decoders make it easy to create a closed-loop speed control system, or analog feedback can be used for position control.
For more information, see the product page.
We’ve added this Micro-USB wall adapter to our catalog. It can supply up to 2.4 A at 5.25 VDC (the USB specification’s maximum bus voltage), allowing for voltage drop due to power draw when powering 5 V electronics. It features a 1.5 m to 1.8 m (5 ft to 6 ft) DC power cord with 20 AWG wires that is terminated by a USB Micro-B connector, which makes it great for powering devices like a Raspberry Pi (especially newer Raspberry Pi models, like the Pi 3, which can draw a lot of current!).
Raspberry Pi connected to a Wall Power Adapter: 5.25VDC, 2.4A, 20AWG MicroUSB Cable.
For more details, see the product page.
Don’t hold your applause: we are now offering the Verbal Machines VM-CLAP1 Hand Clap Sensor! This board is a low-power, microprocessor-based audio sensor that can detect hand claps or finger snaps while ignoring background noises such as human speech or music. It operates from 2.5 V to 5.5 V and offers a simple interface: when a clap or snap is detected, the output pin goes low for 40 ms, and the integrated blue LED lights up.
One of our customers built this six-foot tall balancing robot. The main microcontroller is a Teensy 3.6, and the stepper motors are driven by ST-M5045 drivers. For its drive train it uses two 3 A stepper motors connected to Pololu 90 mm wheels via Pololu universal aluminum mounting hubs.
Here’s what they have to say about using stepper motors:
I used stepper motors to take advantage of high torque at low RPM and zero backlash. This allows very steady stand-still performance. But dealing with the stepper-induced mechanical vibration was an issue. This was mostly solved with analog filters on the IMU and with an Extended Kalman Filter in software.
Additional description and pictures are available on the project page.