The Home Of HEW - The 5-Axis Robot Arm
Raspberry Pi Model B+

We don’t make a “HEW and Cry”* over controlling our robotic arm

*Hue and Cry: noun

A loud clamour or public outcry.

Synonyms: commotion, outcry, uproar, fuss, clamour, racket, storm, ado, stir, furore, ruckus, ballyhoo, brouhaha, palaver, pother.

HEW: a 6-axis robotic arm.

From students and teachers to hobbyists and enthusiasts, HEW has been designed for anyone and everyone to use.

One of our aims when designing HEW was for the arm to be used as an innovative educational tool. One that was fun, interesting and would capture the interest of young people. This wouldn’t be possible if HEW was difficult to programme and control, so we’ve made it easy to do.

What makes HEW so easy to use? PWM…

Interfacing with the HEW robotic arm is simple, using servo motor PWM (Pulse Width Modulation) control.

Pulse width modulation (PWM) is a fancy term in electronics and robotics for describing a type of digital signal. This from the Arduino PWM Tutorial:

Pulse Width Modulation, or PWM, is a technique for getting analogue results with digital means. Digital control is used to create a square wave, a signal switched between on and off. This on-off pattern can simulate voltages in between full on (5 Volts) and off (0 Volts) by changing the portion of the time the signal spends on versus the time that the signal spends off. The duration of “on time” is called the pulse width. To get varying analogue values, you change, or modulate, that pulse width.

Pulse width modulation is used in a variety of robotics applications, including sophisticated control circuitry. The most common way we use PWM here at Blueprint Robotics is to control the direction of HEW’s servo motors.

This from SparkFun:

You can use pulse width modulation to control the angle of a servo motor attached to something mechanical like a robot arm. Servos have a shaft that turns to specific position based on its control line. Our servo motors have a range of about 180 degrees.

Frequency/period are specific to controlling a specific servo. A typical servo motor expects to be updated every 20 ms with a pulse between 1 ms and 2 ms, or in other words, between a 5 and 10% duty cycle on a 50 Hz waveform. With a 1.5 ms pulse, the servo motor will be at the natural 90 degree position. With a 1 ms pulse, the servo will be at the 0 degree position, and with a 2 ms pulse, the servo will be at 180 degrees. You can obtain the full range of motion by updating the servo with a value in between.

PWM is a common output standard with a range of devices, including micro-computers such as the Arduino, Raspberry Pi and mbed, all of which can be programmed using a variety of programming languages such as C, C++, C#, Python, Java and Scratch.

Arduino Uno (R3)

Arduino Uno (R3)

mbed LPC1768

mbed LPC1768

Raspberry Pi Model B+

Raspberry Pi Model B+

Why pay for another dev board that you don’t actually need?

Unlike our competitors, we don’t bundle a dev board in the box with HEW, forcing you to use that particular board and programming language and pay for another dev board that you might not actually need.

We reckon that most HEW buyers will already own at least one programming dev board that they’ll want to use with the arm, and because we don’t bundle a superfluous dev board in the box when you buy HEW we can keep the purchase cost down. This benefits us and also benefits you.

Your choice of dev board & programming language

HEW isn’t tied to one proprietary dev board or programming language, giving you the choice of which options suit you best. You can use an existing dev board that you already own, or buy whichever one you want to work with to control HEW, and programme the arm in the language you’re happiest working in.

You’re free to choose, which is how we think things should be here at Blueprint Robotics.

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