Walter: robot arm with sophisticated movements

(Photo: Jochen Alt)

What happens if a robot goes into retirement? Jochen Alt has turned to a short film. Actor Walter he built himself and calculated his movements in detail and programmed.

Since the 60s in factories industrial robots are used. As for their retirement might look like after 50 years, Jochen Maker Old demonstrates in his new short film "Walter", It is also the name of the robot arm, which he designed and built himself. In addition to a retro look, he relies on as smoothly as possible looking movements. To achieve this, the movements are cleverly planned, calculated and implemented in mechanics.

optimize movements

First, the lanes are planned on specific points that must be controlled during movement. Then the movement is optimized to a Bezier curve to look smooth as possible (see comparison below). Alt also uses velocity profiles for an even finer image so the arm for example, before a corner short braking and then accelerating again. Finally, the necessary changes in angle of the five joints and Walters are calculated manually.

A green robot arm untenausführt a movement to the side and
The basic movement.

A green robot arm that performs a curved movement
described by a Bezier curve, Walters affects movement to the side and down very smooth.
Picture: Jochen Alt

electronic structure

The calculated data is sent to a web server that runs on a ODROID XU4 board. He goes further via a UART interface to an ARM Cortex M4, which controls the five stepper motors and encoders five of the joints and two servos hand. The electronics is in the control box, has the Old on Ebay found. Until the knob for manual adjustment of the zero position of the joint and the reset button the ads, however, are only decoration. The box is painted like the arm in the style of old machines green. The parts of the arm has Alt printed with its 3D printer Zortrax M200.

Overview of the steps Walter
Behind Walters even movements a multi-level system is to electronics.Enlarge
Picture: Jochen Alt

The files used and a detailed documentation in English has provided Old to the Internet. Two years ago, his last creation had inspired us: the interactive Lampe Luci react to people standing in front of her. She remembers quite deliberately to the famous Pixar lamp.(HCH)