Building Renishaw's Gromitronic

August 2018

A team of young engineers at engineering technologies company, Renishaw, has designed and built Gromitronic, an interactive Gromit sculpture for The Grand Appeal's Gromit Unleashed 2 trail. As one of the Trailblazer companies involved, the team was asked to create one of three interactive Gromit sculptures for the trail that represents innovation in engineering and design.

Background

In October 2017, Bristol Children's Hospital charity, The Grand Appeal, asked Renishaw to design and build an interactive Gromit sculpture for its summer 2018 67-sculpture trail. Gromit Unleashed 2 is the third sculpture trail organised by The Grand Appeal, but the interactive sculptures produced by Renishaw, Rolls-Royce and the University of Bristol are the first of their kind in the world. The team designed and built Gromitronic with the aim to create a sculpture that showcases the mechatronic nature of Renishaw's products and to get children and adults excited about STEM subjects, including engineering.

The team working on Gromitronic had the necessary skills in software, electronics, design engineering and mechanical engineering to ensure that the sculpture would work well during two months on show at the M Shed in Bristol. Each member of the team worked on a component of Gromitronic to make sure he was interactive and interesting for the public.

Challenge

The Grand Appeal predicted that over 1.2 million members of the public would take part in the Gromit Unleashed 2 trail. The Renishaw team had to create a sculpture that would appeal to a large audience and remain functional and safe.

“Gromitronic is very different to any product we normally make,” explained Steven Brace, Graduate Mechanical Engineer at Renishaw. “Normally, we can accurately predict the working environment of our products, particularly in machine tool or medical applications. We then spend around two years alpha and beta testing the product to make it perfect.

“When building Gromitronic, we only had a few months to design, build and perfect the sculpture,” continued Brace. “Creating each component was fairly simple, but it was difficult to design a product for such a public space. To make this happen we worked hard to incorporate safety and efficiency in to our designs.”

Working to a short deadline meant that each team member had to work quickly to ensure Gromitronic was interesting to the public, powerful enough to work for the entire trail and safe enough for public interaction.

Solution

Each member of the team used their specific skill set to contribute to a part of Gromitronic. Brace built Gromitronic's eyes, which were engineered to follow visitors during their visits. The eyes were made to move using two servos, which move the eyes on two axes, left and right and up and down.

Apprentice Software Engineer, Lucy Spiteri-Beale, created the eye movement patterns using her software skills. Spiteri-Beale started by creating eyes on screen to test their movement and write a code to control the servos.

“It was a challenge to get the eyes to move naturally,” explained Spiteri-Beale. “To achieve this, we had to think mathematically, adding small movements in lines and curves in a routine. We tested the code until it was perfect – now Gromitronic's eyes move just like Gromit's in the films when he rolls his eyes at Wallace and crosses his eyes when scared.”

The Renishaw team then fitted over 5,000 separate LED lights onto Gromitronic. Controlled by over 10,500 lines of code written using Python, the result means that visitors can press touchpads designed to look like Wallace's inventions to change the colour, pattern and speed of the LEDs.

“With any software program there are always parts that do not work the way you expect,” explained Hannah Howell, Software Engineer at Renishaw. “However, we had to wait for Gromitronic to be designed and painted before fitting any lights and testing them. So, we improvised and built a Gromit Junior to test the LEDs and touchpads system, discovering that it required a lot of power to create a range of patterns.”

The Renishaw team also wanted to showcase its products on the sculpture to get visitors, both children and adults, excited about engineering. The team used its additive manufacturing (metal 3D printing) machines to produce Gromitronic's tail and collar. Ben Collins, Design/Development Technician at Renishaw also metal 3D printed Bristol landmarks that can be seen set in resin studs on the collar.

The team also used additively manufactured cranial plates for Gromitronic's toe nails. The plates are used in healthcare applications to help patients after a serious head injury. Surgeons can design an implant based on a scan of the patient so that a fully customised titanium implant can be produced.

Results

Renishaw team members created a control system for Gromitronic using a printed circuit board fitted with two raspberry pi computers, one to control his eyes and tail and one to control the LED lights.

The team worked for over 2,000 hours to design and build Gromitronic before the start of the trail. The resulting sculpture is designed to look like a circuit board and is full of interactive features, including a plasma ball nose, moving tail and buttons to control his lights. He is now on show along with other sculptures across Bristol and has been seen by tens of thousands of visitors, including a daily record of 8,000 visitors to M shed on one day during July.

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