Personal homepage of Vincent
Welcome to my personal homepage!
I am Vincent Groenhuis, researcher at Robotics and Mechatronics, University of Twente, Enschede, The Netherlands.
E-mail: v.groenhuis@utwente.nl
University of Twente profile
Publications
Reseach videos
Specifications of pneumatic (stepper) motors
Printables designs
Thingiverse designs
MyMiniFactory designs
Patented stepper motor designs (password protected)
Password request form. Fill it in and you immediately get the password.
Doing scientific research is one thing, publishing and communicating the results is also very important. My scientific publications are listed here and we also created many video compilations in the different projects that I am involved in. Below is a more or less complete overview of the research videos (co-)created by me during my research at Robotics and Mechatronics, University of Twente.
The embedded videos are now hosted on YuJa. Some videos are also on my Vimeo channel (ad-free). My research group has a YouTube channel (with ads, unfortunately) and I also have a YouTube channel myself.
Total 31 video compilations. Per year: (2022:) 5, (2021:) 5, (2020:) 3, (2019:) 5, (2018:) 4, (2017:) 2, (2016:) 4, (2015:) 2, (2014:) 1.
Of these 31 compilations 26 were edited by myself; 5 by project students or colleagues.
Many compilations have music and/or voice-over. Most of these were composed/spoken by Tim de Man.
Coming soon
Coming soon
Pneumatic Turing Machine: Main compilation
Can you 3D print a Turing-complete computer which runs on pressurized air? Yes! Although the number of states and bits is somewhat limited in this prototype.
First demonstrated at European Robotic Forum 2022, Rotterdam, The Netherlands.
The 4/2-way valve component can be downloaded at Printables. More components will be published later upon request.
Pneumatic Turing Machine: Busy Beaver
Demonstrates 2-state and 3-state Busy Beaver. These are special programs for a binary Turing machine which gives the maximum possible output given the number of available states.
(Supplementary video to the main Pneumatic Turing Machine compilation)
Robot-Guided Translation of a Preoperative 3d Planning During Open-Vault Reconstruction of Craniosynostosis
Project by Anouck Pilon, Eva Koot, Rémi van der Woude, Lisanne Venix. Supervised by Vincent Groenhuis et al.
Multidisciplinair project (MDO), as part of BSc Technical Medicine.
Control and design of 3D printed biopsy robot using mobile application
BSc project Mart Bluiminck, supervised by Vincent Groenhuis et al.
MURAB technical video
This video shows several steps in the workflow such as path planning, ultrasound scanning, 3D ultrasound reconstruction, biopsy planning, needle insertion and sample validation. Deformations of soft tissue are taken into account.
Miniaturization of MR Safe Pneumatic Stepper Motors
Presented at IROS 2019, Macau
MURAB workflow video as demonstrated at Hamlyn Surgical Robot Challenge 2019. We also demonstrated the physical robot and clinical workflow in London.
Universal Auto-Rewind Spool Holder
Although a hobby project, a combination of this device and Sisyphus spool holder are currently used at RaM for feeding one of our multi-material 3D printers.
Pneumatic Screwdriver
A hobby project using pneumatic stepper motor technology developed at RaM.
Thingiverse link for 3D files and assembly instructions
CatchBot: A Versatile MR Safe Robotic Platform for Image-Guided Endovascular Interventions
Research primarily conducted by Mohamed E.M.K. Abdelaziz. The robot uses practically the same pneumatic stepper motors as in the Sunram 4.
Pneumatic Bourke Engine
This is actually a hobby project, using pneumatic stepper motor technology developed at RaM.
3D printable parts can be downloaded here.
Pneumatic Gripper
A hobby project, again using pneumatic stepper motor technology developed at RaM.
3D printable parts can be downloaded here.
Sunram 5: An MR Safe Robotic System for Breast Biopsy.
Improvements over Sunram 4 include dual-speed motors, a biopsy gun, an emergency needle ejection feature and a curved rack for better angulation of the needle towards the breast.
Dual-speed MR Safe Pneumatic Stepper Motors
Presented at Robotics: Science and Systems (RSS) in Pittsburgh, United States
Sunram 4: An MR Safe Robotic System for Breast Biopsy.
This won the “Best Video” award at Hamlyn Surgical Robot Challenge, London. Over 130 articles (in 16 languages) about this robot appeared online.
The robot has a serial kinematic chain, as opposed to a parallel kinematic chain in the previous iteration.
Visualization of breast phantom and lesions with Hololens
BSc project by Leon Klute, supervised by Vincent Groenhuis.
The needle is tracked using either a stereo camera or an NDI electromagnetic tracker (from 0:31), and visualized in the scene together with the phantom and lesion(s) using augmented reality.
Sunram 3: An MR Safe Robotic System for Breast Biopsy
This robot won the “Best Design” award at Hamlyn Surgical Robot Challenge, London.
Main improvements over Sunram 2 are better motors and overall design, and somewhat larger workspace.
High-Performance Pneumatic Stepper Motors
Two linear and three rotational stepper motors are demonstrated, all 3D printed and quite powerful for its size.
Controlling the Sunram 2: An MR Safe Robotic System for Breast Biopsy
MSc project by Mohamed E.M.K. Abdelaziz, supervised by Vincent Groenhuis et al.
Sunram 2: An MR Safe Robotic System for Breast Biopsy
Sunram 1: first iteration of MR safe robotic system for breast biopsy
Powered Exoskeleton
Internship project at University of Canterbury, Christchurch, New Zealand
Many pneumatic stepper motors, rotary engines and other pneumatic devices were developed during our research. Several were published in research papers and/or 3-D model websites. This page lists nearly all of them, alongside with the most important properties and a link to the downloadable model (if available). If a motor design is not yet downloadable then you can send me a request for it.
Certain motors have extensive printing and assembly instructions and/or a video compilation. If you are interested in 3-D printing one of these motors then there should be plenty of information and designs to start with.
At the moment I subdivided the motors into five categories: linear, rotational, curved, rotary engine and dual. The motor name consists of a character (or two in case of dual-speed) plus a number and sometimes a postfix.
First character(s): T=linear, R=rotational, C=curved, D=dual, H=hollow. The following number indicates the major dimension (length or diameter) of the motor, in mm. The “B” postfix indicates a redesign of an existing model.
In theory it is possible to scale any design along (some combination of) its axes. This should work with some experimentation.
If you need help with a motor then you can post a comment on the associated Printables or Thingiverse (or MyMiniFactory) webpage, and I will look into it. You can also contact me directly at v.groenhuis@utwente.nl. If you designed something cool based on these designs then I am always happy to see it!
Designs are for non-commercial use only (i.e., research, education, hobby). Contact me for IP related questions.
Linear stepper motors
| Picture | Name | Size (mm³) | Step | Force | Piston size (mm²) | Links | Notes |
 | T-08 | 8×8×5.5 | 0.2 mm | 2.5×2.5 | STEP+STL+Solidworks Printables MyMiniFactory YuJa (from 1:35) | Smallest linear pneumatic stepper motor. Challenging to print. | |
 | T-15 | 15×15×11 | 0.25 mm | 4×4 | STEP+STL+Solidworks YuJa (from 1:25) | ||
 | T-26 | 26×21×16 | 0.25 mm | 63 N | 10×10 | STEP+Solidworks Paper YouTube | Used in Sunram 4. Printed at Objet Eden 250 in high quality mode with FullCure 720 material. |
 | T-29 | 29×25×19 | 0.25 mm | 10×10 | STEP+STL+Solidworks | ||
 | T-32 | 32×30×16 | 0.3 mm | 12×10 | STEP+Solidworks MyMiniFactory Paper | Pistons are combination of 3D printed part with laser-cut teeth. Difficult to prototype. | |
 | T-48 | 48×44×34 | 0.67 mm | 20 N | 12×5 | Paper | Laser-cut cylinders. Three-cylinder design. M4 screws. Used in Sunram 3 as “Blue” actuator. |
 | T-48B | 48×44×34 | 0.67 mm | 50 N | 20×8 | Thingiverse MyMiniFactory | M2 screws. Three-cylinder design. Improved version of T-48, with 3-D printed cylinders. |
 | T-49 | 49×40×31 | 1.0 mm | 100 N | 14×14 | STEP+STL+Solidworks MyMiniFactory | Easy to prototype. M4 screws. Used in Sunram 3 as “T-49” actuator (but with larger housing). |
 | T-63 | 63×52×36 | 1.0 mm | 330 N | 20×20 | STEP+STL+Solidworks MyMiniFactory Paper YouTube | M4 screws. |
 | T-63B | 63×52×36 | 1.0 mm | 570 N | 24×24 | STEP+STL+Solidworks | Housing glued together. Top and bottom can be laser-cut so you can see inside. More robust pistons than in T-63. |
 | T-84 | 84×64×32 | 2.0 mm | 20×20 | Thingiverse MyMiniFactory | Easy to print and assemble. Three-cylinder design. M4 screws. |
Rotational stepper motors
| Picture | Name | Size (mm³) | Step | Torque | Piston size (mm²) | Links | Notes |
 | R-10 | 10×10×10 | 12.9° | 0.0012 Nm | 3×4 | STEP+STL+Solidworks MyMiniFactory | Smallest rotational motor. Gear can be laser-cut. ⌀1 mm shaft. |
 | R-25 | 25×25×20 | 6.9° | 0.10 Nm | 10×10 | Housing held together with small clips. Teeth are relatively thin. Superseded by R-25B. | |
| R-25B | 25×25×20 | 10° | 10×10 | STEP+STL+Solidworks MyMiniFactory | Housing glued together. More robust than R-25. | ||
 | R-40 | 40×40×16 | 1.01° | 0.47 Nm | 10×10 | STEP+STL+Solidworks MyMiniFactory | Laser-cut gear. |
 | R-44 | 44×44×31 | 10° | 0.45 Nm | 14×14 | STEP+STL+Solidworks STL | M4 screws. |
 | R-54 | 54×54×16 | 0.00101° | 0.24 Nm | 14×10 | STEP+STL+Solidworks | Completely useless except for demonstration purposes. |
 | R-64 | 64×64×32 | 15° / 7.5° | 24×24 | Thingiverse MyMiniFactory | Three-cylinder design. M2 screws. | |
 | R-80 | 80×80×37 | 10° | 3.7 Nm | 30×20 | STEP+STL+Solidworks | M4 screws. Top and bottom can be laser-cut. |
 | R-90 | 90×90×32 | 90° | 1.6 Nm | 30×20 | Thingiverse MyMiniFactory YuJa YouTube | Bourke engine design. M4 screws. |
Rotary engines (continuously-rotating motors)
| Picture | Name | Size (mm³) | Piston size (mm²) | Links | Notes |
 | R-66 | 66×66×43 | 24×14 | Thingiverse MyMiniFactory YouTube | Five-cylinder rotary engine. Cylinders can be straight or curved. |
 | R-52 | 52×52×36 | 18×18 | Thingiverse MyMiniFactory YouTube | Bourke rotary engine. Easy to construct. More robust and powerful than R-38 or R-66. Used in Pneumatic Screwdriver. |
 | R-38 | 38×38×48 | 16×12 | Thingiverse MyMiniFactory | Bourke rotary engine. Used in Pneumatic Screwdriver. |
Curved stepper motors
| Picture | Name | Size (mm³) | Step size | Radius of curvature | Piston size (mm²) | Link | Notes |
 | C-90 | 90×48×32 | 1° | 100 mm | 20×20 | Thingiverse MyMiniFactory | Similar design as T-84. Part of Pneumatic Ferris wheel. Easy to 3D print. |
 | C-30B | 30×27×14 | 0.5° | 80 mm | 10×10 | STEP+STL+Solidworks MyMiniFactory | Multi-material print. |
 | C-30 | 30×23×14 | 0.25° | 50 mm | 10×10 | STEP+Solidworks Paper YouTube | Fine pitch, difficult to fabricate. |
Dual-speed and multi-axis motors
| Picture | Name | Size (mm³) | Step sizes | Force / Torque | Piston size (mm²) | Link | Notes |
 | DR-32 | ⌀30×32 | 10°, 12.9° | 0.074 Nm | 10×10 | STEP+STL+Solidworks Paper YuJa | Combination of two motors. Accuracy 1°. |
 | DT-50 | 50×32×14 | 1.7 mm, 0.3 mm | 24 N | 10×10 | STEP+STL+Solidworks Paper YuJa | Combination of two motors. Accuracy 0.1 mm. |
 | R3-43 | ⌀43×19 | 12×10 | STEP+STL+Solidworks | Three cylinders. Four pneumatic lines. Three concentric output shafts. M2 screws. | ||
 | R6-56 | ⌀58×25 | 0.056 Nm – 0.114 Nm | 18×13 | STEP+STL+Solidworks Paper YuJa | Four cylinders. Five pneumatic tubes. Six concentric output shafts. M2 screws. |
Multipurpose stepper motors
| Picture | Name | Size (mm³) | Step sizes | Force / Torque | Piston size (mm²) | Link | Notes |
 | M-45 | 45×40×15 | Shaft: 6.9°, 5.3° Rack: 0.46 mm, 0.60 mm | Shaft: 0.5 Nm | 12×10 | STL Printables DOI | Rack is straight, or curved with customizable radius. Used in earlier versions of Sunram 7. Superseded by M-45B. |
 | M-45B | 45×40×15 | Shaft: 6.9° Rack: 0.60 mm | Shaft: 0.36 Nm | 12×10 | Significantly more robust than M-45. |