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  • Dr. Perry
Team Name RoboCodo
Duration Fall 2017 - Spring 2018
  • Logan Hammons
  • Jiachen Shen
  • Meghann Hester
  • Jiawei Liu
  • John Gergen
  • Abby Raveling
  • Genaro Martinez

Therapists often spend hours working with a patient to loosen the elbow joint manually (through humeroulnar distraction) after surgery to help the elbow recover flexion and extension mobility. There is a need for a device that can do this automatically so that the therapist can be free to work on other parts of the rehabilitation process to decrease rehabilitation time and maximize recovery.

Problem Definition[edit]

Problem Statement

The Tecnalia Reasearch & Innovation in Donostia-San Sebasián, Spain has a prototype that weighs more then they expected. They are asked us to make a device that would create a humeroulnar distraction on the elbow. The device has to be less then 1 Kilogram (Kg) and apply 100 Newton (N) linear force 35-40 Newton meter (Nm) torsional force.

RoboCodo Start.png

Design Goals and Deliverables

  • Document which solutions to pursue and which one didn’t work, and explain why it didn’t so they won’t waste there time repeating the same mistakes as us.
  • The gadget should be; confortable, wearable, weight < 1Kg, and have a safety release mechanism.



Keep arm rigid and allow for adjustment of different angles of pronosupination.

The device should allow for a linear motion, which will apply a force just distal to the elbow, as well as a rotational motion, which will apply a torque to the forearm. Once an angle is chosen, the device should hold the arm rigidly in this position. Misalignment or rotation of the elbow during use could cause injury. The primary opposition to holding the arm rigidly is skin slippage. The motion of the skin allows the underlying bone structure to become misaligned even though the arm is being held tightly.


The device should be able to provide a linear force of 100 N and a torsional force of 35–40 Nm. The motion, which the device must recreate, is as follows:

1. A force of up to 100 N is placed just distally to the elbow. This is done to release the ulna from the humerus.

2. After the ulna is released a torque of 35-40 Nm is applied to rotate the forearm.

3. In some cases it is necessary to bring the elbow to its full extension and oscillate back and forth.


Mass should not exceed 1 Kg at the forearm

The device should ideally be as light as possible. The goal is to maximize patient comfort. To accomplish this, an effort should be made to keep the majority of the weight of the device proximal to the shoulder or back. If the weight must be placed distally on the arm, it should not exceed 1kg.


Easy to activate quick release

There is always the possibility that a mechanical device can act in an unexpected way or a patient to react poorly to the procedure. For this reason, the device should have some sort of quick release mechanism, which will immediately release all pressure on the arm. The release mechanism should be easy to activate by both the therapist and the patient.


Position feedback for FES

In order for the FES system to activate at the right time, the mechanical system must be able to provide some sort of feedback which describes its current position.


Grid Power Using Medical Grade Power Supply

Although the final device is intended to be powered by a lightweight and compact battery pack, it is sufficient for this project to power the device using power supply running off of mains power. If possible, the power supply should be medical grade. All of the wiring should be kept neat and should in no way inhibit the movement of the device or increase risk to the user.

Project Learning[edit]

Thermoplastics research and Shoulder Orthosis

Use: for attaching device to forearm and hand to minimize skin slippage during use.

Low Temperature Thermoplastics: can be molded directly onto forearm and hand

Rigidity: of thermoplastic will be adequate to fix forearm in place

Memory: of thermoplastic enables us to reheat and remold our design if it does not mold correctly the first time

Specific Thermoplastics: Rolyan Aquaplast, Omega Max Smooth, Rolyan Orthoplast

Cost: $40-80 per 1/8”x18”x24” sheet

Image Description

Donjoy SCOI Shoulder Brace:

Purpose: Stabilize shoulder and upper arm to help distribute forces to the correct places

on the device.

Abilities: Allows 30°-150° of adduction and abduction range of motion (ROM). Universal

fit: fits both left and right sides. Elbow joint provides full ROM.

Adjustments needed: The forearm piece on this device will need to be modified or

removed and redesigned to transfer 100N force from motor to arm to distract the

elbow. A wrist and forearm orthosis will be designed out of thermoplastic to help

hold the forearm in adjustable degrees of pronosupination.

Micro-Controler / Electronic

Use: for a feedback system.

Remoted by Button or App: for starters we will test the circuit with the button

Cost For all this sensors and microcontrollers we plan to spend around $200. The most costs sensor is the Linear Actuators

Image Description

Wireless Communication

ESP8266 Chip will be used to communicate with the App to the board ESP8266.


Load Cell HX711

Micro Load Cell: Is the sensor we are looking at to measure the fouce of the Linear



Weight Sensor Amplifier HX711

Amplifier: Will messure the presure of the load cell precisly and accurate.

Motor/Linear Actuators

Looked into several linear actuators but found that servos that weight under 100g cannot product more than 200N of force, actuators that can produce over 200N of force jump up to a 800 to 1000 gram range.

For this project it is more ideal to use several 100g actuators than it would be to compromise our weight goal of under 1kg by using the more powerful actuator.

Image Description

140 mm Stroke 44 lb Thrust Light Duty Linear Servo

  • This servo is extremely light and also provides sufficient force for the distraction motion.
  • It does not provide enough force to achieve the desired 40N/m of torsion on the forearm.
  • These motors are small enough that we could run several in parallel to increase the force and achieve 40N/m
  • The motor moves at too slow of a speed to achieve the desired 30 to 90 degrees/sec extension of the arm while maintaining 40N/m, but with correct gear ratios we believe we can complete the extension going at 18 to 36 degrees/sec.

Overall Look of the Design

Our goal for next semester is that we will come up with a prototpye that is illistrated on the bottom.


Next Semester to come[edit]

Team Information[edit]

Biography Discipline
Genaro Martinez

Genaro Martinez (aka Henry) grew up in Burley, Idaho. His academic interests include microelectronics and microcontrollers. Outside of school on his free time, he enjoys playing video games, hanging out with friends and drawing. After graduation, he plans on becoming a hard working engineer in the workforce.

Computer Engineering.
Abby Raveling

I decided to study biological engineering my sophomore year of college when I realized it would give me a unique background for physical therapy. After I graduate, I want to become a pediatric physical therapist and use my engineering background to help develop rehabilitation equipment. My hometown is Hamilton Montana. I enjoy hiking, camping, swing dancing, baking, and rock climbing.

Biological Engineering
John Gergen

Senior in mechanical engineering. John has a strong focus on robotics and control systems. For most of his time at the University of Idaho, John has worked on the Autonomous Underwater Vehicles project which gives him a strong background in the mathematics behind robotics as well as strong skills in data analysis and filtering.

Mechanical Engineering
Jiawei Liu

Jiawei Liu came from china as a transform student, and is a senior in electrical engineering. He is super excited to get to learn about new things, and to know new friends in order to enlarge his social connection; furthermore, willing to make friends with people who comes from different countries to learn different cultures. His favorite things to do are; sports, outdoors activities, swimming and traveling. Growing up he liked cars and machinery and in hopes to utilize his knowledge in actually cases.

Electrical Engineering
Meghann Hester

I am from a town called Woodland, CA. I started mechanical engineering because I enjoyed learning how things worked by taking them apart. I would like to work on prosthetics in the future or some other medical robotics.

Mechanical Engineering
Jiachen Shen

My name is Jiachen Shen and I am currently a senior electrical engineer at the University of Idaho. I grew up in Suzhou China. I started my degree in WenZheng College of Soochow University in the fall 2014, and came to UI in the fall 2017 to become a transfer student. I love photography and playing the piano in my free time and they can make me enjoy life more.

Electrical Engineering
Logan Hammons

I am a senior studying mechanical engineering, I grew up in a small town just outside of Coeur d’Alene ID. Throughout my child hood I learned how much I enjoyed working with my hands to create things, I was always building unique contraptions like catapults or trebuchets. Once I got into high school I gained interest in robotics and mind controlled prosthetics and felt mechanical engineering would give me the best variety of skills to work in that field. I have an entrepreneurial mind set and have a passion for inventing which I hope to use along with my engineering skills to design and develop my own product.

Mechanical Engineering