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Seattle Robotics Society

Page last updated: 12/22/2019

Commentary by S.D. Kaehler

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10/19/19: This month's meeting had a turnout of about 35 people. The meeting was facilitated by Steve Kaehler. We met downstairs at the FIRST Fieldhouse warehouse.

The meeting was kicked off with a video about Meet the UAE-made robot that can tell your mood.

SRS Polo shirts are available at meetings for $30 (card, cash, or check). The 2019 Robothon T-shirt are available for $20.

Club Business

  • Need Other Backup Meeting Leaders (I can't always run the meetings. More alternates are needed.
  • href="">Seattle Christian School this fall. They are 2 weeks in with 8 weeks to go.
  • Consider alternate After-meeting Activities. The workshops have been lightly attended. Robothon contests? Local facility tours? Something else?

If you have ideas or comments, please email me at SeattleRoboticsSociety(at)


Meeting Pictures on Google Photos. If you have other pics you'd like to share please send them to SeattleRoboticsSociety(at) The following people shared something with the group:

  • Ron first showed us his vintage toy car which has programmable routes using an onboard keypad. He is trying to duplicate that item using an SRS Arduino Robot from Parallax and a Sparkfun Wifi board for the robot along with a Raspberry Pi ZeroW and an attached mini touch screen. He has assembled all of the hardware and is now beginning the programming phase.
  • Will has built an MPCNC or Mostly Printed CNC machine. Total cost for this project is around $320 including a parts kit with stepper motors and electronics from The kit does not include a router or the steel or stainless rails. The version that Will built has a 48 x 53 inch frame and can route out parts up to about 4 feet square. Will stated that he can achieve 0.01mm accuracy with this setup which is very good. Will showed us several items he has routed out including parts for the CNC frame and a dog bone shaped doggy step. A picture of routed parts for a chair is attached. Will states a milling speed of 15mm per second for ¾” MDF.
  • Joseph showed us his 4WD robot that he's building. It is in its early stages. He has some trouble with the skid steering system he's trying to use.
  • Terry is a fan of NHK News from Japan and spoke of a recent story describing a ski area/resort powered totally by solar and thermal energy. Far from being a pilot project, this is a real world situation which shows what can be done with imagination and the proper funding.

Feature Presentation

    Our program presenter was Jessica Zistasis gave us a presentation on the pediatric devices she is currently working with. The first is an exoskeletal leg for young children with Cerebral Palsy. For these patients, walk is challenging and learning to walk normally depends upon twice weekly physical therapy stations. A device is needed to assist these patients during the remaining hours of their week at home. Jessica showed us an external frame that belts to the patient around the waist and on the legs.

    This design consists of 3 parts:

    -A hip pulley mechanism with a coiled spring to store energy.

    -Adjustable leg and belt members.

    -A custom foot orthotic.

    The total mechanism weighs about 2 Kg (1 pound). The spring stores energy as the leg swings forward and then gives it back as the leg swings backward. The backward leg swing is the greatest area of difficulty for the illustrated patients. After a patient is fitted with these devices a large number of photo targets or markers are placed on their clothing and then filming analyzes how their walking improves. An 8 camera video system by Qualisys is used and the results are analyzed using OpenSim. Over time positive results are found using this device.

    The second area of study is the E-Mip connected prosthetic ankle. Existing active prosthetic ankles have multiple actuators, complex controls, and cost about $40,000. This device uses a single spring system to absorb heel strike energy and give it back during foot pushoff. The actual spring absorber consists of a small hydraulic piston which charges a small accumulator when the heel is placed and then extends another piston when the ball of the foot pushes off. The entire spring system is passive and the only power is used for valves and electronic controls. The device is limited to one degree of freedom now, but more will be added in the future. In this environment about 1 million patients vie for Medicare help and are limited by the amount of funds available for this issue. Jessica’s team is trying for $4000 to $6000 price point which should make this device available to far more folks.

    Here are her presentation slides.

The Workshop

    The afternoon workshop was canceled due to light attendance. We will have these in the future as long as people want to attend.

If you have comments or opinions on this writing, please email me at SeattleRoboticsSociety(at)

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