|home >||Beeber < FirstStep > Shadow Biped||29 May 2021|
|First-Step by David Buckley||September 1987|
I built First-Step in 1988 because I liked the look of the quadruped built by Hirose and Umetani and published in Robotics Research. However after building it I realised that using the 3d pantograph design to achieve a gravitationally decoupled leg mechanism was not the way to build legged robots. The legs are far too flimsy with too many parts and joints and for the design to work the body must be kept absolutely horizontal. Also work on First-Step came to a halt because it used small multiturn potentiometers for position feeback of the screw jacks, however the sample I used must have been very worn because when I obtained more and fitted them they consumed half the motor power and First-Step couldn't raise its body!
|1997||photograph of First-Step used to illustrate the flier for Robotix97|
1988 - First-Step wins a Silver Medal at the International Model Engineering Show, Wembley, England
First-Step's Silver medal contributed to my being awarded the Fantasy and Science Fiction Trophy for that year. M23 won a bronze medal and Zeaker was 'Highly Commended'.
There wasn't a more suitable category in which to enter working robots so I had to compete with plastic kits etc. and the Gold Medal went to a modified plastic kit.
It is though, still unfinished lacking:-
When First-Step is finished as projected and barring unforeseen snags it will be Britain's only electric powered advanced walking robot. [Britain's only other 'walker' has six pneumatically powered legs.]
The position of each foot is controlled through a parallelogram leg mechanism by three screw jacks each driven by an electric motor.
The parallelogram mechanism allows movement along each of the three axes (forward/backward up/down in/out) to be independent of movement along the other axes and there is one jack for each axis. This arrangement produces a so called gravitationally decoupled leg mechanism wherein the actuators do not have to do work holding up the body but mearly overcome the frictional force in the bearings.
[The display base is not part of the robot but allows it to be posed to show the range of travel of the legs.]
D Buckley Dec. 1987