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# Julia Di

Artist & Engineer

### Alginate Mold

##### For patients with critical limb ischemia

Abstract. Spyndra is our newest open-source quadruped robot platform. It has eight motors, an IMU, and runs Raspberry-PI 3. It requires non-intuitive motor commands in order to locomote, and thus provides an interesting challenge for gait learning algorithms, such as those frequently developed in the Evolutionary Computation and Artificial Life communities.
This open-source robot is composed of off-the-shelf motors and 3D-printed parts, enabling anyone to construct this robot for roughly \$600 in parts plus printing material. We hope other hobbyists and other research teams will modify its design according to their scientific needs.
Further description of the work can be found on the project website, and in this pre-print.

Illustration of Spyndra

(A) Graph of all units and the connections between them; the dashed circles represent (equally-sized) clusters.
(B) Assigning clusters to treatment arms: completely randomized (CR) and cluster-based randomized assignment (CBR).
(C) Assigning units to treatment buckets—treatment and control—using the corresponding strategy.
(D) Computing the treatment effect within each treatment arm: $\hat \mu_{cr}$ and $\hat \mu_{cbr}$, and variance: $\hat \sigma^2_{cr}$ and $\hat \sigma^2_{cbr}$.
(E) Computing the difference of the estimates from each treatment arm: $\Delta = \hat \mu_{cr} - \hat \mu_{cbr}$, and the total variance: $\hat \sigma^2 = \hat \sigma^2_{cr} + \hat \sigma^2_{cbr}$.

Short video of Spyndra walking.