Design of Robotic Hands | Clemens Christoph (ORCA Dexterity) | ETH RWR 2026

In this talk

1. 2:34

   Designing around practical constraints

   Christoph frames hand design as a balance among strength, human-scale dimensions, dexterity, durability, price, accessibility, and control. His team had a $500 project budget and relied on off-the-shelf parts and 3D printing, while aiming for a research hand that cost about $600 to build.

2. 12:29

   Why the hand uses paired tendons

   Tendons can pull but cannot push, so Christoph compares spring-return and more biologically inspired layouts with the team’s antagonistic approach: each joint gets a flexor and an extensor. He describes a ratcheting spool for correcting tendon slack, and tendon paths through joint centers to reduce coupling and make motor movement map more directly to joint movement.

3. 25:25

   Making control and joints more reliable

   The team calibrates joint motion by moving the mechanisms against their hard stops, using motor readings to estimate joint position. To reduce tendon wear, it uses metal pins and Teflon guides, and a small optimization program to improve pin placement. For printed joints, the team adopted a design that can bend or pop free under excess force instead of relying on rolling-contact joints.

4. 34:46

   Open design, trade-offs, and next steps

   Christoph says later versions added tactile sensors, which create cable-routing and fatigue challenges. He contrasts tendon-driven hands with finger-mounted motors, which can offer precise control but add mass and inertia, and notes that the ORCA design still has limits in strength and tendon tension. He says an open-source V3 is planned with a smaller forearm and an additional wrist axis.

5. 44:59

   From research platform to deployment

   Christoph says the company began in August 2025 and chose open source to support research access, partnerships, and its reputation. ORCA currently targets researchers; Christoph expects broader deployment to follow as hardware and policies mature, and says the company is considering how much future hardware to keep open.