Deep-technical articles on joint actuator design, impedance control, and sim-to-real deployment from the Tendonkindle engineering team.
The gap between simulated policy performance and real-world actuator behavior is one of the most persistent challenges in humanoid locomotion research. This article walks through the practical steps Tendonkindle uses to close that gap.
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EtherCAT promises sub-millisecond cycle times across distributed joint networks, but the topology constraints and cabling rules introduce their own integration challenges. A practical field guide.
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Getting MuJoCo to match the dynamics of your physical actuator requires more than dropping in a URDF — motor inertia, gearbox compliance, and damping parameters all need calibrated values.
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Safe physical interaction with humans requires actuators that can yield under unexpected loads — not just software-level force limits. Here is the hardware physics that makes compliance work.
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A quantitative comparison of torque-to-weight ratios across commercially available servo and quasi-direct drive actuator modules, with methodology notes on measurement conditions.
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Building a ros2_control hardware interface for a custom actuator requires careful handling of lifecycle states, command interfaces, and real-time state publishing. A step-by-step walkthrough.
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Adding force-torque sensing directly inside a joint module — rather than at the wrist — changes the bandwidth, wiring complexity, and calibration requirements entirely.
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Impedance control lets a bipedal robot interact safely with uneven terrain — but the stiffness-damping parameter space is large and poorly understood. A first-principles introduction.
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Choosing between a strain-wave and a planetary gearbox for a legged robot joint is not just about reduction ratio — backdrivability, shock resistance, and compliance all factor in.
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Every humanoid robotics team eventually hits the backdrivability wall. Understanding why it is mechanically difficult — and what design choices trade off against it — is the starting point.
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