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Getting Started with Humanoid Robots

68 bytes added, 20:23, 16 May 2024
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Add wikilink to MuJoCo (MJX)
== Building Your Humanoid Robot ==
In humanoid robotics, choosing the right components, for example, actuators and gearboxes is crucial. Folks can use planetary and cycloidal gear actuators for their precision and strength, along with Series Elastic and Quasi-Direct Drive actuators for smoother, more natural movements. Advanced designs like the [https://humanoids.wiki/w/MIT_Cheetah MIT Cheetah ] actuator push the boundaries with fast, agile movements. Projects like the SPIN initiative are also key, as they make high-quality actuator technology more accessible, helping the field evolve and improve.
== Actuators and Gearboxes ==
Series Elastic Actuators (SEAs) are used in applications requiring safe and compliant human-robot interaction. They incorporate elastic elements, allowing for energy absorption and safer interactions. Quasi-Direct Drive Actuators provide a balance between the control fidelity of direct drives and the mechanical simplicity of geared systems, promoting natural and responsive movements.
Some points things to consider:
* Pick Your Springs Wisely: The springs in SEAs are where the magic happens. Choosing the right stiffness is a balancing act between getting precise torque control and getting avoiding sluggish responses. * * Calibrate, Calibrate, Calibrate: Calibration is your best buddy. Since the spring is constantly flexing, you need sensors tuned to give accurate torque measurements. Do it regularly, and you'll keep your those movements smooth and predictable.* * Control Loops FTW: You want finely-tuned control loops to make SEAs shine. A high-frequency loop can make your robot more agile in handling external forces. Go for PID controllers perhapsare a solid starting point, or you can try out some advanced strategies.* * Friction: Friction can really impact your torque control big time, especially in gearboxes and linkages. LowUsing low-friction components and proper lubrication will help keep everything moving smoothly.* * Load Path Matters: Make sure your spring is right in the direct load path positioned directly between the actuator and the joint. If not, your robot won’t get the full benefit of force sensing, and that precision will be lost.* * Watch Out for Fatigue: Springs aren’t indestructible. With If your robot is doing a lot of high-impact activities, they the springs can wear out. Keep an eye on them to avoid breakdowns at the worst possible momentwhen you least expect them.* * Get Your Software Right: SEAs thrive on real-time feedback. Ensure your software can handle data fast enoughquickly, maybe even use using a real-time operating system or optimized signal processing.*
==== MIT Cheetah Actuator ====
====== Isaac Gym ======
[[Reinforcement Learning ]] Training: Enables parallel environments for fast policy training.
PHC Approach: Integrates AMP for real-time pose control, making it easier to teach new skills.
====== MuJoCo (MJX)======
Offers a lightweight open-source alternative, supporting maximal coordinate constraints and easier to work with. The MuJoCo_MPC repository, created by Google DeepMind, is a toolset that combines Model Predictive Control (MPC) with the [[MuJoCo ]] physics engine to create real-time behavior synthesis. With the advanced MJX extension, which uses GPU acceleration, it can simulate multiple environments in parallel. One approach is to try to replicate the techniques detailed in the AMP (Adversarial Motion Priors) paper to achieve agile humanoid behavior. For example, implementing a humanoid get-up sequence, which matches what was described in the AMP research.
There’s been collaboration between different projects, like Stompy, to get humanoid simulations up and running. You could try converting Gymnasium to handle the URDF (Universal Robot Description Format) file format. Although converting to MJCF (MuJoCo's XML-based format) may present some challenges, we can still get it to work and refine the motor and actuator setup.
Although [[MuJoCo ]] can be slower in single-environment simulations, the MJX extension and its parallel processing potential make it a solid competitor. Compared to enviroments, like NVIDIA's Isaac Gym, MuJoCo might stand out for its extensibility and rapid development. One goal could be to try recreate the walking, running, and getting-up behaviors described in the AMP paper and use them as a foundation for training robust humanoid movements in simulation.
====== VSim ======
By understanding the nuances and strengths of each simulator, developers can refine their humanoid robots effectively. Using Isaac Sim, Isaac Gym, and complementary tools, a robust simulation approach ensures smooth virtual-to-physical transferability while reducing development time and costs.
 
More resources are available at [https://humanoids.wiki/w/Learning_algorithms Learning Algorithms]
== Real-World Testing ==
== Advanced Customization and Community Engagement ==
=== Open Source Projects ===
Contribute to or start your own an open-source project. For instance, platforms like GitHub host numerous projects where you can collaborate with others such as K-Scale https://github.com/kscalelabs. Check out [https://humanoids.wiki/w/Stompy Stompy!] 
=== Modular Design ===
Engage in modular robot design to easily swap components or aesthetics. This approach allows for extensive customization and upgrades over time.