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Industrial manipulators do not collapse under their own weight when powered off due to the friction in their joints. Although these mechanism are effective for stiff position control of pick-and-place, they are inappropriate for legged robots that must rapidly regulate compliant interactions with the environment. However, no metric exists to quantify the robot’s performance degradation due to mechanical losses in the actuators and transmissions. This paper provides a fundamental formulation that uses the mechanical efficiency of transmissions to quantify the effect of power losses in the mechanical transmissions on the dynamics of a whole robotic system. We quantitatively demonstrate the intuitive fact that the apparent inertia of the robots increase in the presence of joint friction. We also show that robots that employ high gear ratio and low efficiency transmissions can statically sustain more substantial external loads. We expect that the framework presented here will provide the fundamental tools for designing the next generation of legged robots that can effectively interact with the world.
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mmChoir: Exploiting Joint Transmissions for Reliable 60GHz mmWave WLANs
60 GHz millimeter-wave WLANs are gaining traction with their ability to provide multi-gigabit per second data rates. In spite of their potential, link outages due to human body blockage remain a challenging outstanding problem. In this work, we propose mmChoir, a novel proactive blockage mitigation technique that utilizes joint transmissions from multiple Access Points (APs) to provide blockage resilience to clients. We derive a new reliability metric based on angular spread of incoming paths to a client and their blockage probabilities. The metric can be used to intelligently select joint transmissions that can provide higher reliability. The reliability metric along with a novel interference estimation model, is used by mmChoir's scheduler to judiciously schedule joint transmissions, and increase network capacity and reliability. Our testbed and trace-driven simulations show that mmChoir can outperform existing beamswitching based blockage mitigation scheme with on an average 58% higher network throughput.
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- PAR ID:
- 10075911
- Date Published:
- Journal Name:
- ACM Mobihoc '18 Proceedings of the Eighteenth ACM International Symposium on Mobile Ad Hoc Networking and Computing
- Page Range / eLocation ID:
- 251 to 260
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Industrial manipulators do not collapse under their own weight when powered off due to the friction in their joints. Although these mechanism are effective for stiff position control of pick-and-place, they are inappropriate for legged robots that must rapidly regulate compliant interactions with the environment. However, no metric exists to quantify the robot’s performance degradation due to mechanical losses in the actuators and transmissions. This paper provides a fundamental formulation that uses the mechanical efficiency of transmissions to quantify the effect of power losses in the mechanical transmissions on the dynamics of a whole robotic system. We quantitatively demonstrate the intuitive fact that the apparent inertia of the robots increase in the presence of joint friction. We also show that robots that employ high gear ratio and low efficiency transmissions can statically sustain more substantial external loads. We expect that the framework presented here will provide the fundamental tools for designing the next generation of legged robots that can effectively interact with the world.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3209582.3209608
