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Here is the agenda for today’s seminar. We will recall the principles of controlling a brushless DC motor. Secondly we will discuss the back EMF sensing method used in this sensorless technique. We will also cover the principles of digital filter and the so called majority function. Last section of this seminar discusses the motor start up sequence and the sensorless operation.

Robot motion planning has traditionally been used to avoid collisions when moving a robot arm. Avoiding collisions is important, but many other desirable criteria are often ignored. For example, motions that minimize energy will let the robot extend its battery life. Smoother trajectories may cause less wear on motors and can be more aesthetically appealing. There may be even more useful criteria, like keeping a glass of water upright when moving it around. This summer, Mrinal Kalakrishnan from the Computational Learning and Motor Control Lab at USC worked on a new motion planner called STOMP, which stands for "Stochastic Trajectory Optimization for Motion Planning". This planner can plan paths for high-dimensional robotic systems that are collision-free, smooth, and can simultaneously satisfy task constraints, minimize energy consumption, or optimize other arbitrary criteria. STOMP is derived from gradient-free optimization and path integral reinforcement learning techniques (Policy Improvement with Path Integrals, Theodorou et al, 2010).

Perhaps the most difficult control problem for a drive servo is that of going down a ramp. Any back drivable drive servo will exhibit a freewheeling velocity on a given ramp. This is the speed at which the robot will roll down the ramp in an unpowered state. At this speed, the surface drag and internal drag of the servo are equal to the gravitational force multiplied by the sine of the slope. The freewheeling speed is thus load dependent.

The ARM Cortex™-M4 processor is the latest embedded processor by ARM specifically developed to address digital signal control markets that demand an efficient, easy-to-use blend of control and signal processing capabilities. The combination of high-efficiency signal processing functionality with the low-power, low cost and ease-of-use benefits of the Cortex-M family of processors is designed to satisfy the emerging category of flexible solutions specifically targeting the motor control, automotive, power management, embedded audio and industrial automation markets. The Cortex-M4 processor features extended single-cycle multiply-accumulate (MAC) instructions, optimized SIMD arithmetic, saturating arithmetic instructions and an optional single precision Floating Point Unit (FPU). These features build upon the innovative technology that characterizes the ARM Cortex-M series processors…

It seems robots are getting into acting more and more these days, which makes sense given acting is nothing more than a simulation of real feelings and situations.  Last year we took a look at a few examples, but a UK-based company has been at it since 2005; their latest being the RoboThespian RT3.  Developed by Engineered Arts Ltd, the robot is actuated primarily by Festo air muscles and dc servo motors.  You can see him in person at Pittsburgh’s Carnegie Science Center, where he was nicknamed Andy (short for android) as part of their permanent roboworld exhibit.

Dennis Hong, a professor of mechanical engineering and director of Virginia Tech's Robotics & Mechanisms Laboratory, or RoMeLa, has created robots with the most unusual shapes and sizes -- from strange multi-legged robots to amoeba-like robots with no legs at all. Now he's unveiling a new robot with a more conventional shape: a full-sized humanoid robot called CHARLI, or Cognitive Humanoid Autonomous Robot with Learning Intelligence. The robot is 5-foot tall (1.52 meter), untethered and autonomous, capable of walking and gesturing. But its biggest innovation is that it does not use rotational joints. Most humanoid robots -- Asimo, Hubo, Mahru -- use DC motors to rotate various joints (typically at the waist, hips, knees, and ankles). The approach makes sense and, in fact, today's humanoids can walk, run, and climb stairs. However, this approach doesn't correspond to how our own bodies work, with our muscles contracting and relaxing to rotate our various joints.

German researchers have built an anthropomorphic robot hand that can endure collisions with hard objects and even strikes from a hammer without breaking into pieces. In designing the new hand system, researchers at the Institute of Robotics and Mechatronics, part of the German Aerospace Center (DLR), focused on robustness. They may have just built the toughest robot hand yet. The DLR hand has the shape and size of a human hand, with five articulated fingers powered by a web of 38 tendons, each connected to an individual motor on the forearm.