Page 58 - Mechatronics with Experiments

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5. The ASIMO humanoid robot, developed by Honda Motor Co., is capable of autonomous walking,
navigation, and performing various service tasks such as carrying a tray of objects (Google.com,
Asimo Images). It can run at 6 km/hr speed. ASIMO’s weight is about 54 kg and its height is 130 cm.
The robot is equipped with digital vision cameras, voice recognition sensors, ultra sonic range finding
sensors, as well as joint sensors at its legs and arms which are colocated with the motion actuators.
Assume that each leg has four motorized joints (2 × 4 = 8 degrees of freedom (DOF) for two legs),
each arm has four motorized joints (2 × 4 = 8 DOF for arms), and each finger has three motorized
joints (3x10 = 30 DOF for fingers). In addition, the robot has three rotational degrees of freedom at the
waist (3 DOF) as well as at its head (3 DOF). This results in a total of 8 + 8 + 30 + 3 + 3 = 52 DOF
motion. Design a block diagram representation of a conceptual control system for this robot. The
control system should include a block for actuators (motors), sensors, microcontrollers, and power
sources for the robot motion. Dedicate a separate microcontroller for the vision system, for the voice
recognition system, and the individual closed loop motion control of each leg and arm. Note that the
problem has many possible solutions. It is intended to give the student an idea about the number of
I/O and distributed embedded controllers involved in such a robotic device.
6. Typical high rise buildings have in the range of 60 to 80 floors. Moving people and loads in
high rise buildings safely and efficiently is increasingly important. Since the elevators are used by
general public, safety is very important. In addition, for efficient operation of society, the operation
must be as fast as possible (i.e., 30 km/h) while maintaining the comfort of the passengers. Electric
motor driven elevators are the norm in the modern high rise buildings. Figure 1.33 shows the basic
configuration of an electric motor driven elevator.
Here, we ask the student to do a little research to determine the following aspects of the modern
elevator control systems,
1. The mechanism or the basic mechanical or electromechanical system, analogous to skeleton
of human body.
2. The actuators (similar to muscles in human body analogy), including its power supply and
amplification component which is used to control how much power is allowed to flow into the
actuator from the power supply.
3. The sensors (similar to eyes in human body analogy) used to measure various variables such
as position, velocity, weight, and so on.
4. The controller (similar to the brain in the human body) used to make control decisions.
5. The control logic and simulation: closed loop control model and simulation: model the
dynamics of the elevator, and a PID position loop controller. Simulate a motion from one level
to another under a gravity load disturbance, focusing on the effect of “I” (integral) action of
the PID controller to eliminate the positioning error.