Motor Control Week 1

Question 1

Why is movement easy to us

Answer 1

Just because we can do it doesn’t mean it is easy. Complicated high level control strategies are used by our brain, even when we are thought Lesley doing simple motor tasks

Question 2

What is fitts law?

Answer 2

The law predicts the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target.

Question 3

What problems to engineers face when trying to grab and Apple

Answer 3

Need to
- localisation and planning to reach the apple
- execution and control
- adaptation.
-

Question 4

What is space?

Answer 4

Set (of points) with some added structures

Question 5

What two repensentatives spaces are used in robotics?

Answer 5

Internal and external
- external ( end effector space, task space, operational space)
-internal ( configuration space, joint angle space, body space)

Question 6

What are coordinate systems

Answer 6

Set of numbers that uniquely determine a point in space.
A single space can have multiple coordinates
Also called coordinate frame/reference frame

Question 7

What are the three types of coordinate systems

Answer 7

1) Cartesian coordinates system ( x, y,z)
2) cylindrical coordinate system ( angle, distance, height)
3) spherical coordinate system (two different angles and heights)

Question 8

What are the two types of origins of coordinate systems?

Answer 8

1) egocentric (coordinates systems attached to our body
2) allocentric ( coordinates systems attached to external world or object)

Question 9

What are coordinate transformations?

Answer 9

the transformation between different coordinate systems

Question 10

What is forward and inverse kinematics (coordinate transformations)

Answer 10

inverse kinematics (from furthest point to myself) - configuration space - forward kinematics (myself to furthest point) - end effector space

Question 11

adding forces and torques to kinematics

Answer 11

linear vs angular kinematics (distance vs angle)
linear vs angular kinetics (forces vs torques

Question 12

dynamics : forwards and inverse dynamics

Answer 12

inverse dynamics - kinetics - forward dynamics - kinematics

Question 13

newtons second law

Answer 13

newtons second law defines the relationship between kinematics and dynamics.
F=Ma
f=force
M=Inertia
a= accerleration

Question 14

What is control

Answer 14

manipulating something to do something

Question 15

what are the two types of control strategies?

Answer 15

1) plan in advance
2) policies (case by case action)

Question 16

what are the pros and cons of planning?

Answer 16

pros
- very clear about what to do , so you don’t waste time checking and asking around.

cons
- if you make any mistake the consequences of your mistake is unrecoverable
- if there is any unexpected event
- if you want to for from different stations you need a brand-new plan

Question 17

What are the pros and cons of policies?

Answer 17

pros
- flexible
-robust
-general

cons
- you have to ask every time to fo your action
- people give you random answers can you really trust the,
- slow at giving answers

Question 18

Which control is feedforward and feedback

Answer 18

feedforward (open loop)= plan
feedback (closed loop) = policies

Question 19

feedforward controller pros and cons

Answer 19

pros
- movement can be controlled without external info
-fast

cons
- error made
-no flexibility
-high cost in planning

Question 20

policies pros and cons

Answer 20

pros
- flexible
-robust
-general

cons
- time consuming
-unstable
- unstable when feedbacks are delayed

Question 21

what is variability

Answer 21

even when the same movement is repeated, controller behaviors under uncertainties result in movement patterns

Question 22

What is sensory information needed for?

Answer 22

localisation and planning

intrinsic - in your body, muscle spindles, mechanoreceptors
extrinsic - outside your body, vascular info and auditory info

Question 23

what are spinal reflexes used for

Answer 23

spinal reflexes are mostly involuntary : sensory inputs cause motor outputs directly without intervention of higher brain centers
however voluntary movements require higherlevels cortical control