Lecture 7 - Robot-Aided Gait Therapy Flashcards
Why is physical therapy necessary?
To learn (or re-learn) a movement, you need to practice the movement. Activity-dependent neuroplasticity persists even after injury and in aging.
Give the 4 main components of good physical therapy.
- Dose
- high # of reps
- high intensity - Task-specific
- train complex and task-specific motions - Effort
- high physical effort
- high cognitive effort - Motivation
- high motivation desired
- with minimum stress
List possible secondary complications of a stroke.
- muscle atrophy
- cardiopulmonary problems
- pressure sores (decubitus)
- osteoporosis
- incontinence
- mortality
What are Central Pattern Generators (CPG)?
- neuronal circuits that when activated can produce rhythmic motor patterns such as walking and breathing in the absence of descending inputs
- the CPG in the spine makes a significant contribution to the control of gait
What are some disadvantages of manual training for therapists?
- physically exhausting
- ergonomically inconvenient
What are some disadvantages of manual training for patients?
- limited in time
- gait pattern not optimal
What are some disadvantages of manual training for the healthcare system?
- needs personnel and time
- cost intensive
What are the advantages of robotic training?
- assistance for therapists
- longer training durations for patients
- new motions and new force support
- highly repetitive and comparable
- measurable, quantitative assessment
- increase motivation with games
- provides a safe environment
List the main characteristics of the general design of the Lokomat.
- adjustable to size
- passive parallelogram mechanism for vertical movements of the hip
- weight compensation spring
- speed up to 3km/h
- long training sessions possible
- rather physiological gait pattern
What drives the lokomat?
- DC motors
- linear spindles drives
- redundant joint angle recordings
- integrated force sensors
What is the difference between open- and closed-loop control?
The key difference is feedback. An open-loop control system acts completely on the basis of input; the output has no effect on the control action. A closed-loop control system looks at the current output and alters it to the desired condition; also known as a feedback system, the control action in these systems is based on the output.
Explain position control.
Pure position control works like this:
- You command the robot’s joint and thus arm to a particular position.
- The robot tries to reach that position, no matter what forces are applied against it within its environment.
Explain force control.
Pure force control uses a similar principle to the pure position control described above. The only difference is that you command the robot with a force instead of a position. Thus the robot will try to maintain the force which has been designated on the environment.
Explain indirect force control.
These methods are primarily motion controllers, which only apply a force constraint when the position of the robot deviates from the target position. These controllers do not explicitly “close the force feedback loop.” This means that, technically, they don’t need force torque sensors to be implemented. However, often it is a good idea to use force torque sensor data to improve the controller.
Explain impedance control.
(Type of indirect force control).
This applies a mass-spring-damper between the target position and the actual position of the robot. Imagine that you attach a spring between your finger and some target position in the air. The further you move your finger away from that point, the more force the spring applies to pull you back to that point.
