Information about the Human Dynamics and Controls Lab.


Person moving with ones and zeros within the outline of the bodyThe Human Dynamics and Controls Lab, or HDCL, focuses on investigating and improving movement control and function through two main areas: assistive device development and locomotion biomechanics.

The HDCL’s interest in assistive device development stems from a desire to improve function and the quality of life of persons with disability. To address these areas, we have been involved in the development of powered orthotic devices and multi-speed wheel systems for manual wheelchairs. Significant investments in research and funding have afforded amputees revolutionary breakthroughs in powered prosthetics. In contrast, advances in orthotics have generally been neglected and powered orthotic (exoskeleton) research is in its infancy – despite vastly more people disabled due to impaired limb function as a consequence of neuromuscular pathology or injury. Compared to powered prosthetic devices, which support actuation and power systems within the space of a missing limb, powered orthotics have a substantial challenge of supporting these systems on the outside of existing but weakened limb. Our group is interested in addressing issues of bulk, weight, control, and runtime, which are significant barriers to the development and use of portable powered orthotic devices. Funding as a testbed for the NSF Engineering Research Center for Compact and Efficient Fluid Power (CCEFP) has motivated us to develop powered orthoses to demonstrate barriers and opportunities in compact untethered fluid power orthotic devices.

In terms of locomotion biomechanics, the HDCL has been working on developing new measurement tools to better quantify movement patterns and utilizing these tools to understand movement biomechanics of clinical and workforce populations. Support from the NSF led to new techniques to quantify the complex spatiotemporal relationships observed during movement and locomotion. These techniques use data collected by motion capture technology to better quantify changes in movement symmetry, timing, complexity, variability, and coupling.

Our lab director is Elizabeth T. Hsiao-Wecksler.

Check out our website here, and click the tabs below to learn about our current projects.

Pneumatic Sleeve Orthosis for Loftstrand Crutches: Application of Soft Pneumatic FREE Actuator

While walking with crutches, peak loads observed in the wrist and palm can approach 50% of body weight and the wrist can experience extreme hyperextension. The repetitive, high loads and poor wrist postures associated with crutch use have been shown to lead to joint pain and injury, carpal tunnel syndrome, arthritis, or joint deformity. To address these issues, we are developing a lightweight, pneumatically-powered forearm orthosis to improve wrist posture and reduce loads in the wrist and palm while using Lofstrand, or forearm, crutches. Lofstrand crutches tend to be used by people that need long-term gait assistance. We designed a pneumatic sleeve that is attached to the forearm cuff of the crutch. The user inserts the forearm into the sleeve, which can be actuated to constrict about the forearm. Thus, some of the bodyweight load would be redirected to the cuff of the crutch via the sleeve, instead of the entire load going into the crutch handle via the wrist and palm. The constriction force is created by pressurizing a custom-fabricated McKibben pneumatic muscle actuator that was wrapped around rigid splints attached to the crutch cuff. This custom McKibben muscle is one embodiment of a Fiber-Reinforced Elastomeric Enclosure (FREE) actuator. FREE actuators can be constructed to produce a variety of motion patterns (constriction, expansion, rotation, and coiling). To produce a self-contained system to pressurize the sleeve, we are developing a method to harvest pneumatic energy from the crutch during walking.

The goal is to use a custom piston pump in the crutch tip and store pressurized air into an elastomeric accumulator housed in the crutch shaft. The pump is also expected to operate as a shock absorber to mitigate impulse loading on the body.

Design Of A Passive Hydraulic Simulator For Biceps Spasticity Replication

Spasticity is an abnormal muscle hypertonia behavior, affecting more than 12 million people respectively worldwide and usually associated with the brain lesion caused by spinal cord injuries, strokes, cerebral palsy, etc. The presence of these abnormal muscle behaviors will cause involuntary movements that hinder daily activities and affect the quality of life. The current assessment method for spasticity that relies on qualitative scales, such as the Modified Ashworth Scale (MAS), generally has poor inter-rater reliability rising from its subjective nature. It is crucial for students training for healthcare professions that evaluate patients with spasticity to have a clear understanding of different levels of spasticity and to gain sufficient hands-on assessment experiences. Current methods are inconsistent due to variability in training and limited availability of practice patients. Therefore, there is a clear need to develop a spasticity training simulator that can provide realistic and consistent replication of spasticity at different levels to minimize the need for practice patients.

The goal of this study was to develop a passive upper extremity simulator that can consistently replicate biceps spasticity in the elbow at different levels and be used to train future clinicians. Two generations of the simulator prototype have been developed. The first-generation prototype was capable of replicating most aspects of spasticity at MAS levels 0-4 and the second-generation added more design features to replicate subtle clinical signs of spasticity, such as variable catch angle, reduction in ROM, etc. A clinical evaluation study with a group of experienced clinicians will be conducted to validate the performance/realism of the second-generation training simulator.

Design, Validation, and Testing of a Wearable Device: Position, Velocity, Resistance Meter (PVRM)

We are developing a wearable and ergonomic device which we are calling a Position, Velocity, Resistance Meter (PVRM) to quantify passive arm movement of people with abnormal muscle behavior. A clinician would attach the PVRM on the patient’s arm and perform a manually move the patient’s arm while recording the arm movement data. This project involves a diverse interdisciplinary team of engineers from us, industrial designers from the art and design department, physical therapy students/faculty from Bradley University, and clinicians from Illinois Neurological Institute.

Design of a Soft Robotic Upper-Body Exoskeleton using FREE Actuators

The term “soft robotic” refers to a powered device that uses compliant materials for actuation. Powered exoskeletons developed for the upper extremities are primarily large, heavy, and rigid. There has been limited research into the development of truly lightweight and compliant exoskeletons which are not dominated by a rigid frame. Prof. Girish Krishnan, of the Monolithic Systems Lab, has developed a new class of soft pneumatic actuators called fiber-reinforced elastomeric enclosures (FREEs). FREEs can extend, contract, twist, stiffen, or bend when pressurized, depending on their specific fiber orientation. Their ability to create complex motion and on-demand rigidity makes them ideal components for use in a soft robotic orthosis.

The goal of this project is to take advantage of the unique mechanical behavior of FREEs, as well as the compliance which is the defining characteristic of soft pneumatic actuators, to create an assistive exoskeleton for the upper extremities. Our primary focus will be the design of a hardware test platform using novel architectures of FREE actuators, with consideration given to control schematics following hardware validation. This platform will provide a basis for upper extremity actuation using FREEs.

The project will include three phases:

  1. Biomechanical assessment of the upper extremities to establish design requirements for the exoskeleton
  2. Assessment of FREE hardware and development of novel FREE architectures to establish performance capabilities of the FREE actuators
  3. Development of the exoskeleton using the design requirements and performance capabilities established in Phases 1 and 2, along with preliminary testing of the device.

The Biomechanical Consequences of Body Size Differences in Humans

A Screenshot of our research of locomotor performance and activity distrabutionModern humans display a wide range of variation in body size and shape. While all humans practice bipedalism in essentially the same way, it is unclear how these vast differences in body size affect locomotor performance and activity. This project will evaluate the functional consequences of body size in humans through a lab-based biomechanics study of 80 short and tall male and female subjects and a bone microstructure analysis of 30 femora and tali. Previous studies of scaling patterns in mammals suggest that size-related differences will be present in three major areas:

  1. The specific locomotor events during walking and running gait.
  2. The general changes throughout the gait cycle or activity.
  3. Trabecular and subchondral bone properties.

Data from standing, walking, and running trials will be collected from a 6-camera Qualisys 3D motion capture system and force plates (AMTI, Bertec instrumented treadmill). These kinematic and kinetic data are used to evaluate posture and limb flexion, relative force production, and leg spring stiffness at specific points during gait. They may also be used to assess stride length and frequency, angular excursion, and balance throughout walking/running and standing trials. Analyses of bone microstructure will reveal patterns of habitual loading and posture. These data indicate whether small and large individuals employ different mechanisms to remain upright and locomote bipedally through the world, as well as whether they have implications for the activity and behavior practiced by our hominin ancestors.