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Electric drive and control of three-wheel bicycle without mechanical gear
Abstract
In this paper the idea of an electrically aided pedal-driven vehicle (bicycle) is described. Each of three wheels of the vehicle is driven by electric motor (BLDC) controlled by the central system of power distribution. Velocity of the vehicle and motors power are proportional (with adjustable ratio) to pedaling speed and power respectively. The battery pack is charged by the pedal-driven generator. Description and analysis of the vehicle subsystems are documented with the prototype research results.
The wheelchair is a basic device that provides mobility to disabled people.
As indicated in "The Polish Population’s Health Status" survey by the Central
Statistical Office, 16% of the population is affected by some form of disability
of which 46% are people who suffer from motor disabilities (according to the
National Census of 2002). The data only concerns the Republic of Poland. However,
the number of people with motor disabilities is much higher and, as
evidenced by the WHO reports, it continues to rise globally. Therefore, it should
be acknowledged that the issue of the development of rehabilitation devices and
those that support the functioning of disabled people in society is still relevant
and requires increased efforts aimed at improving the quality of life for many
members of our society.
In the case of motor system disorders, the most common technical solution
which compensates for disability is the wheelchair. The first designs of devices
that meet the functional requirements of a wheelchair can be traced back to 500
BC. They evolved with time taking on various shapes until the one we know
today. The year 1885 can be regarded as significant, as that is when the construction
of a manual wheelchair equipped with rims attached to drive the wheels,
which is still in use today, was presented. The rims were used to propel the
wheelchair using upper limb muscles strength. The first design of an electric
wheelchair was presented as early as 1984. In the case of the former, the only
things that changed over the years were the materials used for construction and
some geometrical features of the structure, while electric wheelchairs, along with
the development of technology, were being equipped with new functions, including
verticalization, seat lifting, functions for overcoming stairs and architectural
obstacles. Despite the broad range of electric wheelchair functions, it has a significant
disadvantage. The person using the electric drive is not physically active,
being only a passive element of the human-wheelchair anthropotechnical system
that does not take an active part in carrying out motor functions, and whose role
is limited only to deciding on the direction and speed of movement. Choosing
this type of wheelchair results in significant impairment of the rehabilitation process,
which is meant to stimulate physical activity.
The choice of a wheelchair type for a disabled person must, first of all, be
based on the degree of physical disability. The manual wheelchair requires its
operator to have upper limb mobility that allows its unrestrained and independent
use. It has to be pointed out that a relatively high fitness level of the upper body
is required to propel this type of wheelchair, and therefore it is basically designed
for paraplegics.
The physical fitness of the manual wheelchair operator affects the distance
and the type of terrain architectural obstacles that it can overcome. In the case of
an electric wheelchair, the electric drive replaces entirely the muscular system of
the operator for propulsion, so that the range of the wheelchair and its ability to
overcome obstacles depends only on its design and the technical solutions
adopted. Electric wheelchairs are designed for all types of disabilities, both for
paraplegics and tetraplegics. In many cases, the operator is unable to use the
manual wheelchair in a satisfactory and effective manner, so he chooses a wheelchair
with an electric drive. As a result, this reduces his physical activity which
is vital since physical activity has a positive effect on maintaining the proper
functioning of the body.
Dilemmas associated with choosing the type of wheelchair resulting from the
degree of physical disability point to the fact that there is a need for new innovative
designs of wheelchair drives. Innovation should result from functional
development or from combining two types of devices, for example, manual and
electrical ones. "Research on the development of wheelchair motor functions"
("Studia nad rozwojem funkcji lokomocji wózków inwalidzkich") presents an
outline of works implemented as part of the Leader VII project: "Research on
the biomechanics of manual wheelchair drive for innovative manual and hybrid
drives" ("Badania biomechaniki napędzania ręcznych wózków inwalidzkich dla
innowacyjnych napędów ręcznych i hybrydowych") (LIDER/7/0025/L-
7/15/2016), financed by the Polish National Center for Research and Development.
One of the objectives of the project was to develop an innovative prototype
of a manual hand rim propulsion and a prototype of a hybrid of manual and electric
wheelchair equipped with an adaptive control algorithm. The research
focused on the experiments on the biomechanics of the wheelchair propulsion
system in relation to the entire human-wheelchair anthropotechnical system. It
enabled to determine the correlation between given biomechanical, kinematic
and dynamic parameters of the entire system, which then allowed us to evaluate
the influence of operating conditions on the functionality of the applied structural
solutions in relation to the propulsion system. Creating measurement and data
processing methods obtained in bench tests was also crucial. As part of the project,
methods were developed to illustrate parameters such as: muscular effort,
speed, acceleration, wheelchair trajectory, phase duration and the position of the
center of gravity of the human body for the tested structures. This lays a foundation
for building and analyzing propulsion systems of conventional wheelchairs,
but also those with an innovative design.
Energy and environmental considerations, new paradigms for urban mobility and transportation increased in the past few years the interest on Light Electric Vehicle (LEV). In that context, Electrically Power Assisted Cycles (EPACs) received a great attention: several efforts have been made in order to improve their performance in terms of autonomy, weight, esthetic and feeling with the driver. In this work, project and realization of a full hybrid electric bike (HEB) are presented. The main idea, borrowed from the more explored 4-wheel world, is to use the possible energy fluxes between cyclist and motor in order to improve the efficiency of the primary engine (the human body) being completely self-sustaining and grid-independent (differently to all the other EPACs). Collected biometric data that lead to the algorithm design are presented in detail focusing particularly on human metabolic efficiency measurement. Finally, an experiment performed in cycling track compares the mechanical and metabolic results between traditional and hybrid electric bike.
This paper describes a study and experimental verification of sensorless control of Permanent Magnet Synchronous Motor. There are proposed novel estimation strategy based on the Unscented Kalman Filter, using only the measurement of the motor current for on-line estimation of speed, rotor position and load torque reconstruction. The Kalman filter is an optimal state estimator and is usually applied to a dynamic system that involves a random noise environment. Control structure such as Kalman filtering, in real time requires a very fast signal processor in special way, adapted to perform complex mathematical calculations. During verification, it is concerned on behaviour of control system in result of desired speed changing. Experimental results confirm the validity of the novel proposed estimation technique. Presented results show good properties of proposed observer.
This paper investigates the issues of torque control strategies for light electric bike systems with human power assistance. The feature of this electric bike equipped with both usual electrical machine power and personal-dependent human power makes its operation distinct from other types of vehicle. To facilitate a reliable and smooth torque control design, a speculation of the human torque exerted during electrical bike's motion is proposed as function of the desired velocity and actual vehicle velocity. Then, three torque control strategies are formulated, termed the manual control, proportional control, and assistant control, respectively. The assistant control approach is proposed in this work as a control signal to compensate the disturbance torque, which comprises the human torque and the resistance torque from various sources, including the wind, the tire, and the gradient angle. Also, three control laws based on these three control strategies are presented, and the evaluation of these control laws is conducted via time response simulation.