KAMANBARÉ

A Tree-climbing Biomimetic Robotic Platform for Environmental Research

Reinaldo de Bernardi

Genius Institute of Technology, São Paulo, Brazil

Department of Telecommunications and Control, São Pau

lo University, São Paulo, Brazil

José Jaime da Cruz

Department of Telecommunications and Control, São Paulo University, São Paulo, Brazil

Keywords: Climbing robots, legged robots, environmental research.

Abstract: Environmental research is an area where robotics platforms can be applied as solutions for different

problem

s to help or automate certain tasks, with the purpose of being more efficient or also safer for the

researchers involved. This paper presents the Kamanbaré platform. Kamanbaré is a bioinspired robotic

platform, whose main goal is to climb trees for environmental research applications, applied in tasks such as

gathering botanical specimen, insects, climatic and arboreal fauna studies, among others. Kamanbaré is a

platform that provides flexibility both in hardware and software, so that new applications may be developed

and integrated without the need of extensive knowledge in robotics.

1 INTRODUCTION

Robotic platforms can be used in countless

applications and in the most varied branches of

activities. Such results, presented over the last two

decades, can be verified in (Armada et al., 2003) and

(Virk, 2005).

It deals specifically with robots provided with

leg

s and with the capability, or ability, to climb

vertical surfaces, while many other

applications/solutions can be found. As an example,

one can mention: robots to climb lower parts of

bridges (Abderrahim et al., 1999), to crawl inside

pipes for inspection purposes (Galvez, Santos,

Pfeiffer, 2001), implemented to perform solder

inspection works in nuclear plants (White et al.,

1998), to climb metallic structures for inspection

purposes (Armada et al., 1990). More examples can

be found in marine industry applications, such as

walking robots to check internal parts solders in ship

hulls, climbing robots for parts solders (Santos,

Armada, Jiménez, 2000) and (Armada et al., 2005),

climbing robots for paint cleaning, underwater

robots for ballast tank inspection, and underwater

robots for hull cleaning (Santos, Armada, Jiménez,

1997a, 1997b).

Robots were demonstrated to be the ideal option

for m

any such applications due to the fact that the

working environment is difficult to access or even

hazardous or risky for human beings, such as

exposure to hazardous substances or environments

and risk conditions. Productivity increase and

quality issues are also extremely relevant and are

considered.

However, besides the varied applications and

areas m

entioned above, there still remains a little

explored area: environmental research. As in any

other area, different applications or problems can be

addressed or solved with the help of a robotics

platform. As an example, one can mention the

activities:

Gathering of Botanical Specimens: g

athering

flower and plant specimen is fundamental for

biodiversity studies. Several host species are found

in high trees, and their collection is actually risky.

Thus, this is an application where a robotics

platform with tree climbing capability can be used to

minimize risks for the researchers involved in this

type of activity.

Kamanbaré means chameleon, on the language of the Brazilian Tupi

indians.

478

de Bernardi R. and Jaime da Cruz J. (2007).

KAMANBARÉ - A Tree-climbing Biomimetic Robotic Platform for Environmental Research.

In Proceedings of the Fourth International Conference on Informatics in Control, Automation and Robotics, pages 478-484

DOI: 10.5220/0001650304780484

 SciTePress

Gathering of vegetable material: collection of

vegetable material is a fundamental activity for

phytochemistry. Every pharmaceutical preparation

that uses as raw material plant parts such as leaves,

stems, roots, flowers, and seeds, with known

pharmacological effect is considered phytotherapic

(extracts, dyes, ointments and capsules). Thus, just

as in botanical collection, this is an activity that can

be accomplished by a robot operating in large-sized

trees, therefore minimizing risk for the humans

involved in the collection.

Gathering of Insect Specimens: usually, for

collecting insects in higher levels, nets spread

around the tree and a source of smoke below it are

used. The great discussion about this technique is

that one not only captures the desired insects, but

one ends up killing most of the insects that inhabit

that tree as well. Thus, one proposes to use a trap,

positioned in the robot, containing a pheromone or

equivalent substance as bait, specific for the insect

species one wants to capture. One can even adapt

cameras and sensors in the trap to gather images of

the moment of capture. With a trap thus

implemented, one reduces the negative

environmental impact of the capture. Another

relevant issue would be the possibility that the robot

moves along the day to capture varied insect

specimens at different heights in different hours, to

check for variations in insect populations according

to the height, and the hour of the day.

Climatic studies: climatic or microclimatic studies

refer to works on microenvironments in native

vegetation and/or reforested areas. It is important to

study the different energy flows:

horizontal and

vertical. The vertical directly reflects the results of

solar radiation, which decisively influences the

horizontal energy flows: air masses, hot and cold

fronts, action centers. Solar radiation determines the

whole system, and may be analized according to its

elements: temperature, pressure, and humidity,

greatly influencing biogeographic characteristics,

geomorphologic and hydrologic phenomena etc.

Thus, the robot can be equipped with sensors for

such measures, to collect data on the desired

elements.

Studies on biosphere/atmosphere interaction:

biosphere environments are the group of biotic or

abiotic factors that interfere in the life conditions on

a certain region of the biosphere. In the case of

forests the aerial environment is studied, and the

most important elements to consider are: light,

oxygen, ice formation, winds, humidity and carbon

gas. In order to register all this information, the

robot can be endowed with specific sensors for each

kind of required measure, to collect data regarding

the elements at hand, and to provide information on

them regarding both height and time variations.

Studies on arboreal fauna: fauna studies are

hampered by the existence of many leaves, or very

dense treetops, as the lack of existing natural light

hinders the observation of the species. Other usually

relevant points are the difficulty to obtain a proper

angle due to the great heights involved, and the very

presence of human beings in that specific

environment, easily detected by their movements,

noise and odors. For this type of task, the robot can

be fitted with cameras to capture both static and

dynamic images. These can then be stored locally in

some type of memory card, or transmitted via

communication interface to a base station.

Sensors Network: robots carrying a group of

sensors and fitted with a communication interface,

for instance Wi-fi or other similar technology can be

dispersed in the forest to capture data regarding the

ecological behavior in the area at hand.

Measurements such as the ones already mentioned in

climatic studies and biosphere/atmosphere

interaction can be shared among robots or even

retransmitted among robots to reach the base station,

without the need for the researcher to “pay visits” to

the reading points.

2 GOAL AND PURPOSE

Thus, considering this poorly explored area, one

proposes the Kamanbaré robotics platform.

Kamanbaré is a biomimetic robot, i.e., inspired in

nature, with the purpose of climbing trees for

environmental research applications. The proposed

work represents a progress in robot applications,

both for the fact of environmental research

applications, and for its tree-climbing ability, with

computer-controlled devices configured to be used

as paws.

The project’s main application is climbing trees

for non-invasive search purposes, reaching points (at

high altitudes) that may offer risk to humans.

The development was driven mainly to seek for

robot stability and efficiency regarding the paws.

The adopted line of research is an implementation

inspired in nature. One must stress here that the

system doesn't mimic nature, by copying an animal

or insect to accomplish the desired work, but rather,

a robot development project that combines the

climbers' best characteristics (insects and lizards)

considering the available technologies and the

associated cost/benefit ratio, in other words, some

parts were inspired in certain solutions found in

nature, while other parts were inspired in different

elements.

KAMANBARÉ - A Tree-climbing Biomimetic Robotic Platform for Environmental Research

479

Ensemble stability, contact stability (paws),

contact position, and contact force (pressure) were

defined and used to implement the strategies and

techniques for dynamic and static control of the

system.

3 BIOLOGICAL INSPIRATION:

THE CHAMELEON

Differently from any other reptile or lizard,

chameleons have paws that were created, or adapted,

to adequately clasp the different types of branches or

shrubs existing in its environment.

The chameleon paws evolved to provide them

with the best possible maneuvering and grip

capabilities on trees. The paws are actually forked,

with three fingers on one side and two on the other.

Frequently they also have powerful and sharp nails

(or claws) that can grip the surface which they hold

on to. This unique arrangement allows them to

position their paws completely around the branches

or shrubs on which they move around, giving them

an amazingly strong clasping capability.

Chameleon paws have five fingers each, divided

in two groups (internal and external), one side

composed of three fingers while the other side has

two, as seen in Figure 1. Front paws have two

fingers pointing to the external side, and three

towards the inner side, while rear paws are

configured in an opposite arrangement, i.e., two

inside fingers and three outside fingers. This

provides the chameleon with the same number of

fingers on each side of the branch, considering all

the paws, allowing a balanced and stable clasping.

Figure 1: Details of the chameleon paw, presenting the

bifurcation and configuration of the fingers.

4 GEOMETRY OF THE

MECHANICAL MODEL

The mechanical structure of the Kamanbaré platform

consists of a central rigid body with four legs,

identical and symmetrically distributed. Each leg

comprises three links connected by two rotating

joints, and is connected to the central body by a third

rotating joint, while each joint has 1 DOF (degrees

of freedom). Identical motor and reduction groups

make the rotary movements. Figure 2 shows the

kinematic configuration of a leg. Each leg also has a

paw, which is forked just as the chameleons,

however with only two fingers, one on each side, for

simplification purposes. The paw connects to the leg

by a rotating joint, and also has another motor and

reduction group that provides for its opening and

closing movements.

Potentiometers and microswitches were inserted

in the joints to supply the signal corresponding to the

opening and closing angle, or position, for the links.

In the paws, more precisely in their plant, a

microswitch was also added to supply the contact

signal with the surface of the object to be climbed

during the movements of the legs.

As each leg has four joints, this means 4 DOF.

Considering the four legs, the platform will have a

total of 16 DOF. Therefore, sixteen motor and

reduction groups were necessary to produce the

global movements.

The prototype of the Kamanbaré platform

presented in this work was developed considering

certain capabilities (abilities), such as: locomotion in

irregular environments (unpredictability of the

branch complexity that compose a tree),

surmounting obstacles (nodes and small twigs), tree

climbing and descent without risking stability, and

keeping low structural weight (mechanics +

electronics + batteries).

Platform development began by considering the

mechanical requirements (structures, materials,

implementation complexity, costs etc.) in parallel

with the electronic requirements (hardware and

software tools, development time, knowledge of the

tools, components availability, costs etc.).

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Figure 2: Kinematic configuration of a leg.

The main dimensions of the platform are: length

of 250 mm, and width varying between 260 and 740

mm, depending on the positioning of the legs. Its

height also depends on the posture and positioning

of the legs, and can vary between 190 and 310 mm.

This configuration, with all the parts

implemented in aluminum, comprises an

approximate total weight of 0.6 kg, not including the

batteries. The geometric model obtained can be seen

in Figure 3. This model was used to generate the

basic locomotion behavior.

Figure 3: Mechanical structure of the Kamanbaré

platform.

5 BASE STATION

ARCHITECTURE

The Base Station provides mission control functions,

sending and receiving data to/from the Kamanbaré

platform via a communication interface such as Wi-

fi.

The station also provides mission start and end

parameters, as well as commands for moving the

robot.

A graphic interface was implemented for a better

display of the data received from the platform,

including a window for image reception, when

appropriate.

Data and command inputs are enabled via

keyboard or, for the robot's control, through a

joystick.

The possibility of using speech recognition

commands was also considered. As the platform has

a motherboard with enough processing capacity and

a Linux operating system, a speech recognition

module can be integrated and commands sent

directly, without the Base Station, via microphone

with a Bluetooth-type serial interface.

6 KAMANBARÉ PLATFORM

ARCHITECTURE

An architecture was implemented for local control of

the Kamanbaré platform. This architecture

corresponds to the robot's functional organization.

Based on the hardware architecture to be

presented in the following section, the development

of the following systems was accomplished

according to Figure 4. This model is based on the

architecture implemented for the MARIUS robot

(PASCOAL et al., 1997).

Figure 4: Kamanbaré Architecture.

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481

Support system: this system controls energy

distribution to the platform’s electronic and

electromechanic hardware, and monitors energy

consumption as well. This system is also responsible

for the startup of other subsystems and, during

operation, for detecting hardware failures, and for

starting and controlling the emergency modes.

Actuators control system: this system is

responsible for controlling the motors, and also for

controlling the movements of the legs. Information

on legs positioning is received from the general

control system. Data regarding joint positions, as

well as the values of the electric currents involved,

are sent to the general control system.

General control system: this system receives

trajectory reference information from the mission

control system. It controls all the robot's movements,

sending the necessary commands to the actuators

control system. Problems occurring in the path, such

as obstacles and absence of support points for the

paws, are handled in this system.

Mission control system: this system is the main

module, the highest hierarchical level of the

platform. It is responsible for receiving commands

via the communications system, and for distributing

them to the systems involved. It also stores

information on the general status of the platform

(battery voltage, position of the legs, angles etc.)

keeping them available in case the Base Station

(described in the following topics) requests them.

This system gathers information from the

Environmental inspection system to be subsequently

forwarded to the Base Station.

Communication system: this system is the module

responsible for the communication interfaces

existing in the platform, managing communications

via Wi-fi and Bluetooth, and exchanging data with

the Mission control system.

Environmental inspection system: this system is

responsible for gathering data from the installed

sensors, and for controlling any additional hardware

necessary for that purpose as well. Every data

acquired are sent to the Mission control system.

7 ELECTRONIC

ARCHITECTURE

Considering the implementation of control

algorithms, processing information from sensors, the

necessary calculations for control and locomotion

strategies, interfacing and communication with the

base station, added to the need of real time control

with position and force feedback, the involvement of

high computing complexity was ascertained, thus

requiring a processor of advanced architecture.

Eventually, it was selected then a development

kit containing a processor based on the ARM9 core,

and the deployment of a Linux operating system.

Other motor control boards were also developed

using a Texas Instruments microcontroller of the

MSP430 family and specific integrated circuits to

implement the power actuation section, based on the

so-called H-bridge technique.

To implement the control systems for the

Kamanbaré platform, an electronic architecture was

defined. Initially considering only one joint, it can

be represented in Figure 5, where the main

components are seen: a DC motor, a potentiometer

and a microswitch.

Figure 5: Representation of a joint.

Thus, for control purposes, the need of a PWM

output (motor control), an analog input

(potentiometer reading, indicating the joint angle),

and a digital input (reading the end, or beginning, of

the joint course) was ascertained.

As already mentioned, the platform has 16 DOF,

corresponding to the need of sixteen copies of the

joint control system described above.

As the robot has four legs, one opted for

distributing the control individually to each one of

them. Thus, each leg control module needs four

groups as mentioned, namely, three for the joints,

and one for controlling the opening and closing of

the claw.

One then developed a motor control board for

this specific purpose, Figure 6, based on the

MSP430F149 Texas Instruments microcontroller,

and the L298 integrated circuit (H-bridge). The

board dimensions are: 60 x 50 mm.

Figure 6: Motor control board diagram.

Due to the control complexity existing in a

robotics platform, it was necessary to adopt a main

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board where the highest hierarchical level control

activities were executed.

As a solution for the main board, the model

selected was the TS-7250 by Technologic Systems.

It was selected because it’s compact, contains

different standard interfaces, and is based on the

EP9302 Cirrus Logic processor, with an ARM9

core, Figure 7. The EP9302 implements an advanced

processor core: 200 MHz ARM920T with support

for a memory management unit (MMU). This

ensemble allows the use of a high-level operating

system, in this case Linux. The ARM920T core has

a 32-bit architecture with a 5-stage pipeline, offering

high performance and low energy consumption

levels. With a 200 MHz clock, the TS-7250 module

offers a performance approximately twice as fast as

other boards based on 586-core processors.

Figure 7: Main board diagram.

Thus, the general electronic architecture for the

Kamanbaré platform was deployed according to the

diagram in Figure 8.

8 IMPLEMENTATION

The control structure described in the previous

section was implemented for the Kamanbaré

platform. The robot has contact and force sensors in

each joint (actually, in the case of the force sensor,

the electric current of the corresponding motor will

be used for this purpose), contact sensors in the

paws, tilt sensor, sensors to measure the distance or

proximity of the body from the surface, and possibly

an accelerometer, intended to measure the

displacement speed, and also to identify a potential

fall.

C language was used for the development of all

software, mainly for reasons of code execution

speed, and easiness of portability in case some other

control board is needed.

A concerning point is the contact detection via

force sensors in the joints. The issue here is that

these virtual sensors only present readings when the

motors are in motion. Thus, whenever a reading is

necessary, a movement must be initiated.

Regarding the movement generation module, it

was initially implemented only the simplest way,

i.e., the robot follows a straight path at the highest

Figure 8: Electronic architecture of the Kamanbaré platform.

KAMANBARÉ - A Tree-climbing Biomimetic Robotic Platform for Environmental Research

483

speed allowed by the surface (no waiting time will

be introduced, besides those produced by the legs

when searching for support points).

Steering and speed commands are provided via

base station and, in the future, via speech commands

over a microphone with Bluetooth technology.

9 CONCLUSION

This work presented the Kamanbaré robot, which is

a four-legged bionspired platform with the main

purpose of climbing trees, for environmental

research applications. The mechanical and

electronics structure, and the software architecture,

were presented.

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