Abstract
Discussed in this paper is the tip-over stability analysis of a pelvic support walking robot. To improve the activities of daily living (ADL) in hemiplegic patients, a pelvic support walking robot is proposed to help patients facilitating their rehabilitation. During the gait training with the robot, the abnormal man-machine interaction forces may lead to the tip-over of the robot, which is not beneficial to the rehabilitation process. A new method is proposed to predict the possibility of tipping over and evaluate the stability of the robot based on statics model, dynamics model, and zero-moment point (ZMP) theory. Through the interaction forces and moments analysis with static case, the safe point (ZMP) is studied, and the influence factors of force/moment are analyzed by dynamics case. An optimization algorithm based on the genetic algorithm (GA) is proposed to reduce the risk of tipping over. The simulation results show that the optimization algorithm can keep the robot from tipping over when the interaction forces exceed the safety threshold.
Highlights
As a result of the acceleration of population aging, the World Health Organization reported over 17 million confirmed cases of stroke in 2016 [1]
Many universities, research institutes, and hospitals have developed mechanical equipment that can help the patients with the gait training. e Lokomat [2] is a highly automated suspension lower-limb rehabilitation robot that connects the lower-extremity exoskeleton system to the suspension weight reduction device through a four-bar mechanism. e robot is stationary and has little possibility of tipping over. e
The man-machine interaction forces may exceed the normal values. ere is a risk that the robot will tip over because the forces acting on the robot are beyond the safety threshold, causing potential harm to the patients
Summary
As a result of the acceleration of population aging, the World Health Organization reported over 17 million confirmed cases of stroke in 2016 [1]. E. Andago [3] assisted rehabilitation robot developed by HOCOMA in Switzerland reduces the load on the lower limbs during the gait training by suspending weight loss on the pelvis. E KineAssist [4] robot uses a pelvic support device with a moving platform to realize the movement of the patient, but the rotation center of the chassis is not on the same vertical line with the rotation center of the human body, directly affecting the patient’s steering comfort. Carleton University developed a mobile limb training robot called GaitEnable [5]. Is robot is smaller and lighter than KineAssist It is a combination of a mobile lower-limb training robot and a walking robot. GaitEnable step trainer is omnidirectional. e device controls the support polygon of the robot, the position of the pelvis, and the posture of the robot. e GaitEnable and KineAssist are equipped with universal wheels to maintain stability via the change of the center of mass
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